MANUAL - Coatings

COATINGS MANUAL

CHEVRON RESEARCH AND TECHNOLOGY COMPANY RICHMOND, CA

December 1998

Manual sponsor:

For information or help regarding this manual, contact R.A. (Rich) Doyle, (510) 242-3247

Printing History Coatings Manual First Edition First Revision Second Revision Third Revision Fourth Revision Second Edition First Revision

October 1988 December 1990 February 1992 August 1992 January 1995 September 1996 December 1998

Restricted Material Technical Memorandum This material is transmitted subject to the Export Control Laws of the United States Department of Commerce for technical data. Furthermore, you hereby assure us that the material transmitted herewith shall not be exported or re-exported by you in violation of these export controls.

The information in this Manual has been jointly developed by Chevron Corporation and its Operating Companies. The Manual has been written to assist Chevron personnel in their work; as such, it may be interpreted and used as seen fit by operating management. Copyright  1988, 1990, 1992, 1995, 1996, 1998 CHEVRON CORPORATION. All rights reserved. This document contains proprietary information for use by Chevron Corporation, its subsidiaries, and affiliates. All other uses require written permission.

December 1998

Chevron Corporation

List of Current Pages Coatings Manual The following list shows publication or revision dates for the contents of this manual. To verify that your manual contains current material, check the sections in question with the list below. If your copy is not current, contact the Technical Standards Team, Chevron Research and Technology Company, Richmond, CA (510) 242-7241.

Section 50 100 200 300 400 500 600 700 800 900 Quick Reference Appendix A Appendix B Index 2000 COM-MS-4042 COM-MS-4732 COM-MS-4738 COM-MS-4739 COM-MS-4743 COM-MS-4771 COM-MS-5005 COM-MS-5006 List of Drawings

Chevron Corporation

Date September 1996 November 1998 September 1996 September 1996 September 1996 September 1996 September 1996 September 1996 September 1996 September 1996 November 1998 None Given January 1995 September 1996 September 1996 January 1996 January 1996 January 1996 January 1996 January 1996 January 1996 January 1996 January 1996 See the list in the Standard Drawings and Forms section of this manual. Current revision dates are shown for Forms. Current revision numbers are shown for Standard Drawings.

December 1998

(This page reserved for future use.)

December 1998

Chevron Corporation

Maintaining This Manual Coatings Manual If you have moved or you want to change the distribution of this manual, use the form below. Once you have completed the information, fold, staple, and send by company mail. You can also FAX your change to (510) 242-2157. ❑ Change addressee as shown below. ❑ Replace manual owner with name below. ❑ Remove the name shown below. Previous Owner:

Title: Last

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M.I.

Current Owner:

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Requesting Signature

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Send this completed form to: Document Control, Room 50-4328 Chevron Research and Technology Company 100 Chevron Way (P.O. Box 1627) Richmond, CA 94802

CRTC Consultants Card The Chevron Research and Technology Company (CRTC) is a full-service, in-house engineering organization. CRTC periodically publishes a Consultants Card listing primary contacts in the CRTC specialty divisions. To order a Consultants Card, contact Ken Wasilchin of the CRTC Technical Standards Team at (510) 242-7241, or email him at “KWAS.”

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December 1998


December 1998

Chevron Corporation

Reader Response Form Coatings Manual We are very interested in comments and suggestions for improving this manual and keeping it up to date. Please use this form to suggest changes; notify us of errors or inaccuracies; provide information that reflects changing technology; or submit material (drawings, specifications, procedures, etc.) that should be considered for inclusion. Feel free to include photocopies of page(s) you have comments about. All suggestions will be reviewed as part of the update cycle for the next revision of this manual. Send your comments to:

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December 1998


December 1998

Chevron Corporation

Coatings Manual Sponsor: R.A. (Rich) Doyle / Phone: (510) 242-3247 / E-mail: [email protected] This document contains extensive hyperlinks to figures and cross-referenced sections. The pointer will change to a pointing finger when positioned over text which contains a link.

List of Current Pages 50

Using this Manual

50-1

100

General Information

100-1

200

Environment, Health & Safety

200-1

300

Coatings Selection

300-1

400

Surface Preparation

400-1

500

Application

500-1

600

Coating Concrete

600-1

700

Downhole Tubular Coatings & Linings

700-1

800

Offshore Coatings

800-1

900

Pipeline Coatings

900-1

Quick Reference Guide Appendices Appendix A Appendix B

Chevron Corporation

QR-1

Conversion Charts Color Chips

December 1998

50

Using this Manual Abstract In this manual, you will find procedures for coating steel and other metal substrates. Additionally, there are individual sections for those surfaces and logistics requiring special consideration: concrete, downhole tubulars, offshore, and pipeline coatings. This section offers broad, general information: the reasons for coatings, the components of a coating and coatings systems, a successful coatings program, and the structure of this manual. Contents

Chevron Corporation

Page

51

Scope and Application

52

Organization

60

Reasons for Coating

61

External Coatings

62

Under Thermal Insulation and Fireproofing

63

Internal Coatings

70

Components of Coatings and Coating Systems

71

Components of Coatings

72

Coating Systems

80

The Successful Coating Program

50-7

90

References

50-7

50-3

50-1

50-5

September 1996

50 Using this Manual

51

Coatings Manual

Scope and Application The Coatings Manual is intended: •

For Company personnel who are responsible for selecting, applying, or inspecting coatings

•

For both entry-level personnel and non-specialists regardless of experience

•

As a source of practical, useful information based on the Company's experiences

Your input and experience are important for improving subsequent revisions and keeping this manual up-to-date; therefore, we have included a form in the front of the manual to facilitate your suggesting changes. Note

52

Do not use this manual as a substitute for sound engineering judgment.

Organization The colored tabs in the manual will help you find information quickly. In summary: White tabs are for table of contents, introduction, appendices, index, and general purpose topics. Blue tabs denote Engineering Guidelines. Gray tabs are used for Specifications and related forms. Red tab marks a place for you to keep coatings documents that are developed at your facility.

Engineering Guidelines The Engineering Guidelines cover: •

An overview of coatings

•

General information about selecting coatings; preparing surfaces; and applying, inspecting, and maintaining coatings

•

Specific information about surfaces and logistics that require special consideration—concrete, downhole tubulars, offshore, and pipelines

Specifications The specifications include:

September 1996

•

A Quick Reference Guide (for selecting coating systems; coatings system data sheets; list of acceptable brands; and Coating Compatibility Chart)

•

The Company's specifications in commented form

•

Standard Forms

50-2

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Coatings Manual


Other Company Manuals Within this manual, there are references to documents in other Company manuals (example: COM-MS-4738 in this manual). These documents carry the prefix of the particular manual. These prefixes are as follows:

60

Prefixes

Company Manuals

CIV

Civil and Structural

CMP

Compressor

COM

Coatings

CPM

Corrosion Prevention

DRI

Driver

ELC

Electrical

EXH

Heat Exchanger and Cooling Tower

FFM

Fluid Flow

FPM

Fire Protection

HTR

Fired Heater and Waste Heat Recovery

ICM

Instrumentation and Control

IRM

Insulation and Refractory

MAC

Machinery Support Systems

NCM

Noise Control

PIM

Piping

PMP

Pump

PPL

Pipeline

PVM

Pressure Vessel

TAM

Tank

UTL

Utilities

WEM

Welding

Reasons for Coating The Company coats structures and equipment for several reasons. Many of these reasons are discussed below.

61

External Coatings External coatings are generally for aesthetics, corrosion prevention, evaporation reduction, and safety.

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Coatings Manual

Aesthetics Coatings improve the appearance of objects, which contributes to good employee morale, advertising, neighborhood relations, and civic pride.

Corrosion Protection Atmospheric corrosion is a significant problem in humid, warm, coastal locations; in chemical and fertilizer plants; and on offshore structures. Regardless of the geographical location, coating is essential for protection against corrosion in most plant areas.

Evaporation Reduction Painted in light colors, the roofs of storage tanks reflect rather than absorb the sun's energy thus reducing evaporative loss of the stored material.

Safety Special coatings mark fire equipment, traffic lanes, and piping that carries hazardous materials.

62

Under Thermal Insulation and Fireproofing A properly designed coating system, applied to the substrate under thermal insulation and fireproofing systems, gives the best long-term protection against chloride stress-corrosion cracking (CSCC) of stainless steel and reduces corrosion of carbon steel. CSCC and increased corrosion occur: •

When moisture permeates the insulation or fireproofing system and condenses against the substrate, creating a condition similar to immersion service

•

Because steel operating temperatures affect the corrosivity of water

•

As long as the temperature of the water remains below its boiling point: the hotter the steel, the hotter the water, the higher the rate of corrosivity

•

When moisture leaches soluble salts that contain chloride or sulfide ions

Again, the hotter the solution, the greater the effect. Because they develop under insulation and fireproofing, these conditions are very hard to detect. Maintenance and inspection are very difficult and usually require removing the insulation or fireproofing. Often the first indication of a problem is an equipment failure. For guidance on choosing coatings, refer to “Coatings Under Insulation and Fireproofing” in the System Number Selection Guide (part of the Quick Reference Guide).

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63


Internal Coatings Internal coatings can maintain product purity, reduce stockside and underside corrosion, and affect potable water.

Product Purity Even at low corrosion rates, some corrosion occurs. An internal coating may be necessary to prevent the products of corrosion—such as iron oxide (rust) or scales— from contaminating the stock and causing problems.

Stockside Corrosion Internal coatings extend the life of the tank or vessel and reduce the chance of leaks, especially in storage tank bottoms. The water layer which settles out in the bottom of the tank causes most of the tank bottom internal corrosion.[1]

Underside Corrosion For tanks, the corrosion rate of the underside depends mainly on soil composition and moisture content. Based on experience, you can predict when underside corrosion may be a problem.[1]

Potable Water The U.S. Food and Drug Administration regulates coatings for lining potable water tanks.

70

Components of Coatings and Coating Systems 71

Components of Coatings A coating consists of a pigment, a vehicle (binder plus solvent), and additives. Pigments give color and protective properties to the paint. The vehicle provides curing to form a continuous film and adhesion to the substrate. The vehicle is made of the binder (which forms the film) and the solvent (which dissolves the binder and adjusts viscosity to improve application). The solvent also partly controls drying rate. Additives are drying and wetting agents, ultraviolet screening agents, etc.

Methods of Film Formation Understanding how binders work is critical when choosing a coating system. For most coatings, film forms in one of several ways. Thermoplastic. The solid resin, melted for application, resolidifies when it cools. Example: Tar in roof coatings.

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Solvent Evaporation. The coating dries as the solvent evaporates (or dries at lower temperatures than those which involve a chemical reaction). If re-exposed to the same solvent, the coating can redissolve. Example: Vinyls, chlorinated rubbers and lacquers. Oxidation. Coatings composed of drying oils cure by reacting with air. Oxygen cross links the resin molecules into a solid gel. Example: Alkyds. Cross Link. Dual-component products cross link at room temperature, either with or without a catalyst. Example: Epoxies (two polymers react, no catalyst), polyesters (catalyzed) and urethanes (catalyzed). Heat Cure. Heat causes direct cross-linking between filmformer molecules, or activates a catalyst to cause cross-linking. Normally, these coatings are shop-applied only, because of the special heating requirements. Example: Baked phenolic linings. Emulsion. When the water evaporates from an emulsion of resin particles and water, the resin particles coalesce to form a film. Example: Latex acrylics.

72

Coating Systems A coating system refers to the layers that make a complete coating: primer, tiecoat or intermediate coat, and topcoat.

Primer Coats Primer coats adhere well to the substrate and inhibit corrosion and undercutting at defects, such as pin holes or holidays (breaks) in the film. Note that holidays are pinholes or thin spots which either develop during application or nicks and scrapes which occur later. Corrosion will start at these spots. Primer coats also bond well to the intercoat, tolerate variations in application conditions and handling, and resist weathering (helpful because delays may occur between priming and topcoating).

Tiecoats Tiecoats (or intermediate coats) build film thickness, bond the primer to the topcoat, and protect substrate and primer from aggressive chemicals in the environment.

Topcoats Topcoats protect the substrate and undercoats from the environment, provide chemical resistance, enhance the surface appearance, and provide non-skid and other properties.

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Some coatings are incompatible. Before choosing coatings to apply over previously coated surfaces, see the Coating Compatibility Chart in the Quick Reference Guide.

80

The Successful Coating Program The successful coating program has four elements: • • • •

Selection Surface preparation Application Quality control (inspection and on-going maintenance)

Each of these elements is described in more detail in this manual.

90

References 1.

Chevron Corporation

Chevron Corporation. Corrosion Prevention Manual, “Corrosion of Storage Tank Bottoms,” Chevron Research and Technology Company. Richmond, CA: January, 1994.

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100 General Information Abstract Among the general information in this section is a description of the coatings and coating systems, which includes the advantages, disadvantages, and uses. Coatings are also described in the individual sections for special surfaces such as: concrete, downhole tubulars, and pipelines. Note This manual does not contain information about coatings for architectural surfaces. Quality control is essential for any project. Among the key elements of quality control for coatings are inspections, monitoring progress, and protecting the Company’s equipment. For assistance with specific questions about coatings, see the listing of the Company’s specialists and coating manufacturers in the Quick Reference Guide.

Chevron Corporation

Contents

Page

110

Coating Descriptions (A-E)

100-3

111

Acrylics

112

Alkyds

113

Epoxies

114

Elastomers

120

Coatings Descriptions (P–Z)

121

Phenolics

122

Polyesters

123

Polyurethanes

124

Silicones

125

Vinyls

126

Zinc-rich Coatings

130

Petroleum-based Tapes

100-21

140

Water-based Coatings

100-21

150

Coating Systems for Immersion Service

100-22

100-1

100-13

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100 General Information

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Coatings Manual

151

Non-reinforced Thin-film Coatings

152

Glass-flake-reinforced Coatings

153

Laminate-reinforced Coatings

160

Quality Control

161

General Information

162

Inspection Programs

163

Inspectors

164

Monitoring Progress

165

General Inspection Procedures

166

Specific Inspection Procedures

167

Instruments, Tools, and Equipment

168

Protecting the Company’s Equipment

170

References

100-27

100-46

100-2

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Coatings Manual


110 Coating Descriptions (A-E) The following coatings are described in this section: • • • •

Acrylics Alkyds Epoxies Elastomers

For details about each type of coating, read the following descriptions. See also Figure 100-1, Summary of Properties in Coatings.

111 Acrylics Acrylic ester resins are polymers and co-polymers of the esters of acrylic and methacrylic acids. As thermoplastics, they soften at high temperatures. Advantages: • •

Good moisture and mild chemical resistance Either fast-drying solvent evaporation or coalescence

Disadvantages: •

Poor resistance to aromatic solvents

Uses: • • •

Solvent acrylic: truck and machinery finishes Latex emulsions: stucco, wood, and masonry By Company: as architectural coatings

112 Alkyds Alkyd resins are basically modified polyesters. An alkyd is the reaction product of a polyhydric alcohol and a polybasic acid. A common alkyd resin uses glycerol as the alcohol and phthalic acid as the polybasic acid. Oxidation in the air cures alkyd coating resins. Adding drying oils to pure alkyd modifies the alkyd into alkyd coating resins. These resins are classified by oil length (long, medium, and short). The alkyd resin without oil modification is hard and brittle. As the oil length increases (more oil added), the film becomes softer and more flexible. Advantages: • • • •

Chevron Corporation

Perform well in moderate environments Easy-to-handle, single-component coatings Inexpensive Fair-to-good performance in most of the Company's environments

100-3

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Fig. 100-1

Coatings Manual

Summary of Properties in Coatings (1 of 2)

Coatings Acrylic

Alkyd

Type of Cure

Effect of Sunlight

Solvent Evaporation

Chalk Resistant

Good

Oxidation

Slow Chalk

Amine-cured & Amine Adduct Epoxy

Cross Linked

Polyamide Epoxy

Cross Linked

Coal-tar Epoxy Polyamide

Cross Linked

Chlorinated Rubber

Solvent Evap.

Epoxy Phenolic

Cross Linked

1. Atmosphere 2. Splash/Spillage

Wet Atmosphere

Acid

Heat Cured

Moisture-cured Urethane (II)

Cross Linked

Silicone

Heat Cured Cross Linked

Oxidizing

Solvent

1. Good

1. Good

1. Good

1. Fair

2. Poor- Fair

2. Poor-Fair

2. Poor-Fair

2. N/R

Poor-Good Yellows

1. Fair- Poor

1. Poor

1. Fair

1. Fair

2. N/R

2. N/R

2. N/R

2. N/R

Chalks Yellow

Excellent

1. Good

1. Excellent

1. Limited

1. Excellent

2. Fair

2. Excellent

2. N/R

2. Excellent

Chalks Yellow

Excellent

1. N/R

1. N/R

1. N/R

1. N/R

2. Poor-Fair

2. Excellent

2. N/R

2. Very Good

Chalks, Cracks

N/R

1. Excellent

1. Excellent

1. Excellent

1. Poor

2. Good

2. Good

2. N/R

2. N/R

Slow Chalk

Excellent

1. N/R

1. N/R

1. N/R

1. N/R

2. Very Good

2. Very Good

2. Good

2. N/R

N/R

N/R

1. N/R(1)

1. N/R(1)

1. N/R(1)

1. N/R(1)

2. Good Baked Phenolic

Alkali

N/R

(1)

1. Good(1)

N/R

Aromatic Yellows; Aliphatic Excellent

Very Good

Excellent

Very Good

2. Very Good 1. Good(1)

2. Lid Mineral Acids(1)

2. N/R

(1)

2. N/R

(1)

N/R(1)

(1)

2. Very Good(1) 1. Poor(1) 2. Outstanding(1)

1. Good

1. Good

1. Poor

1. Excellent

2. Fair

2. Fair

2. N/R

2. Good

1. Good

1. Good

1. Fair

2. Poor

2. Poor

1. Very Good

2. Fair

2. Poor Silicone Alkyd

Vinyl

Organic Zinc-rich Post-cured Inorganic Zinc Solvent-based Self-cured Inorganic Zinc

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Oxidation

Solvent Evap.

Cross Linked

Cross Linked

Cross Linked

Excellent

Very Good

Slow Chalk

Excellent

Chalk

Excellent(2)

None

None

Excellent

Excellent

(2)

(2)

1. Good

1. Good

1. Good

1. Good

2. Poor

2. Fair

2. Poor

2. Good-Poor

1. Excellent

1. Excellent

1. Excellent

1. Poor

2. Very Good

2. Good

2. Good

2. N/R

1. Topcoat

1. Topcoat

1. Topcoat

1. Excellent

2. N/R

2. N/R

2. N/R

2. Very Good

1. Topcoat

1. Topcoat

1. Topcoat

1. Excellent

2. N/R

2. N/R

2. N/R

2. Excellent

1. Topcoat

1. Topcoat

1. Topcoat

1. Excellent

2. N/R

2. N/R

2. N/R

2. Excellent

100-4

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Coatings Manual

Fig. 100-1


Summary of Properties in Coatings (2 of 2)

Coatings

Tank Linings

Immersion

Physical Properties Abrasion

Heat

Hardness

Gloss

Range of Color

Acrylic

N/R

N/R

Good

Limited

Good

High to Semi

Full

Alkyd

N/R

N/R

Fair

Fair

Fair

Chalks to Flat

Full

Amine-cured & Amine Adduct Epoxy

Very Good

N/R

Good

Good

Very hard

Chalks to Flat

Full

Polyamide Epoxy

Very Good

Solvents Water

Good

Good

Hard

Chalks to Flat

Full

Coal-tar Epoxy Polyamide

Excellent

Water

Limited

Excellent

Very Hard

Flat

Black, Red

Chlorinated Rubber

Very Good

Water

Fair-Poor

Poor

Good

Semi to Flat

Wide

Epoxy Phenolic

Very Good

Widerange Solvent

Good

Outstanding

Very Hard

High

Dark

Baked Phenolic

1. Excellent(1)

Wide Resistance

Good

Excellent

Excellent

Excellent

Clear Dark

2. Very Good Moisture-cured Urethane (II)

N/R

N/R

Excellent

Good

Excellent

High

Full

Silicone

N/R

N/R

Good

Excellent

Good

High

Full

Silicone Alkyd

N/R

N/R

Good

Very Good

Good

High

Full

Vinyl

Very good

Water

Fair-Poor

Poor

Good

Semi to Flat

Wide

Organic Zinc-rich

Good(3)

N/R

Good

Good

Very Good

Semi to Flat

Some

Post-cured Inorganic Zinc

Good(3)

Fuels Solvent

Excellent

Excellent

Excellent

Flat

Earth Tones

Solvent-based Self-cured Inorganic Zinc

Good(3)

Fuels Solvent

Excellent

Excellent

Very Good

Flat

Earth Tones

(1) As tank lining (2) When top-coated (3) With epoxy topcoat

•

Good service on large, flat surfaces

Example: Good service is exemplified by this coating’s almost 20 years on Hawaiian refinery tanks. Disadvantages:

Chevron Corporation

•

Long drying time

•

Not chemically resistant; unsuitable for highly corrosive areas such as chemical and fertilizer plants or offshore structures

•

Unsatisfactory for water immersion

100-5

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Coatings Manual

•

Not suited to highly alkaline surfaces such as fresh concrete, galvanized steel, and inorganic zinc

•

Chalk in sunlight

•

Usually fail within a few years on piping and structural components

•

Not VOC-compliant

Uses: •

In external primers and finish coatings

Long-oil Alkyds (60 to 70 Percent Oil) Advantages: •

Good flexibility and wetting properties

Disadvantages: •

Very slow drying

Uses: •

Over poorly prepared steel where the oil penetrates rust and develops adhesion

Medium-oil Alkyds (45 to 60 percent oil) Advantages: •

Hard, tough films

•

Dry faster, generally, than long-oil alkyds

Uses: •

Finish coats

Note

The Company’s most popular choice of alkyd

Short-oil Alkyds (35 to 45 percent oil) Uses: •

Fast air drying and baking enamels for hardness and mar resistance

Note

The Company uses very little of these.

113 Epoxies The most common epoxy resins are formed by the reaction of epichlorhydrin and bisphenol-A. This reaction can be controlled to produce resins ranging from liquids of low-molecular weight to solids of high-molecular weight.

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Complete curing gives epoxies their chemical and water resistance. Curing time increases at temperatures below about 70°F, essentially stopping below about 50°F unless it is a specially formulated low-temperature epoxy. Epoxies have very good resistance to bases and many solvents. Epoxies have poor acid resistance unless modified with a phenolic. Advantages: • • • •

Resist water and chemicals, especially caustics, superbly Resist weather well Adhere well, particularly to concrete Apply easily

Disadvantages:

☞

•

Do not retain color and gloss as well as alkyds

•

Tend to chalk rapidly

•

Do not have good acid resistance

•

Need surfaces between layers of epoxy roughened by solvent or blasting when applying multiple coats as many epoxies cure with a hard, slick surface

•

Need successive coats of epoxy applied as soon as possible to obtain satisfactory adhesion between coats. Manufacturers normally recommend a maximum time between coats.

•

Need long cure time. For epoxy linings at 70°F, curing may take one week. In the field, coatings applicators often accelerate the curing of an internal coating with a low-temperature bake (100 to 150°F).

Caution

Do not put internal coatings into service until they are fully cured.

Uses: •

Epoxy resins are the most popular resin for thin-film coatings on concrete.

There are six groups of epoxy coatings in this section: amine cured, amine adduct, polyamide, coal tar, epoxy mastics, and epoxy novolac.

Amine-cured Epoxies These coatings are epoxy resins cross-linked with one of several amine compounds.

☞

Caution Because the amines can present a health hazard, apply them according to manufacturers’ safety recommendations.

Amine Adduct Epoxies Amine adducts are stable intermediate products resulting from the reaction of a portion of the epoxy resin with an amine curing agent. The amine adduct, instead of the amine, is added to the epoxy coating to cure it.

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Coatings Manual

Advantages: • •

Same properties as liquid amines, but much less hazardous Very good resistance to oils, solvents, and chemicals

Disadvantages: •

Ultraviolet degradation causes rapid chalking

Uses: • •

Lining gasoline storage tanks, chemical tanks Corrosion-resistant primer under polyurethane foam insulation

Polyamide Epoxies Polyamide resins are produced from polyamines and fatty acids. Epoxy coatings for atmospheric exposures are usually polyamides. Mastic coatings which adhere to wet surfaces and which will cure under water are formulated with polyamide epoxies. Advantages: •

Good surface-wetting properties

•

Longer pot life, more flexibility and better water resistance than amine or amine-adduct cured epoxies

•

Good resistance to alkalies, petroleum products, and salt water

Disadvantages: •

Not quite as chemically resistant as amine adduct epoxies.

Uses: •

Topcoats and tiecoats in severe exposures

Coal-tar Epoxies As the name suggests these coatings are blends of epoxy resins and coal tar. Note Coal tar is a suspected carcinogen but is tied up sufficiently in the polymer so that manufacturers consider the cured film safe. Coal-tar epoxies can be either polyamide- or amine-adduct cured. Usually applied in two heavy coats of eight mils each, these coatings are normally self-priming. Advantages: •

Outstanding for water-immersion service

Disadvantages: •

November 1998

Chalk rapidly and fail in (ultraviolet) sunlight

100-8

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Uses: •

Underwater, in water tank linings (except potable water tanks), and on buried structural steel

Note Although coatings manufacturers continue to use them for municipal watertank linings, the Company prefers FDA-approved polyamide or amine-adduct epoxies for potable-water tank linings.

Epoxy Mastics Advantages: • • • •

Perform better than alkyds Adhere to a variety of surface preparations, including tightly adhered rust Adhere to any old coating firmly attached to the substrate VOC compliant

Disadvantages: •

More expensive than alkyds

Uses: •

For less-than-perfectly prepared surfaces

Epoxy Novolac Epoxy novolac resins are second-generation epoxies with greater cross-linking density. Advantages: •

Greater resistance to chemical attack and high temperatures than standard epoxies

Disadvantages: •

More expensive and less flexible than standard epoxies

Uses: •

Common coating for concrete

114 Elastomers An elastomer is a polymeric substance with more than 100 percent elongation in a tensile test. Included in this category are natural- and synthetic-rubber products (which also have the physical characteristics of natural rubber). The chemical, oil, and water resistance of elastomers vary widely. Coatings applicators can apply modified elastomers as coatings. The Company uses many elastomeric coatings, such as chlorinated rubber and hypalon, alone over steel and other surfaces or, as required, with special primers such as inorganic zinc.

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Coatings Manual

There are two classes of elastomers: cross-linking and air-drying.

Catalyzed Cross-linking Elastomers Neoprene, butyl, thiokol, silicone, and hypalon are the most common, catalyticsetting, elastomer coatings. Neoprene. A synthetic rubber, produced by polymerizing chloroprene, neoprene is either pigmented or clear and is manufactured as thin flexible films or mastics. Advantages: • •

Good heat and flame resistance Good acid, alkali, and water resistance

Disadvantages: •

Softened by aromatic solvents

Uses: •

Block insulation coatings

Butyl. A copolymer of isobutylene and isoprene, butyl is polymerized with an aluminum chloride catalyst. Advantages: • •

Exceptionally low water permeability Better sunlight and weather resistance than most rubbers

Disadvantages: •

Unknown

Uses: • •

Coating urethane foam and block insulation Piping tape wrap primers and tape mastics

Thiokol. Thiokol is a polysulfide rubber. Advantages: •

Excellent gasoline and water resistance

Disadvantages: •

Unknown

Uses: • • •

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Caulking compounds Flexible seal over leaking rivet seams in oil tanks Pond and tank linings (in sheet form)

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Silicone Rubber. Silicone rubber is a room-temperature vulcanizing (RTV) silicone. Advantages: •

Good for hot service

Disadvantages: •

Poor solvent resistance

Uses: • • •

Gaskets in hot services Caulking Potting materials

Hypalon. Hypalon is a chlorinated polyethylene resin. Advantages: • •

Excellent sunlight resistance Good chemical resistance

Disadvantages: •

Unknown

Uses: • • • •

Flexible coating vehicles or mastics and sheet lining Mild acid spill protection for concrete (the Company's most popular use) Topcoat over polyurethane foam or block insulation Pond and tank linings

Air-drying Elastomers Chlorinated rubber, an air-dried formulation of hypalon, and butadiene-styrene are the most popular elastomers for air-drying coatings. Chlorinated Rubber. Chlorine and natural rubber latex produce chlorinated rubber resins. When suitably plasticized and pigmented, these resins exhibit outstanding resistance to a broad range of corrosive chemicals and environments. Advantages: •

Shows outstanding resistance to severe chemical environments such as acids, alkalies, salt fog, water, oxidizing agents, bleaches, and cleaning compounds

•

Dries rapidly, allowing application of several coats in one day

•

Produces excellent bond between old and new coats as the solvents in the new coat penetrate the old coat

Disadvantages:

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Does not resist sunlight damage as well as alkyds and acrylics Causes alkyd or oil coatings to blister if applied over them Dissolves in oils and solvents

Caution

Oil spills could potentially soften these coatings.

Uses: • •

Offshore platforms Humid coastal refineries

Hypalon. The air-drying hypalon is a chlorosulfonated polyethelene. Advantages: •

Good weatherability

Disadvantages: •

Unknown

Uses: •

Topcoat elastomers to improve weather resistance

Butadiene-Styrene. The most widely used type of synthetic rubber, butadienestyrene is a copolymer of three parts butadiene and one part styrene. Advantages: • •

Good resistance to alkali, water, and mild acids Excellent external durability if pigmented properly

Disadvantages: •

Embrittles with age if formulated improperly

Uses: •

Vehicles in coatings and mastics for stucco and masonry

Polyurethane Elastomers. Polyurethane elastomers are thermal plastic polymers. Advantages: •

Aliphatic—Excellent color and gloss retention

Disadvantages: •

Aromatic—Yellows badly in sunlight

Uses:

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•

Vehicles for thin or semi-mastic coatings for sealing polyurethane foam insulation

•

Deck and floor coatings

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120 Coatings Descriptions (P–Z) The following coatings are described in this section: • • • • • •

Phenolics Polyesters Polyurethanes Silicones Vinyl Zinc rich

121 Phenolics Phenolic resins, formed by the reaction of phenol with formaldehyde, produce a range of coatings from hard plastics (Bakelite) to oil-soluble resins and from heatreactive varnishes to air drying oils. The Company uses two phenolic resins in coatings: a baked pure phenolic and an air-drying epoxy phenolic.

Baked Phenolics Baked phenolics are almost exclusively shop-applied due to a complicated baking procedure. They contain resins which are polymerized by being heated above 300°F. The reaction time and temperature depend on the modifying oils and resins. Note The Company uses baked phenolics only in the most severe immersion services where no other material will work, such as container inner-coatings and tank car linings. Advantages: • • •

Excellent chemical and water resistance Withstand immersion in almost all petroleum products Good abrasion resistance

Disadvantages: • • • •

Poor wetability (the ability of a coating to flow over a surface) Require maximum surface preparation Poor adhesion Embrittles

Note To overcome poor adhesion and brittleness, some formulas are modified with epoxy resins, giving them better caustic resistance than pure phenolics but not equal resistance to strong solvents.

Epoxy Phenolics Catalytic setting (non-baking) phenolics are usually composed of phenolic resins and epoxies.

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Advantages: •

Better chemical and solvent resistance than pure epoxies

Disadvantages: •

Lower resistance to chemicals and solvents than pure baked phenolics

Uses: •

Lining tanks, vessels, containers, etc.

122 Polyesters While there are two major classes of polyester resins, the Company uses only isophthalic. Isophthalic polyesters, the resin preferred for corrosion protection, is also the main resin in laminate-reinforced systems. While the chemical and temperature resistance of polyester is usually poorer than any of the other resins, they are also the least expensive.

123 Polyurethanes Polyurethane resins are formed by the reaction of isocyanates with polyols and are used for a variety of purposes from foam insulation to air-drying coatings and varnishes. The isocyanate may be either aromatic or aliphatic. There are literally thousands of polyurethane formulations—from hard roller skate wheels to elastomeric materials that stretch like rubber bands—which have many different properties. Some of these properties are: • • • • •

☞

Abrasion resistance Chemical resistance Elasticity Impact resistance Tensile strength

Caution Remember that increases in one property result in decreases in another. Because of this, many elastomeric polyurethanes are not as chemically resistant as the more rigid polyurethanes. The most common polyols are acrylics and polyesters, although there are epoxies, vinyls, and alkyds. Advantages: • • • • •

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Highly resistant to abrasion and impact Catalyzed urethanes are highly chemical resistant Better performance than alkyds Aliphatic—For atmospheric coatings, usually as easy to overcoat as epoxies Aromatic—More chemically resistant than aliphatic urethanes

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Disadvantages: •

More expensive than alkyds

•

Aromatic—Not designed for external exposure as they chalk and yellow; difficult to overcoat because adhesion is poor

Uses: •

Aliphatic—Non-fading, non-chalking external finishes

•

Aromatic—Tank linings, chemically resistant coatings, flexible elastomeric coatings for polyurethane foam insulation coverings

Classifications. Urethane coatings cure by a variety of mechanisms as classified by ASTM D16-75 types. Types II, IV, and V are considered high performance and are described below. Most of the Company's experience has been with Type V, the twopackage polyol-cured urethane. Type II, One-package Moisture-cured. The Company has limited experience with these urethanes which cure by reacting with moisture in the air. The moisture reacts with a prepolymer containing isocyanate so that the isocyanate is released for crosslinking. The reaction also releases CO2 which must migrate to the surface before the film sets up.

☞

Caution In high humidity areas, such as offshore, the reaction can occur so rapidly that the CO2 cannot escape; and the film is filled with gas bubbles and pinholes. Type IV, Two-package Catalyzed. These urethanes cure by reacting with a lowmolecular-weight-reactive catalyst. They cure in a similar way not only to moisturecure (although the catalyst is in a separate package), but also to epoxy coatings. Type V, Two-package Polyol-cured. These urethanes are the Company's most common choice for high-performance coating systems such as for offshore platforms and chemical plants. To cure, polyol-cured coatings react with pre-reacted (adduct) hydroxyl-bearing polyols. They require no additional curing agent; however, coatings applicators may add an agent to promote low-temperature curing.

124 Silicones Silicones are a group of various organo-silicon-oxide polymers available as fluids, elastomers, and resins. Because of their chemical composition, silicones have excellent resistance to heat, weathering, and moisture. Note Repairing silicone coatings is very difficult because almost nothing will adhere to them. For small repairs, sand the failure and apply fresh silicone coating with a brush. For large repairs, remove the coating by abrasive blasting and recoat. The Company uses both classes of silicone coating resins: heat-reactive and modified.

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Heat-reactive Silicone resins are cross-linked polymers which require a high-temperature cure to produce heat-stable films. Catalyzed formulations which cure at room temperature are now available. Non-catalyzed formulations remain tacky until heated above about 300 to 400°F. For this reason, most field applications use the catalyzed, roomtemperature cure. The film thickness of baked silicone coatings is low compared to that of other coatings. A self-primed two-coat application usually produces only 1½ to 2 mils dry film thickness (DFT). Advantages: • •

Excellent sunlight resistance Good durability at high temperatures

Disadvantages: •

Apply only on abrasion-blasted surfaces

Uses: Furnaces and stacks up to 600°F (up to 750°F for aluminum and black colors)

Note

The color and gloss retention of baked silicones depends on the pigments.

Modified or Air-drying Modified or air-drying silicones are produced by reaction with organic resins such as alkyds or acrylics. Advantages: • • •

Excellent gloss and color retention Good weather and sunlight resistance Many resist temperatures up to 300°F

Disadvantages: •

Tend to cure quite slowly even at ambient temperature, taking weeks to harden and resist damage in cool weather.

Note

Topcoat inorganic zinc with an epoxy or silicone acrylic.

125 Vinyls Vinyl resins are formed from the reaction of acetylene with acetic or hydrochloric acids. Varying this process produces resins consisting of 100 percent vinyl chloride, or 100 percent vinyl acetate. The resins in protective coatings are usually co-polymers containing 80 to 90 percent vinyl chloride and 5 to 15 percent vinyl acetate.

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Vinyl resins are hard and brittle and must be combined with plasticizers and dissolved in solvents to form vehicles for coatings. Vinyl solutions contain only 15 to 40 percent solids depending on the co-polymers. The various vinyl-resin solutions are compatible and may be blended to emphasize desired properties. Some blends adhere very well to concrete and metal and are used in formulating primers. Other blends are pigmented and plasticized to produce highbuild films. Used for finish coats, some blends have low solids and adhere poorly to steel but have very good chemical and weather resistance. The Company uses vinyls for many services, often where water exposure is expected such as on floating tank roofs, docks, and on offshore platforms near the water. Advantages: • • • • • •

Excellent chemical, water, and aliphatic oil resistance Excellent shelf life Ready bond to weathered vinyl films Removable with a solvent wash when desired Easy to patch old coatings without blistering or wrinkling Easy to apply by spray

Disadvantages: •

May lose their plasticizer over time and embrittle, a problem with vinyl as a weathercoat over polyurethane-foam insulation

•

Do not have good gloss retention or stain resistance

•

Dissolved by ketones, esters, chlorinated solvents, and some aromatics

•

Need good ventilation to avoid prolonged (solvent evaporation) drying

•

Tend to lift and blister because of the strong solvents

•

Difficult to brush or roll because of their rapid drying

•

Tend to bubble and pinhole when applied over porous inorganic zinc

Uses: •

With alkyds or epoxy esters to improve film build, gloss, and adhesion which are excellent as vehicles: – – –

•

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In rust-inhibiting primers for ferrous metals In seal or tiecoats over inorganic zinc primers to improve adhesion of vinyl, alkyd, chlorinated rubber In epoxy ester topcoats

In formulae ranging from thin-bodied, air-drying coatings to semi-mastic putties and air-drying, baking plastisols

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•

To formulate a wide variety of latex materials in glues, paper sizes, and emulsion coatings

•

In vinyl-emulsion-latex coatings for both internal and external services. The retention of deep colors by vinyl latexes is superior to that of most other coatings.

Vinyl Ester Vinyl ester resin is a reaction product between polyesters and epoxies and shares many of the attributes of polyesters. Advantages: •

Resistance to acid, solvent attack, and high temperatures

Disadvantages: •

More expensive than an isophthalic polyester or normal epoxy

Uses: •

Coating concrete

126 Zinc-rich Coatings Zinc-rich coatings, which have zinc dust as the pigment and inorganic or organic vehicles, are divided into two classes: inorganic and organic zinc. Zinc-rich coatings offer good corrosion resistance for steel due to the sacrificial nature of the zinc pigment. The zinc acts as an anode to protect the steel galvanically and prevent corrosion. This coating is applied alone or as a primer under a variety of topcoats. Under suitable topcoats, all of these primers greatly enhance the life of the coating system in many exposures, especially in marine services. When testing to determine the benefit of zinc in a coating, the Company found the quality of performance to be rated (best to worst) as follows: 1.

Inorganic zincs

2.

Zinc-rich organic coatings

3.

Organic coatings

Inorganic-zinc Coatings Inorganic-zinc coatings consist of two components: •

A pigment composed solely or principally of zinc powder

•

Any of a variety of patented and proprietary inorganic or semi-inorganic vehicles to form the matrix of the coating

Post-cured inorganic zincs have a third component: a curing agent such as phosphoric acid. Among the vehicles are ethyl and sodium silicate, phosphates, and other complexes.

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When properly mixed, applied to blasted steel surfaces, and allowed to cure, the resultant coatings have outstanding resistance to weathering, humidity, elevated temperatures, organic solvents, animal and vegetable oils, both fresh and salt water, and most petroleum products. In addition, these coatings (especially post-cured) have excellent abrasion resistance. The corrosion resistance of the cured film is similar to that of galvanized iron; the weather resistance is superior to galvanized iron. Two types of inorganic zinc coatings are self-cured and post-cured.

Self-Cured Inorganic Zinc Coatings Self-cured inorganic zinc coatings are either solvent- or water-based vehicles. While both produce an inorganic film, their methods differ. Current technology is almost all solvent-alkyl-silicate-resin based. Solvent-based Coatings. The Company uses self-cured, solvent-based, inorganic zincs in many places such as piping, tanks, and offshore. Although manufacturers have used several inorganic silicate vehicles such as ethyl silicate and bi-metallic alkoxide complexes to make these coatings, almost all self-cured inorganic zincs are now alkyl silicates such as ethyl silicate. Ethyl-silicate-based coatings convert to an inorganic, insoluble state in reaction to moisture. Some formulae require long periods (three to four weeks) of high humidity to reach ultimate hardness. Many manufacturers now claim their ethyl silicates can be topcoated almost immediately since enough moisture permeates through the topcoats to cure the primer. Solvent-based coatings are popular because their vehicles show superior wetting ability, they dry fast and resist water immediately, and their film thickness is less critical than for post-cured inorganic zinc coatings. Some self-cured inorganic zincs are modified to include some organic resin for more rapid film formation and increased flexibility. Properly formulated, they can perform as well as normal alkyl silicates.

☞

Caution The Company does not recommend single-component inorganic zincs. Laboratory tests and experience show that these zincs do not perform as well as the two-component zincs. One reason is that the zinc settles in the can and is not easily put back in suspension. The applied coating is, therefore, deficient in zinc. Coatings applicators mix the multi-component zincs at the time of application and agitate them continuously to avoid the settling problem. Water-based Coatings. Tests show that, for weather resistance, water-based coatings are inferior to solvent-based and post-cured inorganic zincs. Note Future changes to clean air regulations may force us to use water-based or new, presently untested, formulations of inorganic zincs. Composed of zinc dust pigment and vehicles containing sodium silicate, or phosphates, the vehicles are water solutions similar to those of the post-cured coatings. After application, the film is water sensitive for some time, the length of which depends on the formula. The vehicle’s reaction with moisture in the air converts the

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water-soluble film to an insoluble film. Conversion time depends on the vehicle and the relative humidity and temperature. Some of these coatings undergo a color change as they cure, indicating when they are completely cured.

☞

Caution Do not topcoat or place these coatings in water-immersion service until they are thoroughly cured.

Post-Cured Inorganic Zinc Coatings Post-cured inorganic-zinc coatings are composed principally of zinc powder and sodium silicate. When mixed, the zinc-dust pigment and sodium silicate produce a water-soluble coating. coatings applicators must keep the applied film dry until it has cured by a chemical curing agent, such as phosphoric acid, which converts the film to a water insoluble coating. Advantages: •

Long life under extreme service conditions such as exposure to marine environments

Disadvantages: •

Sensitivity to moisture until cured

•

White-metal surface preparation

•

Necessity of removing the powder-like post-cure reaction chemicals (by washing very thoroughly) before topcoats will adhere

Uses: •

Extreme conditions such as offshore structures in marine environments.

Note While post-cured inorganic zinc coatings have a long, successful field history, the Company limits post-cured zincs to extreme services where their long life is needed such as near the water on offshore platforms. Today, however, because self-cured inorganic zincs can last almost as long and are much easier to apply properly, you may choose them instead.

Zinc-rich Organic Coatings Epoxies, urethanes, chlorinated rubbers, phenolics, styrenes, silicones, and vinyls are vehicles for zinc-rich organic coatings. Epoxies are most common. The zinc content of these coatings should generally be about 80 percent by weight of total solids. The mechanism for curing zinc-rich organic coatings depends on the binder. (See Section 70 of this manual for methods of film formation.) The coatings can be either single- or multi-component. Performance tends to be a function of the durability of the binder, and epoxies are generally considered superior.

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Advantages: • • •

Excellent water and weather resistance Better wetting ability, because of their organic vehicles, than inorganic zinc Usable over a broader range of surface preparation conditions than inorganic zinc

Disadvantages: •

Not as oil resistant as the inorganic coatings

Uses: • • •

Touch up for inorganic-zinc-primed systems Subsea equipment primers As primers under other coatings

Note Often one coat of IOZ alone gives excellent performance. For higher performance or aesthetics, topcoat with epoxy or epoxy plus urethane. Example: One coat of IOZ has lasted 15 plus years on a Richmond Long Wharf line. Pascagoula successfully used a two-coat system of Carboline Coating Company’s IOZ with Carboline high-build urethane.

130 Petroleum-based Tapes Petroleum-based tapes, such as denso, work well in severe service as a wrapping for pipe and structural components. Advantages: • •

Adheres to moist surfaces with minimum surface preparation Adheres to irregular shapes, valves, and pipe fittings

Disadvantages: •

Could shield cathodic protection if tape fails

Uses: •

Reinforce heavily corroded lines

140 Water-based Coatings Chevron Corporation OpCos are required to use coating systems that meet both federal and local regulations controlling the emissions of VOCs. Because water-based coatings use water instead of solvents as the pigment carrier, they typically do not contain any “Volatile Organic Compounds” (VOC) that could be released into the air. Many OpCos may, in the future, be required to use water-based coating systems in order to meet these regulations. After 6 months of testing the major manufacturers’ water-based coatings, Chevron has concluded that several are acceptable for inclusion in the Coatings Manual. However, since these coatings do not perform as well as solvent based coatings, we

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cannot recommend them for severe exposure environments (ie: offshore or industrial environments). Refer to the “System Number Selection Guide” in the Coatings Manual Quick Reference Guide for a listing of the acceptable brands of water-based coatings for both new construction and maintenance systems.

150 Coating Systems for Immersion Service Coating systems usually include a first coat (primer), second coat (tiecoat), and a final coat (topcoat). There are three types of coating systems for immersion service and each is described below along with its advantages, disadvantages, and cost. The coatings described are: • • •

Non-reinforced, thin-film coatings Glass-flake-reinforced coatings Laminate-reinforced coatings

151 Non-reinforced Thin-film Coatings Typically only 10 to 20 mils thick (thin films), these non-reinforced coatings: •

Contain no glass flakes or fibers or laminates for reinforcement

•

Usually have inert fillers such as silica or carbon to reduce shrinkage during cure and to improve abrasion resistance

•

Resemble some of the high-build layers of external coating systems

•

Usually are spray applied in two or more coats: a primer/sealer and one or two high-build topcoats

•

Have recommended dry film thickness (DFT) of 15 to 20 mils—thicker systems for more severe services

Most thin-film coatings for tanks are based on epoxy resins, although vinyls, inorganic zinc, and other types of coatings have been used. Advantages: • • • • •

Low cost Use least amount of material Require no expensive hand work Easiest to apply Product purity

Disadvantages:

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•

Lack of thickness leads to no resistance to abrasion, severe chemical attack, physical abuse

•

Absence of reinforcement means inability to bridge existing cracks

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•

Always have some damaged areas, called holidays

Uses: • •

Temporary service Protection from mild corrosion, splash, or spillage environments

Note Apply and inspect this coating system properly to ensure that there are relatively few holidays. The small amount of corrosion which occurs will not be a problem in mild-corrosion environments if the product is pure. If the corrosion environment is severe, however, the holidays will initiate pits that quickly become unacceptable leaks. For severe corrosion service, pre-coated tanks may have similar problems if they are scratched or damaged while being erected. For severe corrosion applications, select a thin film coating if the tank’s interior is also cathodically protected to prevent corrosion at damaged areas of the coating. [1]

Life Expectancy The expected life of a thin-film internal coating is approximately ten years. After ten years, the coating commonly blisters, and corrosion at holidays is usually occurring over enough of the surface that blasting and replacing the entire coating are required. Note Early failure due to blistering often indicates either a problem with the surface preparation or an incorrect coating selection. Periodic inspection and repair (touch-up) of the internal coating may extend its life. As the Company inspects tanks on a ten-year cycle, periodic inspection and touchup is usually not possible.

Limitations and Cost Because they can be sprayed, thin-film coating systems are generally the easiest and fastest to apply, and also the least expensive. Example: For a tank over 50,000 bbls, it might take a total of four weeks at a minimum to carry out the entire project: • • •

Approximately two weeks to clean, blast, and prime Approximately one week to apply the coating An additional week for final curing

Ease of application and cost also vary among different categories of thin film coatings. Factors which make a coating easier or more difficult to apply include: • • • • •

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Its ability to flow smoothly and form an even film How well it “hangs” on vertical surfaces without running or sagging Its tendency to form pinholes Its tolerance to inadequate surface preparation The amount of drying time required between coats

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These factors also vary from product to product within a category, so it is difficult to make general statements. Coal-tar epoxies are, however, usually very easy to apply and relatively inexpensive, but the black color makes them difficult to inspect. Straight epoxies (polyamides or amine adduct) are also fairly easy to apply and only slightly more expensive than the coal tars. Epoxy-phenolics are often significantly more expensive and more difficult to apply.

152 Glass-flake-reinforced Coatings Glass flakes in coatings, available in spray and trowel formulae: • •

Make the coating less permeable and more abrasion resistant Reinforce the resin, allowing thicker film buildup

Note

Epoxy and polyester resins are used for glass-flake-reinforced coatings.

The main difference between these two formulae is that the trowel coatings have larger reinforcing glass flakes than the spray. The layers are therefore as follows: • •

Trowel: Two 20 to 40 mil (DFT) coats for a total of 60 to 80 mils (DFT) Spray: Two 15 to 20 mil (DFT) coats for a total of 30 to 40 mils (DFT)

Coatings applicators must roll each layer of both spray and trowel formulae to orient the glass flakes parallel to the surface. Rolling reduces the permeability of the coatings. Cathodic protection should not be required with glass-flake-reinforced coatings (especially trowel-applied types) because they are so thick and are not easily damaged. Advantages: •

Both (trowel and spray) are more protective than thin-film coatings because they are thicker and have fewer holidays.

•

Both are highly advantageous in services where erosion or abrasion would damage thin-film coatings.

•

Spray can be applied at twice the thickness of thin-film systems, and over more uneven surfaces—because of the coating's thickness—than thin film.

•

Trowel is more resistant to chemical attack, abrasion, and physical abuse than either spray formula or thin-film coatings.

Disadvantages:

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•

Spray is marginally more expensive than thin-film coatings and rolling is required to improve resistance to chemical attack.

•

Trowel is much more expensive than thin-film coatings; it is considerably more difficult and time-consuming to apply than either the spray formula or thin films, and hand smoothing and rolling is required.

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Note The cost of glass-flake-reinforced coating may be justified if corrosion rates are expected to be relatively high but not severe, or permeation through the coating is a potential problem. Uses: Recommended for both mild and severe corrosion applications. Generally, select: •

Spray for mild corrosion and for uneven surfaces

•

Trowel for severe corrosion (as an alternative to a thin-film coating with cathodic protection)

Note This coating system is the most widely used one for concrete because of its excellent properties for most environments and lower cost than laminate systems.

Life Expectancy Expect glass-flake-reinforced coatings to last at least ten years before inspection. Depending on the condition of the coating and the service, making necessary repairs may allow the coating to last another ten years. Frequently, however, it will be necessary to replace the coating after only ten years, especially for sprays. Trowel applications have a better chance of lasting through a second decade.

Limitations and Cost The spray-applied glass-flake-reinforced coatings are usually only slightly more difficult to apply than non-reinforced coatings. Rolling the glass flake properly takes additional time during application. Spray-applied glass-flake coatings are more costly than non-reinforced coatings. Trowel-applied glass-flake coatings are considerably more difficult and time consuming to apply than sprays. The coating is hand smoothed and rolled to orient the glass flakes. Coating application may take two to three weeks for an average size tank (increasing the total time to five to six weeks), and the total installed cost will be higher than sprayed glass-flake coatings. Epoxy-glass-flake coatings are generally easier to apply than polyesters or vinyl esters, both of which require a final wax coat to obtain full surface curing. If the coating is premixed with wax, common for sprays, the coatings applicator must apply the second coat within the manufacturer-specified time (known as the maximum allowable time) because the second coat will not adhere well if the wax layer has fully cured the first coat.

153 Laminate-reinforced Coatings The coatings applicator applies laminate reinforced coatings by hand, alternating layers of resin and fiberglass mat to a total thickness of typically 80 to 125 mils. Generally, they apply three layers of resin and two layers of mat. For some services, specifications call for an additional layer of a special surfacing veil of chemical grade glass or polyester and another coat of resin.

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Note The veil prevents any glass fibers from protruding through the resin surface, which could allow wicking or chemical attack of the glass itself. After the completed laminate is inspected, the coatings applicator applies a final coat of resin. For epoxy resins, this gel coat simply provides additional protection from chemical attack. For polyester resins, the coatings applicator adds a wax to the final resin coat to obtain full curing. Without the wax coat the surface of a polyester coating always remains slightly tacky and lacks its optimum chemical resistance, and the body of the laminate cures very slowly. Advantages: •

A laminate-reinforced coating provides the best protection against severe corrosion.

•

Laminates should not require cathodic protection as they should not contain any holidays.

•

A laminate is the only type of internal coating which has significant structural strength by itself.

•

Because it does not need to be as thick, epoxy-resin laminates are less expensive than polyester or vinyl ester laminates.

Disadvantages: •

Compared to thin-film and glass-flake-reinforced coatings, laminates are the most expensive coating.

•

Laminate-reinforced coatings are the most difficult and time consuming to apply.

Uses: •

Laminates are generally used for stockside corrosion only when there is severe corrosion or when underside corrosion is expected or has occurred.

Life Expectancy Laminate reinforced coatings will last for 20 years, but inspect and repair them after 10 years. Eventually, the laminate will start to crack and lose its adhesion to the steel, especially if the tank bottom flexes or settles significantly. If underside corrosion occurs, remove the coupons to check the condition of the steel bottom. Replace the laminate and the bottom if the bottom is essentially corroded through.

☞

Caution

Never apply a second laminate over a failed laminate.

Limitation and Cost Laminate-reinforced coatings are the most difficult and time consuming to apply. The hand layering of fiberglass mat is a slow process, normally requiring at least three weeks for an average-size tank, increasing the total time to a minimum of six

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weeks. Laminates are also expensive. The total cost per square foot is equal to or higher than that of trowel-applied glass-flake coatings. Because it does not need to be as thick, epoxy-resin laminates are less expensive than polyester or vinyl ester laminates. Polyesters and vinyl esters require a final wax coat to obtain full surface curing; however, as they remain fluid longer before starting to cure, they are easier to use. Note

The time between mixing and cure is called the gel time.

The coatings applicator can adjust the gel time by mixing different amounts of catalyst and promoter into the resin. After the resin sets, it will reach 90 percent of full cure in a short time. As epoxy resins do not have a gel time, they cure at a relatively constant rate, starting immediately after mixing, and therefore do not remain as fluid for as long as laminates.

160 Quality Control 161 General Information Do the job right the first time. Essentially a system of checks and balances, quality control helps ensure that a project’s participants fulfill the specification’s requirements. For coatings projects, the process should yield a high-quality result that: • •

Contributes to the maximum service life of the structure and equipment Reduces future expenditures for field maintenance

Offshore Achieving high-quality coatings is more difficult offshore than onshore due to some of the following conditions: •

Adverse weather

•

Simultaneous operations with other platform activities

•

Congested platform areas

•

Limited availability of transportation

•

Existing substrate surfaces that can be deeply pitted and contaminated with soluble surface salts

•

Inaccessible items

Careful design and planning help to minimize the effects of these conditions. A major component of quality for offshore coatings includes cure and recoat times before returning a facility to service. Critical areas are the +/- 10-foot splash zone, work decks and helidecks, and sweating equipment and piping. See detailed information about quality control for offshore coatings in Section 800 of this manual.

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Keys to Successful Projects Comprehensive quality control activities are, however, key to any successful project. The quality control for a specific project depends not only on type of project but also on available resources: financial and personnel. Most projects have the best financial result over the structure’s life by involving qualified individuals in the project at the most appropriate time for as long as necessary to ensure that the specifications are prepared properly and met. Regardless of the size, among the keys to success of any coating project are the specifications, specialists and inspectors, and the Company’s Project Development and Execution Process (CPDEP).

Specifications

☞

Caution Avoid the pitfall of writing specifications so vague and general that they confuse everyone and allow the contractor to provide substandard work. A well-written specification includes: • • • • •

Requirements for the pre-job conference Coating schedule for all items Work schedule Materials, including coatings and abrasive Minimum standards for equipment

Example: Equipment such as moisture traps on coating and blast pots, coating gun types and hose sizes, and quality of compressed air.

Coating Specialists and Inspectors Industrial coating applications are highly specialized work processes that require support from individuals with particular knowledge and experience: the coating specialist and inspector. Coating Specialist. A coating specialist provides the project's engineering team with: •

Advice about selecting, inspecting, and applying coatings

•

Information about premature failures

•

Technical and tactical recommendations for day-to-day activities and interaction with the contractor

Coating Inspector. The goal of the project's coating inspector, usually a contractor, parallels the program's objectives to ensure that all surfaces are prepared and all coatings applied within specification. The inspector: • •

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Enforces the specification during each phase of the work activities Maintains detailed records of the coating activities

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Note These records are extremely important in case of litigation and provide the engineering team with daily work updates and recommendations. See also the sections below on Inspections and Inspectors.

Company’s Project Development & Execution Process (CPDEP) By taking the Front End Loading (FEL) approach of CPDEP (adding coating experts to the team during the design-and-fabrication phases), the projects team eliminates the problem of materials leaving the fabrication yard with an aesthetically acceptable, yet otherwise short-term and non-corrosion-resistant coating. Example: During the 1980’s, one of the Company’s profit centers spent over $15MM to repair fabrication work that had failed prematurely (needing major re-work in four years or less). Costly replacement of corroded equipment/structures and repair of premature coating failures are often attributable to the work in fabrication yards.

162 Inspection Programs An inspection adage states: People do not as you expect. People do as you inspect. Inspecting a coating ensures that it meets specifications for the particular project and provides maximum protection over the coating’s expected life. In the Company, there are three inspection programs: one complete and two levels of partial inspections (Figures 100-2, 100-3, 100-4). The three inspection programs require inspectors of varying levels of qualification. The level of inspection chosen for a coating project is primarily a function of the acceptable risk involved if a coating fails prematurely. Corrosion and aesthetics are the two main reasons for applying an external coating. The engineer must choose the best inspection program to meet the needs of the particular project cost effectively. •

For external coating projects where corrosion is a concern, the Company recommends a complete inspection program, the most conservative, reliable, and costly method of inspection.

•

If aesthetics are the only concern, then either of the two partial inspection programs may be adequate; but some of these projects may require complete inspection.

The Company's representative and the inspector (if different) should agree on a method of reporting the test results and observations of the inspection. A copy of the Company's recommended form, COM-EF-844, is available in this manual. The inspector files a copy of reports with the Company's representative.

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Complete Inspections A complete inspection requires a full-time, qualified inspector. The most conservative and costly of the three programs, a complete inspection is recommended when a coating’s reliability is critical. The complete inspection checklist (Figure 100-2) is a compilation of items the inspector should examine to ensure that the work satisfies all requirements of the specification. While all items are important, they are ranked in terms of relative importance: c—critical, n—necessary, and a—applies. Missing an “a” item has lower potential effect on the life of the coating than missing the others. Fig. 100-2

Inspection Checklist—Complete Inspection (1 of 2)

A qualified coatings inspector ensures the lining work meets the Chevron Specification. The inspector keeps records (using the Company's Standard Form COM-EF-844 or another form agreed upon by the Chevron representative and the inspector) and files a copy of the report with the Chevron OPCO. Each inspection item below has a code letter that indicates its relative importance. Items marked with a (c) are critical, those with an (n) are necessary, and those with an (a) apply. All items are important; but, if an (a) item is missed, the potential impact on the coating life would not be as great as missing a (c) or an (n) item. I. Pre-Job Check Out

❏

A.

(c)

Review Chevron OPCO Specifications.

❏

B.

(c)

Check tank for inaccessible areas, laps, patches, rough welds, weld spatter, etc.

❏

C.

(c)

Check surface for grease, oil, moisture, etc.

❏

D.

(c)

Check abrasive for cleanliness, dryness, etc.

❏

E.

(a)

Check abrasive for type and size.

❏

F.

(c)

Check compressed air for oil and moisture.

❏

G.

(a)

Check nozzle air pressure.

❏

H.

(n)

Check that proper coatings and thinners are present.

❏

I.

(c)

Check to see the coating has not passed its shelf life.

❏

J.

(a)

Record product name, manufacturer, and batch number.

II. Surface Preparation

❏

A.

(n)

Check ambient conditions.

❏

B.

(c)

Check degree of surface cleanliness.

❏

C.

(c)

Check surface for salts or other contaminates.

❏

D.

(n)

Check surface profile.

❏

E.

(c)

Check dust and abrasive removal.

❏

F.

(a)

Take magnetic base reading.

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Fig. 100-2


Inspection Checklist—Complete Inspection (2 of 2)

III. Application—First Coat

❏

A.

(c)

Check surface for flash rusting.

❏

B.

(c)


❏

C.

(n)

Check steel temperature.

❏

D.

(c)

Check proper mix ratio observed.

❏

E.

(n)

Check for proper thinner addition (when necessary).

❏

F.

(a)

Check wet film thickness.

IV. Application—Subsequent Coats

❏

A.

(c)

Check dry film thickness of preceding coats.

❏

B.

(c)

Check recoat times observed.

❏

C.

(c)

Check intercoat cleanliness.

❏

D.

(c)


❏

E.

(n)

Check steel temperatures.

❏

F.

(c)

Check proper mix ratio observed.

❏

G.

(n)

Check for proper thinner addition (when necessary).

❏

H.

(a)

Check wet film thickness.

❏

I.

(c)

Repeat for every coat.

V. Final Inspection

❏

A.

(c)

Check visual appearance.

❏

B.

(c)

Check dry film thickness.

❏

C.

(c)

Holiday test. (Required only for interior coatings)

❏

D.

(c)

Cure test.

❏

E.

(c)

Verify all touch-up and repair work.

❏

F.

(c)

Complete records and copy Chevron OPCO.

❏

1.

Verify compliance to specification.

❏

2.

List work, if any, not in compliance and why.

Partial Inspections The Company has two levels of partial inspection, Level 2 being the more limited. Partial Inspection Level 1. Partial Inspection Level 1 (Figure 100-3) differs from a complete inspection not only in the inspector’s qualifications and time on the project, but also in the number of tests required. The inspector examines or tests particular items—highlighted on the checklist— during and on completion of the work. Time and cost permitting, the inspector may

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also verify the critical and necessary items on the Checklist For Complete Inspection (Figure 100-2) as any extra inspection improves the coating’s reliability. Partial Inspection Level 2. Partial Inspection Level 2 (Figure 100-4) is the minimal inspection for any tank or vessel coating project and is recommended only if the Company is willing to accept the risk of premature failure of the coating

☞ Fig. 100-3

Caution Select Level 2, the lowest recommended level, only after evaluating the project carefully and considering the risks of a premature failure.

Inspection Check List—Partial Inspection—Level 1 (1 of 2)

All items listed are critical to Level 1 Partial Inspection and should be conducted by someone familiar with coatings inspection. This person may be a qualified inspector, an experienced Chevron inspector, or an engineer with a good knowledge of coatings inspection. The inspector should keep records (using the Company's Standard Form COM-EF-844 or another form agreed upon by the Chevron representative and the inspector) and should file a copy of the report with the Chevron OPCO. I. Pre-Job Check Out

❏

A.

Review Chevron OPCO Specification.

❏

B.

Check tank for inaccessible areas, laps, patches, rough welds, weld spatter, etc.

❏

C.

Check surface for grease, oil, moisture, etc.

❏

D.

Check abrasive for cleanliness, dryness, etc.

❏

E.

Check to see the coating has not passed its shelf life.


❏

A.

Check degree of surface cleanliness.

❏

B.

Check dust and abrasive removal.


❏

A.

Check surface for flash rusting.

❏

B.


❏

C.

Check steel temperature.


❏

A.

Check dry film thickness of preceding coats.

❏

B.

Check recoat times observed.

❏

C.

Check intercoat cleanliness.

❏

D.

Check ambient temperatures.

❏

E.

Check steel temperatures.

❏

F.

Repeat for every coat.

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Fig. 100-3


Inspection Check List—Partial Inspection—Level 1 (2 of 2)

V. Final Inspection

❏

A.

Check visual appearance.

❏

B.

Check dry film thickness.

❏

C.

Holiday test.

❏

D.

Cure test.

❏

E.


❏

1. Verify compliance to specification.

❏

2. List work, if any, not in compliance and why.

Fig. 100-4

Inspection Checklist—Partial Inspection—Level 2 (1 of 2)

All items listed are critical to Level 2 Partial Inspection. This is the minimum inspection to be performed when lining a tank or vessel. With a little planning and thought, an OPCO engineer or construction representative can carry out all of these tests. The inspector should keep records (using the Company's Standard Form COM EF-844 or another form agreed upon by the Chevron representative and the inspector) and should file a copy of the report with the Chevron OPCO. I. Pre-Job Check Out

❏

A.

Review Chevron OPCO Specification Know what the specification requires so you can discuss it with the coating contractor.

❏

B.

Check tank for inaccessible areas, laps, patches, rough welds, weld spatter, etc. Linings will not cover irregular or rough surfaces adequately. Welds should be ground smooth and sharp corners rounded. If not possible, apply a stripe coat of the lining material after surface preparation.

❏

C.

Check surface for grease, oil, moisture, etc. The biggest cause of premature lining failures is a contaminated surface. Cleanliness is the single most important step in the lining of a tank or vessel.

❏

D.

Check to see the coating has not passed its shelf life. This is a simple step; old coatings are hard to apply and will not perform properly.


❏

A.

Check degree of surface cleanliness. Linings require abrasive blast cleaning the surface to a “White Metal Blast” (SSPC-SP5). See Abrasive Blast Coating Guide for Aged or Coated Steel Surfaces in the Coatings Manual for a visual guide to judging degrees of abrasive blast cleaning.

❏

B.

Check dust and abrasive removal. Visually check to see there is not any dust or abrasive residue on the surface to be lined. Dust or residue can cause the lining to have poor adhesion.


❏

A.

Check surface for flash rusting. After abrasive blasting, the surface can flash rust due to high humidity or salts on the surface. Linings applied over a rusted surface will fail prematurely.

❏

B.

Check surface for moisture. Do not apply linings if the surface is damp. This usually happens when the surface is below the dew point. Linings applied over moisture will not adhere.

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Fig. 100-4

Coatings Manual

Inspection Checklist—Partial Inspection—Level 2 (2 of 2)


❏

A.

Check recoat times observed. Most linings have a maximum and minimum recoat time. The times are dependent on the temperature; higher temperatures equal shorter times. The lining manufacturer’s data will give you the recoat time at a standard temperature. If your temperature is different, call the manufacturer’s representative.

❏

B.

Check intercoat cleanliness. Make sure the first coat has not been contaminated before applying subsequent coats.

❏

C.

Repeat Sections III & IV for every subsequent coat.

V. Final Inspection

❏

A.

Check appearance. Visually check for runs, sags, skips, etc. If the job looks good, then the contractor probably did a good job. If not, you might want to do some of the testing listed in Partial Inspection, Level 1.

❏

B.

Check dry film thickness. While present, have the contractor calibrate his dry film thickness gage and randomly check the lining to see if it meets the specified dry film thickness.

❏

C.

Final Cure. Check with the lining manufacturer on how long to wait before putting the tank or vessel in service. Circulating hot air through the tank or vessel will shorten the time.

❏

D.

Verify all touch-up and repair work. There will usually be some touch-up or repair work, so verify that it has been done.

❏

E.


❏

1. Verify compliance to the specification.

❏

2. List work, if any, not in compliance and why.

163 Inspectors To carry out a thorough inspection, the inspector may be a Company employee or a contractor but must be trained, experienced, and familiar with a variety of coating methods and equipment. Whether full- or part-time, the inspector should participate in all inspections at the completion of the coating contract and must inspect the finished project before the end of the contractor’s guarantee.

Qualifications Full-time Inspector. A qualified, full-time coatings inspector must have one of the two backgrounds below: Certified and experienced. • •

November 1998

National Association of Corrosion Engineers (NACE)-certified Level III Experience inspecting tank and vessel coatings

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Uncertified, trained, and experienced. •

No certification

•

Some industry-accepted training

•

At least five years of verifiable experience inspecting coatings on tanks and vessels

Example: Industry training coating courses are offered by KTA-Tator, S.G.Pinney, or Bechtel. Part-time Inspector. A qualified, part-time inspector must be: • • •

Familiar with the different methods of inspection Capable of identifying potential problems and analyzing results Experienced in coating inspections

This inspector may be • • •

A qualified third-party inspector An experienced Company inspector An engineer familiar with coating inspections

Responsibilities Full-time inspector. The full-time inspector reviews the project prior to start up and is present whenever the fabricator is working offsite or the contractor onsite and during hold points in the project, normally: • • • • •

Prior to starting work After preparing the surface Prior to applying each coating Following application of the final coating Following the final cure

Part-time inspector. The part-time inspector must be available to examine the coating during the project's hold points.

Guidelines for all Inspectors The inspector: •

Should remain unchanged for the duration of the project

•

Must be able to reject work on any area which satisfies neither the specification nor good practice

•

Should not relax the requirements in the specification without written instructions from the Company's representative

•

Should conduct business in a professional manner at all time and: – –

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Follow positive inspection methods Practice diplomacy with coatings applicators and production personnel 100-35

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– – •

Interact with the foreman on all matters concerning coatings applicator and work practices—not supervising coatings applicators directly Anticipate problems; initiating preventive action

Must have a reasonable period of time to review and become familiar with the specifications, contract documents, and the worksite before the project begins

Note Familiarity with the worksite means learning about the accessibility to and condition of the structure for the coating project.

Evaluation Reports The Company's representative should prepare an evaluation report about the inspector's work.

164 Monitoring Progress The time it takes a coatings applicator to move from one operation to another affects the cost of a project.

Initial Setup Time The first transition period begins when the coatings applicators start work and ends when they begin the first daily activity; usually blasting, coating, or rigging. If a coatings applicator consistently requires more than the allotted time to set up, the inspector should investigate and take appropriate corrective action.

Transition Times Transition time may demonstrate the foreman and crew's effectiveness and the overall organization of the operation. Example: If an eight-man crew has one hour of excessive transition time, the effect is equal to an additional eight-and-a-half manhours for the project. See Figure 100-5. Fig. 100-5

Transition Times for Coating Crews Exceeds Normal Transition By

Additional Man Hours

Setup

30 Minutes

4

Blowdown

20 Minutes

2.5

Paint Pot Refill

5 Minutes (each refill)

2(1)

Activity

Total

8.5

(1) Based on 30 gal (114L) with two 5-gal (19L) setups

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165 General Inspection Procedures See the Quick Reference Guide of this manual for information about ordering inspection tools and standards.

Daily The following should be completed on a daily basis: •

Conduct pre-inspection of work area before blasting and coating, checking for protection of equipment, inaccessible areas, and hazardous areas

•

Meet with the foreman of the coatings applicators to plan daily work schedule, discuss positive aspects and potential problem areas of project, compare paperwork

•

Coordinate work with production activities

•

Order materials on timely basis

•

Check contractor's equipment

•

Check work and safety practices for compliance

•

Ensure that work area is square and clean

•

Prepare and submit reports; report to the Company's representative, as required

Before Surface Preparation Surface preparation is critical to any coating project. Faulty surface preparation is estimated to contribute to 75 to 80 percent of all premature failures of coatings. Example: Surface preparation factors that affect the life of the coating include: •

Residues of oil or grease

•

Residues of chemical salts, rust, and loose or broken mill scale which lead to early failure

•

Tight mill scale, which leads to longer term failure, and surface condensation

•

Defects found before or after surface preparation

Before surface preparation begins, the inspector should:

Chevron Corporation

•

Examine surfaces to decide how much preparation is required; good lighting during examination is very important

•

Record the condition of steel surfaces and include all information on such defects as rolling laps, cracks and pitting

•

State the condition of surfaces other than steel

•

Check for protection of equipment, inaccessible and hazardous areas

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Weather Conditions. The weather required for abrasive blasting is the same as for coating. To ensure that rust does not form on the abrasive-blasted surface before a coating is applied, specify that the area blasted with abrasive be no larger than can be coated within the same day or within eight hours of blasting. The inspector should: • • •

Determine the weather window needed to prepare the surface and apply coatings Check the weather forecast Read the coating data sheets for acceptable temperature and humidity ranges

Air Compressors for Blasting. Air compressors for blasting should supply oiland water-free air at the correct pressure. The inspector should check the compressor regularly (daily, unless tests show the equipment to be in good working order) by releasing air into a white cloth and checking it for moisture or contamination. If surface cleaning is poor or proceeding slowly, the inspector should: •

Test the nozzle's air pressure by inserting a hypodermic needle air-pressure gage into the hose as close to the nozzle as possible

•

Check the nozzle with a nozzle-throat gage to ensure that the orifice is the proper diameter

•

Not rely on pressure readings at the compressor as these differ from nozzle pressure due to pressure loss in the hose. Typically, 100 psig is required at the nozzle to obtain adequate cleaning and productivity.

Abrasive material. Abrasive material should be clean, dry, and the correct type and size for the specific work. The inspector should ensure it meets these criteria.

After Surface Preparation The inspector should check all surfaces when the preparation is completed and immediately before coatings applicators apply any coating. The surface must meet the preparation requirements for the specified coating system. The inspector should judge the preparation quality: •

Of hand-cleaned steel against the relevant SSPC (Steel Structures Painting Council) standard

•

Of blast-cleaned steel against the relevant SSPC or NACE standard

•

By visual comparison against the Swedish standards, NACE Pictorial Standards, or the SNAME (Society of Naval and Marine Engineers) standards

The inspector should measure the roughness of the surface to ensure that the blast profile complies with the specifications. Note Testex Press-o-Film Replica Tape with a spring micrometer is the best way to measure surface profile.

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Before Applying Coatings The coatings applicator arranges for repair and reblast of all surface defects exposed by preparation before applying coating. The Company’s engineer should review and approve the repair method. Coating Supplies. The inspector should check supplies at the jobsite to ensure that: •

The correct coating is on hand

•

Sufficient quantities are available

•

The shelf life is not exceeded

•

The correct thinners are available for thinning the coating material, if required, and for cleaning equipment

•

Storage conditions are adequate

Method of Application. The coating contractor is usually free to choose the method of application; however, it must comply with one of the manufacturer's recommended procedures. If there is doubt, the Company's representative should require the contractor to run a test, proving that the coating film of the proposed method complies with the specification. The inspector should be present during tests and should judge the results. Mixes, Proportions, Incubation. Before the coating is applied, the coating inspector should ensure that: • • •

All coatings are properly mixed Multi-component coatings are in the correct proportions Proper incubation periods are met

Note Inadequate mixing or improper proportioning of multi-component coatings can cause soft spots which may dry a slightly different shade of color.

During Coating The inspector should check that each layer of a coating system meets the specifications for: • • •

Coating thickness General quality of the coating, such as hardness, freedom from pinholes, or sags Dry film thickness (DFT)

The coatings applicator should:

Chevron Corporation

•

Thin the coating according to the supplier's data sheets

•

Check viscosity before applying thinned coatings

•

Check the coating's film thickness with a wet film thickness gage immediately after applying it

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The coating contractor must know the thickness of films specified by the manufacturer. The specifications usually give normal DFT and place a limit on maximum thickness; some give maximum and minimum values. Although coating manufacturers specify only DFTs, inspectors should: •

Use wet film measurements for control during actual application Multiply wet film thickness by the volume percent solids of the coating; the result gives the actual DFT of the coating

•

Measure the thickness of wet-coating films with comb gages A representative from the Company, not the contractor, should approve gages for measuring dry film thickness. The coatings applicator should calibrate the gage daily according to the National Bureau of Standards' Calibration Standards. If films are not the correct thickness, the coatings applicator must adjust both the technique and equipment appropriately to meet the specification and to avoid rework.

Note Refer to industry standard SSPC-PA2, “Measurement of Dry Paint Thickness With Magnetic Gages.”

Five Critical Subjects of a Final Inspection The five critical subjects in the final inspection of a coating project are appearance, dry film measurement, curing tests, touch-up and repair verification, and inspection records. Appearance. The appearance of a coating can highlight problems with aesthetics or suggest probable, premature failures of the coating. The inspector can assure that there are no runs, sags, blistering, or pinholes by checking the appearance of the coating. Dry Film Measurement. The inspector must measure the dry film thickness to ensure that coatings applicators have applied the specified proper amount of coating. Curing Tests. Surface temperature, ambient conditions, coating formulation, and film thickness affect the curing rate. Laboratory testing of coating chips is the only true means of verifying cure. Field techniques include the following: •

☞

November 1998

Solvent rub—On epoxy coatings, the inspector rubs the surface of the coating with a clean cloth saturated in a strong solvent, such as methyl ethyl ketone (MEK) or methyl isobutyl ketone (MIBK). If the material is mixed and cured properly, no color will transfer to the cloth. If the coating is mixed or cured improperly, it will redissolve and the color will transfer to the cloth.

Caution

Do not use the solvent rub test for alkyds and vinyl.

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•

Sandpaper test—The inspector abrades the coating with fine sandpaper. If properly cured, it produces a fine powdery residue; if not, a slightly tacky coating remains on the sandpaper.

•

Hardness test—The inspector checks the coating's cure with a Barcol hardness tester or pencil hardness tester by: – – –

•

Exerting a light, perpendicular pressure on the instrument which holds a hardened steel indentor, ground to microscopic accuracy. Reading the spring-loaded indentor's level of penetration directly from a scale's dial which is divided into 100 graduations. On soft materials, this device takes the highest reading because cold flow permits the spring-loaded indentor to continue penetrating. It is available in several models, according to the relative hardness of the test material.

Thumbnail test (can the coating be scraped or removed?) - Popular with experienced inspectors, the thumbnail test is an effective means of determining the need for more qualitative testing methods.

Touch-up and Repair Verification. The inspector verifies all touch-up and repair work and includes this information in the final report. Inspection Records. The inspector gives copies of all records to the Company's representative and completes the following: •

Daily, written reports of all items checked and verifying that the coating project complies with any specifications, giving reasons for any work that does not

•

A final report not only giving comments on repairs, overall assessment of the project, and ideas for improvement, but also with all daily reports attached

Both the Company's representative and the inspector should sign the final report.

166 Specific Inspection Procedures Downhole Tubular Coatings The inspection section of specification COM-MS-4732 contains the recommended inspection program for coatings projects involving downhole tubulars. Those who need assistance interpreting the specification or have any questions pertaining to the specification should contact the Company's coating specialist listed in the Quick Reference Guide.

Internal Coatings In addition to the general inspection procedures, the following items apply to internal coatings. Temperature and Humidity. Weather conditions are critical to the application and curing of coatings. The inspector must make sure the surface is dry and temperature is above the dew point to avoid condensation. Almost all internal coatings cure by a chemical reaction which produces heat and will not cure properly if the

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ambient temperature is too low. The guidelines for temperature and humidity in COM-MS-4738 are acceptable for most internal coatings, but always check the manufacturer’s instructions too. The inspector must read and then record atmospheric conditions in the daily reports to verify that no moisture is present on the surface to be coated. Film Thickness. Inspectors measure dry film thickness (DFT) with a magnetic filmthickness gage or a Company-approved equivalent. They should check film thickness of each coat and the final thickness of the coating. Each coat should be within the specified range because an extra heavy coat (applied to correct another coat’s insufficient thickness) may crack or cure improperly. The inspector should ensure that the coatings applicator repairs any defects after applying each coat.

☞

Caution

Using a subsequent coat to cover defective areas is unacceptable.

Pinholes and Holidays. The inspector must examine 100 percent of the finished coating for pinholes and holidays. •

Check thin films (1 to 20 mils) with a low-voltage (67-volt), sponge holiday detector, which sounds an alarm if the fluid in the sponge comes in contact with the underlying steel.

•

Check thick-film coatings (20 to 200 mils) with a high-voltage (nondestructive voltages of usually 100 to 150 volts per mil) holiday detector. This voltage gives the spark enough energy to jump across the gap between the coating surface and the underlying steel if a holiday exists, but not enough energy to break through the coating.

Most coating resin materials (epoxies, isopolyesters, vinyl esters) have a dielectric strength of 300 to 350 volts per mil. It is important to have sufficiently high voltage to bridge the pinhole's air gap to the steel substrate without burning through the solid coating. The voltage recommendations of the coating suppliers are normally acceptable. Note If a final wax or gel coat is required, the inspector should carry out the holiday test and require coatings applicators to make any repairs before the final coat is applied. This requirement prevents the wax or gel coat from covering up possible holidays in the underlying coats. If the coatings applicators make any repairs after applying the wax or gel coat, they must remove that coat and re-apply it after completing the necessary repairs. Water Test. Scheduled after the voltage test, the water test involves filling the tank with water (sometimes salt water) and leaving it for several days. After the tank is drained, rust spots on the coating reveal pinholes. The test is more complete than the voltage test because water touches all surfaces of the tank; the low-voltage sweeper may miss some parts. Note The Company runs the water test infrequently as it is expensive and time consuming.

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Testing for Final Surface Cure. The inspector must test the final surface cure of laminates with a Barcol hardness tester and an acetone wipe test. This requirement is particularly important for isopolyester and vinyl ester resins which will not fully cure without a wax coat. Note The coatings applicator must sand off the wax layer to obtain an accurate test because full surface curing is essential for the coating to have its optimum chemical resistance.

Offshore Coatings The inspection process for offshore coatings is detailed in specification COM-MS-4771. Those who need assistance with interpreting the specifications or have other questions pertaining to the specification should contact the Company’s coating specialist (see the Quick Reference Guide).

Pipeline Coatings There are many different types of pipeline coatings, each with many completely different properties and application procedures. The Company therefore recommends following the inspection procedures written as part of the various specifications for each type of coating system. Those who need assistance with interpreting the specifications or have other questions pertaining to the specification should contact the Company’s coating specialist.

☞

Caution Due to the environmental risk associated with the failure of a pipeline coating, the Company recommends following the most complete inspection program available, which includes having a full-time, qualified inspector.

167 Instruments, Tools, and Equipment The inspector must have available all of the instruments, tools, and equipment necessary to perform the inspection tasks properly. The following is a list of coating tests and test tools: •

Ambient Coating Condition –

•

Psychrometer—For determining temperature, humidity, and dew point at the jobsite

Surface Temperature Gage—For measuring the temperature of steel

168 Protecting the Company’s Equipment Many of a project's methods, costs, and problems are related to protecting the Company's equipment. The following are simple, efficient, and cost-effective procedures for protecting common equipment items. The inspector must monitor these procedures closely and ensure the coatings applicators perform them before and throughout blasting and coating operations.

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Wrapping Lights Problem:

Protective light lenses are sensitive to overblast and overspray.

Solution:

Wrap in plastic sheeting and duct tape.

Problem:

Sheeting melts on the protective lenses.

Solution:

Wrap lenses in chicken wire before wrapping in the sheeting. This will prevent sheeting from melting and provide more permanent protection for the entire job.

Plugged Drains Problem:

How to prevent sand from clogging drains while allowing small amounts of water to drain through when raining or when washing area.

Solution:

Stuff filter media (woven polyester fibers, and adhesives for filtering air intakes on engines) into the drain and tie to the cover with a piece of manila twine.

Problem:

Drains surrounded by troughs. Can coatings applicator remove sand without shoveling out each trough?

Solution:

Lay a sheet of filter media over the trough in addition to plugging the drain.

Protecting Sensitive Equipment A common misconception is that, during dry blasting, you cannot filter air intakes on compressors and other engines; therefore, costly wet blasting is necessary. Problem: How to prevent sensitive equipment from the contamination of blasting by taking oil samples, installing filter media, and installing filters. Solution 1 – Oil Samples: 1.

Before blasting operations begin, take an oil sample from each engine and send it to a lab for analysis to identify any previous sand or other particle contamination.

2.

When blasting has started, take an oil sample from each engine at least every two weeks for the duration of the project to identify any potential problems and allow time for corrective action before any major damage occurs.

Solution 2 – Filter Media:

November 1998

1.

Install filter media (to trap particles of five microns or less) with the adhesive side on the outside to catch small abrasive and dust particles and to prevent the unit from sucking the sticky side into the primary filters.

2.

Ensure coverage of all possible air passageways into the equipment, covering each corner and edge of the filter housing.

3.

Install two layers of media, where possible, to ensure 100 per cent filtration at all times and to eliminate unnecessary downtime during blasting. Change the

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outer layer only; leave the inner layer to filter dust during the several-minute changeout process. 4.

Monitor the filtration closely to ensure that it is adequate and installed properly.

Containment Screens Problem:

Isolate particular areas to keep the remainder of a facility clean during blasting (reduces cleaning time).

Solution:

Strategically position containment screens, usually square or rectangular polypropylene solid or mesh screens of various sizes from 40 ft. × 40 ft., to collect spent blast abrasive, dust, and airborne particles of coating.

Protection from Overblast Problem:

How to reduce overblast significantly (and premature failure of coatings) with proper blasting and coating techniques and preventive wrapping and shielding.

Solution 1– Keep your work area square means completely blasting and Squaring Work coating an entire group of items without having to return to the Area: area for additional blasting. Requires proper planning, thorough inspection, and precise instructions to blasters. Note Items in square work area include the tops and bottoms of all piping, braces and stiffeners, the interior of the wide flange beam webs and flanges, and the bottom side of the beam flanges. Solution 2 – Blasting Procedures:

Re-sweep before squaring work area after carrying out several days of rough blasting with appropriately sized blast nozzles and abrasive. Proper blasting technique ensures the blast nozzle is pointed away from previously coated surfaces and toward the surfaces to be blasted, especially during touch-up feathering and spot blasting.

Note Rough or high-productivity blasting calls for larger nozzles, orifice sizes of 5/16 inch or larger venturi; spot and touch-up blasting require smaller nozzles, 3/16 inch or smaller, with straight-bore orifices. Solution 3 – During blasting and coating, wrap to protect all items that will Protective Wrap-neither be blasted nor coated. The cost of the labor and materials ping: necessary to add protective wrapping results in a far superior job and minimizes costs for rework of prematurely failed areas.

Common Shielding Plastic sheeting, tarpaulins, and burlap sacks are some of the more common shielding materials. Problems: •

Chevron Corporation

Plastic sheeting is susceptible to overblast damage.

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November 1998


• •

Coatings Manual

Tarpaulins are expensive and damage easily. Burlap holds blowdown abrasives which could fall on cleaned areas.

Solution: Rubber sheeting and plywood. Both have distinct advantages over common shielding. Rubber Sheeting. Although the initial cost of rubber sheeting is relatively high, $3 to $4, per linear foot ($8 to $10 per linear m) for a 36-inch (90 centimeter) wide section, its purchase is justified because of its many advantages. One-eighth-inchthick (three-millimeter thick) rubber sheeting is •

Pliable – –

•

Works into tight spaces on vessels Wraps around piping and flanges

Resilient, so that abrasive – –

Simply bounces off Causes little damage to sheeting

•

Easy to cut as needed

•

Re-usable

Plywood Sheeting. Normally, most coatings applicators do not use plywood to its full potential. Plywood makes: •

Good flooring material in the mixing area to protect areas such as platform decks from coating spillage

•

Dividers for several men working in a confined area. Drill holes around the perimeter for air circulation and observation, then stand plywood boards upright in a zigzag manner to help keep the boards upright.

•

A suspended ceiling to protect overhead items from overblast and overspray. Tie sections together to form the ceiling.

170 References 1.

November 1998

Chevron Corporation. Corrosion Prevention Manual. Chevron Research and Technology Company. Richmond, CA, January, 1994.

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Chevron Corporation

200 Environment, Health & Safety Abstract This section discusses considerations for coating projects involving environment and health, and includes standards and practices for lead and volatile organic compounds, surface preparation processes such as abrasive blasting, and proper disposal of wastes from coating projects. Information about workers' safety which focuses on the responsibilities of both the Company and contractors' personnel when working on Company projects is also provided along with descriptions of coating-related hazards—fire, explosion, and equipment—and their prevention.

Chevron Corporation

Contents

Page

210

Environment & Health

200-2

211

Air Quality

212

Lead in Coatings

213

Volatile Organic Compounds

220

Safety

221

Workers' Safety

222

Fire and Explosive Hazards

223

Equipment Hazards

230

References

200-17

200-21

200-1

September 1996

200 Environment, Health & Safety

Coatings Manual

210 Environment & Health The vehicles of many coatings described in this manual contain organic solvents which are volatile and are released to the atmosphere as the coating dries and cures. The Federal Environmental Protection Agency (EPA) has set standards limiting the amount of volatile organic compounds (solvents) that coatings may contain. These standards are not uniform throughout the U.S.; urban areas have the most stringent requirements. As a result of these regulations, manufacturers are developing new technologies and alternative products. Currently, they are taking two approaches: water-based coatings and high-solids coatings. To date, evaluations of these compliance coatings show their performances to be definitely inferior to existing products, with the exception of some higher-cost highsolids coatings. The Company now applies some high-performance, high-solids coatings that could substitute for other regulatory-restricted coatings. To help establish a history for new compliance coatings, it would be helpful if all users would: •

Keep records of their durability, application characteristics, and compatibility with existing coatings

•

Report findings to the coating specialist and CRTC's Materials and Equipment Engineering group (see list of Company contacts in the Quick Reference Guide)

211 Air Quality Coatings containing solvents contribute to air pollution during application and drying. It is important, therefore, that those who specify, purchase, or apply coatings know the air pollution-control regulations for the local area.

Background In 1963, the U.S. Congress passed the first regulatory Clean Air Act. Subsequent amendments created the Environmental Protection Agency (EPA) with the power to establish national ambient air quality standards (NAAQS). The Clean Air Act also required each State to create its own State Implementation Plan (SIP). The plan must ensure that all areas of the State meet the national standards. As motor vehicle exhaust and solvent evaporation are two of the biggest contributors to air pollution, the strictest regulations affect densely populated areas. (Many rural areas can meet the national air quality standards without regulation.) Direction. Air-pollution-control regulations are becoming more restrictive and widespread. In some areas, the sale or use of non-compliant coatings can result in fines of up to $1000 for each day of violation. Also, for those who knowingly continue to violate the law, the penalty can escalate to $25,000 a day.

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Note Several good sources of information about those regulations are local enforcement agencies, coating vendors, coating contractors, and CRTC's coating specialists. Contact information for all except local agencies is listed in the Quick Reference Guide.

Blast Cleaning For dry, unconfined, blast cleaning, consider health and environmental safety restrictions when selecting the type and brand of abrasive. Many sand abrasives contain free silica, which, upon prolonged inhalation, can cause silicosis, a condition of massive fibrosis of the lungs that results in shortness of breath. For this reason, regulations often limit the acceptable amount of free silica in abrasives. Example: The Richmond Refinery limits free silica to 1 wt percent which eliminates the use of sand abrasive but not most grit, slag, and shot abrasive. Some abrasives cause a fine dust to form a dust cloud which some government agencies classify as visual-smoke pollution. Example: The State of California Air Resources Board (CARB) restricts the amount of fine particles in abrasives both before and after blasting.[1] Certain California counties also restrict the type of abrasives. Abrasives are tested in accordance with California Test Method No. 371-A, Method of Test for Abrasive Media Evaluation, and must meet the following criteria: • •

Before Blasting: <1 wt percent of abrasive smaller than No. 70 U.S. Sieve size After Blasting: <1.8 wt percent of abrasive smaller than 5 microns

Figure 200-1 lists the dust factors of several abrasives.

Potentially Harmful Ingredients Many coating ingredients are toxic and potentially injurious to human beings. While the human body may withstand small quantities of these substances for a relatively short time, continuous exposure is harmful. Through continued exposure to some materials, such as isocyanate in urethane coatings, it is possible for a person to become so sensitized that subsequent contact with small amounts of the substance may cause a strong reaction. Some materials, such as lead, have a cumulative effect so that exposure over a long time builds up the toxic level in the body until illness results. Toxic materials may be present in the form of vapor, dust, or spray mist and may enter the body by ingestion, breathing, or absorption through the skin. Examples: Toxins are found in lead or heavy metal-bearing pigments (common in industrial primers), solvents such as benzene and methanol, and vehicles composed of epoxies, urethanes, amines, and polyesters.

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Properties of Several Abrasives Used in Air-Blast Equipment

Fig. 200-1

Dust Factor

Free Silica Content

Abrasive Mesh NBS Sizes

Average Height of Profile (Mils)

Sand, very fine

High

> 90%

20/40

1.5

Sand, fine

High

> 90%

16/30

1.9

Sand, medium

High

> 90%

12/25

2.5

Sand, large

Abrasive

High

> 90%

10/20

2.8

Steel grit No. G-80(1)

Very low

None

40

1.3

Iron grit No. 50(1)

Very low

None

25

3.3

Iron grit No. 40(1)

Very low

None

18

3.6

Iron grit No. 25(1)

Very low

None

16

4.0

Iron grit No. 16(1)

Very low

None

12

8.0

Steel shot NO. S-170(1)

Very low

None

20

1.8

Iron shot No. S-230(2)

Very low

None

18

3.0


Very low

None

16

3.3


Very low

None

14

3.6

Flint sand

Moderate

> 90%

8/30

3.4

Granite sand

Moderate

< 5%

12/40

3.0

Garnet sand(1)

Moderate

< 1%

12/40

3.3

Slag

Moderate

< 1%

8/40

3.6

Slag

Moderate

< 1%

10/50

3.5

Slag

Moderate

< 1%

16/30

3.8

Slag

Moderate

< 1%

20/40

2.5

Slag

Moderate

< 1%

16/50

1.5

(1) Only used in blast rooms and cabinets so abrasive can be contained, recycled and reused. (2) Generally used in automatic blast cleaning facilities using centrifugal wheels.

While protective clothing reduces hazards from dust and spray, vapors are harder to control. All solvents vaporize in air, but the degree of toxicity varies with the type of solvent, temperature, degree of confinement, and amount of ventilation. OSHA sets permissible exposure limits for many materials.[2] A permissible exposure limit (PEL) is defined as the maximum-permitted, eight-hour, time-weighted, average concentration of an airborne contaminant in ppm in air.[3] Adequate ventilation is essential to operate within these values. Figure 200-2 shows the PEL for commonly-used solvents in the coating industry.

September 1996

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Coatings Manual

Fig. 200-2


Flammable and Toxic Properties of Commonly Used Solvents (1 of 2) Flashpoint °F of Open Cup

Toxicity P.E.L.(1), PPM in Air

Explosive Limits % of Volume in Air Lower

Upper

6.0

36.5

200

Alcohols Methanol (Methyl Alcohol)

60

Ethanol (Ethyl Alcohol)

60

3.3

19.0

1000

Normal Propyl Alcohol

96

2.6

13.5

200

Isopropyl Alcohol

55

2.5

400

Secondary Butyl Alcohol

74

1.7

150

Normal Butyl Alcohol

115

1.7

50

Cyclohexanol

154

50

Polyols Ethylene Glycols, Vapors

240

3.2

Propylene Glycol

215

2.6

Dipropylene Glycol

260

100 12.6

100 100

Esters Ethyl Acetate

30

2.0

11.5

400

Isopropyl Acetate

60

1.8

7.8

250

Normal Propyl Acetate

65

1.7

8.0

200

Isobutyl Acetate

105

1.6

Secondary Butyl Acetate

89

1.6

15.0

Normal Butyl Acetate

105

1.6

15.0

Amyl Acetate

80

1.1

Acetone

15

2.9

13.0

1000

Methyl Ethyl Ketone (MEK)

35

1.8

11.5

200

Methyl Isobutyl Ketone (MIBK)

75

1.2

8.0

100

Diacetone Alcohol

155

Cyclohexanone

129

Diisobutyl Ketone (DIBK)

115

50

Methyl Iso-Amyl Ketone (MIAK)

110

100

Isophorone

205

5

Ethyl Butyl Ketone

115

50

200 150 150 100

Ketones

50 1.1

50

Miscellaneous Active Solvents Tetra Hydro Furan (THEF)

6(2)

Dimethyl Formamide

153

Ethyl Ether

-40

11.8

200

1.8

36.5

400

10

Isopropyl Ether

Chevron Corporation

2.0

250

200-5

September 1996


Fig. 200-2

Coatings Manual

Flammable and Toxic Properties of Commonly Used Solvents (2 of 2) Flashpoint °F of Open Cup

Toxicity P.E.L.(1), PPM in Air

Explosive Limits % of Volume in Air Lower

Upper

1.2

6.9

Aliphatic Petroleum Napthas Hexane

0

100

Rubber Solvent

0

1.3

6.1

400

Heptane

25

1.1

6.0

400

VM&P Naptha

54

1.1

6.0

Mineral Spirits(3)

110

300 200

Stoddard Solvent

105

1.0

6.0

200

Kerosene(3)

140

0.9

6.0

100

Pentane

-55

1.4

8.0

600

5

1.5

8.0

10

Aromatic Hydrocarbon Solvents Benzene Toluene

41

1.3

6.7

100

Xylene

81

1.0

5.3

100

Hi-flash Coal Tar Naptha

100

1.1

6.0

100

Styrene Monomer

106

1.1

6.1

100

Terpene Hydrocarbons Gum Turpentine

93

100

Steam Distilled Turpentine

91

100

Chlorinated Solvents Carbon Tetrachloride Dichloroethyl Ether Ethylene Dichloride Methylene Chloride, Technical

None

None

None

None

131 59

6.2

15.9

200

None

None

None

None

Glycol Ethers Ethylene Glycol Methyl Ether

120

25

Ethylene Glycol Ethyl Ether

115

115

Propylene Glycol Methyl Ether

100

100

Dipropylene Glycol Methyl Ether

185

100

(1) Permissible exposure limit per OSHA General Industry Safety Order Title 8, Table AC-1 (2) Closed Cub (3) OSHA gave no date. This date is from Chevron's Materials Safety Data Sheets No. 38 for Kerosene and No. 59 for Chevron 350 Thinner (Mineral Spirits).

September 1996

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212 Lead in Coatings Lead is a basic chemical element (Pb) that: •

Exists as a heavy metal at room temperature and pressure

•

Can combine with other substances to form many lead compounds, such as those found in lead-based coating (LBC)

•

Has been used in coating for many years to improve its effectiveness

Alternative primers are, however, more common today than LBC. The Consumer Product Safety Commission (CPSC) Lead Paint Act of 1971 has determined a coating to be lead-containing if the dried coating contains more than 0.06 percent lead by weight. In most Company facilities, specially trained and equipped contractors work in large lead-abatement construction projects with potentially high exposures to lead. The Company's employees are usually involved in short-duration maintenance tasks such as welding equipment with LBC or grinding and chipping to remove LBC from equipment before welding or applying new coatings. Other activities can be a source of lead exposure. •

Abrasive-blast cleaning of steel tanks and other structures with LBC generates high levels of dust.

•

Welding, cutting, and torch burning equipment coated with LBC may cause lead fumes.

•

Spraying LBC to recoat surfaces generates an LBC mist.

Health Hazards Lead adversely affects numerous body systems after periods of exposure from as short as days to as long as several years. Exposure to Lead. Human beings can inhale and absorb lead from dust, fumes, or mist through the lungs and upper respiratory tract. Inhalation of airborne lead is generally the most significant source of occupational lead absorption. People can also ingest lead and absorb it through their digestive systems. Consequences of Exposure to Lead. A significant portion of the lead inhaled or ingested reaches the bloodstream. Once in the bloodstream, lead circulates through the body and is stored in various organs and body tissues, affecting the nervous system, blood system, and kidneys. Chronic overexposure to lead also significantly impairs the reproductive systems of both men and women. Children born of parents exposed to excess levels of lead are more likely to have birth defects, mental retardation, behavioral disorders, or die during the first year of childhood. Some commons symptoms are listed in Figure 200-3.

Chevron Corporation

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September 1996


Fig. 200-3

Coatings Manual

Alphabetic List of Common Symptoms from Overexposure to Lead in Coatings

Anxiety

Insomnia

Colic with severe abdominal pain

Loss of appetite

Constipation

Metallic taste in mouth

Dizziness

Muscle and joint pain or soreness

Excessive tiredness

Nervous irritability

Fine tremors

Numbness

Headache

Pallor

Hyperactivity

Weakness

Test Methods In Company facilities, conduct surveys to identify and quantify LBC in major equipment such as storage tanks, reactors, vessels, and even pilings. An inventory of leadcoated equipment could help to save time and money, protect Company and contract workers, and reduce Company liabilities. Both laboratory and field tests may then determine whether or not lead is present in the coatings. Note See the Quick Reference Guide of this manual for a list of some laboratories that analyze coating and air samples for lead. Atomic Absorption Spectrometry. A common laboratory test for lead in coatings is Atomic Absorption Spectrometry (AAS). AAS requires scraping a coating chip sample (e.g., about 0.5 square centimeter or the size of a dime) and sending it to a laboratory for analysis. The lab scrapes the surface down to the matrix material (i.e., bare metal, wood) because the analysis is based on weight. Processing time normally takes a few days unless the sample is rushed. The AAS method expresses results as weight-to-weight percentage of lead in the dry coating. Portable X-Ray Fluorescence Spectrum Analyzer. A non-destructive fieldtesting method, the portable X-Ray Fluorescence (XRF) Spectrum Analyzer, detects lead in the coating (including all layers of coating and the primer) and expresses the lead concentration in milligrams of lead per square centimeter (mg/cm2) of coated surface. The analyzer displays the result within a minute.

☞

Caution Because these instruments have a radiation source, only trained and licensed users may operate them. Note For information about the XRF spectrum analyzer, contact CRTC's Occupational Safety and Health Team. Chemical Spot Tests. Field-run chemical spot tests provide only qualitative results. These tests may, however, be useful as a screening tool in conjunction with the other test methods.

☞

September 1996

Caution Because the results are not as accurate as those from the AAS and XRF methods, chemical spot tests offer a much higher risk of false positives and negatives.

200-8

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Exposure Standards and Assessment The OSHA Construction Lead Interim Final Rule (29 CFR 1926.62) establishes a Permissible Exposure Limit (PEL) of 50 micrograms of lead per cubic meter of air (50 g/m3) averaged over an 8-hour period, and an action level of 30 g/m3 averaged over an 8-hour period. Note The action level triggers requirements for exposure monitoring, medical surveillance, and training. This rule applies to construction, alteration, or repair, including coating and decorating This rule includes, but is not limited to, removing or encapsulating materials containing lead. For certain tasks, OSHA requires the employer to assume employees are exposed to lead over the PEL until exposure monitoring shows otherwise. Monitoring Requirements. OSHA requires exposure monitoring initially: • • •

For each job classification In each work area Either for each shift or for the shift with the highest exposure level

Note The samples must be full-shift personal samples and representative of daily exposures. Interim Protective Measures. As noted, for certain tasks, OSHA requires the employer to assume employees are exposed over the PEL until exposure monitoring shows otherwise. These tasks, and their assumed exposure level, are shown in Figure 200-4. Fig. 200-4

LBC-Removal Tasks by Exposure Levels. OSHA Construction Lead Interim Final Rule (29 CFR 1926.62)

Exposure Level

LBC-Removal Tasks 3

Above the PEL and not in excess of 500 mg/m (10 times the PEL):

Above 500 mg/m3 and not in excess of 2,500 mg/m3 (50 times the PEL)

Above 2,500 µg/m3

Chevron Corporation

•

Manual demolition of structures

•

Heat-gun applications

•

Power-tool cleaning with dust-collection systems

•

Spray coating with LBC

•

Lead burning

•

Use of lead-containing mortar

•

Power-tool cleaning without dust collection systems

•

Rivet busting

•

Cleanup activities where dry, expendable abrasives are used

•

Moving and removing abrasive-blasting enclosures

•

Abrasive blasting

•

Welding, cutting, and burning on steel structures

200-9

September 1996


Coatings Manual

The following interim protective measures are required for these three groups of LBC-removal tasks: •

Personnel must wear appropriate respirators, personal protective clothing and equipment

•

The employer must provide hygiene facilities, biological monitoring, and training

In many cases for jobs of short duration, exposure monitoring can demonstrate that a respirator with a lower protection factor can be used. Figure 200-5 summarizes the Company's lead-exposure monitoring data for LBC. This information can help determine what level of respiratory protection may be needed. Exposure monitoring often demonstrates that a respirator with a lower protection factor is adequate for projects of short duration. Fig. 200-5

Summary of Coating-Related Occupational Lead Exposures at Chevron’s Facilities Number of Short-Term Air Samples (< 2 Hours)

Exposure Range of Short-Term Samples

Geometric Mean of Short-Term Samples

Number of Long-Term Air Samples (> 2 Hours)(1)

Exposure Range of Long-Term Samples

Geometric Mean of Long-Term Samples

Welding on metal parts or equip-ment which most likely contained some leadbased paint. In some cases, the paint may have been removed prior to the welding.

13

< 1 to 140

15

23

< 1 to 40

4

Short tasks of chipping or buffing to remove old paint from flanges or other equipment before applying new paint or before welding.

8

< 1 to 27

6

Torch burning, arc gouging, and cutting up scraps during demolition of tanks, vessels and towers.

69(2)

<1 to 770

140

Abrasive blasting to remove old-leadbased paint. The air samples were collected outside the blasting hood or helmet.

17(3)

6 to 9,200

130

Abrasive blasting to remove old leadbased paint. The air samples were collected inside the blasting hood or helmet to assess workers’ actual exposure to lead dusts.

6

< 1 to 44

7

Sand-blaster’s helpers maintain and position blasting equipment and carry out other miscellaneous tasks.

8

< 1 to 41

5

Laborers and helpers remove post-blast grits and clean up the blasting equipment.

13

< 1 to 140

9

Description of Lead-Related Jobs or Tasks

(1) Exposures Expressed as 8-Hour Time-Weighted Averages (TWA) in µg/m3 (For Exposure Monitoring Samples Collected Between January, 1984 and August, 1993) (2) Among the 69 long-term samples, 42 showed TWA exposures in excess of the OSHA PEL of 50 µg/m3 for lead. Only 3 of the 69 samples (4.3 percent), however, exceeded 500 (g/m3. On a 95 percent confidence level, therefore, a half-face HEPA respirator (suitable up to 500 µg/m3) can provide adequate protection for these demolition tasks. (3) Although 1 of the 17 samples showed TWA exposures at 9,200 µg/m3 , statistically, that sample can be classified as an outlier. During abrasive blasting, therefore, the commonly used, supplied, air-abrasive, blasting respirators (with loose-fitting hood or helmet, operated in a continuous-flow mode) can provide adequate protection.

September 1996

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Coatings Manual


☞

Caution This information is not a substitute for conducting site-specific exposure assessments.

Methods of Compliance The Company's project engineer must establish a written compliance program prior to each project in which workers' exposure may exceed the PEL. The compliance program must provide for frequent and regular inspections of job sites, materials, and equipment by a competent person. Note

A competent person is one who has both of the following:

•

Ability to identify—in the surroundings or working conditions—existing and predictable lead hazards that are hazardous to workers

•

Authority to take prompt, corrective measures to eliminate those hazards

Written Programs. Written programs should include the following: •

A description of each activity during which lead will be emitted

•

Specific plans for achieving compliance, including engineering plans and studies if engineering controls are required

•

Information on the technology which will be used to meet the PEL

•

Air monitoring data that documents the source of lead emissions

•

A detailed schedule for implementing the program

•

A work-practice program, outlining all regulations for protective work clothing and equipment as well as guidelines for housekeeping and hygiene in the facility

•

An administrative control schedule for job rotation, if needed

•

The details of any arrangements among contractors (on multi-contractor sites) identifying the person responsible for compliance and informing affected employees of potential exposure to lead

Respiratory Protection. Personnel must wear respirators under any of the following circumstances: • • •

When the exposure exceeds the PEL If an employee requests a respirator As an interim protection until exposure levels are assessed

Note Select respirators based on the airborne concentration of lead, according to Figure 200-6. In the absence of site-specific exposure-monitoring data, always assume exposures for arc gouging, torch burning, and abrasive blasting to exceed 2,500 µg/m3. Example: A supplied-air respirator, operated in pressure demand or other positivepressure mode, is required to protect workers performing arc gouging, torch burning, and abrasive blasting.

Chevron Corporation

200-11

September 1996


Fig. 200-6

Coatings Manual

Respiratory Protection for Lead Aerosols

Airborne Concentration of Lead or Condition of Use Not in excess of 500 µg/m3

Required Respirator (1) •

Half mask air purifying respirator with high efficiency filters, (2), (3)

•

Half mask supplied air respirator operated in demand (negative pressure) mode.

•

Loose-fitting hood or helmet-powered air-purifying respirator with highefficiency filters.(3)

•

Hood- or helmet-supplied air-respirator operated in a continuous-flow mode; e.g., type CE-abrasive-blasting respirators operated in a continuous-flow mode.

•

Full facepiece air purifying respirator with high-efficiency filters.(3)

•

Tight fitting powered air purifying respirator with high-efficiency filters.(3)

•

Half mask or full facepiece supplied air respirator operated in a continuous-flow mode.

•

Full facepiece self-contained breathing apparatus (SCBA) operated in demand mode.

Not in excess of 50,000 µg/m3

•

Half mask supplied air respirator operated in pressure demand or other positive-pressure mode.


•

Full face piece supplied air respirator operated in pressure demand or other positive-pressure mode; e.g., type CE abrasive blasting respirators operated in a positive-pressure mode.

Greater than 100,000 µg/m3

•

Full facepiece SCBA operated in pressure demand or other positivepressure mode.



unknown concentration or fire fighting

(1) Respirators specified for higher concentrations can be used at lower concentrations of lead. (2) Full facepiece is required if the lead aerosols cause eye or skin irritation at the use concentrations. (3) A high-efficiency particulate filter (HEPA) means a filter that is 99.97 percent efficient against particles of 0.3 micron size or larger.

The Company's data in Figure 200-5 suggests that a half-face air purifying respirator with a high-efficiency particulate air (HEPA) filter is adequate for arc gouging and torch burning; while the commonly used supplied-air abrasive-blasting hood or helmet (operated in a continuous-flow mode) is sufficient for the task of abrasive blasting. Along with some site-specific local data, refer to the data in Figure 200-5 to select appropriate respiratory protection equipment for workers. Protective Clothing & Equipment. Personal protective equipment is required as follows:

September 1996

•

For exposure to lead above the PEL and lead compounds that may irritate skin or eyes

•

As interim protection until an exposure assessment is completed

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Protective work clothing and equipment which prevent contamination of workers and their garments include such items as: • • •

Coveralls or full-body work clothing Gloves, hats, and shoes or disposable coverlets Face shields and vented goggles

The regulations prescribe methods for cleaning, laundering, or disposing of all protective clothing. Engineering, Work Practice, and Administrative Controls. Engineering, work practice, and administrative controls help to reduce and maintain employees' exposure to or below the PEL. Examples: Engineering controls include sealed containment structures with negative pressure dilution ventilation, power tools equipped with dust collection shrouds exhausted through a HEPA vacuum system, and vacuum blasting. Examples: Work practice controls include housekeeping to remove accumulations of lead dust, and personal hygiene. Examples: Administrative controls include scheduling workers' tasks to minimize exposure levels, and worker rotation. When all feasible and instituted controls are insufficient to reduce exposure to or below the PEL, then use respirators to supplement the work operation. Hygiene Facilities. Employees may not bring food, beverages, tobacco products, and cosmetics to the job site where lead is above the PEL. In addition, they must have clean change areas, shower facilities, and lunchroom facilities or eating areas. Medical Surveillance. Figure 200-7 shows the type of medical surveillance required for various levels of exposure. Fig. 200-7

Medical Surveillance Based on Level of Exposure Description of Medical Surveillance (1)

Level of Exposure •

Occupational exposure to lead on any one day at or above the action level

•

Performing trigger tasks(2) during initial exposure assessment

Blood sampling and analysis for initial exposure assessment

Exposure to lead at or above the action level for more than 30 days a year

Program of routine blood tests made available to employees

Blood level exceeds 40 µg/dl if the exposure is or may be at or above the action level for more than 30 days a year

Full medical surveillance program, including annual medical exams

Routine and follow-up test for blood lead levels exceed the removal criteria of 50 µg/dl

Remove employee from exposure to airborne lead that exceeds the action level

(1) A licensed physician must perform or supervise the performance of all medical examinations. (2) See Figure 200-4 for trigger tasks.

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Employee Information and Training. Employees must receive appropriate training if they will be exposed to lead or lead compounds at or above the action level. Training includes subjects such as: • • • • • • • •

Health hazards Warning signs and labels Contents of the lead standard Work operations Respirators Medical surveillance Engineering controls Compliance plans

A Word About Contractors. Typically, independent contractors remove LBC from the Company's facilities for specific projects. These contractors should: • • •

Receive most or all of their directions from the contractor's personnel Follow the contractor's procedures Use the contractor's equipment

Information in this section is offered as a basis for a pre-project discussion about contractors' lead protection programs. Recommendations for a Contractor's LBC- Removal Project within the Company. The Company representative on the project should:

☞

•

Require that the contractor meet all Federal, State, and local requirements concerning lead

•

Ensure that the contractor has a competent inspector (as defined in this section)

•

Request that the contractor demonstrate that all of the contractor's employees have received appropriate training and are included in a contractor-administered, medical-surveillance program (if necessary)

•

Work with the contractor to ensure that all applicable permits, notifications, and waste manifests are in order and that the contractor disposes of leadcontaining wastes properly

Caution If the contractor's employees are found to be out of compliance with the lead standards, treat this condition as a breach of contract and discontinue work until the contractor remedies the situation.

Environmental Disposal Guidelines Federal and State regulations classify hazardous wastes as those substances that are ignitable, corrosive, or toxic. Waste and water regulations specifically restrict the disposal of lead-containing waste and wastewater. Some unused coating and solvents may qualify for disposal as hazardous wastes.

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Environmental regulations vary among states and may be more restrictive than Federal regulations. Discuss specific regulations that may apply to your waste disposal circumstances with the local environmental compliance specialist. As a minimum, Federal regulations will require the following: •

Lead contamination found in the soil may require additional investigation and clean-up.

•

Wastewater disposal criteria will be different at each facility depending on the conditions in the facility's wastewater-discharge permit.

•

Hazardous wastes must be treated before disposal, depending on the waste and the State's requirements.

Note Some States have additional restrictions on disposal of waste contaminated with lead even when it is not a hazardous waste.

☞

Caution

Diluting waste to remove hazardous characteristic(s) is prohibited.

Threshold of Lead Toxicity as Hazardous Waste. A waste exhibits the characteristic of lead toxicity when a TCLP (Toxicity Characteristic Leaching Procedure) analysis indicates Pb 5.0 mg/ l (ppm) as a measure of leachable lead after extracting the sample with acid. Handle and dispose of a waste that exceeds this threshold as a hazardous waste.

☞

Caution California has an additional analytical criterion that classifies a waste as hazardous with either of the following: • •

Pb 1000 mg/kg (by a total analysis) Pb 5.0 mg/l (by a leachable analysis similar to TCLP)

Figure 200-8 is a summary of Federal Hazardous Waste classification criteria that may apply to lead-contaminated coating wastes. It describes criteria for classifying a waste as hazardous both by lead toxicity and by listed solvent content. Additional State waste classification codes or criteria may also be applicable. Fig. 200-8

Summary of Criteria for Classification as Federal Hazardous Waste Hazardous Waste Threshold

EPA Waste Code

≥ 5.0 mg/l by TCLP method

D008

< 10 percent in spent solvent from degreasing

F001

Xylene, acetone, ethyl acetate, ethyl benzene, ethyl ether, methyl isobutyl ketone, n-butyl alcohol, cyclohexanone, or methanol

< 10 percent in spent solvent

F003

Toluene, methyl ethyl ketone, carbon disulfide, isobutanol, pyridine, benzene, 2-ethoxyethanol, 2-nitropropane

< 10 percent in spent solvent

F005

Constituent Lead Tetrachloroethylene, trichloroethylene, methylene chloride, trichloroethane, carbon tetrachloride, or chlorinated fluorocarbons

Notes:

1. Additional State waste classification codes or criteria may also be applicable to wastes from LBC.

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Waste Sources and Alternatives A variety of waste streams generated during lead abatement might become lead contaminated. Consider the effect of environmental constraints on the project's potential wastes. Examples: Lead-contaminated waste streams may include abrasive media, coating chips or dust, cleaning materials or stripping solvents, rags, wash water, solid debris, protective clothing and equipment, and containment tarpaulins. Source Reduction. From the standpoint of source reduction, determine if leadcontaminated coatings must be removed or encapsulated. Overcoating may serve to: • • •

Prevent further deterioration of lead-contaminated coatings Allow lead-contaminated coatings to remain in place Reduce exposure from the removal-and-disposal activity

Handling. Two handling techniques help to reduce the amount of waste that must be treated as hazardous. •

Segregate wastes to reduce the quantity of hazardous waste. Several types of grit recycling equipment can separate coating chips from blast media.

•

Minimize the contamination of other materials with lead-contaminated waste. Containment tarpaulins or enclosures used to control airborne dust also keep coating chips out of surrounding soil.

During a coating project, some processes generate hazardous wastes. •

Chemical stripping produces a solvent waste that may need to be handled as a hazardous waste.

•

Wet-abrasive blasting or high-pressure water creates a lead-contaminated wastewater stream that is not permitted in some wastewater systems.

Treatment. If treatment is necessary before disposal, the lead-contaminated waste is usually solidified or mixed with cement at the disposal facility. This treatment reduces its leachability. Reclamation and Disposal. Be sure to dispose of all wastes in a Companyapproved facility for either hazardous or non-hazardous wastes. Most lead-abatement work generates hazardous waste. Often the greatest liability from waste disposal, however, comes from industrial waste in poorly operated, nonhazardous-waste facilities. Equipment that is dismantled and sold as scrap can present a liability similar to disposal. Reclamation sites have been the source of the Company's greatest off-site environmental liability. Arrange for contracts involving the sale of scrap metal or surplus equipment to include many of the requirements of the Company's standard environmental services agreements. Local contracts group or legal advisors can help negotiate these terms in agreements with a reclaimer.

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Abrasive-blasting waste may be a hazardous solid waste, especially from surfaces coated with LBCs. Arrange to dispose of these wastes in appropriate sites such as California's Class I (hazardous-waste landfill) sites. There are two choices for small amounts of waste: • •

Test the waste and dispose of it in an appropriate, Company-approved facility Do not to test the waste but dispose of it in a Class I site

The cost is about $500 to run the Extraction Procedure Toxicity Test, Method 1310, for hazardous metals such as lead and chromium and organics such as pesticides and herbicides. [4]

☞

Caution

Always test large amounts to determine the proper disposal site.

213 Volatile Organic Compounds The vehicles of many coatings discussed in this manual contain organic solvents that are volatile and are released to the atmosphere as the coating dries and cures. Volatile Organic Compounds (VOC) are reported in grams/liter, and the Company expects the EPA's regulatory limit to be at or below 340 g/l for coatings. Where applicable, the VOC is noted beside each brand of coatings on the system data sheets (in the Quick Reference Guide); those marked with a bullet comply with the anticipated regulatory limit; but all have less than 420 grams/liter VOC in the can. The VOC is also listed in the Glossary of Acceptable Brands (Quick Reference Guide).

☞

Caution Thinning a coating with solvent increases its VOC level. Be sure to follow the coating manufacturers' directions for thinning. Note Check local standards for current VOC limits and consult the manufacturer's product data sheets before applying any coating.

220 Safety 221 Workers' Safety In general, the Company and its contractors are responsible for the safety of their respective employees. Normally, the employer who creates a hazardous working condition is responsible for correcting it. We should not, however, practice an absolute hands-off policy towards a contractor's safety performance. The Company's representatives have a duty to inform and warn contractors of any known safety hazards, health exposures, or environmental concerns. To minimize the Company's liability, at a minimum: •

Chevron Corporation

Make sure the equipment to be coated is in a safe condition before turning it over to the contractor; or

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Coatings Manual

•

Inform the contractor in writing of hazardous conditions that may be present and of safety procedures and equipment that are necessary; and

•

Require that the contractor's personnel follow general safety rules, such as wearing hard hats, safety glasses, and long sleeves.

Example: Richmond Refinery requires that the contractor follow the refinery's General Instructions and Safety Practices Guide. Other refineries have similar rules. The Company's Loss Prevention Guide No. 25 covers all aspects of Company/ contractor relationships except specific circumstances for temporary workers. Review the Company's safety policy with contractors and have it available for contractors' reference. These safety requirements, based on expert knowledge and specific OSHA requirements, serve as minimal guidelines for work on the Company's facilities and supplement the contractor's own safety program. In general, it is primarily the contractor's responsibility to: • • •

Assure safety of the application personnel Know the potential hazards of the materials and equipment being used Take proper steps to avoid these hazards

Example: The contractor is responsible for providing proper equipment for the safe application of coatings and proper clothing to protect personnel from ingesting and inhaling toxic chemicals or from absorbing them through the skin. The contractor is also responsible for proper disposal of the coating, cans, and solvents.

222 Fire and Explosive Hazards In general, coating and coating components are highly flammable and, in some concentrations, explosive. In Figure 200-2, there is a listing of flashpoints and explosive limits for solvents commonly found in coatings. Note

September 1996

Flashpoint is the explosive limit of a material.

•

Flashpoint: A measure of flammability, flashpoint is the average temperature at which the vapor pressure above a liquid is high enough to form a combustible mixture with air. This mixture will ignite if exposed to flame.

•

Explosive Limits: A measure of explosion potential, explosive limits are the percentages of a material in a volume of air above and below which no explosion will occur. The critical range is considered to be between the lower and upper limits for a given material. Some materials will flash or explode upon ignition if there is just the right amount of them in a volume of air. If there is not enough of the material, it will not support combustion; if too much, there is not enough air for combustion.

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Preventing Fires and Explosions The following fundamental techniques are intended to prevent fire and explosions: •

Prevent fires by keeping a material well below its flashpoint and by isolating it from every possible source of ignition.

•

Prevent explosions with proper ventilation to keep the vapor concentration below the lower explosive limit.

Note OSHA requires sufficient ventilation to keep the concentration of vapors below 20 percent of the lower explosive limit.[5] The Richmond Refinery further limits the concentrations to less than 10 percent.[6]

Abrasive Blasting During abrasive blasting, sparking is a potential fire hazard. There are three possible sources of sparks: •

Abrasive striking metal surface

•

Frictional heating of surface during blasting

•

Build up of static electricity charges due to flow of abrasive through blasting equipment

Tests have shown that sparks from the first two sources do not contain enough heat energy to ignite flammable vapors. If, however, equipment is improperly grounded, sparks from the third source can ignite vapors.[7, 8] To reduce the risk of fire during abrasive blasting, stipulate that, before a coating project begins, the contractor must: • •

Bond and ground all blasting equipment and the surface being prepared Check every connection to assure it is properly bonded and grounded

See also the Company's Fire Protection Manual.[9]

Internal Coatings Refer to both OSHA 29 CFR 1910 and manufacturers' product data sheets when working with internal coatings.[10] Many internal coatings contain flammable vapors or vapors that irritate eyes or breathing or both. •

Workers should follow these basic rules when using internal coatings:

•

Keep coatings away from heat, sparks, and flames.

•

Apply coatings only with adequate ventilation, appropriate respiratory devices, and other protective equipment.

Explosive Mixtures In addition to the potential hazard of a coating, some coating components can be highly explosive if mixed improperly.

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When preparing catalyzed polyester and vinyl ester coatings for application, combine three ingredients: the polyester or vinyl ester resin, the promoter, and the catalyst.

☞

Caution If promoter and catalyst come in direct contact, flash explosions result; therefore, follow this sequence carefully, regardless how much you are preparing: 1.

Mix the resin and promoter thoroughly. Insufficient mixing of the promoter and resin can leave pockets of promoter and cause explosions.

2.

Add the catalyst slowly.

3.

Mix completely.

Frequently, to avoid the potential of explosion, manufacturers sell pre-promoted polyester and vinyl ester (i.e., the promoter and resin are mixed at the factory). However, these mixtures have a shorter shelf life.

☞

Caution It is crucial to follow the manufacturer's recommendations when applying these types of coatings.

223 Equipment Hazards Serious injury may result from improper or careless use of high-pressure equipment, ladders, scaffolding, scrapers, and other coatings applications. Most equipment hazards can be avoided by using common sense.

Ladders and Scaffolding Ladders and scaffolding must meet the guidelines in the Company's Safety in Designs manual.[11]

Aluminum Equipment One potential danger with aluminum equipment involves coatings containing chlorinated solvents. Solvents such as 1,1,1-trichlorethane and methylene chloride can promote corrosion of aluminum. If the reaction takes place in enclosed equipment such as coating pumps or heaters, pressure can build up quickly and result in ruptures.

☞

Caution Avoid aluminum equipment when applying coatings which contain chlorinated solvents. Unfortunately, aluminum is very common in spray equipment for coatings.

High-pressure Liquid Sprayers Another potential equipment hazard involves high-pressure liquid sprayers (airless). The spray from this equipment can penetrate skin.

☞

September 1996

Caution

Handle spray equipment with care as improper use can kill.

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230 References 1.

CARB. Letter to R.D. Sweeney. Materials Laboratory File N21.01. Chevron Corporation, December 11, 1980.

2.

Office of the Federal Register, National Archives and Records Administration. Special Edition of the Federal Register. OSHA General Industry Safety Orders, Title 8, Section 5155, p. 432.262-432.270.12. United States Government Printing Office. Washington, 1995.

3.

———. Special Edition of the Federal Register. OSHA General Industry Safety Orders, Title 8, Section 5155, p. 432.259. United States Government Printing Office. Washington, 1995.

4.

Environmental Protection Agency. Test Method for Evaluating Solid Waste: Physical/Chemical Methods SW-846.

5.

Office of the Federal Register, National Archives and Records Administration. Special Edition of the Federal Register. OSHA General Industry Safety Orders, Title 8, Section 5416, p. 526.6.5. United States Government Printing Office. Washington, 1995.

6.

Chevron Corporation. Richmond Refinery Operating Standard R9920. Richmond, CA.

7.

Bradley, H.P. “Tanks Can Be Sandblasted Safely While in Service.” Petroleum Refinery. January 1961.

8.

Lankford, J. Leon. “Sandblasting Safety Guide for Petroleum Storage Tanks.” American Painting Contractor. Vol. 20, No. 4. August 1980: pp. 2-9.

9.

Chevron Corporation. Fire Protection Manual. Chevron Research and Technology Company. Richmond, CA, December, 1994.

10. Office of the Federal Register, National Archives and Records Administration. Special Edition of the Federal Register. OSHA 29 CFR 1910. United States Government Printing Office. Washington, 1995. 11. Chevron Corporation. Safety in Designs, Chevron Research and Technology Company, September, 1996.

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300 Coatings Selection Abstract This section discusses the basics of coatings selection. Topics covered include: life expectancy, turn-around time, economics, and color. An important part of the selection process, factors that limit selection, is also discussed. For atmospheric, concrete, internal vessel, and coatings under insulation and fireproofing, the selection process is straightforward and is detailed in the Quick Reference Guide. For those surfaces and logistics requiring special consideration, there is also general information in the following sections of this manual: • • • •

Section 600, Concrete Coatings Section 700, Downhole Tubular Coatings Section 800, Offshore Coatings Section 900, Pipeline Coatings

For assistance with specific projects involving those coatings, contact one of the Company's coating specialists listed in the Quick Reference Guide.

Chevron Corporation

Contents

Page

310

General Information

300-3

320

Economics

300-3

321

Initial Costs

322

Lifetime Costs

330

Color

331

Federal and Industry Standards

332

Color Systems for Company Facilities

333

Safety Colors

334

Company Identity

340

Other Factors Affecting Selection

341

Environmental Regulations

342

Surface Preparation

300-11

300-1

300-18

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300 Coatings Selection

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Coatings Manual

343

Permissible Application Methods

344

Weather at the Application Site

345

Service Temperature & Handling

346

Substrate

347

Supply of Coatings

348

Performance & Long-term Aesthetics

349

Generic Internal Coatings

350

References

300-23

300-2

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310 General Information An important element in any coating project is choosing the best coating system for the intended service. Among the considerations are the coating's life expectancy, exposure, maintenance, application, and turn-around time. Life Expectancy. One primary consideration for coating new construction is the longest possible service life. Cost of materials represents only 15 to 20 percent of the total cost of application. Exposure. The coating must be appropriate for its intended service conditions such as temperature and immersion. Maintenance. Because no one material is perfect nor can any be applied economically to perfection, choose coatings that are practical and economical to maintain (both immediately after application and well into the service life). Application. Coatings should be practical and economical to apply, should work with conventional or available equipment and technology, and should be compatible with a variety of other materials. Turn-around Time. Cure and recoat times needed before items are placed back in service are important considerations when selecting a coating. In the Quick Reference Guide, charts provide assistance with selecting the following coatings: • • • •

Atmospheric Coatings (on- and offshore) Concrete Coatings (mild environment only) Coatings under Insulation and Fireproofing Internal Vessel Coatings

For help with specific coating situations involving such surfaces or logistics as offshore, concrete, downhole tubulars, and pipelines (both internal and external), contact the Company's Coating Specialists.

320 Economics The information in this section comes from published references and local experience [1, 2, 3, 4]. While several coating systems may be acceptable for a given project, their costs and durabilities will vary. Choose the system that provides the lowest total cost to the Company over the life of the equipment.

☞

Chevron Corporation

Caution Do not fall into the trap of choosing coatings based on the cost per gallon regardless of the coating's life, cost per mil thickness, or drying time.

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321 Initial Costs Percent Solids Coverage is the main comparison in the percent solids. If one coating is 50 percent solids (i.e., 50 percent solvent, which will evaporate) and the other is 100 percent, the 50 percent solids will take twice as many gallons to cover the same area at the same thickness as the 100 percent solids. The 100 percent solids coating could cost twice as much as the 50 percent one and still be equal in true cost of materials.

Surface Preparation A cleaner surface does not always require more work and cost more. A brushblasted surface is better and often cheaper than a hand-cleaned wire-brushed surface. A more expensive surface preparation often means a longer life for the coating system and may actually give a lower total cost for the coating system over the life of the equipment.

Drying Time While application costs appear essentially the same, there are two points to consider: decreased productivity and ease of handling. Decreased productivity. There is decreased productivity with an alkyd which dries slowly. The coatings applicator must wait for one side of a pipe to dry before turning it over to finish coating it. A fast-drying inorganic zinc may actually save money. Ease of handling. Two coatings may not tolerate handling equally; one may be damaged more easily and require more touch up.

True Cost Estimating the true cost of coating is not simple. Cost and practicality are two considerations, but there are other factors. See Figure 300-1. Note Careful consideration resulted in the coating systems found in the Quick Reference Guide of this manual.

322 Lifetime Costs Preparing an economic analysis helps justify one coating system over another; however, this task can be quite complex and is therefore uncommon. Figures 300-2 through 300-7 give six examples of economic analyses chosen from the dozens of surfaces the Company coats: • • • •

September 1996

Tanks Piping Piping—Surface Preparation Structural Steel

300-4

Chevron Corporation

Coatings Manual

Fig. 300-1


Cost Factors to Consider for Coating Systems Task

Materials Selection

Surface Preparation

Consider

Other Comments

Cost per square foot at specified thickness

Varies with the percent of solids, the specified dry film thickness and the cost per gallon

Paint loss

Typical 15 percent for flat surfaces to 30 percent or more for complex shapes

Cleanliness vs. Life Wheelabrators may take only single pieces of pipe which then need to be welded and reblasted before painting

Application

Complexity of the paint

Single or multiple component?

Complexity of the shape

Flat tank surfaces or small piping?

Cost of access for final coats and maintenance

On ground, in the air, or offshore?

Impact of curing time on the schedule Fig. 300-2

Tanks—Comparing Costs of Coating Systems

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Coatings Manual

Fig. 300-3

Piping—Comparing Cost of Several Coating Systems

Fig. 300-4

Piping—Comparing Surface Preparation Costs of Several Coating Systems

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300-6

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Coatings Manual


Fig. 300-5

Structural Steel—Comparing Cost of Several Coating Systems

Fig. 300-6

Offshore Platforms—Comparing Costs of Several Coating Systems

Chevron Corporation

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September 1996


Fig. 300-7

Coatings Manual

Internal Coating for Tanks—Comparing Costs of Several Coating Systems for Saltwater Immersion (80°F)

• •

Offshore Platforms Internal Coating

Each example shows the net cost of several coating systems where cost includes surface preparation, application, and materials. See the following resources: • •

Figures 300-8, 300-9, 300-10 for cost analyses Figure 300-11 for coating life in various climates

In the six examples (Figures 300-2 through 300-7), the most cost-effective coating system is the one with the lowest, net, present cost at the design's projected life. Additionally:

September 1996

•

Consider systems with almost equal costs essentially equal.

•

Base selection on non-quantifiable factors such as chalking resistance and expected level of maintenance.

•

Consider the system with the longer life if you anticipate little maintenance effort.

300-8

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Fig. 300-8

Surface Preparation Costs—$/Sq. Ft. Abrasive Blast (Shop & Field)

Wheelabrator (Shop)

SSPC – SP3

.45

N/A

SSPC – SP7 (NACE 4)

.60

N/A


.80

.40


1.05

.55


1.25

.60

SSPC – SP3

.40

N/A


.50

N/A


.75

.35


.90

.50


.95

.55

Cleanliness Piping and Structural Steel

Tanks

Source: Jeffco Painting & Coating, October 1994 Their prices are good engineering estimates for Northern California. Costs will vary by location. Estimates are based on 10,000 Ft2 of surface area.

Fig. 300-9

Application Costs—$/Sq. Ft. Coating

DFT (mils)

Field-Applied

Shop-Applied

One Part Primer (alkyd)

2.0

.24

.21

Two Part Primer (epoxy)

4.0

.32

.25

Zinc Rich Primer

3.0

.38

.30

One Part Topcoat (alkyd)

2.0

.22

.21

Two Part Topcoat (urethane)

2.0

.39

.35

One Part Primer (alkyd)

2.0

.15

.14

Two Part Primer (epoxy)

4.0

.20

.18

Zinc Rich Primer

3.0

.35

.25

One Part Topcoat (alkyd)

2.0

.15

.14

Two Part Topcoat (urethane)

2.0

.33

.32

Piping and Structural Steel

Tanks

Source: Jeffco Painting & Coating, October 1994 Their prices are good engineering estimates for Northern California. Costs will vary by location. Estimates are based on 10,000 Ft2 of surface area.

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Fig. 300-10 Cost of Materials Cost $/Sq.Ft.

DFT (mils)

Alkyd (off the shelf)

.08

2

Chlorinated Rubber

N/A

N/A

Epoxy

.09

4

Epoxy Mastic

.16

5

Inorganic Zinc – Self Cure

.21

3

Universal Primer

.07

2

Vinyl

N/A

N/A

Zinc Rich Epoxy

.16

3

High Build Epoxy

.09

4

High Build Vinyl

N/A

N/A

Vinyl

N/A

N/A

Alkyd (off the shelf)

.08

2

Chlorinated Rubber

N/A

N/A

Coal Tar Epoxy (C200 version)

.13

8

Coal Tar Epoxy (Standard)

.12

8

Epoxy

.09

4

High Build Chlorinated Rubber

N/A

N/A

High Build Vinyl

N/A

N/A

Silicone Alkyd

.17

2

Urethane

.14

2.5

Vinyl

N/A

N/A

Primers

Intermediate Coats

Top Coats

Includes 20% spray loss. Source: Jeffco Painting & Coating, October 1994. These prices are good for engineering estimates for Northern California. Costs will vary by location. Estimates are based on 10,000 Ft2 of surface area.

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Fig. 300-11 Application Costs—$/Sq. Ft. Humid Coastal Offshore

DFT

Dry Inland

Moderate Coastal

Alkyd

4

7

5

2

Alkyd - Multi Mil

8

10

7

4

SCIZ/HB

10

30+

25

20

13

30+

25

20

13

30+

25

20

SCIZ/HB Epoxy/HB Epoxy

13

30+

25

20

SCIZ/Silicone Alkyd

6

25

20

15

Vinyl - 5 Coat

8

12

10

7

4.5

12

10

6

Coating

Epoxy/Urethane SCIZ/HB Vinyl/HB Vinyl SCIZ/HB CHL R/HB CHL Rubber

Epoxy/Alkyd with Brush Blast Notes:

SCIZ = Self cured inorganic zinc HB = High build

Assumptions The analyses in Figures 300-2 through 300-7 are based on the following assumptions: •

Re-coating the equipment. Often this may not be true, and it would be better to choose a system with a longer life and pay a somewhat high cost.

•

Coating primarily for aesthetics. Maintaining a good appearance as long as possible is one of the bases for selection.

Note Different assumptions could lead to different lowest-cost systems. There are many coatings systems which will do the job. No one system is perfect. Overall, there is more to gain by working on the quality of surface preparation and application than by working long hours to select optimum materials.

330 Color This section guides you in choosing and matching paint colors for new and existing process plants and tanks. It also emphasizes the proper use of safety colors and Company Identity colors. Building interiors and equipment are not included in this section. The Corporation has chosen to update the Company color scheme to simplify the color palette and improve the compatibility of the colors in the palette. These changes are also discussed in this section.

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Color selection is a management decision, but many facilities have adopted the color systems outlined below. Each system description has suggested uses for each color group to best match the facility's environment with color systems. If a local preference exists it shall take precedence over the color palettes described hereafter. When warranted, a qualified color consultant can be engaged to develop a specific color to blend with the surroundings at a particular site. This is especially encouraged where facilities will have special public impact. Use this approach with care as approval of more than one unique color for a given facility is rare.

331 Federal and Industry Standards Chevron has adopted Federal Color Codes for the existing Company color codes and has adopted ANSI safety colors. The use of these known standards eliminates the need to send out color chips to equipment manufacturers and vendors. While these Federal colors do not exactly match the Company colors, weathering and aging preclude an exact match to existing equipment, even when using the Company's color chips. Federal Standard 595a “Colors” designates colors with a five-digit code. The first digit indicates the gloss, the second digit indicates the predominant color group, and the last three digits indicate the approximate order of increasing reflectance and are assigned non-consecutively. The codes for gloss and color group are: gloss:

1 = glossy 2 = semigloss 3 = flat (lusterless)

color group:

0 = brown 1 = red 2 = orange 3 = yellow 4 = green 5 = blue 6 = gray 7 = miscellaneous (black, white) 8 = fluorescent

332 Color Systems for Company Facilities The following subsections describe each color system, their associated component colors, and how to select and specify those colors for plants and equipment.

Color Systems For new plants the Company most often uses either Pastel or Silver/Gray color systems, depending on the climate and surrounding environment. For special situations the Company uses only the Aluminum and Black colors.

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Pastel. The Pastel color systems are used in moderate and warm climates, where they are compatible with the environment and the visual setting. Pastel-A. Use where the plant is viewed against or within surrounding land forms with little green vegetation. The Pastel-A system consists of: •

Desert Sand/Mojave—Primary Color for the body of the plant including columns, vessels, exchangers, on-plot pipeways and pipeway supports; control houses; office buildings. Mojave is the new primary color for the Pastel - A scheme. As Desert Sand weathers and ages it becomes a pinkish color. A new color, Mojave, was chosen that will alleviate this problem so all new plants shall be painted with Mojave as the Primary Color.

•

Redwood—Trim Color for structural steel, platforms, machinery, pumps, compressors and trim on control houses and office buildings.

•

Warm Black—Dark Color for stacks, furnaces, and flares.

•

Dawn White/White—LPG Sphere and Line Color. Dawn White may be used for painting tanks in a setting where tanks are predominantly silhouetted against a hazy sky.

Pastel-B. Use where the plant is viewed against or within surrounding land forms with green vegetation. The Pastel-B system consists of: •

Palm Green—Primary Color for the body of the plant including columns, vessels, exchangers, on-plot pipeways and pipeway supports; control houses; office buildings.

•

Vista Green—Trim Color for structural steel, platforms, machinery, pumps, compressors and trim on control houses and office buildings.

•


•


Gray/Black. The new Gray/Black color system is a consolidation of the old Chevron Silver Gray, Aluminum/Black, and Black, color systems. The uses are the same. Use the Gray/Black system where pastels are not compatible with the environment, generally in colder climates and bleak industrial settings that are without greenery much of the year. Use aluminum paint as the primary color in plants containing mostly aluminum jacketed vessels and lines or stainless steel equipment. Pastels may be used selectively in this system to relieve monotony. Use black as the primary color for plants (such as asphalt plants) in which colors are not practical. Use adjacent to water, offshore, or where the plant is viewed against the sky. The Gray/Black system consists of: •

Chevron Corporation

Dark Silver Gray/Aluminum—Primary Color for the body of the plant including columns, vessels, exchangers, on-plot pipeways and pipeway supports; control houses; office buildings.

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•

Steel Blue—Trim/Accent Color for structural steel, platforms, machinery, pumps, compressors and trim on control houses and office buildings.

•


•


Plants New Plants. Choose Company-approved colors when painting new plants. However, if the new plant is an addition to an existing plant, you may want to paint it to match the older surrounding plants or equipment. If you are painting a new plant and choose to use the Pastel-A scheme, Mojave becomes the Primary Color for that scheme. If painting to match an existing plant that is of the Pastel-A scheme, use Desert Sand. Existing Plants. Normally we do not maintain painted surfaces in existing plants except to prevent corrosion, or where public appearance is important, or for identification. Don't change paint color unless complete repainting of a piece of equipment is necessary. When making minor modifications use the existing color from the old Company color palette for touch-up painting. When making significant modifications use the new Company color system. Choose an appropriate color system from the Chevron Color Chart in Appendix B if complete repainting is deemed necessary.

Tanks and LPG Vessels Where law dictates the color of tankage, as in some non-U.S. locations, it shall take precedence over the Company guidelines given here. Tanks. The Company paints non-insulated tanks. Although insulated tanks do not require it, sometimes they are painted for aesthetics and to match other noninsulated tanks which may be adjacent. Usually you will choose a color to blend the tank with its surroundings. However, factors such as the service a tank is in, its physical condition or its location may cause you to choose colors other than the primary colors named above. Plant related tankage should be painted the primary color of the selected color system. When completely repainting an older tank, consider using colors from the Company's current list of approved colors. Insulated Tanks. Tanks finished off with cement board sheets (Asbestocite, etc.) need not be painted, but all edges and sides of sheets should be primed before they are installed, to permit later painting if desired. Tanks with aluminum-sheathed insulation need not be painted. If desired, the aluminum weather jacketing may be purchased precoated in appropriate colors or anodized. LPG Vessels. Paint new and existing vessels Aluminum or Dawn White as appropriate to the surroundings.

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Color Matching Paint fades over time, and new paint made to match the original color chip will not match the faded, older paint. For most onplot equipment this mis-matching is acceptable. For structures and equipment in public view, more accurate matching is required. Exact Match Not Required (Both New and Old Facilities). When ordering paint to match most onplot buildings, tanks, equipment, safety indicators, etc. use the Federal Color Codes (the 5-digit numbers on the Chevron Color Chart in Appendix B) or the “Chevron Color Chips.” If necessary, additional Company color chips can be obtained by calling CRTC Technical Standards. Exact Match Required. Where an exact match of old, faded paint is critical, the color chips given in this manual may not be accurate enough. For precise match, it is best to use a chip of the actual paint to be matched. Compare colors carefully. The same paint formulation under different light sources looks different (this is called metamerism). Colors must be examined under the expected type of light source. The angle of illumination, the angle of viewing, and the amount of gloss affect color appearance. It is difficult to match gloss paints with flat paints.

Color Selection Principals in Color Selection. Follow two principals when choosing colors: the color system should be compatible with the surroundings and be economical to apply and maintain. The goal is to harmonize cleanly with the surroundings, to avoid or minimize visual impact where possible, and elsewhere to make an appearance that is acceptable and interesting. Be mindful of economics where trim colors are used. Trim colors should be used primarily on equipment that can be shop painted like railings. Minimize the use of a second color except where the contrasting accent is of real importance to the overall appearance. The cost of masking or other costly preparations should be weighed against the importance of accenting.

Color Codes The Company's standard colors are listed in Figure 300-12 “Chevron Color Names and Corresponding Federal Color Codes.” When writing specifications or purchase orders, always use the color code. The codes for Company Identity Colors are given in Figure 300-13, “Company Identity Color Codes.” Federal Standard 595a “Colors” should be referenced in specifications using Federal Color Codes. Also, ANSI Z53.1-1979 “Safety Color Codes for Marking Physical Hazards” should be referenced when safety colors are specified. The “Chevron Color Chart” in Appendix B shows the actual colors corresponding to the Federal Color Codes. This page is provided only for visual reference and should not be used for color matching. The “Chevron Color Chips” that follow the chart and should be used for color matching.

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Fig. 300-12 Chevron's Standard Color Names and Corresponding Federal Color Codes Chevron Color Name

Federal Color Code

Desert Sand

20450

Redwood

20140

Mojave

20372

Palm Green

24373

Vista Green

24172

Dark Silver Gray

16307

Light Silver Gray

16440

Aluminum

17178

Warm Black

17038

Dawn White

27722

Fig. 300-13 Company Identity Color Codes Company Color Name

Company Code

Black

BK-10

Beige

BR-440

Dark Gray

GY-210

Light Gray

GY-450

White (off-white)

WH-740

Green

GR-110

Gold

GO-110

Chevron Red

RE-370

Chevron Blue

BL-370

333 Safety Colors The Company uses color to identify emergency safety equipment, hazardous equipment and conditions, and toxic or corrosive chemicals. Local, state or Federal regulations take precedence over the common usage listed in Figure 300-14. See also ANSI Z53.1 - 1979 “Safety Color Codes for Marking Physical Hazards.”

334 Company Identity Some colors (i.e., Chevron Red and Blue) are associated with the Company's identity and are not normally part of the color systems. Company Colors should only be used after consultation with the Company Identity Center of the Public Affairs Department. The Company Identity Center maintains color chips for the Identity Colors and may be reached at CTN 894-0260.

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Fig. 300-14 Safety Color Codes for Marking Physical Hazards ANSI STD 2531-1979

Uses

Safety Red

Fire protection apparatus and equipment Fire protection lines Emergency stops and switches Designation of danger

Safety Orange

Mechanical and electrical hazards Noise hazard

Safety Yellow

Chemical hazard Piping with toxic or corrosive material Designation of caution

Safety Green

Locations of emergency safety equipment Containers for emergency equipment (special breathing apparatus). Piping for potable water and respirable air Designation of safety instructions

Safety White

Lines used for vacuum Designation of safety information Delineation of aisles, traffic passageways, housekeeping or cleaning equipment.

Chevron's Other Color Designations

Chevron Corporation

Uses

Yellow and Black

Physical hazards (obstructed access clearances, stumbling and tripping hazards). Yellow and black may be checkered, stripes, or other distinctive combination.

Black on Yellow

Radiation hazards (older purple on yellow may continue to be used until replaced.

Blue

Special meaning in railroad area for warning against starting, use of, or movement of equipment.

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340 Other Factors Affecting Selection There are many other factors that may affect the selection of a coating ranging from environmental regulations to internal coatings, as detailed below. For specific information or assistance with the effect of any of these factors on a particular coating, contact the manufacturer or the Company's coating specialists (both of whom are listed in the Quick Reference Guide).

341 Environmental Regulations Regulations may limit the kind of surface preparation or coatings for a given project. If a local area regulates solvent emission from coatings (see Section 200), then a high-performance system may be required. Note

Depending on the brand, some alkyds may be VOC compliant.

For standard-performance coatings in areas with VOC regulations, consider waterborne inorganic zinc primers (System 1.3.1) as a substitute for the more expensive high-solids, solvent-based inorganic zinc primers (System 1.3). See the Quick Reference Guide for system data sheets.

☞

Caution

Do not make this substitution for high-performance coatings.

342 Surface Preparation No other factor influences the performance of a coating as much as surface preparation. The optimum preparation for many services is white metal blast; however, this method is not always allowed, particularly if the abrasive might affect equipment operating nearby. In these cases, a compromise between desired performance and practicality must be reached. Coatings differ widely in their ability to adhere to a poorly prepared surface. If abrasive blasting and pickling is infeasible, select a coating that tolerates existing surface conditions. Example: You could specify a specially formulated high-performance coating, such as aluminum flake-filled epoxy mastics, for wire-brushed steel surface. Note 1: Tests on brush-cleaned steel show that these mastics perform better than oil-modified alkyds, formerly the coating chosen for these circumstances. Note 2:

Pickling means dipping the steel in acid to remove mill scale.

Blasting Prohibited If blasting is prohibited for surface preparation, there are essentially two choices for coating over hand-prepared surfaces: •

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No VOC requirements—alkyd systems

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•

☞

VOC compliance—higher performance, more costly, surface-tolerant epoxy mastics (including aluminum filled) System 1.8 or 1.81

Caution Specify a blasted surface preparation for high-temperature services; an IOZ cannot be used without blasting.

Drying Time Coatings vary widely in drying time. When choosing a coating, therefore, consider the drying time of the proposed coating as a factor in the time allotted to the project. Drying time is given on manufacturers' data sheets. Quick Drying. For more than one coat per day, choose coatings that dry by solvent release, such as vinyls, acrylics, and chlorinated rubber. For second and third coats in the same day, choose catalytic-setting coatings if the weather is not too cool. Slow Drying. Oxidizing (air-drying) coatings such as alkyds can take from hours to days before it is possible to recoat or handle them. Drying vs. Performance. Compare the materials cost with the cost of waiting for the coat to dry. A fast drying (but more costly) primer such as a self-cured IOZ may allow high enough productivity to make it the more economical choice. See also “Initial Costs” at the beginning of this section of the manual.

343 Permissible Application Methods Some locations prohibit spray application because of overspray damage to nearby objects. At such locations, choose a coating for brush or roller application instead of spray only such as vinyls and lacquers.

Recoating & Maintenance When planning to recoat, verify that the old and the new coatings are compatible. See the Coating Compatibility Chart in the Quick Reference Guide. If it is possible that a surface will need frequent recoating for maintenance, the work involved in recoating should also be considered. Note A harder-to-recoat system may be justifiable if it lasts significantly longer than a system that is easily recoated. Easy to Recoat. Solvent cures, aliphatic urethanes, and chalks are easily recoated. •

Solvent Cures Coatings that cure by solvent evaporation, such as vinyls and chlorinated rubbers, are easy to recoat because the topcoat's solvent bites into the old coating.

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Aliphatic Urethanes The result of the Materials Lab tests show that aged aliphatic urethanes recoat easily without blasting.

•

Chalks Coatings that chalk with age, such as alkyds and epoxies, frequently need only washing before recoating if the surfaces are rust free.

Difficult to Recoat. Some epoxies, urethanes (particularly aromatic urethanes), baked phenolics, and other resins can cure to such a hard, solvent-resistant film that recoating is difficult. Often, a brush blast (lightly blast) of the old films to roughen the surface before recoating must be specified.

344 Weather at the Application Site Weather conditions—such as high humidity, cool or cold temperatures, very dry weather—can all drastically affect curing. It is important that the coating specified for a given site can cure properly under existing weather conditions. Example: The 40°F to 50°F temperatures in Scottish fabrication yards prevented curing of the epoxies that were specified initially for the Ninian offshore platforms. In this case, chlorinated rubber was chosen as a substitute because it is more tolerant of cool temperatures. Cold weather adversely affects curing for most coatings. If the temperatures are expected to fall below the recommended curing temperature, specify that the crew heat the substrate, usually with internal heaters, so that it is above the low-temperature limit. Note As a rule of thumb, consult the coating manufacturer if the temperature is expected to fall below 60°F during curing. Other difficulties involving weather are as follows. •

Some coatings absorb too much water and blush if the humidity is above about 80 percent; however, self-cured IOZs can tolerate up to 95 percent humidity.

•

Some vinyls and chlorinated rubbers can soften in hot climates to the extent that handling can damage them.

•

Post-cured IOZ is water soluble and, before it cures, will wash off in rain.

345 Service Temperature & Handling Maximum allowable temperatures vary widely among coatings. Any non-standard operations such as steamout may cause high temperatures for even a short time. All high-temperature service coatings require an inorganic zinc (IOZ) primer. IOZ is gray; therefore, to change the color:

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•

Specify a topcoat of the desired color

•

Seek an exemption for the topcoat. (For assistance, contact the local area's environmental specialist.)

Specify a blasted surface preparation for IOZ which as a prime coat: • • • •

Gives excellent service Performs well in a wide range of temperature and humidity conditions Resists handling damage very well Is not expensive

For shop-primed equipment subject to handling damage (pipe, structural steel), IOZ is by far the best choice. In many of the Company's environments, IOZ does very well alone (without a topcoat). If color is not a concern, consider specifying one coat of IOZ.

346 Substrate Non-ferrous Metals or Concrete For non-ferrous metals or concrete, there are special considerations such as primers. Under most circumstances, do not coat stainless steel and non-ferrous metals such as galvanized, aluminum, copper, and lead because these substrates resist atmospheric corrosion quite well without coating. Even a well-chosen coating applied properly will not adhere well to these substrates and will soon require recoating. To coat these metals, be sure that the primer: • • •

Adheres to the metal surface Does not react with the metal surface Is compatible with the finishing coat

Note Before being coated, these metals may need pre-treating with an adhesionpromoting product.

Carbon and Stainless Steel under Insulation or Fireproofing

☞

Caution Under insulation or fireproofing, DO NOT USE zinc-rich primers (inorganic or organic) even if they are topcoated. Zinc protects carbon steel by being more active than the steel and corroding first, such as in galvanizing. At temperatures around 170°F, however, the zinc reverses polarity; and the steel corrodes. In solutions containing soluble chloride and sulfur salts, zinc corrodes very rapidly, even at ambient temperature. When exposed to hot and wet conditions, zinc reverses polarity, dissolves too rapidly, and is not very resistant to hot water when formulated with a silicate binder.

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Caution As manufacturers' data sheets normally give temperature resistance to dry heat, do not refer to that resource to select coatings for under insulation or fireproofing. The service-temperature recommendations in the coating system number selection chart (in the Quick Reference Guide) for coatings under insulation and fireproofing give actual steel temperatures and not design temperatures. Note Although a vessel is designed to operate above 300°F, the steel temperature may never reach 300°F in actual operation.

347 Supply of Coatings Two-hundred gallons is the minimum most manufacturers will supply for special orders. For small projects, therefore, select and specify off-the-shelf coatings which are available in sufficient quality and quantity. On large projects, consider using suppliers who are not local to the jobsite if they have lower prices and a good reputation for service and acceptable quality.

348 Performance & Long-term Aesthetics High-performance Coating Systems Compared to standard-performance coatings, high-performance coatings: • • • • •

Are necessary for severe exposures such as those in chemical plants Provide longer life and better aesthetics (generally higher gloss) Cost significantly more Are more difficult to apply Serve as the Company's Volatile Organic Compound (VOC)-compliant system

Standard-performance Coating Systems The standard performance coating systems consist primarily of alkyd coatings which: •

Are inexpensive

•

Are easy to apply

•

Serve well in most of our inland and mild environments

•

Can be applied, if necessary, over surfaces which are only hand-prepared (not blasted)

Long-term Aesthetics Sunlight, in particular ultraviolet light, can cause a coating to chalk, fade, or yellow. Where long-term color retention and appearance are important, choose a topcoat more resistant to sunlight.

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•

Aliphatic urethanes have the best weathering characteristics; they neither chalk nor fade.

•

Alkyds yellow and chalk slowly over time.

•

Epoxies chalk rather rapidly in comparison to alkyds, but that chalking does not adversely affect their corrosion resistance.

349 Generic Internal Coatings To get a good, effective, internal tank or vessel coating is one of the most challenging tasks facing coatings applicators. Poor application, not materials, is the primary cause of premature failures. As a result, Chevron strongly recommends specifying a good inspection program, from pre-bid meeting to final acceptance of the coating system. See Section 150 of this manual. When planning a project of internal coatings, consider the effects of potential business interruption, storage of toxic material, environmental hazards, and leak detection. Business Interruption. Is the tank or vessel scheduled for coating an integral part of the plant's operation? Can we take it out of service to repair a premature coating failure without shutting down the plant or reducing its production significantly? Toxic Material Storage. Is the stored product a toxic or hazardous material? Is the stored product regulated by any environmental agency? What are the consequences of a leak? Potential Environmental Hazards. Is the tank or vessel located near an environmentally sensitive or populated area? Examples: Rivers, lakes, bays, schools, homes, and shopping malls. Would leaking product damage the aquifer? Is there adequate secondary containment to protect the environment? Leak Detection. Is there any leak detection system? How quickly would we detect a leak? Would a small leak go undetected for any length of time?

350 References

Chevron Corporation

1.

Roebuck, A. H. and G. H. Brevoort. “Materials Performance.” In 1988 Paint and Coatings Selection and Cost Guide. June, 1988: p. 29.

2.

Weismantel, Gay E., ed. Paint Handbook. New York: McGraw-Hill, 1981.

3.

Sweeney, R. D. Materials Laboratory File N30-PRCP. Chevron Corporation, June 7, 1983.

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4.

Sweeney, R. D. Materials Laboratory File N30-RLOP. Chevron Corporation, August 30, 1983.

5.

Konet, R.R. “Coatings Costs.” In Materials Division File 6.25, Chevron Corporation, September, 1988.

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400 Surface Preparation Abstract Normally, the coating system dictates the method and amount of surface preparation. The life of a protective coating is directly related, however, to how well it adheres to the surface. Good adhesion, in turn, occurs when the surface has been prepared properly for coating. Surface preparation includes anticipating and stipulating corrective actions for potential problems and removing mill scale, rust, dirt, oil, loose paint, markings from crayons or spray paint, and other foreign materials. In contrast to the 2 to 5 percent of coating failures due to improper coating selection [1], 70 to 90 percent of coating failures result from inadequate surface preparation.[2, 3] These failures can be reduced by specifying appropriate methods, standards, and inspection for surface preparation. There are several methods of surface preparation for steel and other metal substrates. Not all methods for surface preparation fit all situations: some methods are very expensive and very slow, to the point of delaying operations. Others might adversely affect the environment. While the information in this section applies to the surface preparation of steel and other metal substrates only, there is also information about preparing special surfaces in other sections of this manual: • • •

Chevron Corporation

Section 600, Concrete Section 800, Offshore Section 900, Pipeline

Contents

Page

410

Surface Preparation in General

400-3

411

Shop versus Field Surface Preparation

412

Fabrication Details

420

Methods of Surface Preparation

421

Chemical Cleaning

422

Dry-abrasive Blasting

423

Air-Abrasive Wet Blasting

424

Water Blasting

400-1

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400 Surface Preparation

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425

Mechanical-abrasive Blasting

426

Power and Hand Tools

427

New Technology

430

Standards & Specifications

431

Written Standards

432

Visual Standards

440

Selection Criteria

400-14

450

Preparing Steel Substrates

400-15

451

Immersion Service

452

Non-immersion Service

460

Preparing Other Metal Substrates

400-18

470

References

400-19

400-2

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410 Surface Preparation in General Surface preparation is the act of conditioning a substrate to receive a particular coating that will protect it from its environment. The two main components of surface preparation are cleanliness and surface profile.

Cleanliness Probably the most important aspect of surface preparation, cleanliness involves removing all foreign objects such as oil, grease, dirt, loose paint, and mill scale to allow good adhesion of the coating. Improper adhesion is the major cause of premature coating failures. The more severe the environment, the cleaner the substrate must be. To measure cleanliness, the inspector compares the cleaned substrate to a set of visual or written standards, or both. Note Of the many industry standards, the most common are those developed by the Steel Structures Painting Council (SSPC) and the National Association of Corrosion Engineers (NACE). See the Quick Reference Guide.

Surface Profile Surface profile is the result of an abrasive media hitting a surface at high velocity from a mechanical apparatus or high-pressure air. The type of surface profile relates to the abrasive media's velocity, mass, and shape. In Section 200, Figure 200-1 shows a relationship between the abrasive in air-blast equipment and the surface profile. Also called anchor pattern, surface profile is the peak-to-valley height of the microscopic roughness caused by abrasive-blast cleaning. A profile is necessary to achieve full adhesion of the coating to the steel; but, if it is too high, a profile can cause holidays in thin coating systems. A proper profile is a compromise between the pattern needed for adhesion and the height the coating system can cover. Note

As a rule of thumb:

•

For a primer with a dry film thickness of less than 8 mils, the profile height should be about half the thickness.

•

For thicker primers, such as self-priming laminate systems, the profile should be at least 3.5 mils.

Profiles below 1.5 and above 4.0 are difficult to achieve. Profiles are specified in the system data sheets in the Quick Reference Guide and in coating manufacturers' data sheets.

411 Shop versus Field Surface Preparation In general, shop blasting is superior to field blasting. Some advantages of shop blasting are as follows:

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Superior surface preparation Shop blasting usually produces an SSPC-SP10 finish instead of the field-achieved SSPC-SP6. (Figure 400-1 describes these surface preparation standards.) Often, shops prime the blasted surfaces to prevent rusting or contamination.

•

Reduced potential for contaminating surrounding areas such as when field blasting tanks in operating areas or near streets

•

Lower costs of blasting and priming

•

No delays due to weather

412 Fabrication Details Before the surface preparation begins, inspectors should look for fabrication details that will cause problems with either the coating's application or performance. Examples: Skip welds, deep stencil marks, sharp edges, weld spatter, bolting. NACE RP0178-91 is a good source of information about such problems.[4]

420 Methods of Surface Preparation There are various methods and levels of intensity of surface preparation. The choice depends on several factors: the type of structure and its exposure, the quality of the coating, and the initial condition of the surface. Among the methods discussed in this section are chemical cleaning, dry-abrasive blasting, air-abrasive wet blasting, water blasting with abrasive injection, mechanicalabrasive blasting, power-tool cleaning, hand-tool cleaning, and new technology. Figure 400-2 compares the various methods and their production rates.

421 Chemical Cleaning Chemical cleaning is the removal of oil, grease, salts, dirt, and other contaminants with steam, solvents, detergents, chemicals, etc. See Figure 400-3 for a list of typical contaminants and corresponding surface treatments. Coatings applicators must remove these contaminants before beginning any blastcleaning operation to prevent their being worked into the steel surface and causing premature coating failures. The Steel Structures Painting Council has an excellent standard, SSPC-SP1, for the chemical cleaning of structures. [5]

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Surface Preparation Specifications and Standards

Chevron Corporation

Fig. 400-1

400-5


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Fig. 400-2

Blasting

Cleaning

Notes:

Coatings Manual

Methods of Surface Preparation and Their Production Rates

Blasting or Cleaning Method

Production Rate(1) in Ft2/Hr

Dry-abrasive Pressure

200

Best and most common method of surface preparation.

Dry-abrasive Vacuum

20

Equally as good as pressure, but very slow.

Wet-abrasive Pressure

200

Good method; wet surface can cause problems with adhesion.

Water, High Pressure (3000 psi)

600

Good method for preparing any sound, existing coatings for topcoating with a surface-tolerant epoxy.

Water, Ultra High Pressure (10,000 psi)

200

Removes existing coatings; does not create a surface profile.

Water, Abrasive Injection

200

Good method; wet surfaces can cause adhesion problems.

Mechanical, Stationary Machine

500

Very good method but only in shop for new construction.

Mechanical, Portable Machine

50

Good method but slow; on horizontal, flat surfaces rate can be much higher.

New Technology (Ice, CO2, Baking Soda, Plastic Abrasives)

20

All methods can remove coatings in sensitive areas; but they do not create surface profiles.

New Technology (Infra-red), Peelaway Strippers

10

Both can remove coatings in sensitive areas; but neither creates a surface profile.

Power Tool

100

Can clean to bare metal with a surface profile SSPC-SP11; but production drops to 20 sq. ft/hr.

Hand Tool

50

Mainly for cleaning small or hard-toreach areas on existing structures.

Comments

1. Production rates are approximate and vary with surface conditions (mill scale, coated, rusted, etc.) 2. Production rates reflect the normal level of surface cleanliness required by the method for non-immersion service on both new and existing structures.

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Fig. 400-3

Surface Preparation: Using Chemicals to Remove Contaminants

Contaminant

Method

Oil, grease

Wipe with solvent-soaked rags

Dirt, dust, salts

Wash with high-pressure fresh water or detergent. Rinse with fresh waster and dry thoroughly before coating.

Mildew

Scrub with solution of bleach and water in ratio of 1:3. Rinse with fresh water and dry thoroughly.

422 Dry-abrasive Blasting There are two types of dry-abrasive blasting methods: pressure and vacuum system. Note For immersion service, Chevron recommends only these two types of dryabrasive blasting.

Dry-abrasive Blasting under Pressure The most common method of surface preparation, dry-abrasive pressure blasting has the productivity and ability to produce an excellent surface condition for coating. Dry-abrasive pressure blasting is a process during which high-pressure (100 psi) air hurls abrasive media against the substrate. Note While people refer to this process as sandblasting, that term is incorrect unless sand is the abrasive medium. Dry-abrasive blasting not only cleans the surface but also produces a wide range of surface profiles.

Dry-abrasive Blasting with Vacuum System Dry-abrasive blasting with a vacuum system keeps the abrasive within a hooded enclosure. This method produces the same level of cleanliness and surface profile as dry-abrasive blasting under pressure and also: •

Shields the surrounding area from flying abrasive and dust

•

Does not disturb adjacent machinery or workers

•

Recycles its abrasive and produces less waste than dry-abrasive blasting under pressure

The disadvantages of air-abrasive blasting with a vacuum system are as follows: • • • •

Chevron Corporation

Its cleaning speed is slow The surface is not visible to the operator It uses an expensive, recyclable abrasive The hood enclosure must always be held against the surface

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For stainless-steel substrates in non-immersion service, this is one of the best methods of surface preparation available; but it is very slow and limited basically to small areas in sensitive locations that cannot be pressure blasted.

423 Air-Abrasive Wet Blasting Air-abrasive wet blasting is very similar to dry-abrasive blasting except that a stream of water surrounds the abrasive. The advantage of this method is that, while the water does not improve the cleaning, it reduces the formation of dust while not noticeably reducing production rates. Normal reduction in dust can be as much as 50 to 75 percent. Water pressures range from 3,000 psi to 30,000 psi. Note In this manual, Chevron has designated pressures under 10,000 psi as highpressure water blasting and pressures 10,000 psi and above as ultra-high-pressure water blasting. The main disadvantage of this method is that it leaves moisture on the surface which, without a corrosion inhibitor added to the blast water, can cause rusting.

☞

Caution Corrosion inhibitors must be compatible with the coating system selected and must be added according to manufacturers' recommendations; otherwise, the inhibitors will cause coatings to fail prematurely. Air-abrasive wet blasting should be used in situations where heavy dust is intolerable.

424 Water Blasting Water blasting cleans the surface with a stream of high-pressure water. This method does not, however, produce its own profile; but it can remove an existing coating from a structure and expose the previous surface profile. Example: 10,000 psi are necessary to remove existing coatings or loose mil scale. The disadvantages are that water blasting: •

Does not produce a surface profile

•

Leaves the surface wet so that the coatings applicator must add the proper proportion of rust inhibitors compatible with the coating to prevent premature failure of the coating

High-pressure Water Blasting (3,000 psi) If the existing coating system still has a sound primer with less than ten percent rusting, high-pressure water blasting should be the first alternative for surface preparation of stainless steel substrates in non-immersion service. When high-pressure water blasting, the coatings applicator: •

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Washes the surface with high-pressure water

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•

Vacuum blasts or power-tool cleans any rusted areas left after cleaning the surface

•

Gives the bare steel areas an extra coat of surface-tolerant primer

The coatings applicator topcoats the cleaned surface with five to seven mils of surface-tolerant primer, Systems 1.8 or 1.8.1. (See system data sheets in the Quick Reference Guide.) Leave these primers without a top coat; but, for added protection and gloss retention, topcoat them with two to three mils of polyurethane finish, Systems 2.15 or 2.15.1. This high-pressure (3,000 psi) method removes loose coating, dirt, and other material. Its production rate is approximately three times faster than abrasive blasting to SSPC-SP6. The advantages are that, by leaving the existing tight coating, surface preparation time and initial cost are reduced. The disadvantage is a shorter life for the coating system. For several years, the coating industry has been testing this method with good results. As yet, there is no sufficiently long-term data to support the theory that this method will last the more than ten years of an abrasive-blast system. Note The Company has conducted some laboratory tests on six brands of surfacetolerant coatings. Although the results are based on a preliminary evaluation, all six coatings performed equally well. See Figure 400-4. Fig. 400-4

Tested and Acceptable Surface-Tolerant Coatings

Manufacturer Ameron

Brand Amerlock 400 Amerlock 400L

Carboline

Carbomastic 15 Carboline 801

Devoe

Bar-Rust 235 Bar-Rust 239

Note:

Coatings are listed in alphabetical order and do not suggest ranking. All listed coatings ranked equally well in testing.

Ultra-high-pressure Water Blasting (over 10,000 psi) Specify ultra-high-pressure water blasting for surfaces that: • •

Need all the coating removed Cannot use any abrasive-blast method (wet or dry)

Its production rate is similar to all of the abrasive pressure blasting methods.

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Water Blasting with Abrasive Injection Water blasting with abrasive injection thrusts abrasive into a stream of high-pressure water at the nozzle. This method does produce a surface profile but at a much slower production rate than dry-abrasive blasting. Wet blasting with abrasive injection has the same problem with the potential for corrosion as wet blasting and also solves that problem with inhibitors. Use this method for reducing dust.

425 Mechanical-abrasive Blasting There are both stationary and portable mechanical-abrasive machines. In both cases, a rotating wheel centrifugally hurls abrasive on the surface at a high velocity. As in dry-abrasive blasting, these methods clean the surface and produce a variety of surface profiles.

Stationary Machines Usually found only in fabrication shops, large machines blast clean a wide variety of irregular and complex shapes. Operated properly, these machines can achieve the same surface cleanliness and profile as dry-abrasive blasting but at a lower cost. For new construction, consider having a fabrication shop prepare the surface and prime the steel.

Portable Machines Because of their size, portable machines are normally used on horizontal surfaces primarily for surface preparation of concrete or steel floors. They have difficulty reaching corners, fillets, or irregular areas. They are, however, found on the jobsite. Portable machines are designed to contain all of the dust, abrasive, and contaminants. With properly operated portable machines, therefore, workers need neither special protective clothing nor containment screens.

426 Power and Hand Tools Power and hand tools produce a poor surface for coating; however, they are used for repairing small, hard-to-reach areas. Another important reason for using power or hand tools is to clean the rusted areas of a structure while leaving most of its coating intact.

☞

Caution With these methods, select a surface-tolerant primer to improve coating life.

Power Tools There are three basic categories of power tools for cleaning, all of which clean the surface and produce a surface profile but not to the quality of abrasive blast cleaning:

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•

Impact cleaning tools such as chipping hammers, scaling hammers, and needle guns

•

Rotary cleaning tools using three types of cleaning media: nonwoven abrasive, wire brushes, and coated abrasive

•

Rotary impact tools operating on the same principle as the other impact tools— cutting, and chipping—and using three types of cleaning media: cutter bundles (or stars), rotary hammers, and heavy duty rotary flaps

Hand Tools As the name implies, this method involves cleaning with hand tools and is the least desirable method, being one of the slowest and least effective. Examples: Wire brushes, abrasive pads, scrapers, chisels, and knives.

☞

Caution When cleaning stainless steel with carbon steel wire brushes, the brush wires can come loose and stick in the steel at welds, crevices, and flanges, where they start a corrosion cell.

427 New Technology Several new methods exist for cleaning steel substrates. While most are either in the development stage or very expensive, they may be useful when normal methods of surface preparation are not feasible. The following discussion details the more promising techniques.

Blasting with Ice, CO2 Pellets, and Baking Soda Initially developed for the U.S. Navy to descale ship hulls and remove paint from aircraft, these blast media work with equipment similar to the common abrasiveblast method. The main difference is the blast media. The advantages of ice, CO2, pellets, and baking soda blast media are that: • • •

They create very little toxic waste or dust plumes Used properly, they can remove paint or other materials from delicate equipment CO2 pellets are non-conductive and have cleaned operating electrical equipment

The main disadvantages of ice, CO2 pellets, and baking soda as blast media are that: • • •

They have very low production rates They do not produce a surface profile CO2 pellet blasting can cool a steel substrate to subzero temperatures

Plastic Blasting Similar to common abrasive blasting, plastic pellets are the blast medium. To date, the aircraft industry is the only user; and they remove paint from airplanes with this method. It produces negligible toxic waste or dust plumes.

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Its biggest disadvantages include: • • •

Low production rates No surface profile Ineffective at removing thick layers of epoxy coatings

Infra-red Light Still under development and expensive, the concentrated infra-red light heats the coating to combustion without affecting the substrate. This method does, however, have some interesting properties as it: • •

Removes coatings by the layer or all at once Leaves a small pile of ash as its only waste

Consider this method under the special circumstance of removing one layer of a multi-layer coating.

Peel-away Stripper Designed to remove lead-based coatings (LBC), this industrial-strength, alkalinebased stripping material is sprayed on the substrate. Coatings applicators then power wash or scrape off the coating. Note Brush blasting is recommended to remove any vestiges of the stripper before recoating. Consider this method as a means of removing LBCs but not for removing general industrial coatings. Because of the containment costs involved when abrasive blasting LBCs, however, this stripper can be very cost effective. The cost of removing the waste stream is the main disadvantage of this method.

430 Standards & Specifications To ensure proper surface preparation, there are two important references: written and visual descriptions of surface cleanliness and profile. Of the written and visual standards available for surface preparation, those described below are easiest to understand and follow.

431 Written Standards The Steel Structures Painting Council (SSPC) has published surface preparation specifications that are widely accepted by the coating industry.[5] The specifications define degrees of abrasive blasting, solvent cleaning, and hand- and powertool cleaning. Because of the chronological order of definitions for surface preparation standards, the SSPC numbering system is not consistent with the logical order of degrees of cleanliness.

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Examples: SP-10 (near white) is better than SP-6 (commercial) but not as good as SP-5 (white). The National Association of Corrosion Engineers (NACE) adopted the SSPC definitions for abrasive blasting, but renumbered them to improve their organization and our retention of them. [6] Figure 400-1 gives numbers and short descriptions of the SSPC and NACE specifications, along with corresponding Canadian, Swedish, and British standards. Note Although NACE adopted the SSPC abrasive blasting description, they did not adopt the specifications for solvent, hand-tool, or power-tool cleaning.

432 Visual Standards When specifying abrasive-blast cleaning, supplement written definitions with references to visual standards. Although there are several standards, some are better than others.

☞

Caution Do not substitute pictorial standards for a complete surface-preparation specification, because the pictorial standard is based upon appearance only and does not consider other factors such as surface profile, removing contaminants, cleaning procedure, and re-rusting. The Society of Naval Architects and Marine Engineers (SNAME) has published very good, color, pictorial standards for abrasive blasting.[7] A copy of these standards is appended to this manual. They are extremely useful, as they take into account the effect of various original conditions on the appearance of the blast cleaned surfaces. The SSPC and ASTM adopted visual surface-preparation standards developed in Sweden.[8] These standards, referred to as SSPC-Vis1 and ASTM D2200-85, are not included in the manual. Instead, Chevron prefers the use of the SNAME standards, which are more complete and convenient. NACE also sells visual standards in the form of plastic coated pieces of steel which have been prepared to degrees of cleanliness corresponding to NACE Surface Preparation Specifications 1 through 4. Again, these comparative samples are extremely useful in the field and are available from NACE. (See listings of resources in the Quick Reference Guide.) Brush blast, commercial blast, near-white metal blast, and white metal blast are represented in all of the above visual standards. Variations in shade, tone, color, pitting, mill scale, etc., are due to the original condition of the steel surface. Consider and compensate for these variations when comparing the surface to the visual standards.

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440 Selection Criteria To select the most appropriate method of surface preparation, consider the type of coating material now on the surface (e.g. lead-based), toxic wastes, the new coating system that will be applied, cost, and sensitive areas.

Presence of Lead-based Coatings (LBC) Answers to the following questions will help select the most cost-effective method of surface preparation for a coatings project. • • •

If LBC's are present, do they need to be removed? What are the containment costs? Is the condition of the LBC good enough to be encapsulated?

Toxic Waste The following questions highlight reasons for producing low amounts of toxic waste. •

What are the disposal costs for toxic waste?

•

Is there a possibility of contaminating nearby rivers, streams, lakes, or other environmentally sensitive areas?

New Coating System The coating system is one of the most important items to consider when selecting a method of surface preparation. In this manual, the system data sheet (in the Quick Reference Guide) for each coating lists the recommended method of surface preparation and the anchor pattern. Another source of information about the level of cleaning and the surface profile is the manufacturers' data sheet.

Costs Short- versus long-term costs can also dictate the method of the surface preparation. •

Is it more important to reduce today's cost by selecting a surface preparation method that could lead to early repair or replacement of the coating?

•

Is it better to spend more money today on premium surface preparation and have the coating system last longer?

See also Economics in Section 300 of this manual.

Sensitive Areas Sensitive equipment or other items in the vicinity of the jobsite may influence the choice of surface preparation. Examples: The possibility of abrasive-blast media entering the air intakes of rotating equipment or potential over-blasting of nearby automobiles.

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450 Preparing Steel Substrates 451 Immersion Service Immersion service needs the best possible surface preparation because it is usually the most severe service for a coating system.

New & Existing Construction For both new and existing surfaces in immersion service, Chevron recommends:

☞

•

Dry-abrasive blasting as the only method of surface preparation for immersionservice coatings

•

SSPC-SP5 (white metal blast) for surface cleanliness

Caution Some coating manufacturers will accept SSPC-SP10 (near white metal blast) which Chevron finds unacceptable. The blast medium is the only change recommended for these surface-preparation methods. If contaminated substrates can turn the blast medium into a toxic waste, there are two possible solutions:

☞

•

Select an abrasive medium with the lowest concentration of contaminates that are regulated in the local area. If low enough, the contaminates from the blasting operation may not make the blast medium a toxic waste.

•

If the preceding solution will not work, consider a recycled abrasive-blast system, usually a combination of steel shot and grit. Because the abrasive is cleaned and reused, the only waste produced is the material removed from the substrate which can be as much as one-tenth of normal dry-abrasive blasting.

Caution Recycled abrasive blast systems are very expensive because workers use them when working in contained areas with abrasive that must be collected and cleaned. When working on a coatings project that may involve these systems, initiate a cost analysis to weigh the cost of waste disposal against the cost of a recycle system. Note For coating projects in California, recycled blasting systems are becoming more common as the cost of waste disposal increases.

Existing Construction Tanks which have been in service and are corroded may need a considerable amount of patching to restore the bottoms or shells to an acceptable condition before applying an internal coating. Plug welding, weld overlaying, or patching with plate are all acceptable, depending on the size of the area to be repaired. Stipulate that all surfaces be ground smooth and all sharp corners rounded off (minimum radius: one-eighth inch) to allow good coating coverage. Note

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This requirement applies to all areas of the tank, not just to repairs.

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Pitted areas may be repaired either by welding or by filling with putty as described below.

☞

Caution If coatings applicators are not going to carry out the restoration, one of them should be made responsible for ensuring that the restoration is completed properly before they begin abrasive blasting. Solvent cleaning prior to abrasive blasting is very important for tanks that have been in service; otherwise, an oily residue remains after blasting and causes problems with coating adhesion. Remove other types of residue such as soluble salts with a water or detergent wash before blasting. Soluble salts can cause the coating to blister; osmotic pressure causes water to diffuse through the coating more rapidly, to dilute the salts. Repairing Pits with Putty. A smooth surface is necessary to achieve a coating of uniform thickness; however, the thicker the coating, the less sensitive it is to small irregularities in the surface. For thin-film coatings, even small pits can become sites of early failure. It is very important to fill sharp, pitted areas properly. Note Surfaces roughened by relatively uniform corrosion may be acceptable without any putty. The shape of the pits is the most important factor when determining the need for filling. Do not fill wide, shallow pits with rounded edges. Always fill narrow, deep pits with sharp edges. Note It is usually easier to fill all the pits rather than to decide which ones to fill and which ones not to fill. The coatings applicators should grind and round off sharp corners or edges before abrasive blasting. They should also apply an extra coat over these areas and over all welds to prevent thin spots. Rivet seams require a coat of seam sealer to fill in all the gaps around the rivets. Spray-applied glass-flake coatings are generally less sensitive to small irregularities than thin-film coatings. Trowel-applied glass-flake coatings are so much thicker that the coatings applicator needs to fill only relatively large pits. Laminate coatings are much more sensitive at corners and edges than at small pits, because the fiberglass mat cannot conform to sharp changes in direction. The application details in Section 14 of Specification COM-MS-4738 require a gradual slope or radius at all direction changes. Fill the larger pits to provide a smooth working surface for the coating; a rough surface causes many up-turned fibers which the coatings applicator must sand before applying the final layer. Putties and sealers are specified on the system data sheets in the Quick Reference Guide.

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452 Non-immersion Service New Construction Whenever possible for new construction in non-immersion service, choose a surfacepreparation system that produces a surface profile and cleanliness equal to or better than SSPC-SP6 (commercial blast). This means dry-abrasive or mechanicalabrasive blasting methods.

☞

Caution Some coating manufacturers claim that SSPC-SP2 or SP3 (hand- or power-tool cleaning) is sufficient for their coatings; however, experience has shown that improved surface cleanliness can increase the life of a coating from 50 to 100 percent. Most fabrication shops have stationary and portable mechanical-abrasive machines, capable of preparing a surface for coating at one-third the cost of field preparation.

☞

Caution The only disadvantage with shop blasting is that the steel substrate will rerust if not primed immediately. If the specified coating system includes an IOZ primer, have it applied in the shop immediately after blasting. IOZ primers are very durable and will resist the abuse of shipping and installation. Other primers (alkyds, epoxies, urethane, etc.) are not as durable as IOZ and require a considerable amount of touch up after shipping and installation. The amount of touch up may be equal to or greater than the savings from shop blasting. If the new steel has tightly adhering mill scale, it might be cost effective to have it shop blasted and primed with a one-mil-thick, fast-dry, shop primer to prevent rerusting. After shipping and installation, a light abrasive blast will remove the shop primer. Depending on the original condition of the steel substrate, this approach could be more economical than the field blasting necessary to achieve the specified anchor profile and cleanliness.

Existing Structures Surface preparation is extremely important; in some cases, the life of the coating has doubled as a result of changing the preparation from power-tool cleaning (SP3) to abrasive blasting (SP6). For the best, long-term, coating performance, complete surface preparation by dryabrasive blasting to a cleanliness of SSPC-SP6 (commercial blast) for existing structures in non-immersion service. Blasting in the field can be very expensive or impossible, however, so Chevron recommends several alternative methods: high-pressure water blasting, dry-abrasive vacuum blasting, hand- and power-tool cleaning, air-abrasive wet blasting, and water blasting with abrasive injection, ultra-high-pressure water blasting, and new technology.

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Each of these methods is described in another part of this section. See also Figure 400-2 for a list of all methods of surface preparation, production rates, and other comments.

Alternative Methods of Surface Preparation If dry-abrasive blasting is not feasible and an alternative is necessary, study the project to find the answers to questions about the conditions and restraints, such as: •

What is the condition of the existing coating?

•

Is the coating system exposed to a mild or severe environment, i.e., desert or heavy industrial?

•

How long must the coating system last?

•

Can the coating system be easily repaired?

•

Is it more cost effective to save money today through less surface preparation and accept a shorter coating life?

•

Is it more cost effective to spend the extra money today for surface preparation that will give the longest coating life?

•

How does waste disposal impact coating costs?

•

How will surface preparation impact surrounding equipment?

•

How will surface preparation impact the environment?

460 Preparing Other Metal Substrates Galvanized Iron and Steel Galvanizing offers sufficient protection from atmospheric corrosion so that coating is unnecessary and is generally for aesthetics. Because there are chemical and physical differences between galvanized steel and bare steel, special surface preparation is necessary to establish a good bond between the galvanizing and the coating. This surface preparation consists of two steps: 1.

A solvent cleaning to remove oil

2.

An application of a vinyl butyral wash primer (System 1.7) prior to topcoating

For rusted or previously painted galvanized steel, the coatings applicator should solvent clean and then wire brush the surface to remove deposits before applying the wash primer.

Uncoated Stainless Steel Uncoated stainless steel does not need coating for corrosion protection. If coated for aesthetics or protection from chloride attack, the surface preparation is the same

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as for carbon steel; however, blasting is only needed to produce an anchor pattern, not to remove rust.

All Previously Coated Surfaces Previously coated surfaces need proper preparation for good coating performance. Generally, brush-off blasting is sufficient: • •

For surfaces with spot rusting or flaking, peeling, or blistering coating To roughen hard or glossy surfaces to obtain good adhesion

470 References

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1.

Griffiths, J. Dave. “Coatings Application: Is Compromise Necessary Between Manufacturers' Recommendations and Repair Yard Practice.” Shipcare and Maritime Management. May 1980: pp. 27-30.

2.

Weismantel, Guy E. “Paints and Coatings for CPI Plants and Equipment.” Chemical Engineering. April 20, 1981: pp. 130-143.

3.

National Association of Corrosion Engineers. “Causes and Prevention of Coatings Failures.” NACE Publication 6D170. Item 54192. March 1979: pp. 32-36.

4.

National Association of Corrosion Engineers. Fabrication Details, Surface Finish Requirements, and Proper Design Considerations for Tanks and Vessels to be Lined for Immersion Service. NACE RP0178. 1991.

5.

Steel Structures Painting Council. Surface Preparation Specifications. January 1971.

6.

National Association of Corrosion Engineers, Standards of Task Group T-6 G-2, November 17, 1962.

7.

The Society of Naval Architects and Marine Engineers. Abrasive Blasting Guide for Aged Coated Steel Surfaces, Technical and Research Bulletin No. 4-21. New York, April 1986.

8.

Swedish Academy of Sciences. Photographic Standards, 1967 ed.

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500 Application Abstract Second only to surface preparation, the method of applying a coating determines its performance and ultimate life. [1] During a project, coatings applicators must mix and thin materials properly, allow them to cure, and store them according to manufacturers' guidelines. See Section 200 for the safety factors affecting coating projects.

Chevron Corporation

Contents

Page

510

Methods of Application

500-2

511

Spray

512

Roller

513

Brush

520

Other Factors Affecting Application

521

Handling

522

Selection of Coatings Applicators

523

Structure and Surface to be Coated

524

Multiple Coats

525

Weather and Atmospheric Conditions

530

Touch Up

500-10

540

Reference

500-10

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510 Methods of Application The most common methods of application are spray, roller, and brush, each offering advantages and disadvantages and each requiring particular equipment and techniques. These methods affect not only the film thickness (Figure 500-1) but also the loss per gallon. With any method, coatings applicators can lay on a coating too thickly, causing it to sag or run. Only with a brush or roller, however, can they spread coatings too thinly. Fig. 500-1

Average Film Thickness by Type of Tool

Tool

Average Film Thickness (DFT)

Brush

2 mils

Roller

3 mils

Spray

0.5 to 20 mils

To calculate the theoretical coverage of a coating, use the following equation, based on the film thickness and solids content: 1604S T.C. = --------------t (Eq. 500-1)

where: T.C. = theoretical coverage, square foot/gal. S = solids content, volume percent t = desired film thickness, mils Actual coverage, however, may be 10 to 50 percent less than theoretical coverage when allowing for application technique (amount of overspray), surface roughness, and spills. Brushes have the lowest loss per gallon for a given coating; rollers, slightly higher. Losses from spray application depend on the type of surface, the type of gun, and the skill of the operator Airless spray guns are capable of producing only slightly higher losses than rollers. While some air-atomized, external-mix guns lose up to 20 percent of coating in overspray, a typical loss value for airless spray on the smooth surface of a steel plate is 15 percent.

511 Spray Spray guns and associated equipment vary physically but operate similarly. The spray system atomizes the coating and deposits it on the surface. Common types of

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500 Application

spray systems include internal and external mix, airless, hot, electrostatic, and catalyst-and-resin sprays. See Section 200 of this manual for hazards associated with spray equipment. Coating applicators can minimize overspray by working parallel to the surface without any arcing motion. For areas that forbid sprays because of historical property damage from overspray, specify specially formulated coatings for roller or brush. Advantages: •

The fastest and most cost-effective method of application; in general, about twice as fast as roller application and four times faster than brush coating

•

The most efficient method for large areas

•

Effective at creating a uniform appearance and thickness

•

Capable of achieving the desired total thickness in fewer coats than with roller or brush

Note Because each coat is a labor- and cost-intensive step, applying fewer coats reduces the total cost of a coating system. •

Suitable for certain coatings, including vinyl, lacquer, multimil alkyd enamel, and those specially formulated for spray application

Disadvantages: •

Spray equipment needs special care not only during operation but also for its maintenance. There are filters to clean, and fine orifices to keep open as some coatings cure quickly in the hose and form solid plugs, shutting down the work. The most frequent problems come from misusing equipment.

Note As coatings applicators own their spray equipment, however, they take great pains to keep it operating at maximum efficiency. •

Overspray means that fine particles of coating are blown into the air and do not strike the object to be coated. Overspray: – – –

Represents a loss of 20 percent or more material on small objects such as pipes Produces a rough, sandy appearance if dry overspray blows on a freshly coated surface Constitutes a potential hazard to health, fire, and property

Example: Overspray of zinc primers on stainless steel has the potential to cause liquid-metal embrittlement.

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512 Roller There are many types of rollers and roller covers: • • •

From hand dip to pressure feed From one-inch to 16-inches wide With naps up to two-inches thick

The most common rollers have a simple handle with a metal roller core and a removable cover. Some can accommodate extension handles. Roller covers are made of lamb's wool, mohair, Pronel, Dynel, and other synthetic fibers. Note Cover material must be compatible with the coating being applied. See Figure 500-2. Fig. 500-2

Recommended Roller Covers

Roller Cover Lamb's Wool

Resistance Most solvent-resistant fiber

Comments Mats badly in water; not for water-based coatings Excellent for polyester resins

Mohair

Good water resistance

Good for synthetic enamels and other smooth finishes

Dynel, Pronel

Excellent water resistance and fair solvent resistance

Not for ketones or styrene solvents Not for lacquers, vinyls, or polyester coatings which dissolve the fibers. Dynel, an acrylic, is most popular for general-purpose rollers

Advantages: •

Little training is necessary for coatings applicators.

•

Rollers can produce an orange-peel appearance.

•

Rollers with long handles attached can reach high places without scaffolding.

•

Roller coating is relatively fast, at least twice as fast as brushing, especially if the substrate surface is rough.

•

Compared to spraying, rollers produce less splatter or overspray.

Disadvantages:

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Rollers are inefficient for small jobs since they hold too much coating—up to one-half pint.

•

Roller application is only about half as fast as spraying.

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•

Rollers are more difficult to clean than brushes and, if used improperly, can produce overspray.

•

Coating applicators tend to select thick naps (the fiber length on the surface of roller) which hold more coating and can produce bubbles on the applied coating. If the coatings applicator re-rolls the coating to eliminate the bubbles, the resultant film may not meet the specified minimum thickness.

Note

Any contract with a coating supplier should specify the required nap size.

513 Brush Brushes come in many shapes and sizes, designed for specified applications. More importantly, bristles come in a variety of types, both natural and synthetic. Highquality brushes have flagged bristle tips, enabling them to hold more coating and resulting in finer bristle marks on the surface. Specify a bristle compatible with the coating. Advantages: •

For primer coats, brushing improves the coating-to-surface bond, especially if the substrate is rough, dusty, or slightly contaminated.

•

Brushing requires a minimum of tools.

•

Often, a brush is the only practical tool for corners, edges, odd shapes, trim, and small areas.

•

For small shapes or if spraying requires excessive protection for surrounding areas, brushing can be faster than spraying.

Disadvantages: •

Brushing is usually the slowest application method for large areas.

•

Brushing produces a non-uniform film and often such defects as brush marks, laps, sags, and runs.

•

The wide variety of brushes and levels of the coatings applicators' skills produce an inconsistent quality of coating.

520 Other Factors Affecting Application From the standpoint of safety when working with coatings, either: •

Make sure the equipment to be coated is in a safe condition before turning it over to the contractor, or

•

Inform the contractor in writing of hazardous conditions that may be present and of safety procedures and equipment that are necessary.

See also safety information in Section 200 of this manual.

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The following factors can affect the application of a coating: handling, coatings applicators, structure and surface, multiple coats, geographic weather, and atmospheric conditions.

521 Handling Among the elements involved in handling a coating are mixing, thinning, drying, curing, and storing the material.

Mechanical Mixing Coatings applicators should mix coatings mechanically, even small amounts of viscous coatings, mastics, and catalyzed coatings with small quantities of catalyst. Mechanical mixing is fast and efficient. Among the other reasons for mixing coatings are to:

☞

•

Ensure homogeneity for single-component coatings such as alkyds which can settle and thicken during storage

•

Achieve proper cure and performance of coatings with two or more components

Caution Coating applicators should not mix coatings manually because serious problems can occur if multiple-component coatings are not mixed mechanically and completely.

Thinning To ensure compatibility between a thinner and coating, select both products from the same coating manufacturer and follow the manufacturer's directions about amounts and procedures. Reasons for Thinning. Thinning is necessary: •

To spray some coatings that are supplied in the viscosity range for roller or brush

•

During cold weather, when coatings can thicken

Disadvantages of Thinning. Thinning has the following disadvantages: •

A thinned coating deposits fewer coating solids per square foot, resulting in thinner films and the possibility of needing more coats than an unthinned coating.

•

Excessive thinning causes coatings to run and sag and catalytic-cured coatings to crack.

Drying & Curing Plans for a coating project must include the amount of time needed for drying before handling the surface or returning it to service and for curing the coating. Drying. Drying times vary considerably. The following factors affect drying time; some can be controlled to reduce drying time.

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500 Application

• • • • •

Coating Type and Manufacturer Temperature Humidity Ventilation Film Thickness

If necessary, specify specially formulated, quick-drying coatings. Curing. Complete curing is essential before putting coatings into service in areas of immersion or exposing them to chemicals or foot traffic. After mixing and before applying some high-performance two-component coatings, such as epoxies and urethanes, specify that the coatings applicators allow an incubation period for these materials to begin curing. Applied too early or too late, the coatings will cure improperly. Note As curing time varies among coating types and brands, always follow the manufacturer's instructions for curing.

Storing Coatings

☞

Caution •

Follow the manufacturers' recommendations to avoid such problems as coating curdling, gelling, and skinning.

•

Store the coating in a protected area, such as a building, to shield it from extremes of temperature and humidity.

•

Check the shelf life of any coating before applying it and do not use a coating older than its recommended life.

See also Section 800 of this manual for information about storing coatings for offshore projects.

522 Selection of Coatings Applicators Coatings applicators and coatings contractors have the most influence on a coating's quality. A poor or inexperienced coatings applicator can ruin a coating project or, at best, achieve mediocrity. Evaluate coatings applicators carefully before selecting one. Questions that should be answered are:

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•

Does the applicator have experience with the Company's projects locally? If so, attempt to locate the foreman to discuss this person's performance.

•

Does the applicator have experience in other industries? If so, contact engineers or maintenance supervisors in these industries for references.

•

Does the applicator have the proper equipment for the job?

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500 Application

Coatings Manual

•

Do coating manufacturers know and recommend this applicator? Manufacturers have a vested interest in having their products applied properly.

•

Is the applicator currently working on a job that you could visit? If so, ask the owner's engineers if they are satisfied with this coatings applicator's performance.

After the coatings applicator is selected, he should choose the coating method after considering several factors: • • •

Type of structure and surface to be coated Type of coating, the coating thickness, losses, and coverage Weather conditions expected during application

523 Structure and Surface to be Coated The structure itself is another factor in determining the best coating method because of its: • • • • •

Size and shape Accessibility of its components Service Location relative to other structures (roads, parking lots, furnaces, electric lines) Geographical location (level, hilly, mountainous terrain, near water)

Other important factors in application include the type of material to be coated and the extent of surface preparation. See Figure 500-3. Fig. 500-3

Recommended Coating Methods by type of Surface Surface

Brush

Roller

Spray

x(1)

Cyclone fence Hand-cleaned or rusted

x

Large, rough

x x

Large, flat

x x

Masonry, stucco, concrete

x

x

Metal

x

x

x(2)

Piping

x

x

x

Abrasive blasted

x

x

x

Small

x

x

(1) Unless special electrostatic equipment is available. (2) Usual method

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500-8

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500 Application

524 Multiple Coats When planning a project with multiple coats, choose the most efficient method for multiple-coat applications and the coating formula with a high content of solids to reduce the number of coats needed for the desired thickness of film. Note While multi-mil alkyds can be four mils in one coat, normal alkyds need two coats to achieve that thickness. Thick coatings are hard to roll or brush.

525 Weather and Atmospheric Conditions Coatings Formulation Coatings are often formulated to work well in the manufacturer's geographical area but may have problems elsewhere. •

Coatings formulated for a cool or coastal area may prove unsatisfactory when applied in a hot, dry, or high-altitude area.

•

Leafing problems of metallic pigmented coatings are associated with environmental changes.

•

Manufacturers recommend a range of the atmospheric conditions for applying coatings.

Atmospheric Conditions Atmospheric conditions for coatings include temperature, humidity, and wind. Temperature. If the temperature is too low (less than 50°F), most catalytic coatings do not cure; air-dry coatings are hard to apply and dry slowly. In hot weather or strong sunlight, coatings may dry too rapidly for entrapped solvents to escape, producing defects such as blistering, cratering, wrinkling, and overspray marking. Many catalytic-curing coatings will not cure in damp weather. Humidity. Coatings applied over damp surfaces will peel and wrinkle.

☞

Caution Never apply coatings under the following conditions: •

Over damp surfaces

•

When relative humidity exceeds manufacturer's written recommendation

•

When surface temperature is less than 5°F above the dew point

Wind. High winds/drafts increase overspray and the danger of damage to nearby objects. Dust and sand blown on freshly coated surfaces mar the coating finish or form defects where coating deterioration may begin.

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500 Application

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☞

Caution

Do not apply coatings in strong winds or drafts, especially by spraying.

530 Touch Up Touch up is important for newly coated or installed items after welding activities are completed. Generally, welding, shipping, and handling damages the coating on new structures. Weld burns and cable scars need prompt attention to prevent unnecessary metal loss on damaged areas. It is important to protect the weld and damage areas from corrosion while the degree of rusting is still minor. Delays can be costly due to expanding undercreepage of the existing coats and worsening degree of corrosion around the damaged areas. A relatively minor touch-up operation in the beginning can turn into a sizable project in just a few years. An increase in costs up to 20 percent per year over the original cost are possible when including the associated costs for an increased work scope, additional labor time, and materials.

540 Reference 1.

September 1996

Weismantel, Guy E. “Paints and Coatings for CPI Plants and Equipment.” Chemical Engineering. April 20, 1981: pp. 130-143.

500-10

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600 Coating Concrete Abstract This section focuses on basic projects for coating concrete. Topics covered include: the most suitable coatings and coating systems, how to assess and repair the concrete surface, and issues peculiar to coating concrete. Before preparing the surface, it may be necessary to repair common, non-structural damage to the concrete such as holes and cracks. For structural repair of concrete, which is beyond the scope of this manual, contact the Company's civil and structural engineers. When selecting a concrete coating, it is important to know its intended exposure, such as environment, temperature, and immersion. The selection guides and data sheets for coating concrete in mild environments are available in the Quick Reference Guide. For critical projects, consult one of the Company's coating specialists (also listed in the Quick Reference Guide). From the standpoint of application, there is no one standard technique because of the complexity of this surface. While general information is offered in this section, specific assistance is available both from manufacturers and the Company's coating specialists.

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Contents

Page

610

Coating Concrete in General

600-3

611

Existing Structures or New Construction

612

Engineering Assistance

613

Reasons for Coating Concrete

620

Descriptions of Coatings for Concrete

621

Coatings

622

Coating Systems

630

Selection

631

Defining Conditions

640

Assessing and Repairing Concrete

641

Assessing the Surface

600-4

600-9

600-1

600-10

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600 Coating Concrete

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Coatings Manual

642

Repairing Non-structural Damage

650

Surface Preparation

651

Pre-application Requirements

652

Precleaning

653

Mechanical and Chemical Cleaning

660

Application

661

Recommended Process

662

Reviewing an Application Procedure

670

Inspection

600-23

680

References

600-25

600-21

600-22

600-2

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Coatings Manual


610 Coating Concrete in General There are many factors to consider at the outset of a concrete coating project. Some factors are: •

Whether or not the structure is existing as that affects the level of surface preparation required

•

The level of engineering assistance necessary for the project

•

The reasons for coating concrete which fall basically into two categories: practical maintenance and safety regulations

611 Existing Structures or New Construction Because of the extra surface preparation required, an existing structure is usually more difficult to coat than a new structure. Existing structures may require: • • • •

Removal and repair of corroded or damaged concrete Repair of corroded reinforcing bars Repair of existing cracks Removal of two to three inches of contaminated concrete

These repairs may involve rebuilding the structure with either fresh concrete or an epoxy polymer material. During initial design, review all potential problems with coating or lining a new structure. If new construction is designed to accept a coating or lining, the coating will cost less and will be less likely to fail prematurely.

612 Engineering Assistance Coating or lining concrete has so many variables that this section cannot cover all of the possible situations. This section represents an overview of the information required to coat or line concrete. Before coating or lining a concrete structure, evaluate the difficulty of the project and, for critical projects, contact the Company's coating specialists listed in the Quick Reference Guide. Example: One criterion for a critical project is that a premature failure could seriously affect the Company.

613 Reasons for Coating Concrete Practical maintenance, safety, and complying with regulations are the main reasons for coating concrete.

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Practical Maintenance and Safety The following discussion details reasons for coating concrete on the basis of practical maintenance and safety. Protection from the environment. One of the most important factors in selecting a coating system is its environment: exposure to temperature, physical abuse, and immersion service. Concrete may require protection from its environment in API separators, sulfur pits, pump bases, floors, or other primary containment. Protection from wear. One of the main uses of coatings for concrete is to protect floors from wear. There are coating systems designed for foot, light vehicular, and heavy equipment traffic. Maintenance. Because concrete is a porous material, it retains dirt and stains easily. Coating concrete can reduce significantly the cost of routine cleaning. Safety. Non-slip or skid resistant coatings are available for traffic safety on concrete.

Regulations In addition to practical maintenance, existing regulations require owners to protect concrete with coatings and linings. A discussion of some regulations follows. Under the Resource Conservation and Recovery Act (RCRA), owners must install secondary containment, such as impoundment basins, for aboveground tanks that store hazardous wastes. While concrete is one of the most cost-effective materials for this service, RCRA does not consider concrete a material suitable for containing hazardous wastes unless it is coated or lined. Example: An impoundment basin is one form of secondary containment. Under the Oil Pollution Act of 1990, Congress mandated that the Environmental Protection Agency (EPA) study the need for regulating aboveground petroleum storage tanks. This impending regulation could result in the Company having to line or provide secondary containment for all petroleum storage tanks. It is also possible that State and local environmental agencies might create and enforce equal or more stringent regulations for secondary containment. Regardless of current regulations, consider coating concrete wherever it is necessary to contain or exclude fluid.

620 Descriptions of Coatings for Concrete While there are many resins available for coating concrete, none are perfect. Selection depends on the coating's environment and exposure to corrosive media, temperature, and physical abuse. When several resins are equivalent, then cost and ease of application become the selection criteria.

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Listed in alphabetical order, the five major resins for coating concrete structures are: epoxy, isophthalic polyester, novolac epoxy, polyurethane, and vinyl ester. General information about some of these resins is also available in Section 100 of this manual. The four main systems for coating concrete are as follows: non-reinforced thin film, flake-reinforced, glass-flake laminate, and elastomeric polyurethane. As most coating systems for steel are equally suitable for concrete, see Section 100 of this manual for general information about non-reinforced, thin-film, and glassflake-reinforced coatings.

621 Coatings Epoxy Epoxy resins are the most common, thin-film coatings for concrete. Advantages: • •

Very good resistance to bases and many solvents Good adhesion to concrete and are easy to apply

Disadvantages: •

Poor resistance to acid unless modified by a phenolic

Isophthalic Polyester There are two major classes of polyester resins, but the Company uses only isophthalic which is the main resin in laminate-reinforced systems. Advantages: • •

Corrosion protection Least expensive resin

Disadvantages: •

Poorer resistance to chemicals than other resins

Epoxy Novolacs Novolacs are second generation epoxies with greater cross-linking density. Advantages: •

Greater resistance to chemical attack and high temperatures than all other epoxies

Disadvantages: •

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More expensive and less flexible when compared to standard epoxies

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Coatings Manual

Polyurethane There are literally thousands of polyurethane formulations from hard roller-skate wheels to elastomeric materials with the elasticity of rubber bands. Advantages: Through its wide variety of formulations, polyurethane can have many different properties. • • •

Chemical, abrasion, and impact resistant Tensile strength Elasticity

Note Because increases in one property mean decreases in another, many elastomeric polyurethanes are not as chemically resistant as the more rigid polyurethanes. Disadvantages: •

Some elastomeric formulations are not very resistant to chemicals.

Vinyl Ester A reaction product between polyesters and epoxies, vinyl ester shares many of the attributes of polyesters. Advantages: • • •

Resistant to acid Resistant to solvent attack Resistant to high temperatures

Disadvantages: •

More costly than an isophthalic polyester or normal epoxy

622 Coating Systems Thin Film Thin film is only 10 to 20 mils thick and contains no flakes, fibers, or laminates for reinforcement. Usually, this coating has some inert fillers such as silica or carbon to reduce shrinkage during cure and to improve resistance to abrasion. A thin-film system needs two or three coats: a primer/sealer and one or two high-build topcoats. Recommended dry film thickness (DFT) is 15 to 20 mils, with thicker DFT for more severe services. Advantages: •

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Low cost due to use of the least amount of material, no expensive hand work required, and easiest to apply

600-6

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Disadvantages: •

Thinness of film which leads to lack of resistance to abrasion, severe chemical attack, and physical abuse

•

Unreinforced film which means it will not bridge existing cracks

Uses: • • •

Mild service conditions Splash or spillage environments Temporary service

Flake-reinforced The flake-reinforced coating system is the most common system for concrete. Flake-reinforced coatings come in both spray- or trowel-applied formulae. Spray is generally applied in two 15 to 20 mil (DFT) coats for a total of 30 to 40 mils (DFT). Trowel applied, with a larger reinforcing flake size, is generally applied in two 30 to 40 (mil) coats for a total of 60 to 80 mils (DFT). Advantages: •

Excellent properties for most environments

•

Better than thin film at resisting chemical attack (parallel flakes reduce the coating's permeability) and physical abuse by abrasion

•

Cost less than laminate systems

Disadvantages: •

☞

Rolling is necessary for each layer of either formula so that the flakes lie parallel to the surface.

Caution Although some manufacturers claim their spray formulae are self leveling and do not require rolling, always roll this coating to improve its properties. Flake-reinforced Sprays. The flake-reinforced spray is applied much like a thinfilm system. Advantages: •

Twice the thickness of thin films; covers a more uneven surface than thin film

Disadvantages: •

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Because they require rolling and extra material, these sprays are marginally more expensive than thin films but not as costly as the trowel-applied formula.

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Trowel-applied Flake-reinforced Coatings. Advantages: •

More resistant to chemical attack, abrasion, and physical abuse than either the flake-reinforced spray or thin-film systems

Disadvantages: •

Application considerably more difficult and time consuming than either the flake-reinforced spray or the thin-film systems; hand smoothing and then rolling is necessary to orient the glass flakes

Glass-flake Laminate Laminate-reinforced systems are applied by hand in alternating layers of resin and glass mat. These coating systems: •

Generally have three layers of resin and two layers of fiberglass mat

•

Have a total thickness is 80 to 125 mils

•

May require a special surfacing veil and final resin topcoat for some of the more aggressive services; chemical glass or polyester are the most common surfacing veils.

After inspecting the completed laminate system, apply a final 10 mil (DFT) resin coat without which the surface would remain tacky and lack optimum chemical resistance. With epoxy resins, this coat gives additional protection from chemical attack and is called a gel coat. With polyester and vinyl ester resins, the final coat is a 90/10 mixture of resin and wax. Advantages: • • •

For severe applications Adds structural strength Best chemical, wear, and impact resistance

Disadvantages: •

Hand-applied, laminate-reinforced coatings are by far the most expensive

Elastomeric Urethanes Elastomeric urethanes, developed as internal coatings for tanks, are thicker than most non-reinforced coatings (30 to 60 mils or more). Applied in one coat, these tough, rubbery coatings are suitable for certain special applications but are not among the standard systems because the Company has limited experience with them. There are two types of elastomeric systems: textile-reinforced and non-reinforced, both of which can be applied at 40 mils (or greater) DFT.

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Advantages:

☞

•

Depending on their formulation, elastomeric systems can have very good resistance to impact, abrasion, and wear.

•

Because they are elastomeric, manufacturers also claim they can bridge cracks.

Caution While the claim about bridging cracks may be true to some extent, be certain to design and specify proper repair of all cracks and joints before coating. Disadvantages: •

All elastomeric systems have a modified polyurethane resin which makes the system more expensive than some flake-reinforced and thin-film systems.

•

Polyurethanes are very moisture sensitive during application.

630 Selection For definitions of environment, physical abuse, and exposure, see Figures 600-1 through 600-5. See the Quick Reference Guide for selecting concrete coatings in mild environments. For coating concrete in moderate-to-aggressive conditions, contact the Company's coating specialists listed in the Quick Reference Guide. Fig. 600-1

Definitions of Environment, Physical Abuse, and Exposure for Concrete Coatings

Description

Environment

Physical Abuse

Exposure

Mild

< 140°F, mild acids, bases, solvents

No coating loss due to abrasion; possible light foot traffic. No physical impact on coating.

N/A

Moderate

< 140°F, strong acids, bases, solvents

Moderate coating loss due to abrasion, light equipment wear. Possibility of impact on coating.

N/A

Aggressive

> 140°F, strong acids, bases, solvents

Severe coating loss due to abrasion, heavy equipment wear. Definite potential for impact on coating.

N/A

Continuous

N/A

N/A

Exposed to the corrosive medium for longer than 24 hours.

Intermittent

N/A

N/A

Exposed to the corrosive medium for less than 24 hours— usually splash or spillage that is cleaned up within 24 hours

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631 Defining Conditions Before calling the Company's coating specialists, know the following information about the conditions anticipated for the concrete coating. Refer to Figure 600-1 for definitions, and also Figures 600-2 through 600-5 Environment. To what temperature and corrosive media is the coating exposed: aggressive, moderate, mild? Physical Abuse. To what extent is the coating exposed to abrasion such as from foot traffic, light cleaning, automobile traffic: aggressive, moderate, mild? Exposure. Is the coating exposed to chemicals continuously or intermittently? Fig. 600-2

Coating Recommendations for Continuous Immersion

640 Assessing and Repairing Concrete All concrete must be clean, dry, and in sound condition to receive a coating or lining system. While this surface may be easy to achieve with new construction, it may be expensive for existing structures. Before concrete can be prepared to accept a coating, ensure that the substrate:

September 1996

•

Is properly cured and dry. The coatings applicator should tape a black plastic sheet over the substrate and check for moisture after 24 hours (ASTM D-4263).

•

Has a minimum compressive strength of 3,000 psi

600-10

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Coatings Manual

Fig. 600-3


Coating Recommendations for Continuous Immersion Service

Recommendation #1: Use a laminate reinforced system to resist physical abuse and chemical attack. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be an epoxy novalac or vinyl ester resin. Because of the severe service obtain the assistance of a specialist knowledgeable in repairing and coating concrete. See the Quick Reference Guide for a list of recommended specialists.

Obtain the assistance of a specialist in coating concrete. By evaluating specifics of your project, he may be able to recommend a flake reinforced system instead. Depending on the size of your project this could result in considerable cost savings. Recommendation #5: Use a flake reinforced system to resist the chemical attack. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be an epoxy, epoxy novalac, or vinyl ester resin.

Recommendation #2: Use a flake reinforced system to resist chemical attack and the reduced physical abuse. A laminate system would work here but at twice the cost. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be a novalac epoxy or vinyl ester resin. Because of the aggressive corrosive media, obtain the assistance of a specialist knowledgeable in repairing and coating concrete. See the Quick Reference Guide for a list of recommended specialists. Recommendation #3: Use a flake reinforced system to resist chemical attack. Even with the mild physical abuse do not use a thin film system. The thicker flake reinforced system is required to resist the severe environment. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be a novalac epoxy or vinyl ester resin. Because of the aggressive corrosive media, obtain the assistance of a specialist knowledgeable in repairing and coating concrete. See the Quick Reference Guide for a list of recommended specialists. Recommendation #4: Use a laminate reinforced system to resist physical abuse. A flake reinforced system would be adequate to resist the chemical attack. The resin selection should be reviewed

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with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be an epoxy, novalac epoxy, or vinyl ester resin.

Recommendation #6: Use a flake reinforced system to resist the chemical attack. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be an epoxy, epoxy novalac, or vinyl ester resin. Recommendation #7: Use a laminate reinforced or a textile reinforced urethane system to resist the physical abuse. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be a polyester, epoxy, or modified urethane resin. Recommendation #8: Use a flake reinforced or a textile reinforced urethane system to resist the physical abuse. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be a polyester, epoxy, or modified urethane resin. Recommendation #9: Use a flake reinforced or a textile reinforced urethane system. Because this is immersion service, use a reinforced system. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be a polyester, epoxy or modified urethane resin.

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Fig. 600-4

Coatings Manual

Coating Recommendations for Intermittent Immersion/Splash/Spillage

•

Has a surface strength of at least 200 psi. To measure the surface strength, the inspector or Company's representative should attach a metal piece to the concrete with adhesive and measure the force needed to remove it (ASTM Standard Method M-4541).

•

Has a uniform surface free of excessive defects and laitance. To finish new concrete, the coatings applicator should smooth once over the surface with a wood float and then use a steel trowel.

Note Laitance is the film caused when a water-rich cement rises to the surface during finishing. Remove this 5- to 50-mil-thick film before applying any coating.

641 Assessing the Surface New Structures During the initial design of a new structure, investigate potential problems involving coatings or linings to reduce costs and premature failures. If laid properly, new concrete requires only cleaning of surface dirt, oil, laitance, etc., before abrading. There may, however, be other items to consider such as vibration, agents and slivers, and curing.

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600-12

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Fig. 600-5


Coating Recommendations for Intermittent Immersion Service

Recommendation #10: Use a laminate reinforced system to resist the physical abuse and chemical attack. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be an epoxy, novalac epoxy, or vinyl ester resin.

selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be an epoxy, novalac epoxy, or vinyl ester resin.

Depending on the type of physical abuse, a flake reinforced system could be used. This should be confirmed with someone experienced with coating concrete.

Recommendation #15: Use a thin film system to resist the chemical attack. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be an epoxy, novalac epoxy, or vinyl ester resin.

Recommendation #11: Use a flake reinforced system to resist the chemical attack and the reduced physical abuse. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be an epoxy, novalac epoxy, or vinyl ester resin.

Recommendation #16: Use a laminate reinforced or a textile reinforced urethane system to resist the physical abuse. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be a polyester, epoxy, or modified urethane resin.

Recommendation #12: Use a flake reinforced or thin film system to resist the chemical attack. The selection of reinforced or thin film will depend on the amount of mild physical abuse. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be an epoxy, novalac epoxy, or vinyl ester resin.

Depending on the type of physical abuse, a flake reinforced system could be used. This should be confirmed with someone experienced with coating concrete.

Recommendation #13: Use a laminate reinforced system to resist the physical abuse and chemical attack. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be an epoxy, novalac epoxy, or vinyl ester resin. Depending on the type of physical abuse, a flake reinforced system could be used. This should be confirmed with someone experienced with coating concrete. Recommendation #14: Use a flake reinforced or thin film system to resist the chemical attack. The selection of reinforced or thin film will depend on the amount of moderate physical abuse. The resin

Chevron Corporation

Recommendation #17: Use a flake reinforced or elastomeric urethane system to resist the moderate physical abuse. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be a polyester, epoxy, or modified urethane resin. Depending on the type of physical abuse, a thin film system could be used. This should be confirmed with someone experienced with coating concrete. Recommendation #18: Use a thin film or elastomeric urethane system. The resin selection should be reviewed with the coating manufacturer to ensure it is resistant to the corrosive media. It will probably be an epoxy or modified urethane resin.

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Vibration. Vibration consolidates the concrete but can also cause water and air bubbles to move out to the face of the form, resulting in tiny voids or holes in the concrete surface. Before coating or lining concrete, fill all holes, including those opened during surface preparation. Agents and Slivers. Many forms are built with commercially available plywood or wood planks. When removed, these forms may leave other materials in the concrete such as release agents that facilitate the removing forms, or large slivers of wood. Remove these materials, then repair and smooth the area before coating it. Curing. Unless the concrete cures properly, it may crack; if so, repair all cracks before coating or lining.

Existing Structures Attacked by chemicals, contaminated by hydrocarbons, and damaged by mechanical means, existing concrete may require extensive repairs and surface preparation. A careful inspection should determine whether or not the existing concrete is structurally sound. Corrosion. Depending on the amount of corrosion in the steel reinforcement, the concrete will require the following: •

Corroded - Coating or cathodic protection in aggressive environments

•

Severely corroded - Replacement of steel reinforcing and the affected concrete or epoxy-polymer material

Contamination. Depending on the level of contamination, concrete that has been exposed to oils or other impurities may require high-pressure detergent-and-water cleaning. It also may require replacing as many inches of concrete as necessary to remove the contaminants.

642 Repairing Non-structural Damage There are several common kinds of non-structural damage to concrete, such as cracks, holes, expansion joints, and drain and pipe penetrations.

Cracks Among the choices for repairing concrete based on the size and activity (still moving) are the following: • • •

Filling them with a sealer Making them into expansion joints Filling them by pressure injection

Begin with the basic procedures for filling concrete cracks, regardless of size.

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Basic Procedure for All Cracks. To repair all cracks, begin by:

☞

1.

Blowing any standing water out of the crack

2.

Removing oils or chemicals in the crack

Caution Do not inject solvents into cracks to remove oils or chemicals because this process actually dilutes the contaminants and carries them further into the concrete surface. Instead use an injection grout that will solubilize the oils and water, bond to the concrete, and cure with suitable properties for the intended purpose. Continue the repair—depending on the size of the crack—by following the steps either for small or for large cracks, below. Additional Steps for Small Cracks. alternatives.

To repair small cracks, there are two

Alternative One: Filling with Sealer 1.

Grind the crack into a V shape with an opening that is a minimum of ½-inch wide at the surface of the concrete.

2.

Pour or trowel the sealing grout into the crack.

3.

Scrape off excess grout.

Alternative Two: Creating Expansion Joints. Convert small cracks into expansion joints, which allow concrete to expand and contract with changes in temperature or movement of the substrate. See Figure 600-6, Detail “C.” This figure also covers corrosion control of floor-to-wall expansion joints and floor-to-wall control joints. As they are highly susceptible to premature failures, design expansion joints carefully ½- to 1-inch wide and as shown in Figures 600-6, 600-7, and 600-8. Note Figure 600-7 shows sealant system for corrosion control in mild environment; Figure 600-8, for more severe environments. The steps for creating expansion joints are as follows:

Chevron Corporation

1.

Place sufficient joint material between the concrete surfaces to allow the closed-cell foam-backing rod to come within ½- to 1-inch of the concrete surface.

2.

Pour or trowel on a flexible joint sealant to bring the joint up to the level of the concrete surface.

3.

Place 2-inch-wide, vinyl, electrical tape over the joint to provide a bond breaker.

4.

Place a ½-ounce glass mat, saturated with resin, over the tape.

5.

Apply the corrosion coating system over the mat.

600-15

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Coatings Manual

Fig. 600-6

Corrosion Control Treatment of Sealed Expansion Joints, Control Joints, and Cracks in Concrete Foundations

Additional Steps for Large Cracks. To repair larger cracks, fill them by pressure injection. The steps for pressure injection are as follows:

September 1996

1.

Grind the crack into a V shape.

2.

Select an appropriate size of copper tubing.

3.

Drill holes along the crack 1/8-inch larger than the tubing and to the depth of desired penetration.

4.

Insert the tubing into the crack.

5.

Grout the crack on the surface to seal it and hold the tubing in place.

600-16

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Fig. 600-7

Corrosion Control Treatment of Exposed Expansion Joints in Concrete Integral with Monolithic Floor/Lining System

6.

Install a grease fitting in the first tube when the grout is cured.

7.

Inject grout into the tube with a pump.

8.

Allow the grout to flow out of the next tube until the color approaches the original mixture to ensure removal of all contaminants.

9.

Repeat the process, filling all tubes.

Holes This section provides information on filling both small and large holes. Small Holes. During blasting, air pockets open in or just below the surface of most formed concrete. There are two mixes for filling these holes.

Chevron Corporation

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Fig. 600-8

September 1996

Corrosion Control Sealing of Expansion Joints, in Concrete Integral with Monolithic Floor/Lining System

•

Resin-based material is the Company's preferred method of repair. Some are powders mixed with the primer and trowel applied which gives a smooth surface for good coating adhesion. Others are epoxy grouts.

•

Portland-cement materials require expert installation and generally need an additive to reduce shrinkage during cure and to improve adhesion to the old surface. The problems with this cement are that it does not bond well to cured concrete; does not cure well in thin layers; and usually leaves a carbonate layer on the surrounding concrete which can, if not removed, cause coating failures.

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Large Holes. There are two main choices of fill for larger holes, both of which need special handling: •

Concrete - Undercut the hole to guarantee mechanical bonding or apply a chemical bonding agent.

•

Compatible resinous grout - Treat forms with a release agent for easy removal. As formed resinous grouts usually cure with a glazed surface, abrasive blast or grind this glazing to roughen it to ensure that the coating adheres well.

Drain and Pipe Penetrations Drain and pipe penetrations are almost as vulnerable to failure as expansion joints. Usually, they are not concrete and have very different thermal coefficients of expansion. Improper design can cause leaking at the penetrations. For drains, see Figure 600-9. Figure 600-10 shows details of installing a corrosioncontrol system for pipes. Fig. 600-9

Chevron Corporation

Floor System Termination at Floor Drain

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Fig. 600-10 Corrosion Control Treatment of Pipe Penetration through Concrete Wall or Floor

In either case:

September 1996

1.

Dig a groove ¾-inches wide and ¼-inch deep around the drain or pipe penetration.

2.

Fill the groove with sealant.

3.

Butt the corrosion control system against the sealant for mild environments or extend it to the drain cover in more aggressive environments.

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650 Surface Preparation The life of a coating is directly related to surface preparation. After designing joints and penetrations and repairing all cracks, holes, and other defects, establish the method of surface preparation necessary to clean away all loose concrete, oil, grease, dust, laitance, grime, and other foreign materials. There are several methods of surface preparation for coating concrete. The mechanical methods—abrasive blasting, scarifying, and blastracking—produce the best surface for coating adhesion.

651 Pre-application Requirements See Assessing and Repairing Concrete (above) for the four conditions required of a concrete substrate to be ready to accept a coating.

☞

Caution Do not accept broom finishing as it can leave an irregular surface with excess laitance; and, in the case of air-entrained concrete mixes, it can open large holes at the surface.

652 Precleaning To preclean a concrete surface, follow the ASTM D4258 method: 1.

Remove: – – –

2.

Dirt and caked grease manually or with an acid wash Grease and oils with low-foaming detergents Animal fats or vegetable oils with saponifying agents

Patch test to determine the best cleaning procedures for the surface.

Clean or remove the surface until it meets the pre-application requirements.

653 Mechanical and Chemical Cleaning Abrasive-blast Cleaning Abrasive-blast cleaning is the Company's preferred method of surface preparation. Note There is additional information about abrasive-blast cleaning in Section 400; and, although that section relates to surface preparation for steel substrates, some details are applicable to concrete. Advantages: • •

Chevron Corporation

Gives high production rates for all surface configurations Leaves an excellent surface condition for coating

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Disadvantages: •

Creates excessive dust and waste material as the abrasive breaks down

Blastracking Blastracking is similar to abrasive blasting but uses metal shot instead of abrasive Advantages: •

Produces comparable surfaces to abrasive blasting with less dust and waste material

Disadvantages: •

Restricted to horizontal surfaces because it is a fairly large machine

Scarifying (Air Hammer) Scarifying is often the alternative when field or other conditions prevent blasting of concrete surfaces. Note A scarifier is an apparatus with steel hammers that hit a surface, removing loose material. Advantages: •

Produces an acceptable surface with less clean-up, set-up, and dust.

Disadvantages: •

Produces a rougher surface than abrasive blasting.

Acid Etching Acid etching is the least acceptable cleaning method, but may be used if needed. The steps for acid etching are:

☞

1.

Mix one part of concentrated hydrochloric acid with two parts water to form the etching solution.

2.

Brush the solution on the concrete.

Caution If the etch does not produce a 60-grit, sandpaper-like profile, repeat the etch. Diluted acid permeates the concrete surface dissolving salts and other contaminants. There is, however, an undesirable side effect; as it dries, the acid deposits the contaminants on the surface, adversely affecting the bond between the coating and the concrete.

660 Application Because of the complexity of coating concrete and the different systems and resins available, it is impossible to have one uniform application procedure.

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661 Recommended Process The recommended application process is to: 1.

Select the coating system and resin. Either refer to the Quick Reference Guide (for mild environment) or obtain the assistance of the coating manufacturer and the Company's concrete coating specialist (for other environments).

2.

Request detailed application procedures from the manufacturer for the coating selected.

3.

Review application procedures with the coatings applicator and the coating manufacturer, resolving differences until the procedure is acceptable to all.

662 Reviewing an Application Procedure Here are some points to consider when reviewing or writing an application procedure: •

Many concrete coating systems require a primer for optimum application results.

•

The temperature of concrete slabs should be between 50°F and 85°F when coating; the slab's temperature must be 5°F above the moisture dew point.

•

For optimum results from the application: – –

Apply the primer coating out of direct sunlight. Apply the primer and topcoat when the slab's temperature is cooling rather than rising.

•

An order of cost (low to high) for coating systems is thin films, flakereinforced films, and laminate-reinforced films.

•

An approximate order of cost (low to high) for resins is as follows: polyesters, epoxies, novolac epoxies, vinyl esters, and polyurethanes.

•

Epoxy resins are the easiest to apply, followed by novolac epoxy, polyester, polyurethane, and vinyl ester.

•

Polyester and vinyl ester require a final wax coat (mixture of wax and resin) to obtain full surface cure.

•

Thicker is not always better. All coatings and linings have a maximum allowable thickness.

670 Inspection Inspection is an integral part of the quality of a coatings project. The following references offer guidance about the degree of inspection needed and how to select a quality inspector.

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•

Coatings Manual, Section 100 The inspection procedures for steel can be used for inspecting concrete, in most cases.

•

National Association of Corrosion Engineers RP0288, Inspection of Linings on Steel & Concrete.

•

American Society for Testing and Materials D453786, Procedures to Qualify and Certify Inspection Personnel for Coating Work in Nuclear Facilities. (Good information about qualifying any coating inspector.)

Some construction details in concrete may need particular attention from the inspector.

Concrete-to-Steel Interface In addition to penetrations, other potential concrete-and-steel interfaces need coating. See Figure 600-11, Detail “A,” for one example of sealing a pedestal/pipe stand in a concrete pit. Fig. 600-11 Corrosion Control Treatment of Steel-to-Concrete Interface

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680 References The following publications give additional information for repairing and coating concrete.

Chevron Corporation

1.

American Society for Testing and Materials. Standard Practice for Surface Cleaning Concrete for Coating (R 1992). ASTM D4258. 1983.

2.

———. Standard Practice for Abrading Concrete (R 1992). ASTM D4259. 1988.

3.

———. Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method (R 1993). ASTM D4263. 1993.

4.

———. Standard Practice for Determining Coating Contractor Qualifications for Nuclear Powered Electric Generation Facilities. ASTM D4286. 1990.

5.

———. Standard Guide for Establishing Procedures to Qualify and Certify Inspection Personnel for Coating Work in Nuclear Facilities. D4537. 1991.

6.

———. Standard Test Method for Pull-off Strength of Coatings Using Portable Adhesion Testers. ASTM D4541. 1995.

7.

National Association of Corrosion Engineers. Monolithic Organic Corrosion Resistant Floor Surfacing. NACE RP-03-76.

8.

———. Inspection of Linings on Steel and Concrete. NACE RP-02-88.

9.

———. Linings for Concrete Surfaces in Non-Immersion and Atmospheric Services. RP-0591-91.

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700 Downhole Tubular Coatings & Linings Abstract In this section, there is general information about coatings and linings—selecting, purchasing, handling, installing, and operating guidelines—drawn from field experience, industry publications, and vendors. Internal coatings and linings are two choices for preventing corrosion in the steel base metal of downhole equipment. Internal coatings enhance the flow of fluids and may help prevent the build up of paraffin. Linings can salvage tubing. The purpose of a coating or lining for downhole equipment influences both its selection and the means of achieving the desired performance. Connections are an important consideration. For downhole tubing in oil and injection wells, the American Petroleum Industry's (API) eight-round connections are commonplace, coated routinely, and difficult to install holiday free A high-integrity internal coating may be more difficult to achieve on premium connections and typically requires more intensive evaluation and attention. Consider selecting connections designed specifically for IPC and lined tubing. See also Section 120 of this manual—for information on inspections and inspectors, including specific procedures for downhole tubing—and the Quick Reference Guide—for contacting Company's coating specialists, who are a primary resource for these specialty coatings and linings.

Chevron Corporation

Contents

Page

710

Coated Tubing Versus Linings

700-3

711

Wells Suitable for Coating or Lining

720

Descriptions

721

Coatings

722

Linings

723

Connections

730

Selection

731

Economics

700-4

700-10

700-1

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700 Downhole Tubular Coatings & Linings

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Coatings Manual

732

General Guidelines

740

Application

741

Steps in Application

742

Holiday-free Coated Tubing

743

Used Tubing

750

Handling Coated or Lined Tubing

751

Coated Tubing

752

Lined Tubing

760

Installation

761

Coated Tubing and Accessories

762

Guidelines for Installing IPC Accessories

763

Guidelines for Installing Lined Tubing

770

Guidelines for Well Operation

700-19

780

References

700-21

700-12

700-13

700-16

700-2

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710 Coated Tubing Versus Linings Coated tubing, commonly called internally plastic-coated (IPC) tubing, has liquid or powder coating applied to the inside diameter (ID) to a thickness of 5- to 30-mils dry film thickness (DFT). The coated surface reduces the frequency of corrosion-related failures by a factor of five (average). IPCs limit damage to local areas, avoid expensive fishing jobs, and increase the percentage of salvageable tubing. Note

Fishing jobs refers to retrieving parted tubing.

Plastic-coated tubing may also reduce rig time. Corrosion can thin the walls of uncoated tubing so badly that multiple parting failures occur when tubing is pulled during workovers. One hundred percent holiday-free coated tubing adds about ten percent to the cost of a coating project but is justified for the following: • •

Waterflood, water-disposal, and CO2 wells Corrosive services when anticipating long life and expensive rework

Lined tubing has much thicker internal-corrosion barriers which, with one exception, are physically inserted into the tubing. The exception is cement lining which is spun centrifugally on the ID surface. Linings offer truly holiday-free systems.

711 Wells Suitable for Coating or Lining The following types of wells are suitable for coated or lined tubing: Wells that produce a separate water phase. At 25 to 50 percent watercut, a well usually becomes corrosive. Note Watercut is the percentage of water to total fluids produced, such as oil plus water. Marginal wells. Wells in these circumstances may not justify a workover. While installing a coated tubing string may allow depletion of reserves, an uncoated string may fail before reserves are depleted. Note

A succession of joints of tubing makes a string of tubing.

Waterflood or water-disposal wells. Gas-condensate and high GOR (gas/oil ratio) wells. Gas wells are usually corrosive, particularly when producing connate water. Note

Connate water is defined as water trapped in a rock matrix.

Gas-lift wells with high-watercut. The well is especially susceptible to corrosion if the gas contains carbon dioxide or hydrogen sulfide. Note Gas-lift wells are those into which we inject gas to lift the oil out of the reservoir.

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Offshore wells. Wells located in remote or offshore areas make workover and chemical treatment expensive. The cost of a coated string is usually a fraction of the cost of a well or workover.

☞

Caution Because the constant rubbing damages the coating/lining, wells using sucker-rod pumps for artificial lift are not typically considered candidates for coatings or linings.

720 Descriptions All coatings are available as 100 percent defect (holiday) free; however, damage may occur during handling, installing, and well operations. For maximum corrosion protection, coated tubing may need a suitable corrosion inhibitor.

721 Coatings Thin-film coatings are generally 5 to 9 mils DFT; thick-film coatings generally 10 to 30 mils DFT. See Figure 700-1. Properties of Coatings

Fig. 700-1

Chemistry

Type

Thickness (mils)

Phenolic

Liquid

5–9

Modified Phenolic

Liquid

5–9

Epoxy-Phenolic

Liquid

5–9

Epoxy

Liquid

8–15

Epoxy

Powder

12–20

Epoxy-Cresol-Novolac

Powder

12–20

Nylon

Powder

12–25

Phenolics The Company has the longest history with phenolic coatings. Advantages: • •

Resistant to chemical attack (from pH 2 to pH 12) Withstand temperatures up to 300°F or higher

Disadvantages: • • • •

September 1996

Brittleness which limits their usefulness in preventing corrosion Limited DFT; not to exceed 9 mils DFT as brittleness worsens Gas-decompression problems, especially above 7,000 psi and if the coating is thick Susceptibility to mechanical damage from hitting or bending the pipe

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Uses: • •

As a primer under other thicker, more flexible coatings In high-temperature environments

Note Phenolics may be the only available coating material that can withstand very high temperatures. •

☞

Primarily for flow enhancement

Caution When using phenolics for corrosion control, consider a corrosioninhibitor-injection program to protect the steel in areas of coating damage.

Modified Phenolics Modified phenolics were developed to overcome the blistering of phenolics in highpressure gas wells. Decompressing high-pressure gas caused straight phenolics to blister because the gas could not escape from the coating fast enough. Modified phenolics contain calcium silicate to enable them to outgas more quickly. Advantages: •

More resistant to decompression damage than straight phenolics

•

High temperature, chemical, and H2S/CO2 resistance similar to the straight phenolics

Disadvantages: •

Brittleness

Epoxy Phenolics Adding epoxy to the phenolics reduces the brittleness of the coating. Advantages: • • •

Improved flexibility Improved alkali resistance Temperature resistant to about 250°F (some brands, even higher)

Disadvantages:

☞

Chevron Corporation

•

Reduced temperature and chemical resistance

•

Reduced acid resistance

•

Susceptible to mechanical damage or defects from handling, installation, and operations such as wirelining

Caution Consider applying corrosion inhibitors to protect steel exposed by damaged coatings.

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Modified Epoxies Two types of modified epoxies are discussed below: powder-applied and cresol-novolac. Powder-applied epoxies. Powder-applied epoxies are more flexible and tougher than liquid-applied epoxies, which are being phased out in the industry. Advantages: • •

Temperature limit of about 150–200°F Good chemical resistance to both acids and alkalis

Disadvantages: • •

Somewhat brittle Corrosion inhibitors necessary if primarily for corrosion control

Cresol-novolac-modified epoxy. Adding cresol-novolac to epoxy results in cresol-novolac-modified epoxy or epoxy-cresol novolac. To optimize overall performance, vendors have varied the amount of cresol-novolac for chemical resistance and flexibility. The propensity for mechanical damage may limit this coating's usefulness in service. Advantages: • •

Greater chemical resistance than straight epoxies Temperature resistant to approximately 250°F

Disadvantages: •

Brittleness increases in relationship to increased chemical resistance

Nylon Nylon is a relatively new coating for downhole tubing and accessories. A thermoplastic, rather than the thermoset of most IPCs, nylon has superior flexibility. Advantages: • • • •

Easy to apply One hundred percent holiday free Good chemical resistance up to about 180°F Very flexible and durable


Extremely poor resistance to damage from wire-line tools Deterioration from acidizing when HCI above 15 percent or for extended periods

Uses: •

September 1996

Excellent for a low-temperature line pipe (small diameter) in corrosive service

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722 Linings Linings are holiday-free systems and have thicker internal corrosion barriers than coatings. Except for cement, which is spun centrifugally on the ID surface, all linings are physically inserted into the tubing. The four lining materials presently available are cement, fiber-glass, PVC, and polyethylene. Suppliers are also investigating other materials such as carbon fiber. See Figure 700-2. Properties of Linings

Fig. 700-2

Lining

Thickness (mils)

Cement

150–210

Fiberglass

60–80

PVC

60–80

Polyethylene

130–150

Cement Cement lining has been available for many years. Advantages: • • • •

Cost effective Resists chemicals Withstands normal handling and installation Tolerates wireline work

Disadvantages: •

At a thickness of 150 to 210 mils, cement causes a significant reduction of the tubing ID.

•

Acids (HCl and mud acid) can damage cement.

Note

Special additives are available to improve the acid resistance of cement.

•

The weight of the cement limits the depth at which it can be used, with a practical limit of about 10,000 feet.

•

For wells between 7,000 and 10,000 feet deep, the weight of the cement can influence tubing selection.

•

The temperature limit is about 300°F, primarily because of the plastic inserts installed in the connections.

•

Availability may be a problem in remote areas.

Uses: •

Chevron Corporation

Holiday-free service in injection wells or non-rod-pumped producing wells

700-7

September 1996


•

Coatings Manual

Good choice for salvaging used tubing

Fiberglass Fiberglass-lined tubing is made by inserting a fiberglass tube of an aromatic aminecured epoxy inside the steel tube and then filling the annular space between the two with cement grout. The resulting liner is about 60 to 80 mils thick. Advantages: • •

Holiday-free service Chemical resistance up to a maximum operating temperature of 350°F


Some ID reduction Additional restrictions at flares on tubing ends

Uses: • • •

Primarily in injection wells Good service in non-rod-pumped producing wells Good choice for salvaging used tubing

PVC PVC-lined tubing is similar to fiberglass-lined tubing, with either a cement grout or an adhesive between the PVC and the steel tube. The thickness of the liner is 60 to 80 mils. Advantages: •

Holiday free

Disadvantages: • • •

ID reduction Unsuitable for gas wells (the risk of liner collapse from gas permeation) Unsuitable with solvents (such as paraffin cutting agents)

Uses: • •

Most suited to water injection wells up to about 150°F Good choice for salvaging used tubing

Polyethylene Polyethylene-lined tubing is a recent development and has little proven field experience. The polyethylene liner is swaged down and pushed or pulled through the tubing. It then re-expands into the tubing, leaving the polyethylene liner in compression. The end of the liner is molded to fit within the connection J area. The coating industry is addressing concerns about gas permeation, softening at maximum service temperature, and connection integrity.

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Check with the CRTC's coating specialists (listed in the Quick Reference Guide) for the latest information on the status of polyethylene linings. Advantages: • •

Extremely rugged Holiday-free and mechanical-damage-free service

Disadvantages: • • • • •

Significant ID reduction (150 mils thick) Temperature limit of about 150°F Concerns about gas permeation Softening at maximum service temperature Concerns about connection integrity

Uses: • •

Most suited to water injection wells up to about 150°F Good choice for salvaging used tubing

Carbon Fiber An ultra-high-temperature carbon-fiber liner and premium connection system is presently undergoing testing. This product may have a working temperature of up to 450°F.

723 Connections Most downhole tubing in oil wells and injection wells have API eight-round connections. They are easy to coat but difficult to install 100 per cent holiday free. Premium connections may be more difficult to coat internally.

Coated Tubing Connections There are basically two approaches for coating tubing with API eight-round connections: •

Coat the exposed threads on the coupling ID with Ryton (the best-known method).

•

Select specially made couplings that have a Teflon or reinforced-elastomer insert in the J-section.

Some premier connections with external torque shoulders do not require torque gages for make up. Both couplings use a marking system to make up the coupling to position; they may also solve the following problems: • • •

Chevron Corporation

Turbulent flow or sand-impingement damage at the J-section Moderate wirelining Failed Ryton-coated couplings

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Coatings Manual

Advantages: •

Connection with a flush ID instead of the discontinuous J-section in standard API eight-round couplings

•

Better seal

•

Protection for the coating on the pin-ends in the J-section from wireline tool damage

Disadvantages: •

Cost about three times as much as a standard coupling

Lined Tubing Connections Each lining has a different technique for protecting the coupling and pin-ends. •

For cement-lined tubing, polypropylene inserts are cemented into the end of the tubing; and pin-ends are embedded in an acrylic putty.

•

For fiberglass- and PVC-lined tubing, a nitrile rubber ring is fitted between the two pin-ends.

•

For polyethylene-lined tubing, an integral portion of polyethylene covering the pin faces mates when connected.

Premium Connections Non-API premium connections are highly specialized. Evaluate their suitability for coating or lining on a case-by-case basis with the connection manufacturer and the coating or lining applicator. Some premium connections may be unsuitable for holiday-free coating application. Surface preparation (e.g., abrasive blasting), coating, and make-up procedures must comply with the connection manufacturer's recommendations.

730 Selection For help in selecting coatings or linings, contact the coatings specialists listed in the Quick Reference Guide.

731 Economics Costs for coated or lined tubing and accessories vary significantly depending on the size of the order, the location of the job, market conditions, and other factors.

Purchasing Guidelines •

September 1996

For coated tubing and accessories, refer to Specification COM-MS-4732, Oilfield Tubular Goods and Accessories—Internal Coating Application.

700-10

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•

For cement-lined tubing, refer to API RP 10E There are no Company or industry specifications for purchasing cement-lined or fiberglass-lined tubing. Industry participants purchase these products from major suppliers and accept their specifications. See the Quick Reference Guide for a list of suppliers.

•

For PVC-lined tubing, refer to API Specification 15LT

•

There are no Company or industry specifications for purchasing polyethylenelined tubing.

732 General Guidelines In this manual, there are only general guidelines for selecting coatings and linings as it would be impossible to cover every conceivable well condition.

Environmental or Operating Conditions In some situations, downhole environmental conditions or planned operating criteria and procedures preclude effective use of coatings or linings. In such circumstances and if corrosion is anticipated, the only alternatives may be to install either bare-steel tubing with corrosion inhibitors or alloy tubing.

Influences of Materials on Selection Coating names are often different in the US market and overseas; some coatings with the same name exist but may be a modified version. Manufacturing space and equipment limit some manufacturer-owned application facilities so that they cannot apply their full product line of coatings. As few applicators offer cement linings in the US, the limitations of local applicators' facilities influence the choice of coating system.

Assistance For guidance on selecting coatings and linings, consult the Company's coating specialists (listed in the Quick Reference Guide). The following databases are also available: • • •

Company-purchased database of ARCO's lab test of coated tubing The Company's field-experience database The Company's lab-test database

The Company's databases are updated periodically to reflect the latest experiences with tubular coatings and linings. Please send relevant field experience or lab test information to the Company's coating specialists listed in the Quick Reference Guide.

Chevron Corporation

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740 Application See Figure 700-1 which lists common coatings for tubing.

741 Steps in Application To apply coatings, follow these steps: 1.

Bake at about 700°F to burn off oil and loosen scale.

2.

Abrasive-blast the surface to white-metal finish (NACE No. 1 or SSPC-SP 5).

3.

Apply primer, if appropriate, and cure.

4.

Apply the coating. – –

Apply multiple coats of liquid coating with a spinning spray head. Apply powder coatings with a vacuum or blow-in process, from one or both ends of the tubing.

5.

Bake at about 400°F to cure the coating.

6.

Visually inspect the coating; check thickness.

7.

Holiday test.

8.

Install couplings and thread protectors.

742 Holiday-free Coated Tubing Refer to Figure 1 of Specification COM-MS-4732 and follow this procedure to guarantee 100 percent holiday-free coatings: 1.

Round the end of the threaded tube to a smooth radius.

2.

Coat and holiday test the end of the tubing to the first major thread.

3.

Repair any holidays according to the specification.

743 Used Tubing Use any of the existing linings (see Figure 700-2) rather than coatings for used tubing. Fiberglass lining can bridge small holes in steel pipe (up to about ½-inch in diameter) and withstand pressure up to several thousand psi. Polyethylene liners also have this capability but to a lower pressure. Because coatings are relatively thin, they are not as effective for protecting used tubing if the ID surface is roughened from corrosion. Thick-film powder-applied coatings, especially nylon coatings, are better than thin-film coatings for recoating corroded used tubing. It is possible, however, that both types of coatings may fail to cover all peaks or bridge all gaps or pits on severely corroded steel surfaces. As a result, these uncoated or unbridged areas become exposed to the corrosive environment and cause premature failure of the coating and the steel.

September 1996

700-12

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The roughness of the surface (and not necessarily the depth of corrosion) determines the difficulty in applying a good coating. A uniform 50 percent wall loss from generalized corrosion is easier to coat than a wall loss of only 5 percent covered with sharp-edged pits. To determine whether or not the tubing is NSC (Not Suitable for Coating), the coatings applicator should inspect each length of tubing after cleaning and blasting and again after coating and holiday testing.

750 Handling Coated or Lined Tubing 751 Coated Tubing Because of the brittle nature of coatings, damage to coated tubing and accessories is virtually inevitable with the possible exception of those coated with nylon. The guidelines in this section are intended to minimize damage to plastic coatings from handling, installation, and well operations. Minimizing coating damage prolongs tubing life by decreasing both the number and extent of locations subject to corrosion attack and the number of locations that need protection from corrosion inhibitors. As long as defects are small (i.e., the coating is not coming off in large chunks or sheets), the life of a coated tubing string can be significantly longer than a baresteel string. Proper handling of IPC tubing and accessories prevents or minimizes damage to the coating, metal, and threads. Excessive bending, deflection, or impact can damage the coating.

☞

Caution Do not place clamps, hooks, bars, rods, or other foreign objects inside the tubing or other coated equipment. Either make drifts or rabbits from rubber, plastic, or wood, or rubber- or plastic-coat them. The tubing must be free of debris that could damage the coating during drifting. Note Drifting means testing the tubing for roundness; rabbits help test for and clear obstructions in the tubing. The coatings applicator spreads API-modified thread compound (or alternative thread compound, when specified) on exposed threads with a soft-bristle brush (not a wire brush) to clean threads or apply thread compound. The coatings applicator also installs closed-end plastic or steel-reinforced plastic thread/end protectors, which remain in place during handling, storage, and transportation.

Storing Coated Tubing and Accessories Note the following guidelines when storing coating tubing and accessories. Guidelines for Yard Storage. •

Chevron Corporation

Rack the tubing to prevent excessive bending and damage during loading and unloading.

700-13

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Coatings Manual

•

Place pipe racks on stabilized soil.

•

Do not pyramid-stack (cradle) tubing.

•

Support tubing by three evenly spaced pipe racks that keep the pipe at least 18 inches above the ground.

•

Place bolsters (hardwood stripping) between pipe layers, perpendicular to the pipe.

•

Align bolsters vertically one above the other and directly over the pipe racks.

•

Place stripping on the racks to prevent direct contact between the pipe and pipe rack.

•

Install chocks (about one- or two-inch wood or plastic blocks) at both ends of each bolster to keep the pipe from moving.

•

Do not stack pipe higher than ten feet.

•

Rack the pipe with all couplings at one end.

•

Stagger adjoining lengths about the length of the coupling.

•

Store IPC accessories on wood pallets, concrete pads, or other suitable installations that keep the accessories off the ground.

•

Apply an external protective coating to control external corrosion.

•

Inspect tubular goods (both IPC and non-IPC) stored outside at least every six months to check for detrimental external attack from atmospheric corrosion. Coastal areas may require more frequent inspection.

Guidelines for Job- or Wellsite Storage. •

Store IPC tubing on properly loaded flatbed trailers, wooden sills, or prefabricated steel pipe racks.

•

Do not use old drums or other thin-walled materials as pipe racks.

•

Use proper pipe chocks on both sides of the bottom tier to prevent rolling.

•

Do not stack pipe higher than five tiers (layers).

•

Do not stack other equipment on top of racked IPC tubing.

•

Do not use racked tubing as a workbench.

•

Rack tubing with the couplings facing toward the well.

•

Store IPC accessories on wood pallets, concrete pads, or other suitable installations that will keep the accessories off the ground.

Loading and Unloading Tubing. •

September 1996

Do not allow IPC tubing to drop or experience long, fast rolls.

700-14

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•

Do not use cheaters to move or roll the pipe.

•

Do not strike the pipe with any metal object.

Transporting Coated Tubing Note the following guidelines when transporting coated tubing. In General. •

Rack IPC goods for transport to prevent excessive bending and damage during loading and unloading.

•

Do not pyramid-stack (cradle) them.

•

Load and unload tubing carefully, supporting each piece firmly and gently lifting or gradually rolling them down sills.

•

Avoid high-speed rolling to protect the coating and the threads.

•

Do not hoist tubing from a single point.

•

Use nonmetallic slings when loading or unloading with cranes; do not use spreader bars.

•

Select forklifts with forks of sufficient spread to avoid excessive bending of the pipe.

•

Never insert pry bars or similar objects inside the pipe.

Guidelines for Trucking. •

Use flatbed trailers.

•

Do not use pole trailers.

•

For Range 2 or longer tubing, use at least three bolsters on the truck bed and between layers. Align bolsters vertically.

•

Use nonmetallic tiedowns for accessories.

•

Load tubing with all couplings facing the same direction.

•

Re-tighten tiedowns to remove slack due to settling after traveling a short distance. Add bolsters if more tiedowns are needed. Do not pull tiedowns so tight that they bend or bow the tubing or accessories.

Guidelines for Rail Transport.

Chevron Corporation

•

Transport IPC goods and accessories in open gondola cars, following rules of American Association of Railroads (AAR).

•

Secure the load according to AAR rules to prevent coating damage when in transit or from excessive bending with bolsters, stakes, headers, high-tension banding.

•

Do not allow the height of the load above the car floor to exceed ten feet.

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Guidelines for Sea Transport. •

Do not store IPC goods in or near bilge water, chemicals, or other corrosive materials.

•

Prevent excessive bending or coating damage in transit with proper dunnage, such as bolsters, stakes, headers, high-tension banding, and clips.

752 Lined Tubing Most of the information about handling coated tubing also applies to lined tubing. While linings (especially polyethylene linings) are generally more rugged and damage-resistant than coatings, they must still be handled with care. Treating lined tubing in the same manner as bare-steel tubing can ruin a potentially holiday- and damage-free installed tubing string. The following are key points about coated tubing that also apply to lined tubing: •

Keep protectors in place until the pipe is about to be made up. Do not remove thread protectors when the pipe is being hauled or handled.

•

Do not insert bars, hooks, or any unloading tools inside the pipe.

•

Do not drop the pipe or turn it loose to roll on the sticks.

•

Do not hit the pipe with a hammer or other metal object, or in any way subject the pipe to impact.

API RP 10E also gives guidelines on handling cement-lined tubing.

760 Installation 761 Coated Tubing and Accessories • •

Arrange to have a vendor's representative present. Visually inspect IPC tubing before running. – –

• •

September 1996

Reject joints with damage to coating, metal (body, upset, or coupling), or thread. Remove the thread protectors for the inspection and then reinstall them, leaving them on until ready to make up the connection.

Pick up the tubing gently with the rig. Assign a person to tail the rigged tubing to the derrick.

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762 Guidelines for Installing IPC Accessories •

Visually inspect IPC accessories before installation. – –

•

Leave thread/end protectors in place until immediately before make up of the connection. – – –

•

Unless impractical, reject pieces with coating, metal, or thread damage. Remove the thread protectors to inspect the threads, and then reinstall them.

Visually inspect the threads again after removing the protectors. Clean and lubricate (re-dope) the threads in a way that will not damage the coating. Apply thread compound.

For connection make up, use equipment and follow procedures to protect coating. – – –

Do not use pipe wrenches. For threaded connections, use large contact surface-area tongs, wrenches, and backups. Start the make up of the connections by hand, and then follow with the tongs in low gear.

•

The guidelines for proper make up of API and premium connections for tubing also apply to accessories.

•

For drift bars or rabbits, use wood, plastic, or hard rubber or plastic- or rubbercoated. Do not use steel, aluminum, or other metal drifts. – –

•

For both running and pulling pipe, use elevators, slips, and tongs (including backups) that have 360-degree wrap-around surface-contact areas. – –

Note •

Verify that the drift diameter is correct. Refer to API RP 5A5, Section 4.8, for verification of procedures and recommended drift diameters.

Ensure that the equipment is in good condition and the proper size to grip the tubing. Repair or replace any equipment showing excessive wear or sharp contact surfaces. Slip-and-tong damage (e.g., crushing) can crack the coating.

Leave the thread protectors on until the pipe is vertical, and you are ready to stab the joint. When tubing is being pulled, install the thread protectors immediately after breaking each stand or joint.

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September 1996


•

After removing the thread protector, clean and lubricate (re-dope) the threads, being careful not to damage the coating. – – –

•

–

Stab each connection with a properly sized rubber, plastic, or plasticcoated stabbing guide. Lower the tubing into the stabbing guide slowly to prevent coating or thread damage.

Start tubing make up by hand; then use the tongs in low gear, at less than 25 rpm. – – –

•

Use a soft-bristle brush to clean connections. Never use a wire brush. Visually inspect each pipe end again and reject damaged joints.

Always use stabbing guides to prevent damage to the coating on the pin end. –

•

Coatings Manual

Use backup tongs during make up, set only on the box. Do not use pipe wrenches for make up. Do not use slips for back up.

To ensure contact of the pin and the coating in the standoff area of the coupling, make up API connections properly. – – – –

Unless an alternate procedure is required, make up API connections to position while monitoring the torque to API specifications. Expose no more than 1½ threads after make up. Use a torque gage that reads directly in ft-lbs. Calibrate the torque gage every three months.

•

Make up premium connections according to the connection manufacturer's written recommendations.

•

Stop travel of the IPC string completely before setting the slips. Lower the string gently into the slips.

•

Do not strike the pipe with any metal object (e.g., a hammer or pipe wrench) even when breaking out connections. Do not allow the pipe to hit any metal object (e.g., the mast).

•

To pull the tubing and set it in stands in the derrick, install thread protectors on the pin-ends or place a resilient pad or carpet on the rig floor to protect the coated end of the tubing while it rests on the rig floor. If we are to lay the tubing down through the V-door, install thread protectors on all pin-ends.

763 Guidelines for Installing Lined Tubing The guidelines for installing coated tubing also apply to lined tubing. Linings are generally more damage-tolerant than coatings; however, mishandling can cause damage that will spoil an otherwise holiday-free, damage-free tubing string installation. Key points are noted or repeated below:

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• • •

Arrange to have a supplier's representative on site during installation. Always use a stabbing guide. Run power tongs at low speed. This is especially critical when: – –

The pin-end starts to contact the corrosion barrier ring (CBR) on fiberglass- or PVC-lined tubing. The pin contacts the plastic insert on cement-lined tubing.

•

Follow the supplier's instructions to insert CBR, Permitek, and so on.

•

For linings with a CBR, run a properly sized (nonmetal) drift through each made-up joint to ensure proper clearance through the CBR.

•

When running cement-lined tubing, use a sinker bar to smooth out the acrylic putty applied to the plastic insert in the box end.

•

When pulling lined pipe, install a thread protector before laying the pipe on a rack or standing it on end.

•

Do not stand lined pipe on end—not even on a cushioned mat—without thread protectors in place.

•

Do not hammer on the pipe to loosen collars.

API RP 10E also has installation guidelines for cement-lined tubing, similar to those listed above.

770 Guidelines for Well Operation The following guidelines are based on the National Association of Corrosion Engineer's (NACE) recommended practices for coated tubing, many of which also apply to lined tubing. Note Lined tubing is more common in injection wells rather than in producing wells.

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Chevron Corporation

Caution At times, it is impossible or impractical to follow the guidelines given below. If so, expect damage to the coating and premature failure of the tubing. Even when following these guidelines, expect some damage to the coating. •

Clearly identify those wells with coated or lined tubing and coated accessories in the well files, in workover procedure sheets, and at the wellsite. Include the coating/lining type and installation date.

•

Make personnel aware that the well has coated or lined tubing so that they take proper precautions.

•

Use rod guides in rod-pumped wells.

•

When practical, install IPC tubing following completion of wireline work, perforating, cementing, etc.

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September 1996


•

When a workover requires fishing, squeezing, drilling, or caustic or acid treatments, pull the IPC tubing and use a work string, if possible.

•

Do not use a coated string as a work string if that string is later intended to be production or injection tubing in a corrosive well.

•

If caustic or acid treatments through the IPC tubing are unavoidable, use the lowest possible concentrations of acid or caustic and minimize contact time with the coating. – – –

Do not shut in wells with unspent acid or caustic in the tubing. Consult the coating/lining manufacturer or the coatings applicator for information about coating chemical resistance. Keep records in the well file of chemical treatments through coated or lined tubing and accessories.

•

Because severe corrosion can occur at locations of major coating damage caused by wireline tools, avoid wirelining through IPC tubing. (Using a work string may save your coated tubing.)

•

If wireline work through IPC tubing is unavoidable, follow these procedures: – – – –

– –

– – –

– •

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Inform the wireline operator that the well has coated tubing. Use streamlined wireframe tools, sinker bars, and rope sockets with smooth, padded contours. Do not use angular or sharp-edged tools. Use single-strand, coated, nonbraided wireline. If you must use braided line, make sure it does not have splices or burrs, which tear the coating. Keep wireline speeds—both going into and coming out of the hole—at less than 100 feet per minute. The Company recommends a reduced speed of 50 feet per minute. Maintain a stiff line with weight on the indicator. Do not let the tool free-fall. Provide special protection—such as elastomeric shrink sleeves or plastic coating—for fishing necks, pressure bombs, temperature tools, etc. Use sufficient stand-off pieces in the tool string. Avoid knuckle joints, knuckle jars, tubing end locators, wireline grabs, explosive jars, paraffin cutters, or scrapers. Use swaging tools rather than gage cutters. If possible, avoid swabbing through IPC tubing strings. If unavoidable, swab as slowly as possible because the swab itself is usually braided line. (Using a slick line would be better.) Swabs should be flexible, fabric-reinforced, or all rubber; they should not be wire-reinforced. Use double cups or double mandrels, or both. Try to avoid downhole caliper surveys. If unavoidable, use calipers with feelers designed not to cut, mill, or damage the coating.

If possible, avoid coil tubing workovers in coated tubing. If unavoidable, use plastic or aluminum centralizers and carefully manipulate the coil tubing. Do not use aluminum with acid or caustic because it will corrode severely.

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•

When hydrotesting IPC tubing, advise the testing company that the well has coated tubing. Obtain special hydrotest tools with rubber-encapsulated parts (seal rings). As an alternative, consider external pressure-testing devices.

•

With coated tubing and accessories in gas service, depressure at a rate no greater than 2,000 psi per hour.

•

Train crews involved in drilling, workover, pulling, wireline, and other field work in the proper handling of coated or lined tubing and accessories. Films, seminars, and other aids are available in the industry, and vendors are generally willing to provide training.

780 References 1.

Boyd, J.L. and Al Siegmund. “Plastic Coated Tubular Goods: Proper Selection, The Key to Success.” NACE Paper 214: Corrosion ‘89.

2.

L. J. Klein. “Database Package: Coatings for Downhole Tubular.” CRTC Materials Engineering File 6.30. Chevron Corporation. March 5, 1990.

3.

Mitchell, R.K., “Coated Tubular Testing, Field Test Results, Hobbs Division,” June 18, 1987 and August 27, 1987.

4.

Strickland, L.N., “Mitigation of Tubing and Mandrel Failures in High Volume Gas Lift Oil Wells, Thompson Field, Ft. Bend, TX.” NACE Paper 70: Corrosion 1992.

5.

Turnipseed, S.P. Internal Plastic Coatings Qualification Tests: Interim Report. Chevron Corporation. April 15, 1992.

6.

———. Final Report. Chevron Corporation. December 16, 1992.

7.

American Petroleum Industry. Recommended Practice for Application of Cement Lining to Steel Tubular Goods, Handling, Installation and Joining. API RP 10E. Washington, DC.

8.

———. Specification for PVC Lined Steel Tubular Goods. API 15LT. Washington, DC.

9.

———. API RP 5A5, Section 4.8, National Association of Corrosion Engineers. Care, Handling, and Installation of Internally Plastic-Coated Oilfield Tubular Goods and Accessories. NACE RP0291. 1991.

10. ———. The Application of Internal Plastic Coatings for Oilfield Tubular Gords and Accessories. NACE RP0191-91. 1991.

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800 Offshore Coatings Abstract The primary objective of any offshore coatings program is to preserve the structural integrity of platforms and producing facilities by preventing metal loss using highquality protective coating systems coupled with systematic and routine maintenance. Offshore coatings are very similar to high-performance (onshore) coatings in terms of selection, surface preparation, application, and inspection. This section contains information that is unique to offshore coatings programs. For basic coatings information that is applicable to offshore work, refer to the following sections in this manual: • • • • •

Section 50, Using This Manual Section 100, General Information Section 300, Coatings Selection Section 400, Surface Preparation Section 500, Application

To select offshore coating systems, refer to the Quick Reference Guide.

Chevron Corporation

Contents

Page

810

In General

800-3

811

Background Information

812

Comparing Off- and Onshore Coatings

820

Quality Control

821

Design Solutions

822

Platform Maintenance

823

Project Planning [1]

824

Protecting Coatings Materials & Equipment Offshore [1]

830

Protecting Human Health & the Environment

831

Typical Hazards Offshore

832

Environmental Issues

840

Selection

800-3

800-18

800-20

800-1

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800 Offshore Coatings

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850

Surface Preparation

800-20

860

References

800-21

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810 In General As there are many similarities between offshore and high-performance onshore coatings, the focus of this section is on the aspects of coatings projects unique to offshore structures.

811 Background Information Offshore structures and wharves represent a very severe, if not the worst, coating service. Coating systems are selected to balance service life, and assure ease of maintenance, local availability, quality, and suitability for application under prevailing climatic conditions. The relative importance of these factors differs from location to location.

812 Comparing Off- and Onshore Coatings Offshore coating systems are comparable to onshore high-performance systems, except that frequent wetting and high humidity make some upgrading necessary offshore. Example: Splash-zone areas subject coatings to intermittent immersion. Mechanical equipment, valves, pumps and motors are a particular problem offshore if manufacturers of these items coat them with materials adequate for inland or coastal environments, but which fail quickly offshore. Normally, you can purchase larger pieces of equipment and custom-fabricated equipment, such as compressors and vessels, with the Company's coating system already applied. The Company highly recommends doing so. It is generally not economical, however, for the equipment manufacturer to offer custom coatings for commodity items such as pumps or motors. Therefore, apply the complete system at the fabrication yard according to the Company's specifications.

820 Quality Control High-quality and cost-effective coatings are essential, but much more difficult to achieve offshore than onshore. Offshore, there are some adverse factors over which you have little or no control; but you can recognize them and reduce their effects with good planning.[1] Some of these factors are: • • • •

Adverse weather conditions Simultaneous operations with other platform activities Limited availability of transportation Substrate surfaces that are deeply pitted and contaminated by soluble surface salts

You can reduce the costly re-work of prematurely failed coatings by promoting quality control and quality assurance during fabrication. To perform work offshore

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costs approximately ten times as much as the same work in fabrication yards. Design solutions are, therefore, key considerations for offshore coating projects.

Maintenance An effective maintenance program for offshore coatings begins with comprehensive quality assurance and quality control (QA/QC) when applying the initial coating during fabrication. Ensuring that the fabrication yard has applied the coating properly and according to specifications allows you to: •

Obtain a high-quality coating that contributes to the maximum service life of the platform and equipment

•

Reduce future expenditures for field maintenance

New Construction For new construction, the offshore QA/QC program is a team effort among the project engineers, contractors, coating suppliers, third-party inspectors, and inhouse coating personnel. A system of checks and balances, this QA/QC program makes certain that—regardless of the size of the project—the services of all participants fulfill the requirements of the specification.

The Successful Project A successful project includes quality control, particularly as it relates to the following items (discussed below): • • • •

Design Solutions Platform Maintenance Project Planning Protecting Materials & Equipment Offshore

The remaining essential elements of a successful project are surface preparation (discussed below) and application (Section 500 of this manual). One definition of a successful project is that all the work meets the specification at the lowest cost possible, with no accidents, minimal turnover of personnel, and within budgetary constraints.[1]

821 Design Solutions Good design can minimize and repair defects in fabrication and therefore reduce the costs of future coating maintenance by reducing areas which lead to the failure of a coating and resulting corrosion damage. Good design also reduces the cost of current coating projects by correcting problems before or during surface preparation that will improve the ease and efficiency of application. The basic principle of corrosion-resistant design is to keep structures as simple as possible and reduce the surface area to be coated as much as practical. Balance these considerations against necessary engineering requirements for safe and effective service regardless of the coating problems.

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Detailed below are problems and solutions for the following design issues: beams, congested and inaccessible areas, decks, elevated structures, sharp edges, stainless steel bands and tubing, surface laminations, welds, and u-bolts.

Angle, Channel, H- and I-Beams Problem: The angles and edges on these basic structural shapes cause many problems. They often receive inadequate dry film thickness (DFT) because proper spray technique is hard to achieve in these areas. The web/flange interface is also a difficult area to coat. Most high-performance coatings exhibit considerable surface tension upon drying which can cause the coating to pull away from corners. These areas are also susceptible to dry spray and overspray which break the bond between the applied coating and the substrate. As flat surfaces generally allow proper application technique, they receive better deposits of film. Note For a proper spray technique, hold coating guns perpendicular to substrates, approximately eight to ten inches from the surface. Solution: To achieve adequate film on angles and interfaces of all hard-to-coat areas, specify a brush coat (extra coat) of the first intermediate—usually of contrasting color—over the primer before applying the remaining coats.

Congested and Inaccessible Areas Problem: Congested and inaccessible areas are primary contributors to coating failures and increased costs of maintenance. Problems begin at the fabrication yard and continue throughout the life of the platform. These areas are extremely costly because space restrictions: •

Limit movement of the coatings applicators

•

Prevent many items from receiving adequate coating

•

Cause the work to proceed slowly

•

Contribute to the high risk of substandard coatings as adequate coating coverage is difficult to achieve

Congested and inaccessible areas are the first to fail, requiring more frequent maintenance cycles at escalated costs. Many congested areas involve production equipment and piping, which are the most critical items on the platform. Example: Inaccessible areas that seldom receive adequate coating protection include: • • •

Non- or skip-welded back-to-back angles Box beams Through-deck piping surrounded by pollution rings, and under-deck piping

Maintenance of under-deck piping is costly as it requires erecting a scaffold for all work, including routine, non-destructive testing.

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Solutions: The following solutions are intended to reduce coatings problems in congested/inaccessible areas: •

Do not design, if at all possible, any structure with items that are congested and inaccessible.

•

Route all piping at least six inches above solid decks.

•

Design pollution rings to include at least a six-inch clearance from throughdeck piping.

•

Do not design box beams and back-to-back angles, if possible. (If back-to-back angles are necessary, specify seal welds.)

Decks—Diamond Plates Problem:

Any of the following problems can occur with diamond deck plates:

•

Rust may form at the peak of elevated diamonds where the coating is sheared by equipment placed on or dragged across the surface.

•

The angles of the diamonds can trap moisture and salt, causing the coating to undercreep to the flat area of the plate. Entire decks begin to rust and coatings de-laminate. This often requires 100 per cent blasting as surface preparation to remove the lifted coating.

•

Diamond decks can become expensive to maintain in terms of time and abrasive to blast each elevation from different angles to remove loose scale and oxidation.

•

Diamond decks can require up to two times the amount of coating for flat plate because of the greater surface area.

Solution: Install flat plates whenever possible. The service life of a coating is longer on flat plates than on diamond deck plates.

Decks—Solid Problem: Depending on their height above water, solid decks need recoating every three-to-five years. Solid deck coatings are expensive to maintain in terms of time, labor, equipment, and materials needed to blast and coat both the top and underside. Solution:

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September 1996

The following are two suggested solutions:

•

Install galvanized grating, which performs well except at waterlines. (This is the standard on most of the Company's platforms.) Service life at the 10-foot level is about four-to-five years.

•

Install fiberglass grating, which has given excellent results at several of the Company's locations after 12 years of service.

Caution Although environmental and containment concerns restrict grating decks, install them whenever possible.

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•

Solid decks are used around production equipment to prevent spills into the water.

•

Grating decks are used on the bottom levels of the platform where water could cause a solid floor to be slippery.

•

Solid floors are typically used on the upper decks where crew living quarters are located.

Elevated Structural Members at +10-foot Level Problems: The waterline is the most corrosive and most difficult area to maintain on the platform. •

Structural members (horizontals and diagonals that are close to the water) are more susceptible to corrosion and are more expensive to maintain than higher ones.

•

Boat landings present major problems. In the Company's older designs, boat bumpers also serve as support members and are usually installed on three sides of the platform. The bumpers' elevations range from five-to-eight feet above the tidal area. The bottom third is in water much of the time and is covered with marine growth so that only the top portion is accessible for blasting and coating. Boat bumpers are in congested areas with vertical members spaced every several feet. Adequate blasting and recoating is possible only for the top portion; and, at best, those areas require extensive recoating at least every five years.

Solutions: The following solutions are designed to reduce maintenance of +10-foot areas. •

Design +10-foot areas as high as possible from the tidal zone and minimize the surface areas of boat bumpers.

•

Include horizontal members 15 feet above the tidal area (as compared to older ones, which are 5-to-8 feet above the tidal area).

•

Keep the size and number of boat bumpers to a minimum.

Note Surveys indicate that the service life of coating systems on newer designs is at least double the service life of older designs; service life of bumpers is unchanged. Analysis of past coating jobs on deep-water four- and six-pile platforms indicates that coatings of elevated designs are completed in half the number of days of lower designs, resulting in substantial savings of maintenance costs.

Sharp Edges Problem: Sharp edges left on overlapping plates or edges by shearing or cutting will cause coatings to fail, almost without exception. Surface tension and shrinkage during curing pulls the coating away from the edges, leaving areas of low DFT or holidays (or both). Additional film defects occur when, as is normal, the crew applies the coating on tangent to the edges rather than perpendicularly.

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Solution:

To achieve the best protection, the design should stipulate:

•

Grinding the edges smooth or increasing the thickness on the edge areas (or both) to help achieve the best protection

•

Applying an additional coating to the edge before each coat, followed by the normal coating that is extended over the edge with several inches of overlap

Stainless Steel Bands/Tubing Problem: Stainless-steel bands, holding emergency shut-down (ESD) tubing in place on vessels and piping, are primary causes of corrosion damage. The protective coating on vessels and piping is usually damaged during installation when the bands are crimped to the item. The remaining bands eventually rub off the coating. Any small coating defect causes dissimilar metal action between the bands and the carbon steel substrate. Pitting begins in a relatively short time after moisture and salts are trapped at the interface. Stainless-steel tubing produces similar results. Solution: To prevent pitting, specify bands with neoprene or similar lining and elevate tubing from the substrate on either rubber or Teflon blocks.

Surface Laminations Problem: Difficult to coat, surface laminations include sharp, jagged protrusions with gouges and voids on the undersides. Solution: To facilitate applying the coating, the design should stipulate grinding/ removing laminations before abrasive blasting and coating.

Welds—Flux Problem: Highly alkaline and hydroscopic, residual weld flux eventually delaminates from the surface, causing blisters—the site of early coating failure—in the coating. Solution: To help prevent residual weld flux from delaminating, the design should stipulate removing weld flux before abrasive blasting and coating.

Welds—Rough Problem: Surface irregularities on rough welds make it difficult to apply coatings in a continuous film, free from voids and pinholes. Small defects in a coating allow moisture to penetrate to the surface, causing localized corrosion cells. These cells, combined with the weld's being a heat-affected area, accelerate the corrosion rate. Solution: To achieve a smooth surface without voids and pinholes, the design should stipulate grinding all rough welds before coating.

Welds—Skip Problem: Skip welding is a common technique for reinforcing areas where a continuous weld is not necessary. It is impossible to coat the resulting crevices— between the welds at the interfaces of the metal pieces—adequately.

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Example: On offshore platforms, constant vibration can cause the coating—bonded at the interfaces—to rub off and the surface to accumulate moisture and salt deposits, which accelerate corrosion rates. Solution: For coated surfaces which are exposed to vibration, specify continuous seal welds instead of skip welds.

Welds—Splatter Problem: Weld splatter is small balls of metal that adhere to the surface. The applied coating literally flows off the splatter, leaving exposed areas which eventually undercreep to the coated item. Small crevices also develop around the bases of the splatter, creating voids where coatings cannot penetrate. Coating applied to weld splatter will eventually fail. Solution: To prevent splatter from exposing areas of surface and causing crevices in the coating, the design should stipulate removing weld splatter before blasting and coating.

U-bolts Problem: Galvanized or cadmium-plated u-bolts which support piping on metal supports cause damage to the coating when subjected to platform vibration and other movement. The rubbing action results in metal-to-metal contact which causes pitting. Solution: To prevent pitting, specify neoprene-coated u-bolts with neoprene pads or Teflon blocks on the support bracing to prevent metal-to-metal contact.

822 Platform Maintenance Long-range planning optimizes overall expenditures and timing in the following ways: •

Distributes expenditures over the life of the platform

•

Keeps facilities in good condition by arranging for appropriate levels of maintenance

•

Reduces the need for major maintenance (50 percent top to bottom) in a given year

•

Limits the need for major coating projects toward the end of a platform's producing life

•

Realizes savings by reducing platform downtime and preventing premature failures from corrosion

A maintenance program should begin as soon as a platform is in service. As a platform nears the end of its producing life, critical cost factors such as time, labor, equipment requirements, materials, etc. become increasingly important, sometimes over-shadowing service life.

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Work Priorities The priorities of platform maintenance change as service conditions change, often being revised several times over the producing life of a platform. Setting work priorities for an offshore coating project involves the following factors which are also important when assessing a coating to determine repair procedures and costs: • • • •

Coating type and existing condition Percentage of surface breakdown Degree of corrosion Type of item (structural or equipment)

Condition of the Existing Coating. Judge the corrosion on structural members and equipment to establish priorities, define the scope of work, and forecast expenditures. Severity of Corrosion and Recommended Repairs. The following examples are typical offshore coating failures and recommended repair procedures. •

Zinc/epoxy/urethane systems tend to be brittle, to chalk, and to exhibit topcoat delamination from the zinc primer. Corrosion, usually local during early failure mode, tends to undercreep the epoxy topcoats by sacrificial action of the zinc primer. Limit maintenance to selective spot blasting and coating with compatible epoxy and urethane topcoats before the system is badly damaged. Otherwise, the surface may need complete blasting and recoating.

•

Solvent-based vinyl coating systems tend to remain soft and flexible, with relatively good adhesion. Most vinyl coating failures are the result of osmotic blistering (water penetrating to the substrate), mechanical damage or application defects such as holidays (breaks or flaws) in the wash primer, low dry-film thickness (DFT), and overblast damage. Corrosion is usually uniform over a larger surface area, but pitting is not as severe as with zinc/epoxy/urethanes. Vinyls are easy to spot blast, sweep, and topcoat with other vinyl systems because solvents redissolve easily, allowing for easy tie-in or adhesion of the new coating to the existing coating.

Operating Service of Equipment and Structural Items. For cost-effective coatings maintenance, avoid complete top-to-bottom work by developing evaluationand-ranking criteria for platform items such as those shown in Figure 800-1. In this figure, priorities are determined by varying degrees of coating breakdown and rust and by safety, type of service, and location of the item. Safety and Environmental Concerns. Normally, safety-related items such as vessels, piping, stairwells, and heliports take priority over others when coating and corrosion are equal. Adequate wall thickness, however, is always an overriding concern. If wall thickness of a given item does not meet minimal requirements, replace that item. For more information, refer to Protecting Human Health & the Environment later in this section.

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Sample Platform Survey Report

Fig. 800-1

❒ Major

Platform type (check one)

Date

Location

9/1/95

Typical Platform

❒ Satellite

❒ MW Caisson

❒ SW Caisson

❒ Monopod

❒ 8 Pile

❒ 4 Pile

❒ 3 Pile

❒ Wellguard

Job type (check one)

❒ Deck

Heliport size 20/60

❒ Boat

Capacity Crane 30 tons

Capacity Quarters 15 man

Condition Evaluation Scale

Priority Percent Breakdown

1—Light rust only

A—0 to 10

1—Work in 1 year

2—Light to medium rust

B—11 to 25

2—Work in 2 years

3—Light to medium scale

C—26 to 40

3—Work in 3 years

4—Light pits/light scale

D—41 to 60

4—Work in 4 years

5—Light pits/medium scale

F—over 60

6—Light pits/severe scale 7—Medium pits/medium scale 8—Severe pits/severe scale 9—New construction item Item

Coating Type

Condition

Priority

Est. # Days

1. Heliport a. Top b. Underside

Polyester

C5

1-2

6

ZN/EP/URE

B2

3

N/A

2. Top Deck Level a. Deck Plates

Comments Condition warrants work in near future

No work needed this year; fair condition; no estimate needed Coating undercreepage and delamination

Polyester

D7

1

10

b. Escape Capsule Davit

ZN/EP/URE

A9

1

3

New addition; welds need touchup

c. Skid Beams

ZN/EP/URE

C6

1-2

5

Severe impact damage on topsides; severe scale under flange; needs work soon

d. I-Beams/STR. MEM

ZN/EP/URE

A1

4

Looks good; no est. required

e. Grating Areas

Galvanized

F8

1

Several sections need changeout schedule for welding

a. Overhead Piping

ZN/EP/URE

C5

1

14

Coating in failure mode; needs work

b. New 2" Fuel Gas Lines

ZN/EP/URE

A-9-2

1

4

New items - welds need TU and remainder needs spot blast and paint

c. Vessels

ZN/EP/URE

A1

4+

Good shape; no work needed

d. Top Deck Supports

ZN/EP/URE

A1

4+

Ditto

e. I-Beams

ZN/EP/URE

A1

4+

Ditto

f. Grating

Galvanized

B2

3-4

Needs changeout 3-4 years

4. Under Superstructure

ZN/EP/URE

C5

2-3

5. Risers

ZN/EP/URE

A1

4

6. Waterline

ZN/EP/URE

F8

1

3. Under Top Deck

Chevron Corporation

800-11

14

Coating undercreepage; scale on beams & piping Looks good; no est. required

21

Severely corroded; needs work ASAP

September 1996


Coatings Manual

Remaining Life of the Facility. See Figure 800-2. Fig. 800-2

Priority 1 Coating Maintenance Items Based on Facility’s Life Expectancy and Existing Condition Based on Life Expectancy & Existing Condition Long Term (7+ years)

Priority 1 Items

Medium Term (5-7 years)

Short Term (less than 5 years)

All primary safety items, including process vessels, interconnecting piping, risers, stairwells, walkways, and heliports

C4 or worse

C5 or worse

D7 or worse

Structural items such as waterline members, decking, I-beams, support trusses, plate girders, and legs

D5 or worse

D7 or worse

Defer until the facility depletes, is sold, or changes to another category.

Recommend plugging and abandoning or selling any property that does not meet the economic criteria to perform the necessary maintenance to operate safely. In all cases (except for certain short-term properties), touch up bare welds and scar damage on new installation items. Before deferral, if conditions equal or exceed C4, or if the item’s integrity is in question, verify by non-destructive evaluation (x-ray or ultrasonic testing) that the remaining wall thickness of vessels, piping, and structural steel remain within safe operating limits.

Prevailing Economic Conditions. Coating maintenance programs vary depending on the prevailing economy. Protective coating maintenance programs are vulnerable during difficult economic conditions. A selective deferral strategy: •

Postpones non-critical, borderline work and concentrates on critical work

•

Reduces overall expenditures in the short term and in locations that have a number of platforms and facilities

•

Allows spot maintenance on more platforms (providing adequate levels of maintenance levels, although less than desirable in some cases)

The disadvantages of selective deferral are that deferred items: •

Continue to deteriorate

•

Cost more to repair after several years because of additional mobilization costs, inflation, and increased work scope

Favorable economic conditions may justify greater expenditures: •

Accomplishing more work on necessary items, including those deferred from previous periods

•

Reducing the number of spot-maintenance cycles

Forecasting Work A forecaster needs the following information to prepare budgets, project future work, and make adjustments: • •

September 1996

Both short- and long-term field economic strategies Conditions of the platform

800-12

Chevron Corporation

Coatings Manual


– –

Historical—timing and quality of the previous coating Current—existing coating system, service conditions, comprehensive annual or bi-annual topside coating surveys about the platform's current condition

Often, you need to prepare a pre-project survey before you can establish detailed work and coating schedules and arrange for equipment and personnel.[4] See Figure 800-1 for forecasts; Figure 800-3 for pre-job planning.

Background Information for Forecasting For onshore projects, effective quality control during fabrication helps to ensure the longest service life from the initial coating work (exceeding offshore work by 25 to 30 percent). Achieving the same degree of quality offshore is difficult because the surface becomes contaminated by salts, oils, grease, or pitting, and access to work items is limited. The higher the quality of each fabrication, the longer the coating lasts. A long-lasting coating minimizes future work and lowers cost. Structural members and piping at the +10-foot waterline areas and superstructure undersides generally require more frequent maintenance intervals (every five to seven years) than upper elevations for the following reasons: •

Coating damage can be severe due to high levels of exposure to saltwater, spray, and salt deposits.

•

The waterline area is subject to wave action, floating debris, and damage from the impact of cargo and crew boats.

•

Production risers at the +10-foot level are more critical than structural members because of high operating pressures, product volume, and potential for pollution.

•

Metal loss of 40 mils or more per year can occur near the waterline.[3]

Elevated structural members, piping, and other items may require maintenance intervals of 7 to 12 years. Mechanical damage occurs in coatings of high-traffic, high-impact areas such as helidecks and production decks, requiring maintenance intervals of 5 to 7 years.

Annual Surveys Survey reports provide information on the conditions of a platform, enabling the forecaster to: • • • • •

Chevron Corporation

Adjust forecasted expenditures Establish priorities for specific tasks over the next three-to-five years Provide options for scheduling critical or deferring non-critical tasks Optimize expenditures by scheduling tasks appropriately Estimate the cost of projects

800-13

September 1996


Fig. 800-3

Coatings Manual

Questionnaire for Pre-Job Platform Inspection Offshore Coatings Category/Item

Yes

No

Comments

Percentage of Coating Breakdown and Severity of Corrosion Do the platform and equipment items need to be spot or 100% blasted & painted? Are there any severely corroded items that need changeout? What is the condition of the clamps and u-bolts? What is the condition of sight glasses, valves, etc.? Type of Existing Paint System What is the general condition of the coating? Is the specified system compatible? Can this system be feather-edged and tied into the new system? Do any items need specialty coatings (e.g. hot or submerged equipment & piping?) Platform Layout Is there sufficient space for equipment and supplies? What type of rigging will be required? Are there any special considerations for rigging? What is the crane’s capacity? What is the fuel capacity? Are there sufficient living accommodations for the crew? What is the potable water capacity? Is the platform a high traffic area? Platform Equipment Setup Do any equipment items need filtration or wrapping? Is any shut-in time needed for blasting and painting? If so, what is the estimated down time? Do any areas require wrapping for overblast and overspray prevention? Are there any drains which need plugging? Are there any special safety concerns (e.g. hot piping, confined spaces, fall hazards)? Are there any sweating lines which will require shut-in for blasting and painting?

September 1996

800-14

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Coatings Manual


Candidates for conducting annual surveys include NACE International Certified Coating Inspectors who have a sound working knowledge of offshore coatings operations, coating systems, and general corrosion principles and who can assess platform conditions, priorities, and estimates. A thorough survey includes the following information: • • •

Platform type (major, satellite, multi- or single-well caisson, or other) Number of piles Crew set-up needed for proposed work (e.g., deck crew, boat crew, jack-up barge) • Heliport size and weight limitations • Capacity of the crane • Capacity of quarters • Coating system on specific areas/items • Coating condition on specific areas/items • Work priority (estimated time of next maintenance work) • Estimated number of days required • General comments (e.g., change-out items, type of crew base camp set-up, type of surface preparation, coating required) • A comprehensive pictorial of each platform to document items that may soon require attention Figure 800-1 is a typical completed survey report form.

823 Project Planning [1] Of the key considerations in project planning, there are two of special interest to offshore coating projects: • •

Pre-inspecting the Platform Coordinating Jobs

Pre-Inspecting the Platform Pre-inspecting the platform helps to determine work and coating schedules and assists in overall project coordination. The following tasks should be part of a prejob inspection: •

Inspect the platform to determine the specific job scope and plan for personnel and equipment set-up.

•

Consult platform operators about operating routines and production equipment, preferably with the designated inspector and crew foreman present.

•

Check the platform and its operating equipment.

See Figure 800-3: Questionnaire for Pre-job Platform Inspection.

Chevron Corporation

800-15

September 1996


Coatings Manual

Coordinating Jobs Job coordination is a cost-saving practice that eliminates unnecessary downtime, keeps the coatings applicator on a favorable work routine, and helps prevent potential problems. For example, offshore platforms have logistical limitations—each flight and supply boat run adds to the job cost—so forethought results in a much smoother project. Schedule flights and supply runs: •

To minimize transportation costs

•

In the morning, to minimize disruption of coating operations during critical project phases in the afternoon

Ensure that the inspector and crew foreman maintain updated and accurate inventories of material and anticipate needs for materials. In addition: •

Replenish fuel and water on each boat run.

•

Maintain ample supplies of abrasive and coatings in the event of extended periods of bad weather.

Transition times—during which the coatings applicators change from one operation to another—can also make a significant difference to the cost of a project. See Section 100 of this manual.

824 Protecting Coatings Materials & Equipment Offshore [1] The condition of abrasives and coating materials affects the service life of applied coatings. Offshore, abrasives and coatings are subject to a harsh environment— baked in sun, flooded in high seas, contaminated by saltwater, banged, broken, or dropped. As these materials also have unique transportation requirements, take special precautions to preserve their integrity. Proper handling and storage are high priorities. Realize short-term savings by replacing bad material infrequently (including reducing downtime while waiting for re-supply and additional boat runs). Handled and stored properly, the materials stay in good condition and result in long-term savings from the increased service life of the coating.

Abrasives For high-production blasting, large-volume bulk blast pots require massive amounts of abrasive. A typical, high-production, 100-per-cent blasting needs 25 to 30 tons of workboat-transported abrasive weekly. Good planning is essential to maintain sufficient quantity on board. It is important to store the abrasive in bulk containers to keep it dry and uncontaminated. Each bulk container holds about two tons of abrasive and may be any of three major kinds: vinyl, disposable bulk bags, or metal hoppers. The first two are most common.

September 1996

800-16

Chevron Corporation

Coatings Manual


Follow these procedures to keep bags safe and functional: •

Check for damage before and after each use. Look for wear and for holes in the sides, tops, or funnels. Note any missing or worn tie ropes on the top and bottom funnels. Replace as necessary.

•

Report all damaged bags to the appropriate authority.

•

Remove damaged bags from circulation until repaired; or, if disposable bags, discard altogether.

•

Prepare accurate use-and-damage reports for each bag.

•

Identify the number of uses for disposable bags by coating a slash or mark on the outside. Do not use disposal bags more than the recommended number of times.

•

Transport and store both empty and full bags on pallets to prevent contamination by seepage.

•

Store empty bags away from sunlight and in a dry place. Immediately after emptying, fold the ends of the bags inward, roll lengthwise, and tie each bag separately with manila twine. Tie a bundle of bags to a pallet for shipment.

Coatings Coating containers begin to deteriorate from sunlight and salt as soon as they arrive at the shorebase. Proper storage of coatings is essential because coatings must be mixable, sprayable, and free from contamination. Follow these procedures for storing coatings:

Chevron Corporation

•

Store coating cans in a well-ventilated area.

•

Keep cans away from direct sunlight in a coating-storage building dockside, and in the shade at the job site.

•

Store cans on pallets. They should not come into direct contact with solid decks (which can reach 130ºF in summer months) and should not sit in salt water for extended periods of time during shipping.

•

Do not cover coating cans with tarpaulins during hot months; the oven-like effect literally cooks the material.

•

Maintain tight inventory control. Keep cans in one area; do not allow them to be scattered around the platform.

•

Rotate the coating stock weekly.

•

Apply the coating material as soon as possible after opening a container.

•

Remove coating residue from empty cans before disposing of them.

800-17

September 1996


Coatings Manual

–

– –

Dispose of empty coating cans by removing the bottoms, crushing the cans, and tying them in bundles to save trash basket space and minimize handling time after removing cans from the work site. Store empty cans separately from regular trash because they will probably require special handling for disposal. Ensure that the proper Material Safety Data Sheets (MSDS) and Hazardous Material Shipping Manifests accompany the coating at all times.

Equipment Nav-aid lights make the platform visible to boat traffic at night. They need protection from overblast or overspray because even small amounts distort the light beam and affect visibility. Even minor damage to these lenses requires costly replacement. During a coatings project, crews must cover and uncover these lights. To cut costs of material and manpower, they can use a cylinder-shaped cover of chicken wire wrapped with plastic. These covers are inexpensive, easy to install and remove, and durable. For additional information about protecting the Company's equipment, see Section 100 of this manual.

830 Protecting Human Health & the Environment Workers' safety and the environment are among the foremost concerns of any coatings project. General information on these subjects is provided in the Section 200 of this manual, however, there are some special considerations for offshore work.

831 Typical Hazards Offshore Many hazards are associated with offshore coatings activities, some with job-site conditions that change daily. In general, offshore safe practices for coatings projects should include: •

Ensuring that the Company's representative has a good understanding of offshore work processes, equipment set-up, and potential hazards [2]

•

Choosing contractors who specialize in offshore coatings work and who have high-quality safety and training programs, good equipment, and competent personnel[2]

Some typical hazards offshore are offloading equipment and supplies; lead and other regulated, hazardous, heavy metals in the existing coating; and scaffolding.

Offloading Equipment & Supplies Offloading equipment for a crew of 8-to-10 workers takes up to 12 hours and requires about 60 lifts from a cargo boat. Equipment can include 750-CFM or larger air compressors, 8-ton bulk abrasive blast pots, air-volume tanks, scaffolding,

September 1996

800-18

Chevron Corporation

Coatings Manual


hoses, 4,000-pound bulk-abrasive bags, cargo baskets filled with coating materials, portable bunkhouses, or galley buildings.[1] Concern. •

Transferring equipment, material, and personnel from the cargo boat safely

Factors to Consider. •

Weather and sea conditions

•

Qualifications of coatings applicators (should be rigger-certified)

•

Qualifications of the crane operator and boat captain

•

Organization and coordination of the loading activities

•

Level of communication among all involved, especially the crew foreman, crane operator, hook-up personnel on the boat and the platform, and the boat captain

Lead and Other Regulated, Hazardous, Heavy Metals Exposure to elevated levels of lead/heavy metals can have adverse and chronic effects on the human central nervous and reproductive systems. Concerns. •

The degree of lead/heavy metals in coating systems on offshore platforms

•

Workers' exposure to elevated levels of lead/heavy metals when removing the coating with abrasive blasting, hand tools, or power tools

Safe Practices. •

Inform the contractor of any potential for exposure to lead/heavy metals to ensure that the contractor provides necessary monitoring and appropriate protection for workers as mandated by OSHA, 29 CFR 1926.62, 1926.63, and 1926.55. The Company's representative should contact local ES&H authority for guidance and assistance.

•

Determine the exposure level from workers' personal monitors worn in a particular work area or platform.

•

Require a degree of protection for workers corresponding to the level of exposure. (Workers' protection includes respirators, protective clothing, and changeand-wash facilities.)

Refer to OSHA guidelines about lead in industrial protective coatings [5, 7].

Scaffolding Crews often perform blasting and coating from scaffolding. Cable scaffolding is generally set up for work on deck undersides (under heliports and superstructures. Cable scaffolding consists of 1- by 16-foot wooden timbers or aluminum boards

Chevron Corporation

800-19

September 1996


Coatings Manual

tied by manila rope to cable strands. Cable clamps and net hooks secure the cables and nets. Concerns. •

Possibility of falling from scaffolding above deck, under the superstructure, or at the +10-foot waterline level

•

Inadequate offshore scaffolding techniques

Safe Practices. •

Require that personnel wear full-body harnesses to prevent back injury in case of a fall.[2]

•

Ensure that rigging follows accepted practices of five cables—two to support the timbers, two to support the nets, and one as a safety line for safety lanyards.

•

Secure cables with double cable clamps; position the live end on the U-bolt side of the clamp.

•

Do not use old, rusted cables.

•

Do not splice cables.

832 Environmental Issues Environmental issues have a significant effect on offshore coatings programs as regulatory agencies become increasingly concerned about offshore activities. Many operators are reviewing their onshore programs and adopting applicable environmental protection practices for offshore work. Those responsible for overseeing coatings activities should be thoroughly familiar with the applicable laws to ensure that the Company is operating in compliance with them. Local environmental, safety, and health specialists are a good resource of information about environmental protection offshore.

840 Selection See the Quick Reference Guide for the selection process and selection guides for offshore coating systems.

850 Surface Preparation Achieving the surface preparation outlined in the Company's specification is crucial.[8] While this is really no different than for any other coating job, the greater expense of offshore repairs makes it even more important to pay close attention to this vital part of a coatings job.

September 1996

800-20

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Coatings Manual


860 References 1.

Conlin, T.M. “Fundamentals of Offshore Coating Operations: It's the Little Things that Really Make the Difference.” Journal of Protective Coatings & Linings, Vol. 7, No. 9. Steel Structures Coating Council. September 1990.

2.

Loss Prevention Guide No. 25 - Health, Environment & Loss Prevention. Chevron Corporation. May 1991.

3.

Munger, Charles G. Corrosion Prevention by Protective Coatings. National Association of Corrosion Engineers. 1986.

4.

National Association of Corrosion Engineers. NACE Coating Inspector Training and Certification Program - Session 1, Organizational Development Systems, Inc. Houston, Texas: 1982.

5.

Office of the Federal Register, National Archives and Records Administration. Special Edition of the Federal Register. OSHA Safety and Health Standards, 29 CFR 1910/1926, U.S. Department of Labor, 1991 and 1993.

6.

Roebuck, A.H., T.M. Conlin, and Durwood Broussard. ”Offshore Coatings Work.” Proceedings of Steel Structures Coating Council. 1991.

7.

Office of the Federal Register, National Archives and Records Administration. Special Edition of the Federal Register. Safety and Health Standards, 29 CFR 1926.62, Construction Industry Standard. United States Government Printing Office. Washington: 1995.

8.

Chevron Corporation. “Specification COM-MS-4771 Offshore Structures Coatings.” Coatings Manual Chevron Research and Technology Company. Richmond, CA: January, 1995.

9.

Office of the Federal Register, National Archives and Records Administration. Special Edition of the Federal Register. OSHA 29 CFR 1926.63. United States Government Printing Office. Washington: 1995.

10. ———. Special Edition of the Federal Register. OSHA 29 CFR 1926.55 United States Government Printing Office. Washington: 1995.

Chevron Corporation

800-21

September 1996

900 Pipeline Coatings Abstract This section contains general information about external and internal pipeline coatings. External pipeline coatings are described in figures which highlight the definition, recommended services, and other key elements of a coating. Quality control is viewed from the standpoint of specifications, planning (based on a coating's service conditions, durability and resistance, construction factors, and application factors), and inspection. The selection section covers new construction and rehabilitation coatings. Pipe is coated or lined internally to prevent corrosion or to increase flow rates by reducing friction losses. In some cases by installing linings through existing piping, a corroded line which would otherwise have to be replaced can be salvaged. In this section, the term, coatings, means the relatively thin paint, while linings are much thicker cement or plastic. Field-applied means applying a lining or coating to an existing pipeline. Internally coated pipe is the main issue, with linings introduced only in terms of alternatives to internally coated pipe. Both linings and coatings can be shop- or field-applied. For general information about: • • •

Surface preparation, see Section 100. Environment, health, and safety as they relate to coatings, see Section 200. The economics and colors of Company coatings, see Section 300.

For more detailed information about cement- and plastic-lined pipe, refer to the Company's Pipeline and Piping Manuals.

Chevron Corporation

Contents

Page

910

Pipeline Coatings in General

900-3

920

External Pipeline Coatings

900-3

921

Selection

922

Quality Control

930

Internal Pipeline Coatings

931

Shop-applied Internal Pipeline Coatings

900-1

900-54

September 1996

900 Pipeline Coatings

September 1996

Coatings Manual

932

Field-applied Internal Pipeline Coatings

933

Weld-joint Application & Inspection

940

References

900-59

900-2

Chevron Corporation

Coatings Manual


910 Pipeline Coatings in General The information in this section about pipeline coatings is general in nature. For assistance with specific projects, contact the Company's coating specialists listed in the Quick Reference Guide.

920 External Pipeline Coatings The figures at the end of this section describe external coatings, both pipeline and girth-weld protection. These figures highlight the definition, recommended services, status, maximum service temperature, surface preparation, application, thickness, small repairs, handling/storage, protection, discussion, brands, and references of these coatings. Quality control is viewed from the standpoint of specifications, planning (based on a coating's service conditions, durability and resistance, construction factors, and application factors), and inspection.

921 Selection There are numerous factors to consider when selecting a pipeline coating. Figure 900-1 is a selection flowchart for choosing an appropriate mill-applied coating. Figure 900-2 lists recommended external pipeline coatings for new construction projects. The coatings in Figure 900-2 are listed in order of preference. Figure 900-3 compares advantages and disadvantages of several types of external pipeline coatings. For detailed information on various types of coatings, consult Figures 900-4 through 900-21. Splash-zone Coating for Offshore Platform Risers. See Figure 900-22 for operating temperatures of splash-zone coatings for offshore platform risers. Valves, Fittings, Tie-ins. Their unique shape makes valves, fittings, tie-ins, and other buried objects of irregular geometry hard to coat. As FBE is a shop-applied coating, choose a spray or hand-applied coating from the list in Figure 900-23 Pipeline Fitting & Valve Coating Systems. Protection. •

Girth Weld See Figure 900-24 for a list of generic coatings for girth-weld protection. Figures 900-4 through 900-21 contain more detailed information on girth weld protection for specific coatings.

•

Rock Choose any acceptable rockshield material (Tuff-N-nuff, Ametek, Rock Shield, Armor Rock) to protect coatings from mechanical damage from rocks or backfill in a ditch. The rock protection is: –

Chevron Corporation

Wrapped around the pipe and bound with plastic straps

900-3

September 1996


Coatings Manual

– –

Installed just before the pipe is put into the ditch Perforated to prevent cathodic shielding

See also comments about rock protection in the Protection portion of Figures 900-4 through 900-21. •

Construction Boring

Topcoat FBE with Protegal UT 23-10 or Powercrete to give the coating added protection from damage during slick-bore construction, particularly where rocks in the soil may abrade the FBE. Both Protegal and Powercrete have greater abrasion resistance than FBE coatings. Fig. 900-1

Mill-Applied Coating Selection Flowchart

September 1996

900-4

Chevron Corporation

Coatings Manual

Fig. 900-2 Rank 1.

2.

3.

4.


Recommended External Pipeline Coatings for New Construction—Ranked in Order of Preference (1 of 2) Buried Onshore Line

Extruded Plastic with FBE • Service temp. to 200°F •

All soils except hydrocarbon contaminated

•

Coating thickness per pipeline's operating temperature

In-plant Short Buried Lines(1)

Subsea Line

Elevated Temperature

Extruded Plastic with FBE Primer • Higher service temperature to 230°F

Extruded Plastic with FBE Primer(2) • Higher service temperature to 230°F

Liquid Epoxy • Some have same chemical and temperature resistance as FBE

•

Moisture resistant

•

Moisture resistant

•

•

Field experience currently limited

•

Field experience currently limited

•

Hydrocarbon damages outer plastic jacket

•

Hydrocarbon damages outer plastic jacket

Also can be field applied; so, suitable for high and ambient temperature lines, especially for in-plant lines

•

Cure can be up to 24 hours before service, per temperature during application

FBE • Service temp. between -76°F and 200°F

FBE • Higher service temperature to 200°F

FBE(3) • Service temperature up to 200°F(4)

Plastic-backed Tape Wraps • Mixed success with butyl adhesives as most are:

•

All soils

•

•

•

Not resistant to hydrocarbons

•

Coating thickness per use

•

Poor resistance to soil stress and pipe movement

•

Not applied generally under ideal conditions

•

Least cost, easy to apply

Extruded Plastic with Butyl Rubber or Asphalt Adhesive • Very economical •

Service temp. to at least 100°F, some to 180°F

•

Suitable for low-soil stress areas

•


Coating thickness per temperature

Coal-tar Enamel • Service temp. 140°F • •

Good if selected and applied correctly Hard to handle: brittle when cold, soft when hot

Coating thickness per temperature

Extruded Plastic with Butyl Rubber Adhesive • Very economical •

Service temp. to maximum of 180°F

•

Suitable for low-soil stress areas

Coal-tar Enamel • Service temp. 140°F

Tape Wrap(5), (6) • Low soil-stress areas

•

Good if applied correctly

•

•

Hard to handle: brittle when cold, soft when hot

Select only specialty, high-temperature tape wraps for service over 140°F(7)

•


Chevron Corporation

900-5

September 1996


Fig. 900-2 5.

Coatings Manual

Recommended External Pipeline Coatings for New Construction—Ranked in Order of Preference (2 of 2)

Tape Wrap(7) • For low-soil-stress areas •


Concrete (Weight) Coating—Normally, we apply a concrete (weight) topcoat to FBE and other offshore coatings for negative buoyancy and coating protection. For small-diameter lines, FBE does not need protection; therefore, extra steel can provide negative buoyancy. A weighted topcoat not only protects coal tar from UV rays before we lay the pipeline but also prevents handling damage. See the CRTC Pipeline Manual for additional information about concrete (weight) coatings. Extruded Plastic—Continuous plastic coating (either polyethylene or polypropylene) is extruded on a pipe at elevated temperatures. There are two distinct subcategories of coatings: plastic coatings with a soft-extruded-butyl rubber of flood-coated-asphalt rubber-mastic adhesive, and plastic coatings with a cured-hard-epoxy adhesive. Sometimes, a copolymer adhesive bonds the plastic outer layer to the epoxy inner layer. There are also two methods of extruding the plastic coating portion of the coating system: a side or T-shaped die, or a crosshead or circular die [3]. (1) The cost of materials is proportionally higher than for a large project. Weigh the cost against the importance of the pipeline, its access, its location (populated area vs. wilderness), and soil conditions. Lower costs of future repairs or refurbishing may offset the initial expense of high-quality coatings. (2) For abrasion protection against thermal expanding and contracting of elevated temperature lines, increase the thickness of the polyethylene or polypropylene coating. (3) FBEs permeability to water increases with temperature; but this problem has been solved to date by increasing the thickness of the FBE according to service temperature. Consider the cost of the increase in thickness. (4) Currently, FBE is the only economical line coating for temperatures over 180°F. Aramco has successfully pushed FBE to 225°F (22 mils) in sandy soil; but, the coating softens notably above 210°F. There is a cohesion failure if a knife can remove the coating. Company recommends only three brands for service over 150°F: Nap-Gard (7-2501 and 7-2504), Valspar D1003, and Scotchkote 206N based on field experience and test data. (5) Company recommends only shop-applied Rayclad 120 for protecting new pipelines. (6) The high cost of good-quality, high-temperature, tape wraps restricts them to large-radius bends. (7) Check the service history of non-specialty tapes for service temperatures above 100°F. Manufacturers often overstate the upper limits.

September 1996

900-6

Chevron Corporation

Coatings Manual

Fig. 900-3


Advantages and Disadvantages of External Pipeline Coatings (1 of 2) Coating

Fusion Bonded Epoxy

Liquid Epoxies (Thermosets)

Extruded Plastic with Butyl Rubber Adhesive (Pritec)

Extruded Plastic (Mapec, Elf Atochem, and Himont FBE/PE or PP brands)

Extruded Plastic (Du Val FBE/PE or PP)

Chevron Corporation

Advantages

Disadvantages

•

25+ years experience

•

Near white metal surface preparation required

•

Low current required for cathodic protection

•

High application temperatures

•

Good resistance to cathodic disbondment

•

Thinnest coating

•

-40°F to 200°F temperature range

•

Difficult to apply holiday free

•

Available in all pipe sizes

•

Difficult to apply consistently

•

Excellent hydrocarbon resistance

•

Not susceptible to cathodic shielding

•

Excellent adhesion to steel

•

Continuous coating

•

Temperature resistance up to 200°F

•

Long cure time (minutes to 24 hours)

•

Spray or hand apply in field

•

May need near white blast surface

•

Good chemical resistance

•

Expensive

•

Use for odd shapes

•

Can be applied while pipe is in service

•


•

High initial costs for small diameter pipe

•

Minimum holidays on application

•

Susceptible to cathodic shielding

•


•

Do not use on spiral-welded pipe

•

Self-healing adhesive

•

Hard to handle when warm

•

Wide range of sizes

•

•


Susceptible to damage from thermal expansion and contraction

•

Continuous coating

•

Cannot be used on bends

•

Limited hydrocarbon resistance

•


•

Limited hydrocarbon resistance

•

Minimum holidays on applications

•

•


Limited experience with high temperature service

•


•


•

Continuous coating

•

Wide range of pipe sizes

•

Low water absorption

•

200°F + temperature resistance

•

Limited experience (less than 5 years)

•

Low water absorption

•

High cost

•

Coating for girth welds and shop bends is the same as for lines

•

Girth welds difficult to coat

•

•


Coating damage hard to patch but progress is being made

•


•


•

Excellent adhesion FBE to PE or PP

•

Continuous coating

900-7

September 1996


Fig. 900-3

Coatings Manual

Advantages and Disadvantages of External Pipeline Coatings (2 of 2) Coating

Advantages

Extruded Plastic, Asphalt Adhesive (Plexco, Bredero Price, and Shaw)

Tape Wraps (services < 140°F)

Coal/Tar Enamel

Fig. 900-4

Disadvantages

•


•

Minimum adhesion to steel

•


•

Do not use above ground

•


•

Limited storage life

•


•

Tears in jacket can go length of pipe

•

Adhesive flows at low temperatures

•

Poor hydrocarbon resistance

•


•

Hard to handle when hot

•


•


•

Easy to apply

•

Poor coating-to-coating bond at overlap

•

Can be used for bends

•

Must be applied at proper tension

•

Can be used to coat all sizes of pipe

•

Susceptible to soil stresses

•

Can be applied to pipe while in service

•

Temperature limited

•

Non-continuous coating

•

Poor service history

•


•

Carcinogenic fumes when applied

•


•

Poor UV resistance

•


•

Cracking problem below 32°F

•

Good resistance to cathodic disbondment

•

Soft when hot (100°F)

•

Good subsea experience with weight coating

•

Poor hydrocarbon resistance

•

Available for all sizes of pipe

Description of External Pipeline Coating—Asphalt Wrap Coatings

Definition

Asphalt wrap coatings consist of filled, air-blown, asphalt enamel that is reinforced with asphalt-embedded glass cloth or felt and covered with felt

Holiday Detection 1250

coating thickness ( mils )

Note: Lower holiday detection voltages may be required to prevent coating damage. Recommended Service Status

☞Caution

The Company no longer recommends this coating because of its poor service history.

In the recent past, no-one has applied asphalt-wrap coatings; therefore, pipeline grades of asphalt are no longer available in the United States. Asphaltic wraps have a poor service history and are susceptible to hydrocarbon attack and general deterioration in the ground. The Company has deleted the standard drawing for these wraps from the Piping Manual because these coatings are now obsolete.

Small Repairs

Choose an asphalt-based mastic to patch an asphalt (P-2) wrap.

☞Caution

Coal-tar mastics usually are not compatible with asphalt coatings.

The American Asphalt Institute had a classification system for coding asphaltic pipeline coatings that they have discontinued. P-2 identified the number of wraps and type of asphalt. this system of classification was similar to the NAPCA (National Association of Pipe Coating Applicators) system in which TGF-3 is an example for coat-tar-enamel pipe coating.

September 1996

900-8

Chevron Corporation

Coatings Manual

Fig. 900-5


Description of External Pipeline Coating—Asphalt Mastic (1 of 2)

Definition

Somastic—an asphalt mastic—is a tar-like mixture of •

Inert mineral fillers - 13 per cent

•

Sand aggregate - 64 per cent

•

Fiberglass fibers - 0.1 per cent

•

Asphalt binder

Recommended Service

Offshore and onshore ambient-temperature lines where hydrocarbon-soaked soils are not present.

Status

Limited availability and marketing have affected Somastic's popularity.

Max. Service Temp

Surface Prep

Field experience has found manufacturers’ temperature limits to be very optimistic.

☞Caution

The Company does not recommend Somastic for temperatures above 140 °F.

Abrasive Blast Other


Application


•

Heat and mix Somastic ingredients

•

Continuously extrude the mixture over primed pipe to form a thick, seamless coating

•

Whitewash the black mastic to prevent its softening and aging in sunlight

Girth-weld Coating •

Melt Somastic chips and pour the fluid into a mold that compresses the hot mixture around the girth weld.

•

Taper the Somastic joint coating at the ends to accept heat-shrink wraps for coating the girth welds.

Thickness

> 250 mils

Small Repairs

Heat-shrink sleeves UT.

☞Caution

Select mastics that are compatible with asphalt for repairing coating damage. Coal-tar mastics are usually incompatible with asphalt coatings such as Somastic.

Handling/Storage

Aboveground Storage Limit: One year

Protection/Resistance

UV Resistance: Poor See also Advantages and Disadvantages under Discussion below.

Chevron Corporation

900-9

September 1996


Fig. 900-5

Coatings Manual

Description of External Pipeline Coating—Asphalt Mastic (2 of 2)

Discussion

Three grades of Somastic are currently available, differing in chemical makeup of the asphalt and temperature ratings. •

Somastic I - 120°F

•

Somastic II - 150°F

•

Somastic III - 190°F

Choosing a higher grade (higher temperature limit) decreases flexibility at low temperatures. Service History Originally developed in 1922 by Standard Oil Company of California, Somastic has been selected for offshore and high-temperature onshore service. Its thickness and toughness make it especially resistant to mechanical damage; however, Somastic will fail in hydrocarbon-contaminated soils. FBE has replaced asphalt enamels because of poor performance. FBE and Pritec have replaced it as an onshore hot-oil pipeline coating because Somastic has performed poorly in this service. Most of Somastic's failures occur at elevated temperatures. One of these failures occurred at the Company's Hawaii Refinery on a 180°F line; however, the Company and other operators have had many successful Somastic applications at long-term ambient temperatures. Several failures have also occurred on hot-oil pipelines in California. Poor quality control inspection during pipeline construction or incompatible mastics may have caused some failures of Somastic-coated girth welds. Advantages •

A good coating with a long service history

•

Adheres well

•

Flexible

•

Good resistance to impact, penetration, and cathodic disbonding

Disadvantages •

Not always available

•

Susceptible to hydrocarbon attack

•

Brittle when cold (< 40°F)

•

Soft when hot

•

Heavy (expensive to ship)

•

Not performed well as a hot-oil pipeline coating

As asphalt-wrap coatings absorb water, there have been questions about applying Somastic offshore. Water absorption could increase the current requirements for cathodic protection and cause a coating failure. Shell Oil recently reported that one of their Somastic-coated offshore pipelines was only 5 percent bare after 20 years of service. At present, there is no evidence that Somastic coatings are unsuitable for offshore service. Girth-weld Coating

Heat-shrink sleeves (Taper Somastic coating transition area to 45 degree angle.)

Brands

Somastic I and III. Currently available only from Bredero Price International (formerly Energy Coating) in Harvey, Louisiana.

See Also

September 1996

NACE International Standard RP-0276 (Discontinued)

900-10

Chevron Corporation

Coatings Manual

Fig. 900-6


Description of External Pipeline Coating—Coal Tar Enamel (1 of 2)

Definition

Coal-tar enamel is a hot, shop-applied, black tar-like coating of iron-mill-coke byproducts. It is layered with inner or outer wraps (or both) of glass fiber or asbestos felts.

Recommended Service

On subsea lines with concrete (weight) coatings.

Status

For onshore lines, operators are replacing coal-tar enamels with FBE and extruded plastic; offshore, coal-tar is very popular.

Max. Service Temp

140°F

Surface Prep

Abrasive Blast: SSPC SP6 Other

Holiday Detection

12,000 to 18,000 volts

Application

Although we can field- or shop-apply coal-tar enamels, field application is rare because of problems with inadequate pipe surface preparation, inspection [8], and air quality when melting the coating. The coating mill sprays or pours heated coal-tar enamel (400°F) on a pipe primed with coal-tar primer. Simultaneously, they layer two or three glass-fiber, felt-reinforcement wraps that improve the coating's strength, uniformity, and resistance to soil stresses and mechanical damage.

☞Caution Thickness

Solvent emissions during application can be an environmental problem.

156 mils The total thickness of the coating including the outer wrap is about 100 mils. Typically ranges from 62 to 188 mils.

Small Repairs

The following repair methods are acceptable in the United States, except melted enamel which is prohibited in some states with strict air quality regulations. The melted enamel repair is expensive and is only warranted if there are many repairs. •

Coal-tar mastic

•

Cold- or hot-applied tape made for coal tar (must first remove the damaged coal-tar enamel completely)

•

Melted coal-tar enamel is granny ragged (the process followed to handwrap hot coal-tar enamel on the bottom half of the pipe’s surface) or poured into a mold formed around the pipe

☞Caution

Make all mastic repairs with a coal-tar mastic because asphalt mastics are incompatible with coal-tar coatings.

Many gas-transmission pipeline operators do not approve of any mastics as this substance has failed in service, allowing corrosion to develop. Handling/Storage

Aboveground Storage Limit: Six months +


Protection For an outer coating, we recommend fiberglass filler mat and a felt or kraft paper (or both) outer wrap. The outer wrap protects the coal tar from mechanical damage when it is soft. Coating applicators usually give the pipe a reflective outer coating of kraft paper, whitewash, or white emulsion to protect it unless it is concrete (weight) coated. Any of these outer coatings will reduce the temperature of the coal tar to a minimum in the sun and protect it from UV rays. Hydrocarbon Resistance: Poor

Chevron Corporation

900-11

September 1996


Fig. 900-6

Coatings Manual

Description of External Pipeline Coating—Coal Tar Enamel (2 of 2)

Discussion

Choosing mineral rather than asbestos felts affects both the cost and the quality of the coating. Mineral felts are generally comparable with asbestos and cost more as they come from eastern Canada. Regardless, select mineral felts because repairs to coal-tar-enamel lines with asbestos felts would be more costly due to asbestos-handling procedures. Service History Coal-tar enamels have been popular for over 70 years. For offshore service, coal-tar enamel is common as 33 percent of the companies responding to an Oil and Gas Journal survey [9] report using it. For more than 20 years, Aramco has applied coal tar enamel successfully offshore [10]. While this coating has also been applied successfully onshore, it is hard to handle, becoming brittle at about 40°F and soft above about 90°F. The concrete-weight coating applied over the coal tar for subsea applications protects the coal tar and eliminates the handling problem.

Girth-weld Coatings

Shrink wraps or cold applied tape wraps.

Note: The materials of heat-shrink wraps are generally more expensive than cold-applied tape, but heatshrink wraps are quicker to apply and less sensitive to an inexperienced worker. Heat-shrink wraps also reduce the possibility of water ingress as it eliminates the overlap inherent with cold-applied tape wraps. Brands

The coating material is available from Reilly Tar and Chemical Corp., but the number of coal-tar coating applicators is decreasing because of strict air quality regulations. Per NAPCA specifications, CUSA production typically orders this coating system as TGF-3.

See Also

•

Company’s Pipeline Manual for information on weight coatings

•

NAPCA Bulletin 1-65-94 “Recommended Specification Designations for Coat Tar Enamel Coatings”(1)

•

NAPCA Bulletin 2-66-94 “Standard Applied Pipe Coating Weights for NAPCA Coating Specifications” (1)

•

NAPCA Bulletin 3-67-94 “External Application Procedures for Hot Applied Coal Tar Coatings to Steel Pipe”(2)

•

NAPCA Bulletin 6-69-94-1, “Suggested Procedures for Hand Wrapping Field Joints Using Hot Enamel.”(3)

•

AWWA Standard C-203

•

COM-MS-5006, Coal-tar Enamel Corrosion Coating of Submarine Pipelines, in this manual for application specifications

•

Application specifications for coal-tar enamel and concrete (weight) coatings in Figure 900-21: Coating Specifications for Buried Pipelines.

(1) Chevron USA follows these specifications when ordering coal-tar-enamel coatings (2) Chevron USA Production typically follows this specification when ordering coal-tar-enamel-coated pipe. (3) Although this NAPCA specification is for coating girth welds, we follow the same technique for making repairs with hot coal-tar enamel.

September 1996

900-12

Chevron Corporation

Coatings Manual

Fig. 900-7


Description of External Pipeline Coating—Coal Tar Epoxies

Definition Recommended Service

A two-part liquid epoxy compound containing coal-tar pitch Refurbishing old pipelines, girth weld coatings, tie-ins, valves, and fittings.

☞Caution

Unsuitable for hot-oil pipelines.

Status

More commonly used as a tank lining, coal-tar epoxy has seen limited use as a buried pipeline coating system; however, most coal-tar epoxies are incompatible with cathodic protection current.

Max. Service Temp

140°F

Surface Prep

Abrasive Blast SSPC SP-10

☞Caution

Any less than SSPC SP-10 for buried pipeline may result in cathodic disbondment.

Other Holiday Detection 1250

Application


Spray, brush, or roll Cure time: Very slow

Thickness

16-20 mils

Small Repairs

Patch with same material per manufacturer’s guidelines

Handling/Storage

—


Cathodic Disbonding A zinc primer may improve resistance to cathodic disbonding of the coal-tar epoxy's outer layer. Applying high-built coal-tar epoxies in two coats increases resistance to cathodic disbondment. Soil Stress & Hydrocarbon Resistance: Excellent

Discussion

Applied correctly, coal-tar epoxies are excellent coating systems for buried pipelines; but they are unsuitable for hot-oil pipelines.

Girth-weld Coatings

—

Brands

International Tarset Maxi-Build 7080 and Corroguard EP are the only coal-tar epoxies currently recommended, but there are many other coal-tar epoxies on the market that make excellent buried pipeline coatings.

See Also

NAPCA Bulletin 14-83-94, External Application Procedures for Coal Tar Epoxy Protective Coatings to Steel Pipe

Chevron Corporation

900-13

September 1996


Fig. 900-8

Coatings Manual

Description of External Pipeline Coating—Cold-Applied Tapes (1 of 2)

Definition

Recommended Service

There are two types of tape wraps: hot- and cold-applied. Hot-applied wraps generally have a higher bond strength. Cold-applied tapes can be field- or shop-applied by machine or by hand. Cold-applied tape wraps are: •

Continuous strips of a plastic-backing material, either polyethylene (PE) or polyvinylchloride (PVC)

•

Coated with a butyl-rubber adhesive (Polyken or Tapecoat) or modified bituminous compound (Polyguard RD-6)

•

Spirally wound on primer-coated pipe

Tapes are still viable because otherwise we cannot accomplish the following tasks economically: •

Repairing damaged coatings (FBE, extruded plastic, and coal-tar epoxy)

•

Coating bends that cannot be FBE coated in the field

•

Refurbishing old lines that must stay in service

•

Refurbishing short new lines in dry, low-soil-stress areas more economically than with extruded plastic or FBE

☞

Caution Because PVC embrittles badly and shrinks at temperatures of 104 °F or higher, we recommend PE for all tape applications [6, 7].

☞Caution

Our experience does not substantiate manufacturers' claims that cold-applied tapes are suitable for hot-oil pipelines.

Status

Introduced about 40 years ago [5] as an over-the-ditch system, tapes replaced coal-tar enamels and asphalts that required heating. The tape on thousands of miles of pipe has given mixed results and is now being replaced with extruded plastic or FBE as the main mill-applied coating for pipelines.

Max. Service Temp

Elevated-Temperature Service Most high-temperature tape systems are hot-applied tape systems. The temperature limits of coldapplied tapes, depending on the manufacturer, include: •

140°F for most polyethylene-backed tapes with butyl adhesives

•

150°F for polypropylene-backed tape with bituminous compound (Polyguard RD-6)

•

Above 140°F for specialty tapes

A cold-applied tape may suffer thermoshock when raised to the service temperatures of hot-oil pipelines. Surface Prep

Abrasive Blast: SSPC SP-2 Other While an abrasive blasted surface is ideal, coatings applicators most often field-apply tapes, making surface preparation difficult. Over-the-ditch cleaning machines have rotating wire brushes to clean the pipe ahead of primer application. Power tools are essential if cleaning by hand. There are coatings with minimum sensitivity to surface preparation.

Holiday Detection

3000 to 8000 volts per manufacturer’s guidelines

Application

Whether mill- or field-applied: •

Prepare the pipe surface

•

Apply a primer

•

Spirally apply one layer of tape

•

Spirally apply one or more offset layers of tape over the first.

When wrapping the tape around a pipe, there are three critical elements for success: pipe surface preparation, tape tension, and amount of tape overlap. (Check with the tape manufacturer for recommendation). In a two-layer system, it is also important to stagger the overlaps of each tape layer so that water has no direct path to the pipe surface. Before applying the first tape layer, the coating applicators tape any weld seams (girth and longitudinal) that are not flush with the surface of the pipe. This base layer of tape prevents the spirally applied tape wrap from leaving a void at the weld seam that may become filled with moisture and create a shielded corrosion cell. The primer causes a chemical reaction in the adhesive, which helps bond the adhesive or compound on the inner layer of tape to the pipe's surface, thus increasing its bonding strength. In a two-layer system, the first layer of tape provides corrosion protection; the second, and any subsequent layers, provide mechanical protection for the first layer.

September 1996

900-14

Chevron Corporation

Coatings Manual

Fig. 900-8


Description of External Pipeline Coating—Cold-Applied Tapes (2 of 2)

Application (continued)

The outer wrap (or rock shield) over the tape system must be bonded or not bonded to the tape depending upon the recommendation of the tape manufacturer. Non-bonded outerwraps create a slip plane between the inner and outer wraps that helps protect the inner wrap from soil stresses. A nonbonded outerwrap may cause a cathodic protection shielding problem if it is a solid plastic coating. Shop-applied tapes outperform field-applied tapes because quality control and inspection are easier in the coating mill. To improve field application of cold-applied tapes, relatively small and lightweight wrapping machines are now commercially available that are power or hand operated. They can also be equipped with a constant tension brake system to provide uniform tension across width of rolls and through its entire length.

Thickness

Varies with coating system. The average thickness (not including a rock shield or outer wrap) of a two-layer tape wrap is about 70 mils; of a single-layer tape system, 50 mils.

Small Repairs

Generally, coating applicators repair tapes by taping over the damaged tape or by using a mastic. In the Northwestern Business Unit, Chevron Pipe Line has been successful with Tapecoat's 10/40W system using a one-inch overlap.

Handling/Storage

—


UV and Hydrocarbon Resistance: Poor

Discussion

Service History Many early tapes •

Were applied with poor surface preparation, no primer, no tension, and no protective overwrap

•

Failed in service

•

Have given tapes the reputation of being poor pipeline-coating systems

Advantages Cold-applied tapes are easy and inexpensive to apply in the field. If applied properly and used in the proper environment, cold applied tapes are an acceptable pipeline coating. Tapes are still viable because of the tasks listed under Recommended Service, above. Disadvantages Tapes may encounter problems in long-term service, because of improper application, service conditions, pipe diameter, or product design. As they are not a continuous coating, the tape's overlaps greatly increase the chance of water penetration. Also, the overlaps may bond poorly, catch on the soil (stress), and pull open. The Company has not verified the suggestion that some new tapes have resolved these problems. Some tapes are pressure sensitive (Tek-Rap, Royston) and depend primarily upon mechanical means, memory, to keep the overlaps closed. If outside forces such as soil stress disturb this memory, the tape may loosen. Too much or too little tension during application can cause a coating failure from loss of memory. For protecting buried pipelines, pressure-sensitive tapes are not as desirable as tapes with an adhesive that bonds at overlaps to the pipe's metal surface and the coating. Most failures of tapes occur on large-diameter pipe (greater than 12 inches in diameter). Soil stress becomes a greater problem as the pipe's diameter increases because the soil has more coating surface area to grab. Girth-weld Coatings

For coating-mill-applied tape wraps (through 12 inches in diameter), shrink sleeves or hand-wrapped tape

Brands

Tapecoat’s 10/40W, Polyken, Polyguard RD-6

See Also

•

NAPCA Bulletin 16-94, “External Application Procedures for Plant Applied Tape Coating to Steel Pipe”

•

NAPCA Bulletin 6-69-94-9, “Suggested Procedures for Coating Field Joints, Fittings, Connections, and Pre-fabricated Sections Using Tape Coatings”

Chevron Corporation

900-15

September 1996


Fig. 900-9

Coatings Manual

Description of External Pipeline Coating—Extruded Plastic with FBE or Liquid Epoxy Primer (1 of 2)

Definition

Continuous plastic coating (either polyethylene or polypropylene) with an epoxy primer.

Recommended Service

Buried onshore and offshore pipelines up to 200°F.

Status

Although this coating system is quite new to the United States, it has been available in Europe for a long time. Himont, DuVal, and Elf Atochem are the suppliers; Bredero Price (formerly Encoat) has two coating mills that apply this coating in the United States.

Max. Service Temp

•

Himont, an Italian company, is forming an alliance with 3M and Shell Chemical to enter the U.S. pipecoating market.

•

DuVal is an alliance between Du Pont Canada and Valspar.

•

Du Pont Canada and Shaw manufacture polyethylene three-layer systems in Canada. Shaw's has a liquid-epoxy primer.

200°F Polypropolene; 180°F Polyethylene

☞Caution

We do not recommend polypropylene for service temperatures above 200°F without additional laboratory or field testing.

Surface Prep

Abrasive Blast: SSPC SP10 Other: Blast clean the pipe and then transfer it to the extrusion line.


Application


To produce a bonded, overlapped coating to a specified thickness: •

Apply an epoxy primer with or without a co-polymer adhesive (Mapec, Himont, Du Pont Canada, DuVal, Elf Atochem).

•

Immediately extrude overlapping layers of melted plastic on the pipe, followed by water quenching.

Apply Shaw YJII by the crosshead-extrusion process over a liquid-epoxy adhesive layer; apply other coatings with the side-extrusion process over an FBE primer. Quality control standards are more rigid for multi-layer coating systems such as DuVal, Himont, Du Pont Canada, and Elf Atochem as the adhesive (FBE) must still be tacky when we apply the plastic topcoat.

☞Caution Thickness

Applying the topcoat:

•

Too quickly results in improper curing of the FBE and poor bonding to the pipe's surface.

•

Too slowly may produce an improper bond between the plastic and FBE layers.

The thickness of the plastic topcoat may be 1.5 to 3 mm or more depending upon the pipe's diameter and the service requirements. DuVal has a standard 14-mil thickness of FBE as compared to the 75 to 125 microns in the three-layer systems. Elf Atochem: 59 to 118 mils; DuVal: 20 to 45 mils.

Small Repairs

Heat-shrink sleeves

Handling/Storage

Aramco has had good experience with Mapec, which is reportedly easier to ship and handle than FBE.


UV Resistance: Excellent See also Discussion below

Discussion

Considered the best pipeline coating system available. Company has limited experience with it. Resistance and Strength Extruded plastic coatings generally have good impact strength, resist water penetration well, and do not shrink at elevated temperatures. Physical properties of polyethylene vary with density, high-density polyethylene having superior resistance to impact and moisture. The shear strength of butyl or asphalt adhesives is poor and decreases substantially with increases in temperature [4]. This situation allows the pipe to move inside the coating during thermal expansions and contractions and subjects the outside of the coating to soil stresses. The resulting problems are loss of adhesion, wrinkling, and, eventually, exposed steel. The adhesives in Elf Atochem, Himont, Du Pont Canada, DuVal, and Shaw YJII coating systems have greater shear strengths and temperature resistance than butyl or asphalt adhesives. Mapec gave excellent results in the early 1980's testing, but did not equal thick FBE in hot (250°F) subsea testing in the late 1980's [15].

September 1996

900-16

Chevron Corporation

Coatings Manual

Fig. 900-9


Description of External Pipeline Coating—Extruded Plastic with FBE or Liquid Epoxy Primer (2 of 2)

Discussion (continued)

Operating Temperatures •

Service Temperatures < 150°F Acceptable—30214 Mapec's low-density polyethylene plastic.

•

Service Temperature of 180°F – Uninspected but in service (Shaw YJII and a thermo-insulation outer jacket. /DuVal polypropylene with no thermo-insulated outer jacket – Chevron Canada Resources has a hot-oil pipeline operating at 180°F, which is coated with Shaw YJII and a thermo-insulation outer jacket. The girth welds were coated with liquid epoxy and Raychem high-temperature heat-shrink sleeves. To date, this pipeline has not been inspected and has been in service for four years. – The Chevron Pipe Line Western Business Unit has DuVal polypropylene on a hot-oil pipeline operating at 180°F. This pipeline has no thermo-insulated outer jacket, has not yet been inspected, and has been in service for about two years. They experienced quality control problems during the coating's mill- production run and when CCSI field coated the girth welds. While Mobil Pipeline reports that most of these problems have been corrected, a British Petroleum project also had quality control problems in South America during 1993-94.

Elf Atochem's coating system has three plastic (polyolefin) top coats that they rate for the following service temperatures: •

Low-density polyethylene (-40 to 149°F)

•

Medium-/high-density polyethylene (-40 to 167°F)

•

Polypropylene (-4° to > 212°F)

☞

Caution We do not recommend DuVal Polypropylene for service temperatures above 200 °F without additional laboratory or field testing. Du Pont Canada and Valspar rate their DuVal Polyethylene at a maximum operating temperature of 180°F and their DuVal Polypropylene at a maximum operating temperature of 230°F. Layers Because of higher costs of materials, two-layer coatings (e.g., DuVal) are more expensive than threelayer systems (e.g., Mapec, Elf Atochem, Du Pont Canada, and Himont). Valspar is considering changes for DuVal to bring its maleic anhydride content nearer the levels of three-layer coating systems. DuVal must have the proper concentration of maleic anhydride to bond the two layers to each other. Bredero Price (formerly Encoat) performs a test on DuVal’s raw, modified, plastic material to verify that there is a proper concentration of maleic anhydride. The middle adhesive layer of the Elf Atochem multilayer system bonds the top plastic and FBE layers with maleic anhydride and other chemicals such as terpolymer of ethylene and acrylic ester. DuVal and Elf Atochem coatings are not as easy to apply as other pipeline coatings such as FBE and Pritec. Although it is possible to field-apply a two-layer system over girth welds, field conditions can make it difficult to achieve a quality coating. Girth-weld Coatings Brands

•

Induction-heat-applied FBE and plastic is recommended.

•

Shrink sleeves

☞Caution

Many pipeline operators are using Himont, DuVal, and Elf Atochem polypropylene coating system at operating temperatures up to 230°F on both offshore and onshore pipelines. The Company has limited experience with this coating system at temperatures above 200°F. We do not recommend Elf Atochem Polypropylene or DuVal polypropylene for service temperatures above 200°F without additional laboratory or field testing. The following systems offer superior performance often equal to or better than FBE alone at a premium price.

See Also

Chevron Corporation

•

Mapec’s low-density polyethylene plastic is acceptable for maximum service temperatures of 150°F.

•

The Mapec, Du Pont Canada, Himont, DuVal, and Elf Atochem systems have an FBE primer, and either a polypropylene or polyethylene jacket.

•

Shaw YJII has a liquid-epoxy primer with a polyethylene outer jacket.

•

The Mapec, Du Point Canada, Himont, Shaw YJII, and Elf Atochem systems bond the epoxy and outer plastic with a copolymer adhesive

•

The DuVal system has an adhesive copolymer incorporated in the plastic top coat formula.

•

CAN/CSA-Z245.21-M92 L’Association Francaise De Normalization NF A49-710

•

Mobil Pipeline Specification CM-251-880

900-17

September 1996


Coatings Manual

Fig. 900-10 Description of External Pipeline Coating—Extruded Plastic—Crosshead-Extruded Plastic with Asphalt Adhesive (1 of 2) Definition

Continuous plastic coating (either polyethylene or polypropylene) extruded on a pipe at elevated temperatures.

Recommended Service

Onshore pipelines operating below 160°F where FBE is uneconomical or unavailable. Prices and the performance of the systems (particularly at higher temperatures) vary substantially. See Discussion below

Status

Extruded polyethylene and polypropylene coatings of various costs and qualities are very popular and readily available in the United States and Canada.

Max. Service Temp

Varies with manufacturer. Onshore, < 160°F. (100°F for some brands)

Surface Prep

Abrasive Blast: SSPC SP-6 Other


Application[3]


The crosshead extrusion method involves: •

Flooding the pipe with a hot asphalt-rubber adhesive

•

Passing the pipe through a wiper ring to maintain a nominal ten-mil adhesive thickness

•

Passing the pipe through the center of the crosshead die where the plastic is uniformly extruded in a cone shape around the pipe

•

Water quenching that causes the plastic to shrink tightly to the adhesive and pipe

☞Caution ☞Caution

Unlike side-extrusion, crosshead extrusion limits size of pipe diameter. Never apply soft adhesives to spiral-welded pipe.

Thickness

35-70 mil

Small Repairs

•

Heat-shrink sleeves

•

Tapes, if soil stress not a problem

Handling/Storage

Above-ground Storage Limit: One year


Disbonding Tests of the early 1980's show differences in adhesive strengths and resistance to cathodic disbonding. Plexco and Encoat (now Bredero Price International) were not as good as Pritec (extruded plastic with butyl rubber mastic) and Mapec (extruded plastic coating with FBE primer). [2, 4, 13, 14]. Recently Bredero Price (Encoat) improved the mastic in its Entec coating. Plexco will supply a superior mastic if requested. UV Resistance: Fair. The orange (polypropylene) and yellow (polyethylene) coatings do not resist UV damage well. They became brittle and cracked when stored for a year in the Californian sun. (This is not a problem with Yellow Jacket). Impact, Moisture, Shrink, and Temperature Resistance Extruded-plastic coatings generally have good impact strengths, resist water penetration well, and do not shrink at elevated temperatures. Physical properties of polyethylene vary with density, high-density polyethylene having superior resistance to impact and moisture. Polypropylene offers superior temperature resistance in hot-oil pipeline service, but the mastic has the lowest temperature limit.

September 1996

900-18

Chevron Corporation

Coatings Manual


Fig. 900-10 Description of External Pipeline Coating—Extruded Plastic—Crosshead-Extruded Plastic with Asphalt Adhesive (2 of 2) Discussion

Costs Wide range in costs. The former X-Tru-Coat coatings (Plexco Plexguard, Bredero Price (Encoat), Entec, Shaw Yellow Jacket, and Shaw Black Jacket) are inexpensive and work well at ambient temperatures [12]. Temperature A Company product, the Plexco coating is very economical. Chevron Canada Resources reports that the high-temperature grade of Yellow Jacket (maximum 185°F limit) works well at 140-160°F. Although current Plexco and Bredero Price (Encoat) literature places maximum temperature limits of 140°F (polyethylene) to 170°F (polypropylene), be cautious with these products in temperatures above 100°F without additional testing or documented high-temperature field experience. Yellow Jacket should work up to 160°F, based on the Canadian experience. Black Jacket is a new coating with a mastic superior to Yellow Jacket, but the Company has no experience with Black Jacket. Strengths The shear strength of hot-melt-asphalt adhesives is poor and decreases substantially with increasing temperature [4]. This situation allows the pipe to move inside the coating during thermal expansions and contractions and subjects the outside of the coating to soil stresses. The resulting problems are loss of adhesion, wrinkling, and, eventually, exposed steel.

Girth-weld Coating

Heat-shrink sleeves

Brands

The crosshead extrusion method was formerly licensed under X-Tru-Coat but current brands are Bredero Price (Encoat) Entec, Shaw Yellow Jacket and Black Jacket, and Plexco (Plexguard). Shaw, Bredero Price (Encoat), and Plexco apply this coating system.

See Also

Chevron Corporation

•

The former X-Tru-Coat coatings (Plexco Plexguard, Bredero Price (Encoat)

•

Entec, Shaw Yellow Jacket, and Shaw Black Jacket) are inexpensive and work well at ambient temperatures [12].

•

The Plexco coating is very economical.

•

Chevron Canada Resources reports that Yellow Jacket works well at 140-160°F.

•

NAPCA Bulletin 15-83-94, “External Application Procedures for Polyolefin Pipe Coating Applied by the Cross Head Extrusion Method of the Side Extrusion Method to Steel Pipe”

•

ANSI/AWWA C215

900-19

September 1996


Coatings Manual

Fig. 900-11 Description of External Pipeline Costing—Extruded Plastic—Side-Extruded Polyethylene with Butyl-Rubber Adhesive (1 of 2) Definition

Continuous plastic coating (polyethylene) with butyl rubber adhesive.

Recommended Service

Onshore pipeline operating below 180°F rather than FBE for cost or supply reasons

Status

Bredero Price (Encoat) applies Pritec at several coating mills in the United States.

Max. Service Temp

180°F

Surface Prep

Abrasive Blast: SSPC SP-10 Other: Blast clean the pipe and then transfer it to the extrusion line.


Application


The side-extrusion method produces a bonded, overlapped coating to a specified thickness and involves: •

Running a rotating pipe past the extrusion die at the side of the pipe

•

Applying a butyl-rubber-adhesive mastic

•

Immediately extruding overlapping layers of melted plastic on the pipe, followed by water quenching

☞Caution

Never apply soft adhesives to spiral-welded pipe.

Thickness

Typically, plastic top layer is 40 mils, but it can be up to 240 mils. Offshore, Pritec has been applied at a nominal thickness of 15 mils for the butyl rubber layer and 60 mils for the polyethylene layer. See Protection, Rocks, below.

Small Repairs

Patches work well and are cheaper than shrink wraps but be sure that the edges of a patch adhere tightly to the surface. Coating Removal With a knife, scribe the area to be removed, freeze the coating with CO2 or liquid nitrogen, and jerk the coating off quickly. (In cold weather, it may be possible to remove the coating without artificial cooling.)

Handling/Storage

Aboveground Storage Limit: One year Ship all plastic coated pipe with rubber spacers between (or 5/8-inch rope rings around) the pipes to prevent rubbing when the pipe is not nested. When nesting the pipe, use padded skids and handle the coated pipe with padded equipment and slings. Cinch-lifting methods apply a torque force to the coating and can damage it.


Disbonding Pritec's polyethylene coating system has significantly superior adhesion and resistance to cathodic disbonding because of the butyl-rubber adhesive [2,4]. Pritec is specified by its mastic and polyethylene thickness; e.g., Pritec 10/40 is 10 mils of adhesive and 40 mils of PE. While Bredero Price, Inc., recommends Pritec 10/40 up to 180°F, CRTC's M&EE Unit has run cathodic disbonding tests that show thicker coatings being more resistant to disbondment [2]. Pipe Supports As polyethylene expands and contracts with temperature changes much more than steel, the supports for the pipe and welded line can damage the coating. On the Rangely CO2 line, gunny sacks full of pine needles or sawdust provided the best support, while rubber strips or tires and sand bags did not work well.[4]

September 1996

900-20

Chevron Corporation

Coatings Manual


Fig. 900-11 Description of External Pipeline Costing—Extruded Plastic—Side-Extruded Polyethylene with Butyl-Rubber Adhesive (2 of 2) Protection/Resistance (continued)

Rocks Backfill with soil or sand as Pritec 10/40 does not resist the impact of rock. Be careful of rocks protruding from the side of the ditch that would damage the coating as the pipe is being lowered into the ditch. Increase the thickness of the polyethylene layer from its normal 40 mils to 50, 60, 70, 80, 90, or 100 mils when expecting rocky backfill to prevent damage to this coating. From experience, the Company and others have learned that Pritec 10/40, a common choice, may not be thick enough in a rocky or high-soil-stress environment. UV Resistance: Excellent Hydrocarbon Resistance of butyl rubber mastic & heat-shrink sleeves: Lacking Impact, Moisture, Shrinkage Extruded-plastic coatings generally have good impact strengths, resist water penetration well and do not shrink at elevated temperatures. Physical properties of polyethylene vary with density, high-density polyethylene having superior resistance to impact and moisture.

Discussion

Shear Strength The shear strength of butyl-rubber adhesives is poor and decreases substantially with increasing temperatures [4]. This situation allows the pipe to move inside the coating during thermal expansions and contractions and subjects the outside of the coating to soil stresses. The resulting problems are loss of adhesion, wrinkling, and, eventually, exposed steel.

Girth-Weld Coating

Shrink sleeves

Brands

Entec Pritec 10/40

See Also

•

Girth-weld Protection Coatings, Figures 900-19 to 900-21

•

NAPCA Bulletin 14-83-94, “External Application Procedures for Polyolefin Pipe Coating Applied by the Cross Head Extrusion Method of the Side Extrusion Method to Steel Pipe”

•

NACE International RP0185

•

COM-MS-5005, “Side Extruded Plastic/Butyl Rubber Adhesive Line Pipe Corrosion Coating,” in this manual

Chevron Corporation

900-21

September 1996


Coatings Manual

Fig. 900-12 Description of External Pipeline Coating—Fusion-Bonded Epoxy (1 of 3) Definition

A thermosetting powder sprayed on a hot pipe. The heat melts the powder and causes chemical reactions, converting the epoxy into a hard, continuous coating.

Recommended Service

•

Onshore and subsea pipelines

•

Drilled crossings (Pipe pushed through drilled hole under river or road.)

•

Field joints and fittings up to 200°F

Choose FBE over all other coatings for buried onshore lines. Status

Max. Service Temp

Currently, FBE is one of the most widely-used pipeline coatings. Many applicators are available worldwide. Its cost is significantly lower now because of its popularity and the reduced level of pipeline construction. 150°F to 200°F depending on coating. Currently, FBE is the only economical coating to withstand pipeline temperatures up to 200°F.

Surface Prep

Abrasive Blast: SSPC SP-10 Near-white Finish Other: •

Pretreat with phosphoric acid or a chromate surface to enhance FBE/pipe bond, if necessary. Both pretreatments are recommended especially for pipeline operating temperatures > 150°F.

•

Heat surface 425°F to 475°F

☞Caution

Keep the preheat below 500 °F to prevent possible changes in properties of the pipe.

Holiday Detection

125 volts/mil

Application

When the surface reaches the specified temperature, apply the FBE powder by one of these methods: •

Electrostatic spraying (pipe, elbows, or tees)

•

Dipping the part (elbows or tees) in a bed of (fluid) powder

The heat already in the steel is normally sufficient to cure the coating; if not, heat it again, depending on coating thickness, pipe-wall thickness, and type of epoxy powder. Thickness

Depends on the pipeline's service. Rules of thumb

Small Repairs

•

Subsea or dry lines: (150°F, 14 mils (min.) > 150°F, 30 mils (min.)

•

River /drilled crossings; highly irrigated / continuous wet-and-dry areas; or areas with agricultural chemicals: (150°F, 20 mils (min.) > 150°F, 30 mils (min.)

Melt-on Patch Stick Thermoplastic materials that soften with increasing temperature, the patch stick is a quick, effective repair method; but, if applied improperly, the patch falls off. To check the bond, pick at the repair with a knife.

☞Caution

Do not use patch sticks on pipelines operating at > 100 °F.

Two-part Epoxy Patching Compound Thermoset that does not soften when heated, the two-part epoxy chemically decomposes when heated above a certain temperature but can match the temperature limits of the FBE. A much-higher-quality coating that has properties closer to FBE than the patch stick, two-part epoxy has a relatively long cure time (from 30 minutes up to 24 hours, depending on the pipe's temperature); and so contractors do not like it.

Note: For large repairs, use heat-shrink sleeves if soil conditions permit.

September 1996

900-22

Chevron Corporation

Coatings Manual


Fig. 900-12 Description of External Pipeline Coating—Fusion-Bonded Epoxy (2 of 3) Handling/Storage

Aboveground Storage Limit: Two years Handling Move FBE-coated pipe carefully with padded equipment or wide slings. Separate coated pipe that is to be stacked with: •

Nylon rope rings for small-diameter thin-wall pipe

•

Rubber spacers for heavy pipe

☞Caution

Do not use rubber spacers with lightweight pipe Lightweight pipe cannot compress rubber spacers, and the stack of pipe will become unstable.

Storage Stored FBE pipe has


•

Relatively good UV resistance, losing about one mil per year from UV chalking.

•

A tendency to blister if stored in humid sea air for over a year without protection from the atmosphere

UV Protection Excellent; protect pipe if it is to be stored in hot, humid, sea-air areas (e.g., climate similar to Gulf Coast) for more than six months. Concrete (Weight) Coating Apply concrete (weight) coating by one of two methods: compression coating or impingement. •

Compression coating involves rotating the pipe above a conveyor belt while the belt compresses concrete on the pipe. The rotating pipe moves perpendicularly to the conveyor during the application.

•

Impingement involves spraying the concrete on the pipe after applying an intermediate coating to protect the corrosion coating from the sprayed concrete.

Note: This process is preferred because it does not damage the coating.

Note: Typically we should apply a barrier coating or increase the FBE thickness to 30 mils or more to avoid creating holidays in coating during the impingement process. Cathodic Disbonding At thicknesses greater than 15 or 16 mils, Aramco has found significant improvement in FBE's resistance to ambient-temperature cathodic disbondment. Aramco specifies 17-22 mils thickness because they have regions where power supplies do not exist and they often try to throw cathodic protection down the line to these spots. Moisture-resistant Pipeline Coatings While all pipeline coatings absorb moisture during service, plastic coatings do so less than FBE coatings. Multi-layer coatings are designed with an epoxy as a primer and a plastic topcoat. Increasing the thickness of FBE for hot-oil pipelines does decrease the moisture absorption rate but creates other problems such as higher cost and reduced flexibility. Suitable for a pipeline operating temperature of up to 200°F, thicker coatings of FBE do not appear practical for higher operating temperatures. Lower-moisture-absorbing FBE coatings do exist, but many are inflexible and unacceptable for pipe that may be field bent. British Gas Pipeline in the United Kingdom uses 3M's Scotchkote 226N. The claim is that this coating has a greater resistance to moisture absorption than Scotchkote 206N. As this coating system became commercially available only recently in the United States, there is limited information about it.

Chevron Corporation

900-23

September 1996


Coatings Manual

Fig. 900-12 Description of External Pipeline Coating—Fusion-Bonded Epoxy (3 of 3) Discussion

Bends Bends are not easy to coat with FBE. There are two possibilities: •

Heat bends with induction coils and hand spray them in a shop.

•

Coat bends that are small enough in a bed of (fluid) powder.

In order of preference, options for coating bends in the field are two-part liquid epoxies or tape wraps. High-temperature Pipeline Coatings High-temperature pipeline coatings for hot-oil service need a pipeline coating for a wet-soil environment at operating temperatures over 200°F. Existing FBE coatings cannot meet this need. Although both DuVal and Elf Atochem’s polypropylene coatings claim to have operating temperatures up to 230°F, there is limited field experience with these coatings. It seems unlikely that any polypropylene coating can survive at continuous operating temperatures over 210°F.

Caution! Presently, the Company does not recommend any polypropylene pipeline coating for operating temperatures more than 200 °F without additional laboratory testing or field experience. Nap-Gard's new FBE coating may be suitable for hot-oil service temperatures over 180°F. This coating is the first dual or polymer-powder-modified FBE coating system [24]. The FBE primer is Nap-Gard 7-2501. The water-penetration-resistant FBE topcoat, Nap-Gard 7-2504 (also called Nap-Gard Gold) will bond directly to steel pipe. Any FBE-pipe-coating mill can apply this system which is easier to apply than any existing multi-layer coating system.

☞Caution

The Company does not recommend the Nap-Gard 7-2501/7-2504 coating system for operating temperatures over 180 °F without additional laboratory testing or field experience.

In California, Shell Pipe Line applied FBE with Pritec as an outer jacket for hot-oil service. This may be the first multi-layer coating system of this type in the USA. The Pritec protects the FBE from moisture, but the Pritec mastic is the weak link in this multi-layer coating system.

☞Caution

The Company does not recommend using FBE with Pritec for operating temperatures over

180 °F.

Girth-weld Coating

•

Induction, heat-applied FBE is the best.

•

Liquid epoxies may be used.

•

Heat-shrink sleeves acceptable in low-soil-stress areas.

☞Caution Brands

In hydrocarbon-contaminated soil, use FBE or liquid epoxies.

By Temperature •

> 150°F: 3M Scotchkote 206N, 3M Scotchkote 226N, Valspar D1003LD, Josun D1003LD, Nap-Gard 7-2501, and Nap-Gard 7-25014

•

> 180°F: Nap-Guard’s new FBE coating (7-2504) may be suitable for hot-oil service.

Multi-layer Brands DuVal, Elf Atochem, Himont, Mapec, Du Pont Canada, and Shaw YJII See Also

September 1996

•

COM-MS-4042 for specifications about purchasing and installing FBE-coated pipe.

•

Extruded plastic film for information about multi-layer coating systems with epoxy primers

•

Company’s Pipeline Manual for additional information about concrete (weight) coatings.

•

AWWA C213

•

NAPCA 12-78-94

•

CAN/CSA Z245.20-M92

900-24

Chevron Corporation

Coatings Manual


Fig. 900-13 Description of External Pipeline Coating—Hot-Applied Tapes Definition

Depending on its type, a hot-applied tape is coated on a pipe that is either •

Heated in a furnace

•

Heated with a torch or the tape itself may be heated with a torch

Recommended Service

The Company has very limited experience with hot-applied tape systems; therefore, we cannot report any field experience or provide much detail about them.

Status

—

Max. Service Temp

160°F Raychem states that Rayclad 120 accepts a temperature of 248°F (120°C).

☞Caution

The Company has no experience with Rayclad 120 and gives it a temperature rating of 200 °F until there is additional data from laboratory testing or field experience.

Surface Prep


Holiday Detection

10,000 to 18,000 volts

Application

Coating applicators can use torches for field-installing hot-applied tapes such as Raychem Flexclad and Canusa Wrapid tape.

Thickness

> 27 mils

Small Repairs

Heat-shrink sleeves or tape

Handling/Storage

—


UV Resistance: Poor Soil-Stress/Hydrocarbon Resistance Raychem Flexclad and Canusa Wrapid tapes have better soil stress resistance than cold-applied tapes, but they have poor hydrocarbon resistance Disbonding Initially, Polyken Synergy had problems with thermoshock that caused the coating system to disbond in service. Coating applicators using Synergy report a solution: preheat the tape before applying it to the pipe's surface.

Discussion

Advantage Tend to resist soil stresses better than cold-applied tapes. Disadvantage More expensive than cold-applied tapes. In General Polyken Synergy is less expensive than FBE, about the same cost as Pritec, and more expensive than Plexguard and Entec. It has no marketable characteristics that make it superior to existing mill-applied coating systems. Synergy has to be mill applied, and it cannot be applied by a portable coating plant due to its thermoshock problems.

☞Caution

The Company does not recommend Polyken Synergy because we carried out all of our laboratory testing on thermoshocked samples that failed. CRTC's M&EE specialists will reconsider Synergy if it passes testing by an acceptable independent coating laboratory or if pipeline operators report favorable field experience after five years of service. A high-temperature, hot-, mill-applied tape that other pipeline operators report to be successful is Raychem's Rayclad 120. A portable coating mill helps coating applicators to apply this tape properly in the field. Raychem Rayclad 120 have radiation-crosslinked hot-melt adhesives and polyethylene-based backings. The fact that the polyethylene plastic is radiation-crosslinked gives it greater temperature resistance and lower moisture-absorption rates than other non-radiated plastic tapes. The radiation-crosslinked hotmelt adhesives have lower moisture absorption, higher temperature resistance, and higher bond physical properties than the non-radiated mastics of other hot- and cold-applied tape systems. Girth-weld Coatings

—

Brands

Examples of heat-applied tapes are Canusa Wrapid Tape, Raychem Flexclad, Polyken Synergy, and Raychem Rayclad 120.

See Also

—

Chevron Corporation

900-25

September 1996


Coatings Manual

Fig. 900-14 Description of External Pipeline Coating—Petrolatum and Petroleum-Wax Tapes Definition

Petrolatum tape, a synthetic fiber, is coated with petrolatum compound containing inert fillers and thermal extenders. Petroleum wax tapes are petrolatum-based corrosion-preventative waxes, impregnating a synthetic fabric backing, and applied over a petroleum-wax primer.

Recommended Service

•

Coating pipes in the splash zone underneath wharves

•

Field coating irregularly shaped, buried, pipe fittings (i.e., valves, ties, bends, etc.)

•

Protecting transition zones where buried piping comes above ground

•

Coating buried pipe in areas where soil stress is not a problem

•

Filling shorted pipeline road casings (petroleum wax)

Note: Excellent for fittings and irregular shapes as long as soil stress is not a problem. Status

This specialty pipe coating has proven very successful for specific applications for over 50 years.

Max. Service Temp

135°F

Surface Prep

Abrasive Blast Other

Holiday Detection

Use wet spronge jeep

Application

Hand apply •

Brush or wipe the surface clean of dirt and all other foreign matter

•

Apply a thin film of primer

•

Apply the wax tape

☞Caution

If the pipe's surface is wet, rub and press the primer to displace the moisture and ensure that the primer is adhering to the pipe's surface.

Thickness

45 mils

Small Repairs

Patch with same material per manufacturer’s guidelines

Handling/Storage

—


UV Resistance: Good Hydrocarbon Resistance: Poor Add a rock shield material to protect the coating from penetration by rocks or soil-stress activity. Without a rock shield, add special backfill (sand) to a minimum thickness of six inches (150 mm).

Discussion

Advantages •

Conforms to irregular shapes

•

No drying or curing time required before backfilling

•

Easy application with minimum surface preparation

•

Easily removed

•

Can be applied over wet surfaces

•

Excellent resistance to moisture absorption

Disadvantages Low soil-stress resistance; not recommended for soil-stress areas. Girth-weld Coatings

—

Brands

Major manufacturers include Trenton, and Denso North America, Inc. Recently, Tapecoat introduced some petrolatum products.

See Also

—

September 1996

900-26

Chevron Corporation

Coatings Manual


Fig. 900-15 Description of External Pipeline Coating—Phenolic Epoxies Definition

A solvent-free, ultra-high-build, high-solids content, amine-cured, phenolic epoxy A solvent-free epoxy requires no evaporation in the curing process and has advantages for elevated temperature service because it is not as susceptible to solvent retention, which can cause the coating to break down on high-temperature lines [22].

Recommended Service

Field- or mill-applied coating system for high-temperature pipeline service

☞Caution

The Company has no experience with this coating system; it is included here as an introduction only.

Status

In Australia, Vessey Chemical manufactures Vepox CC703, reportedly an excellent high-temperature pipeline coating. Coating mills apply other phenolic-epoxy systems as a powder similar to FBE.

Service Temp

This coating system is rehabilitating Australian high-temperature gas pipelines with operating service temperatures as high as 248°F (120°C).

Surface Prep

Abrasive Blast: SSPC SP-10 with surface profile of 70-100 microns Other

Holiday Detection

Vendor’s recommendation.

Application

May field apply this coating system with conventional spray equipment using premixed material or with airless spray equipment [22].

Thickness

—

Small Repairs

—

Handling/Storage

—


—

Discussion

Bends Phenolic epoxies are superior to FBE in temperature resistance, but typically we cannot field bend them. Coatings applicators can field coat field bends with a liquid-phenolic epoxy.

Girth-weld Coatings

—

Brands

—

See Also

—

Chevron Corporation

900-27

September 1996


Coatings Manual

Fig. 900-16 Description of External Pipeline Coating—Polyester Epoxies Definition Recommended Service

Flake-reinforced polyester epoxies are two-part liquid-epoxy coatings. Refurbishing old pipelines, tie-ins, valves, and fittings.

☞Caution ☞Caution

Where hydrocarbon contamination or soil stress present, use cold-applied tapes. Polyester epoxies are not recommended for hot oil pipeline service.[22. 23]

Status

Although this coating has had limited pipeline use because of the high cost of raw materials, it is an excellent coating system for pipeline valves both atmospheric and buried.

Max. Service Temp

160°F

Surface Prep


Holiday Detection

4,000 volts

Application

•

Spray, brush, or roll

•

Very slow cure time

Note: Spray recommended; brush acceptable for patching small areas. Thickness

35-40 mils

Small Repairs

Patch with liquid epoxy per manufacturer’s guidelines.

Handling/Storage

—


—

Discussion

Polyester epoxies have excellent resistance to UV, hydrocarbon, and soil stress.

Girth-weld Coatings

—

Brands

Master Builder's Ceilcoat Flakeline 251 is one recommended brand, but other excellent polyester epoxies are available.

See Also

—

September 1996

900-28

Chevron Corporation

Coatings Manual


Fig. 900-17 Description of External Pipeline Coating—Polyurethane (1 of 2) Definition

The reaction of isocyanates with hydroxyl-containing compounds makes the resins in polyurethane coatings. Two types of urethanes are available for buried pipelines: elastomeric and highly crossed linked. •

Elastomeric Polyurethane—Generally has tensile and elongative properties, producing elongation in excess of 20 percent.

•

Highly Cross-linked Polyurethane—Molecular cross linking takes place in a thermoset material during cure. High cross-linked materials generally have better resistance to chemicals; lower crosslinked materials have lower resistance to chemicals but often have very high elongation.

Other forms include

Recommended Service

•

Moisture-cure Polyurethane—Single component, generally TFT, systems applied in thin-film depositions; rely on a level of moisture for curing.

•

Single-component Polyurethane—Base and activator exist as mix; remain fluid until applied.

•

Dual- or Plural-component Polyurethane—Separate base resin and an activator are mixed just before applying.

•

All services up to temperature limits of the coating system

•

Refurbishing old pipelines where hydrocarbon contamination or soil stress prevent use of cold tapes

•

Field recoating pipelines

•

Mill-coated protection for FBE-coated pipe from construction damage during boring or as a rock shield

☞Caution ☞Caution Status

Do not select elastomeric polyurethane as a primary pipeline coating Not recommended for hot-oil pipeline service

Under the tradename, Protegal, TIB Chemie makes most polyurethane coatings applied during pipeline rehabilitation projects. Others are Madison Chemical's Corropipe and Valspar's Valpipe 100.

Max. Service Temp

☞Caution

Surface Prep

Abrasive Blast: SSPC SP-5

Not recommended currently for service temperatures above 180 °F [22].

Other Holiday Detection Application

125 volts per mil of coating thickness Type of Polyurethane •

Moisture-cure single-component polyurethanes: brush or roll on the pipe's surface.

☞Caution •

TDI, an isocynate, makes it dangerous to spray moisture-cure polyurethanes.

Dual-component polyurethanes: spray for major projects; brush or roller for spot touchup and small repairs to coatings; also, trowel.

Method •

Spray: Typically, coating applicators spray dual-component polyurethanes on a pipe's surface with special plural-component equipment that helps combat difficulties with temperature and ensures better adhesion.

•

Brush, trowel, roller: Cure time of dual-component polyurethanes is typically longer when it is applied this way. Tack-free condition is normally 30 minutes to 4 hours depending on ambient temperatures; hot air accelerates the cure cycle.

Thickness

25-30 mils

Small Repairs

Use manufacturer’s recommended polyurethane patching material

Handling/Storage

—


See Discussion below.

Resistance

UV & Hydrocarbon: Excellent See also Discussion below.

Chevron Corporation

900-29

September 1996


Coatings Manual

Fig. 900-17 Description of External Pipeline Coating—Polyurethane (2 of 2) Discussion

Most moisture-cure polyurethanes are •

Slow in curing

☞Caution

The curing process combines with oxygen in the atmosphere; do not use in production runs.

•

Sensitive to high-low humidity

•

Lower in mechanical/abrasive resistance than dual-component polyurethanes, FBE, and liquid epoxy coatings

•

Not high build and several coats (4-6 mils) needed to reach the desired total thickness

Elastomeric polyurethanes have •

Higher moisture-absorption rates than highly crossed-linked polyurethanes

•

Higher mechanical/abrasive resistance that may make them desirable as rock shields for other pipe coatings.

Advantages The high solids, high build, and fast cure properties make dual-component polyurethane suitable for pipeline-rehabilitation projects. Highly crossed-linked polyurethanes have low rates of moisture absorption. The exothermic nature of the iso/polyol reaction allows us to spray aromatic polyurethanes at temperatures as low as -20°F (-29°C) and as high as 140°F (60°C). While cure time is temperature dependent, urethanes are less temperature dependent than other systems such as liquid epoxies. To accelerate cure time, normal practice is to pre-heat the pipe to 180°F in the mill; to 150°F by induction coil in the field. Disadvantages Existing pipe-coating mills are not equipped to apply this coating system economically. Dual-component polyurethanes require special, plural-component, heated, spray equipment that has a pot life of less than 30 seconds. Service History In Texas, some major, large-diameter, gas-transmission pipelines were recoated with TIB Chemie's Protegal. Soil stresses had damaged the original asphalt or coal-tar enamel. There has been no report of any coating failures to date. Girth-weld Coating

As we typically field-apply polyurethane, the coating applicators coat the girth-weld and joint surfaces at the same time. They may coat girth welds at coating transitions with cold-applied tapes or heat-shrink sleeves.

Brands

TIB Chemie Protegal UT32-10, Madison Chemical Corropipe, Valspar Valpipe 100

See Also

—

September 1996

900-30

Chevron Corporation

Coatings Manual


Fig. 900-18 Description of External Pipeline Coating—Thermoset Epoxies Definition

A two-part, liquid, thermosetting compound that cures without heat.

Recommended Service

Liquid epoxies are good for repairing FBE coatings and for refurbishing old pipelines, girth-weld coatings, tie-ins, valves, and fittings.

Status

Two-part liquid epoxies have worked well in accelerated laboratory tests and in limited field use. Both Hempel Epoxy 8553 and Hempel Nap-Wrap Epoxy 8553 passed CRTC's hot-subsea-coating test. Previously, only 20+ mil-thick FBE coatings passed it consistently. The hot-subsea-coating test subjects a coated pipe to 250°F internal temperature and -0.90 volts of cathodic protection while the pipe is suspended in 65°F sea water for 90 days. Aramco is replacing tape wraps with Hempel Epoxy 8553 as their primary refurbishing and tie-in coating. They apply the coating to a 20-25 mil thickness in two coats.

Max. Service Temp

225°F

Note: Aramco has had success applying Hempel Nap-Wrap Epoxy 8553 to 200°F lines in operation. Surface Prep


Holiday Detection

125 volts/mil

Application

•

Spray, brush, or roll

•

Can be field applied

•

Cure time very slow

Thickness

20-30 mils

Small Repairs

Patch with Hempel Nap-Wrap Epoxy 8553 per manufacturer’s guidelines.

Handling/Storage

—


The tape wrap or membrane in Hempel Nap-Wrap Epoxy 8553 gives the coating added strength and resistance to abrasion. High-temp (225°F) Hydrocarbon & UV Resistance: Excellent Chemical Resistance: Good

Discussion

Advantages Because it is a thermoset, this epoxy does not soften with temperature; but, it has chemical, temperature, and mechanical properties similar to FBE. Tape We can apply Hempel Epoxy 8553 either alone or with a tape wrap (Hempel Nap-Wrap Epoxy 8553).

Girth-weld Coatings

—

Brands

Hempel Epoxy 8553 and Hempel Nap-Wrap Epoxy 8553

See Also

—

Chevron Corporation

900-31

September 1996


Coatings Manual

Fig. 900-19 Description of External Pipeline Coating—Girth-Weld Protection—Heat-shrink Sleeves (1 of 2) Definition

Shrink sleeves are tubes or wraparound strips of a heat-shrinkable backing of cross-linked polyethylene. The backing has either a butyl-rubber adhesive or a semi-crystalline adhesive.

Recommended Service

Field joints, tie-ins, small pipeline recoating jobs, and mechanically damaged mill-applied coatings

Status

Heat shrink sleeves are readily available from manufacturers in pre-sized or bulk (cut-to-fit) packages.

Max. Service Temp

—

Surface Prep

Abrasive Blast: SSPC SP-3 for most sleeves. Refer to manufacturer’s guidelines. Other



or Vendor’s recommendation Application

Basic •

Prepare the surface (minimum: clean with hand power tools).

•

Bevel the edge of the pipeline coating (only for thick coatings such as coal-tar enamel and asphalt mastic).

•

Position the shrink sleeve.

•

Apply heat by torch or induction, depending on the adhesive.

Tubes •

Place tubes loosely on the pipe near the girth-weld area before fit-up and welding.

•

Apply tubes over the girth-weld area as soon as possible after welding is completed because adhesive is exposed to the atmosphere.

Strips (Wraparound sleeves) •

Apply the strips any time after welding is completed and before the pipe is buried.

•

Wrap the strips around the field joint until the ends overlap.

•

Seal the overlapping seam with a strip of the coating.

•

Apply heat to shrink the coating into place.

Aramco uses induction coils to apply heat shrink wraps at a rate of 120 per day.

☞Caution

Consult the manufacturer for instructions on application procedures.

Thickness

70 to 80 mils

Small Repairs

—

Handling/Storage

—


Shrink sleeves are thick, therefore, abrasion resistant. When heated, the adhesive melts and the polyethylene backing shrinks. This forces the adhesive to flow into the irregularities of the area to be coated. The shrunken wrap is an abrasion-and- penetration-resistant coating. CRTC's Materials and Equipment Engineering group conducted dragging tests to simulate an offshoretow installation. The leading edge peeled and eroded, and tape wraps failed at overlaps because every protruding surface eroded. Because of these tests, the Company bonded a sacrificial half-sleeve in front of the actual shrink sleeves of a Pritec-coated offshore line. The Company installed this pipeline successfully, despite dragging it across an ocean floor. See also Disadvantages and Selection in Discussion, below.

September 1996

900-32

Chevron Corporation

Coatings Manual


Fig. 900-19 Description of External Pipeline Coating—Girth-Weld Protection—Heat-shrink Sleeves (2 of 2) Discussion

Advantages •

Quick and easy to apply, requiring a minimal surface preparation and skill

•

Service temperature ratings between -30°F and 230°F

•

Compatible with FBE, extruded plastic, tape wraps, coal-tar enamels, asphalt mastics, liquid epoxies, and polyurethane coatings.

Disadvantages •

The polyethylene backings expand when exposed to hydrocarbons.

•

A torch, required for the applying the wraps, can damage the primary coating.

•

Some heat shrink sleeves have low resistance to damage from soil stress.

Selection

Choice of Adhesive: The adhesive establishes two categories of temperature limits for sleeves, each having specific characteristics: •

150°F or lower: typically a butyl-rubber adhesive which – Can flow when heated by torch which causes no damage to the PE backing or line coating. – Generally changes color at the proper temperature, allowing less-experienced workers to apply the sleeves properly.

•

150°F or higher: typically a semi-crystalline adhesive which – Needs greater heat to melt the adhesive than butyl-rubber adhesives. – Needs induction coils for a more even, consistent heat and to prevent damage to the pipeline coating and sleeve from the flame of the torch. Torches are also acceptable for heating the pipe.

The properties of the adhesive may also affect the sleeve's selection: •

Semi-crystalline or hot-melt adhesives have good physical properties and bond strengths but generally have poorer resistance to cathodic disbonding than butyl-rubber adhesives.

•

Butyl-rubber adhesives are generally more susceptible to soil stresses but have a higher resistance to cathodic disbonding.

Other Selection Factors: The choice of sleeve may also depend on the pipe's size, construction schedule, and the experience of the people applying it. •

Wraparound – Less costly – No time constraints for application (can apply after creating any weld) – Bulk, cut-to-fit sizes

•

Tube – Must place loosely over pipe before creating weld – Only for 3/4-inch- to 12-inch-diameter pipe – Quicker and easier to apply than wraparound sleeves – Superior to wraparound because there are no seams

Brands

In the U.S., the Company usually selects Raychem and Canusa sleeves. Other brands currently available are UBE Industries, Ltd., Tokyo and Nitto Electric Industrial, Ltd. For DuVal, Himont, and Elf Atochem polyethylene girth welds, there are heat-shrink sleeves compatible with the coating and rated for the operating temperature of the pipeline. Canusa has developed a multilayer heat-shrink sleeve for coating the girth welds of multi-layer coatings such as Shaw YJII, Mapec, Himont, Elf Atochem, and DuVal. Raychem is developing heat-shrink sleeves for polypropylene pipe coated with Elf Atochem, Himont, and DuVal brands.

See Also

Chevron Corporation

—

900-33

September 1996


Coatings Manual

Fig. 900-20 Description of External Pipeline Coating—Girth-Weld Protection Coating—Induction Heat-Applied FBE Definition

Applying FBE to the girth-weld area by induction heat

Recommended Service

To protect girth welds of FBE- coated pipelines

Status

Common on large projects, critical lines, and high-temperature lines. It was expensive, but the cost now nearly equals heat-shrink sleeves due to improved application techniques on large projects.

Max. Service Temp

—

Surface Prep

Abrasive Blast SSPC SP-10 Near-white Metal Finish Other After welding, clean the pipe chemically and then blast it to SSPC SP-10. Brush blast the field joint and two inches of FBE on either side of the joint to clean and roughen the coating's surface.

☞Caution

Proper surface preparation is critical to this type of coating. Also, protect the pipe's surfaces from high humidity, rain, or surface moisture [9, 11].

Holiday Detection

125 volts/mil

Application

•

Induction heat the weld zone to approximately 500°F (depending on the coating manufacturer's specifications).

•

Immediately apply the FBE powder so that residual heat in the pipe cures the coating. A motorized unit, called a powder application ring, sprays the powder on the joint as the sprayer rotates around the pipe.

☞Caution

Do not force cool or quench, which means that the pipe must be out of service during the coating process to prevent cooling too quickly.

Thickness

—

Small Repairs

—

Handling/Storage

—


—

Discussion

Advantages Induction heat-applied FBE is the best girth-weld area protection coating for FBE-coated pipelines because it is the same material as on the pipe's joint. Disadvantages Application requires abrasive blasting and accurate heat control. It is sensitive to environmental effects such as humidity.

Brands

Commercial Resins Company, Commercial Coating Services Incorporated (CCSI), and Pipeline Induction Heat Ltd. (PIH) are among the contractors who have equipment and trained personnel for field applying FBE over pipeline girth welds.

See Also

•

September 1996

Figure 900-3 Advantages and Disadvantages of External Pipeline Coatings

900-34

Chevron Corporation

Coatings Manual


Fig. 900-21 Description of External Pipeline Coating—Girth-Weld Protection—Induction Heat-Applied Plastic with FBE Primer Definition

Induction heat-applied plastic with FBE primer is a field-applied process for coating EPHA girth welds.

Recommended Service

For joints coated with extruded plastic with hard adhesive (EPHA) In EPHA, hard adhesive is liquid epoxy or FBE primer.

Status

Common on high-temperature pipelines Coating the girth welds on pipe joints coated with Elf Atochem, Himont, and DuVal polypropylene is difficult; however, Raychem is developing a heat-shrink sleeve for coating girth welds on these joints.

Max. Service Temp

Vendors claim up to 230°F.

Surface Prep

Abrasive Blast: SSPC SP-10 Near-white Metal Finish Other: Chemical cleaning and blasting to an SSPC SP-10

Holiday Detection

—

Application

•

Heat the weld and adjoining FBE coating from 438°F to 463°F with an induction coil.

•

Apply the FBE powder to the heated surface.

•

Apply the top, plastic layer(s), at the proper time, over the FBE primer.

Note: Post heating of the plastic layer may be required depending upon the coating thickness Timing Requires excellent timing when applying the plastic layer over the FBE layer. •

Too quick: improper curing of the FBE and poor bonding to the pipe's surface

•

Too slow: improper bonding between the plastic and FBE

Thickness

—

Small Repairs

—

Handling/Storage

—


—

Discussion

Advantage The best girth-weld protection for EPHA- coated pipelines because it is the same material as the pipe joint Disadvantages

Brands

See Also

Chevron Corporation

•

Requires abrasive blasting

•

Requires accurate heat control; otherwise, the joint coating near the girth-weld may become damaged

•

Requires excellent timing during application

•

Is sensitive to environment, such as humidity

There are two companies experienced with applying specific brands of these coatings: •

Commercial Coating Services Incorporated (CCSI) with DuVal

•

Pipeline Induction Heat Ltd. (PIH) with DuVal, Himont, and Elf Atochem

—

900-35

September 1996


Coatings Manual

Fig. 900-22 Operating Temperature for Splash-Zone Coating for Offshore Platform Risers Temperature

Coating

Below 140°F

Sprayable (Tidegard 171)

Up to 180°F

Vulcanized Neoprene

Up to 250°F

Monel Sheathing

Fig. 900-23 Pipeline Fitting and Valve Coating System Generic Type

Coating Name

Max Svc Temp °F

Holiday Detector Voltage

Coating Thickness (Mils)

Surface Prep

Hydrocarbon Resistant

Soil Stress Resistant

300 V

16-20

SSPC SP-10

Yes

Yes

20-45

SSPC SP-10

Yes

Yes

14-30

SSPC SP-10

No

Yes

>27

SSPC SP-3

No

No

>27

SSPC SP-3

No

No

Coal Tar Epoxy

Tarset Maxi-Build 7080

14

Extruded Plastic with FBE Primer

Du Val

200

Fusion Bonded Epoxy (FBE)

Scothkote 206N

200

Heat Shrinkable Tape

Canusa Wrapid Tape

135

Heat Shrinkable Tape

Raychem FlexClad

135

Petroleum Tape

Denso HT

120

use wet spronge jeep

45

SSPC SP-2

No

No

Polyester

Flakeline 251

160

4000V

35-40

SSPC SP-10

Yes

Yes

Polyurethane

Protegal UT 32-10RG

180

150 V/Mil

25-30

SSPC SP-5

Yes

Yes

Polyurethane

Protegal UT 32-50RG

180

150 V/Mil

25-30

SSPC SP-5

Yes

Yes

Polyurethane

Protegal UT 32-10

135

150 V/Mil

25-30

SSPC SP-5

Yes

Yes

Polyurethane

Valpipe 100

160

125 V/Mil

25-30

SSPC SP-5

Yes

Yes

Polyurethane

Madison Corropipe 2TX

135

125 V/Mil

25-30

SSPC SP-5

Yes

Yes

Thermoset Epoxy

Nap-Wrap Epoxy 8533

225

125 V/Mil

20-30

SSPC SP-10

Yes

Yes

Wax Tape

Trenton #1 Wax

120

use wet spronge jeep

70-90

SSPC SP-2

No

No

1250

September 1996


125 V/Mil

1250


1250


900-36

Chevron Corporation

Coatings Manual


Fig. 900-24 Generic Coatings for Girth Weld Protection Suggested Coating Material for the Girth Weld Preferences Original Coating Asphalt Enamel

Joining Coating

1

2

3

4

Asphalt Enamel

Heat Shrink Wrap

Asphalt Enamel

FBE

Heat Shrink Wrap

Tape

EPSA

Heat Shrink Wrap

Tape

Polyester Epoxy

Heat Shrink Wrap

Tape

Polyester Epoxy

Tape

Tape

Coal Tar Enamel

Heat Shrink Wrap

Coal Tar Epoxy

Tape

Coal Tar Enamel

FBE

Heat Shrink Wrap

Tape

Liquid Epoxy

Coal Tar Enamel

EPSA

Heat Shrink Wrap

Tape

Asphalt Enamel

Heat Shrink Wrap

Tape

Coal Tar Epoxy

Asphalt Enamel

Polyester Epoxy

Heat Shrink Wrap

Polyester Epoxy

Tape

Tape

Tape

EPHA

EPHA

EPHA

Heat Shrink Wrap

Tape

EPSA

EPSA

Heat Shrink Wrap

Tape

EPHA

Heat Shrink Wrap

Tape

Polyester Epoxy

Heat Shrink Wrap

Tape

Tape

Tape

FBE

FBE

Heat Shrink Wrap

EPSA

Heat Shrink Wrap

Tape

EPHA

FBE

Polyester Epoxy

Heat Shrink Wrap

Tape

Tape

Tape

Tape

Coal Tar Enamel

FBE

Tape Note:

Liquid Epoxy

5

Asphalt Enamel

Liquid Epoxy

Tape

EPHA

Heat Shrink Wrap

Liquid Epoxy

Polyester Epoxy

Tape

Mastic

Tape

EPSA = Extruded Plastic with Soft Adhesive EPHA = Extruded Plastic with Hard Adhesive

Note:

Chevron Corporation

900-37

September 1996


Coatings Manual

Rehabilitation Coatings There are two ways to refurbish an old line: replace the pipeline or remove the old coating and recoat. Replacing the Pipe (Coating the Transition Girth Welds). Consider cold-applied tapes or heat-shrink sleeves to coat tie-in girth welds because these coatings are compatible with almost all coating systems. Note Tie-in girth welds connect the replacement section of pipe to the existing pipe. If soil stress is not a problem, apply either heat-shrink sleeves or cold-applied tape to girth welds on the tie-in (coating transition). If soil stress is a problem, apply heat-shrink sleeves on the tie-in. If the soil has hydrocarbon contamination, select FBE-coated pipe over extruded plastics. Avoid heat-shrink wraps or cold-applied tapes on the girth welds, and select liquid epoxy for the girth welds of the pipe replacement. If there is both soil stress and hydrocarbon contamination, select liquid epoxy rather than cold-applied tapes or heat-shrink sleeves. Replacing the Coating. Pipeline recoating may be carried out in-the-ditch or overthe-ditch. Note In-the-ditch means that the pipeline is neither removed from its site nor from service and may still be under pressure. Over-the-ditch means that the pipeline is taken out of service and the pipe removed from the ground.

☞

Caution While recoating a pipeline that is under pressure, follow all pipeline safety guidelines. Be aware that machinery for recoating pipe may be unsafe for a pressured pipeline. When replacing the coating, grit or sand blast to remove the old one completely if local air quality regulations permit. If the old coating system contains asbestos, follow special asbestos-handling procedures such as work wet, use plastic containment, and wear special protective clothing. Asbestos-containing coatings include Somastic, most asphaltics such as P2, Modified P2, P3, and P4 Wraps, and coal-tar enamel. Note To identify asbestos-containing coatings on Company pipelines, research construction records and pipeline inventory line sheets for coating information. CRTC's M&EE Unit has project files that may also contain information about pipeline coating projects. For the latest information about asbestos-removal techniques for pipelines, contact Chevron Pipe Line Company's Health, Environment, & Loss Prevention personnel.

September 1996

900-38

Chevron Corporation

Coatings Manual


☞

Caution Government regulations about removing asbestos vary across the United States and change periodically. Review the current asbestos-removal regulations before starting a pipeline-rehabilitation project. Selecting the Coating. Factors involved in choosing a field-applied rehabilitation coating system include consideration of the following: • •

Soil Temperatures – – –

Operating temperature of the pipe Temperature of the pipe during recoating Dew point temperature during coating

See Figure 900-25 for a brief description of field-applied, pipeline coating systems for rehabilitating pipelines. The coating systems are listed in order of preference.

922 Quality Control Among the elements of quality control for external pipeline coatings are specifications and standards, planning, service conditions, durability and resistance, construction factors, application factors, and inspection.

Specifications and Standards The following figures list specifications to help ensure the success of an external coatings project. • •

Coating Specifications for Buried Pipelines (Figure 900-26) Industry Standards for Pipeline Coatings (Figure 900-27)

Planning There are many factors involved in planning an external coatings project for pipelines. The main ones are as follows: •

Service Conditions – – –

•

Durability and Resistance of Coatings – – – – – –

Chevron Corporation

Maximum continuous service temperature Soil conditions Accessibility of the line for field application and repair

Durability Chemical Resistance Ultraviolet (UV) Resistance Resistance to Mechanical Damage Resistance to Temperature Cathodic Shielding and Disbonding

900-39

September 1996


Coatings Manual

Fig. 900-25 Field-Applied Rehabilitation Coating Systems in Order of Preference Rank 1.

System Liquid Epoxies • Excellent resistance to chemicals and temperatures •

Poor (long) cure times

•

Dust and insects can contaminate this coating while it is curing, causing holidays

•

Poor choice during winter, more practical during ideal dry summer weather

•

Brush, roll, or spray with standard spray equipment

There are basically four types of liquid epoxies: coal-tar, thermoset, phenolic, and polyester epoxies.

2.

3.

4.

•

For all services: thermoset and phenolic

•

Not for hot-oil pipelines: polyester and coal-tar epoxies

•

For temperatures up to 220°F: phenolic and some thermoset epoxies

Polyurethane • Excellent resistance to chemicals and temperature •

Preferred over liquid epoxies for faster cure time

•

Summer: Fast-cure urethane coatings may be buried within 15 minutes

•

Winter: Fast cure urethane coatings can take from one to five hours to cure enough for burial, depending on the method of application

•

Spray with required, heated, plural-component, spray equipment

•

For temperatures up to 180°F

Hot-Applied Wraps and Tapes(1) • Recoating for short sections of pipe •

Needs a rock shield in high-soil-stress environment

•

Too labor intensive for rehabilitating major pipelines

•

Low resistance to hydrocarbon – not for hydrocarbon-contaminated soils

•

Available as high-temperature heat shrinkable wraps and tapes

•

May not be applied to pipelines in service if flowing product prevents pipe surface from being heated properly

Cold-Applied Tapes(1) • Very economical •

Needs proper tension during application

•

Needs an outer wrap of rock shield in high-soil-stress areas

•

Low resistance to hydrocarbon and temperature

(1) If this coating fails, it may cause a shielded corrosion cell, creating a corrosion leak on a cathodic protected pipeline

September 1996

900-40

Chevron Corporation

Coatings Manual


Fig. 900-26 Coating Specifications for Buried Pipelines Coating

Spec Number(1)


COM-MS-4042

Fusion Bonded Epoxy for External Coating

Company's Standard Spec

3/31/88

09-AMSS-089

Shop-Applied External FBE Coatings

Aramco Spec

8/10/85

PA 131

Fusion Bonded Epoxy External Line Pipe Corrosion Coating

Mesquite Pipe Line Project

6/30/87

P-I-002

Fusion Bonded Epoxy Corrosion of Submarine Pipelines

Western Producing Spec (Platform Gail)

8/21/84

PA 129

Extruded Polyethylene Corrosion Coating with Butyl Adhesive

Point Arguello Pipeline and Natural Gas Companies

7/6/84

09-AMSS-090

Shop-Applied Extruded PE External Coating System

Aramco Mapec and Pritec Spec

3/27/85

COM-MS-5005

Side Extruded Plastic/ Butyl Rubber Adhesive Line Pipe Corrosion Coating


1996

Coal Tar Enamel Wrap


1/3/85

Spec for TGF-3 Pipeline Coating

Northern Producing Spec

9/17/87

Water Line Coal Tar Enamel Corrosion Coating

Point Arguello Pipeline Company

12/20/85

Coal-Tar Enamel Corrosion Coating of Submarine Pipelines


1996

PA 136

Pipe Weight Coating


2/20/85

PA 176

Pipe Weight Coating Quality Assurance


4/15/85

Pipeline Continuous Concrete Coating

Sudan Petroleum Development Project

2/24/84

PA 132

Polymer Cement Barrier Coating (over FBE Powder Pipe Coatings)


7/6/84

E-4512

Concrete Weight Coating for Submarine Pipelines

Richmond Deep Water Outfall Project

9/23/86

—

Spec for Over-the-Ditch Application for Mainline Pipe and Facility Piping

Rangely

2/26/85

PA 150

Polyethylene Tape Wrap with Butyl Adhesive


7/6/84

09-AMSS-095

Hand-Applied Pressure Sensitive Tape Wrap for Temperatures up to 55°C (130°F)

Aramco Spec

9/22/85

09-AMSS-096

High-Temperature Heat Shrink Sleeves

Aramco Spec

9/22/85

Extruded Plastic

Coal Tar Enamel

PA 171 NR-2510 PA 155 COM-MS-5006

Concrete Weight Coating

—

Field-Applied Tape Wrap

Shrink Sleeves

Spec Title

Project

Date Written

(1) See CRTC's Materials Engineering File 6.55.70 Specifications PA Specifications were written by Chevron Pipe Line Company

Chevron Corporation

900-41

September 1996


Coatings Manual

Fig. 900-27 Industry Standards for Pipeline Coatings (1 of 2) Spec. No.

Description American Petroleum Institute (API) Standards

RP 10E

Application of Cement Lining to Steel Tubular Goods, Handling, Installation, and Joining

RP 5L1

Recommended Practice for Railroad Transportation of Line Pipe

FP 5L5

Recommended Practice for Marine Transportation of Line Pipe American Water Works Associated (AWWA)

ANSI/AWWA C203

CT Protective Coating & Lining for Stl. Water Lines

ANSI/AWWA C205

Cement Mortar Lining for Steel Pipe 4" & Larger

ANSI/AWWA C209

Cold-Applied Tape Coatings for Special Sections

ANSI/AWWA C210

CTE for the Interior & Exterior of Steep Pipe

ANSI/AWWA C213

FBE for the Interior & Exterior of Steep Pipe

ANSI/AWWA C214

Tape Coating for the Exterior of Steel H20 Pipes

ANSI/AWWA C215

Extruded Polyolefin for Exterior of Steel H20 Pipes

AWWA C602

Cement Lining Water Lines 4" & Larger—in Place British Standard

BS 4164

Coal-Tar Protective Coatings and Linings for Steel Water Pipelines, Enamel, and Tape Hot-Applied British Gas Standards

PS/PA3

Painting at Site of New Components for Long Term Protection

PS/CW1

External Wrap of Line Pipe using Coal Tar

BGC/PS/CW2

Cold-Applied Wrapping Tapes & Tape Systems

PS/CW3

External Wrap Operations using Hot-Applied Bitumen

PS/CW5

Code of Practice for the Selection and Application of Field-Applied External Coating (Other than Resin)

MR0274

Material Requirements for Polyolefin Cold-Applied Tapes for Underground Submerged Pipeline Coatings

PUB. 6H189

A State-of-the-Art Report of Protective Coatings for Carbon Steel and Austenitic Stainless Steel Surfaces Under Insulation and Cementitious Fireproofing Canadian Standards

CAN/CSA-Z245.20-M90

External FBE Coating for Pipe

CAN/CSA-Z245.21-M92

External Polyethylene Coating for Pipe German Standards (DIN)

DIN 30670

Polyethylene Coating of Steel Pipes and Components

DIN 53516

Determination of Abrasion Resistance L'Association Française De Normalisation (AFNOR) Standard

NFA 49-710

Steel Tubes External Triple-Layer Polyethylene-Based Coating Application by Extrusion NACE International Standards

RP0169

Control of External Corrosion on Underground or Submerged Metallic Piping Systems

RP0285

Control of External Corrosion on Metallic Buried or Submerged Liquid Storage Systems

RP0181

Liquid Applied Internal Protection Linings and Coatings for Oil Field Production Equipment

RP0185

Extruded Polyolefin Resin Coating Systems for Underground or Submerged Pipe

RP0188

Discontinuity (Holiday) Testing of Protective Coatings

September 1996

900-42

Chevron Corporation

Coatings Manual


Fig. 900-27 Industry Standards for Pipeline Coatings (2 of 2) Spec. No.

Description NACE International Standards (continued)

RP0190

External Protective Coatings for Joints, Fittings, and Valves on Metallic Underground or Submerged Pipelines and Piping Systems

RP0274

High Voltage Electrical Inspection of Pipeline Coatings Prior to Installation

RP0490

Holiday Detection of Fusion Bonded Epoxy External Pipeline Coatings of 10 to 30 Mils (0.25 to 0.76 MM)

RP0675

Control of External Corrosion on Offshore Steel Pipelines

TM0170

Visual Standard for Surfaces of New Steel Airblast Cleaned with Sand Abrasive

TM0174

Laboratory Methods for the Evaluation of Protective Coatings used as Lining Materials in Immersion Services

TM0175

Control of Internal Corrosion in Steel Pipelines and Piping Systems

TM0183

Evaluation of Internal Plastic Coatings for Corrosion Control of Tubular Goods in an Aqueous Flowing Environment

TM0185

Evaluation of Internal Plastic Coatings for Corrosion Control of Tubular Goods by Autoclave Testing

TM0186

Holiday Detection of Internal Tubular Coatings of 10 to 20 mils (0.25 to 0.76 MM) Dry Film Thickness

TM0375

Abrasion Resistance Testing of Thin Film Baked Coatings and Linings using the Falling Sand Method

TM0384

Holiday Detection of Internal Tubular Coatings of less than 10 mils (0.25 MM) Dry Film Thickness National Association of Pipe Coating Applicators (NAPCA) Standards

Bulletin 1-65-94

Designation for Coal Tar Enamel Coatings

Bulletin 2-66-94

NAPCA Coating Specifications for Standard Applied Pipe Coating Weights

Bulletin 3-67-94

External Application Procedures of Hot Applied Coal Tar Coatings to Steel Pipe

Bulletin 5-69-94

NPACA Specifications for Pipeline Wrappers

Bulletin 12-78-94

External Application Procedures for Plant-Applied Fusion Bonded Epoxy (FBE) Coatings to Steel Pipe

Bulletin 13-79-94

External Application Procedures for Coal Tar Epoxy Protective Coatings to Steel Pipe

Bulletin 14-83-94

External Application Procedures for Polyolefin Pipe Coating Applied by the Cross Head Extrusion Method for the Side Extrusion Method to Steel Pipe

Bulletin 15-83-94

External Application Procedures for Plant-Applied Tape Coating to Steel Pipe

Bulletin 6-69-94-1

Suggested Procedures to Hand Wrap Field Joints using Hot Enamel

Bulletin 6-69-94-2

Suggested Procedures for Coating of Girth Welds with Fusion Bonded Epoxy

Bulletin 6-69-94-3

Suggested Procedures for Coating Field Joints, Fittings, Connections, and Pre-Fabricated Sections using Tape Coatings

Bulletin 6-69-94-4

Suggested Procedures for Field Joint Application using Mastic Mix and Field Mold

Bulletin 6-69-94-5

Suggested Procedures for Coating Field Joints using Heat Shrinkable Materials

Chevron Corporation

900-43

September 1996


Coatings Manual

•

Construction Factors – – – – – –

•

Impact Resistance Flexibility in Cold Weather Field Repair Limitations of Temporary Storage Climate During Construction Project Construction Methods During Project

Application Factors – –

Cost Site

Service Conditions Note FBE has the widest range of operating temperatures, greatest resistance to chemicals and soil stress of all pipe-coating systems. •

Maximum Continuous Service Temperature Figures 900-23, 900-28, and 900-29 list information about service conditions of various field- or mill-applied coatings and coatings for fittings and valves.

•

Soil Conditions (sand vs. clay, wet or dry, hydrocarbon or other chemical contamination, pipe-soil stresses, soil resistivity data) –

Hydrocarbon or Chemical Contamination To combat hydrocarbon or chemical contamination, it is necessary to apply a pipe coating that is resistant to the chemicals in the soil.

–

Soil Stresses Soil stresses occur mainly in clay soils; not usually in sandy soils. Soil stresses resulting from wet/dry or freeze/thaw seasonal cycles can, however, damage pipe coatings.

–

Soil Corrosivity Typically, soil corrosivity increases with decreasing soil resistivity. In highly corrosive soils, you may need to apply a high-performance coating system to the pipe.

–

Microbiologically Influenced Corrosion (MIC) Activity Some pipe coatings, such as cold-applied tapes, have low resistance to bacteria-generated, chemical byproducts that are also corrosive to the steel pipe.

•

Accessibility of the Line for Field Application and Repair Pipe laid under river crossings, offshore, or in other hard-to-access locations may need low-maintenance pipe coatings.

September 1996

900-44

Chevron Corporation

Coatings Manual


Fig. 900-28 Mill-Applied Pipeline Coating Systems (1 of 2) Surface Prep Generic Type Asphalt Mastic

Asphalt Mastic

Coal Tar Enamel

Trade Name Somastic Type I

Somastic Type III

Reilly #230A Enamel

Max Svc Temp. °F


140 1250


1250


1250


1250


1250


1250


1250


140

140

Resistance

SSPC SP-

Hydrocarbon

Soil Stress

Black

6

No

Yes

Yellow

6

No

Yes

Black

6

No

No

Black

6

No

Yes

Yellow

6

No

Yes

Yellow

6

No

Yes

Orange

6

No

Yes

Color

Crosshead-Extruded Plastic with Asphalt Adhesive

Shaw Black Jacket (Polyethylene)

150


Shaw Yellow Jacket (Polyethylene)

160


Encoat Entec (Polyethylene)

100


Encoat Entec (Polypropylene)

100


Plexco Plexguard (Polyethylene)

100

10,000 V

Yellow

6

No

Yes


Plexco Plexguard (Polypropylene)

100

10,000 V

Orange

6

No

Yes

Dual FBE

O'Brien Nap-Gard “Gold” 7-2501 & 7-2504

200

125 V/Mil.

Gold

10

Yes

Yes


Elf Atochem (Polyethylene)

180

Black

10

No

Yes


Elf Atochem (Polypropylene)

200

Gray

10

No

Yes


Du Val (Polyethylene)

180

Blue

10

No

Yes

Chevron Corporation

1250


1250


1250


900-45

September 1996


Coatings Manual

Fig. 900-28 Mill-Applied Pipeline Coating Systems (2 of 2) Surface Prep Generic Type

Trade Name

Max Svc Temp. °F


Resistance

SSPC SP-

Hydrocarbon

Soil Stress

Blue

10

No

Yes

Color


Du Val (Polypropylene)

200

FBE

3M ScotchKote 206N

200

125 V/Mil.

Green

10

Yes

Yes

FBE

O'Brien Nap-Gard 7-2501

200

125 V/Mil.

Red

10

Yes

Yes

FBE

Valspar D1003LD

200

125 V/Mil.

Beige

10

Yes

Yes

FBE

Lilly Pipeclad 1500

150

125 V/Mil.

Green

10

Yes

Yes

Heat-Applied Tape

Raychem Rayclad 120

20

Black

3

No

Yes

White

6

No

No

Black

10

No

Yes

Heat-Applied Tape

Ygill

Side-Extruded Polyethylene with Butyl Rubber Adhesive

1250


1250


1250


140

Pritec 10/40

180

14,000 V

Durability & Resistance Durability. Proper surface preparation is essential to prevent premature failure of coatings. Minimum specifications for the surface preparation of pipeline are listed in Figures 900-23, 900-28, and 900-29 for mill- and field-applied pipeline coating systems and for pipeline fittings and valve coating systems. See also the list of standards for surface preparation in Figure 900-30. In the Company's pipe-coating specifications, there are details about the quality control inspections necessary during the coating mill's production run. Chemical Resistance. Chemical resistance is important in a coating if: • •

There was a spill where the pipe will be laid The location has a high potential for a spill

Figures 900-23, 900-28, and 900-29 give the rates of hydrocarbon resistance for various pipeline coatings. The rating for extruded plastic and tape wraps is based on the following: Polyvinylchloride (PVC) is more resistant than polypropylene which, in turn, is more resistant than polyethylene.

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Fig. 900-29 Field-Applied Pipeline Coating System

Manufacturer

Trade Name

Generic Type

Surface Prep

Resistance

Max Svc Temp °F


Color

SSPC SP-

Hydrocarbon

Soil Stress

Hempel

Nap-Wrap Epoxy 8553

Thermostat Epoxy

225

125 V/Mil

Gray

10

Yes

Yes

Celcoat

Flakeline 251

Polyester Epoxy

160

4000V

White

10

Yes

Yes

Porter Int'l

Tarset MaxBuild 7080

Coal Tar Epoxy

140

3000V

Black

10

Yes

Yes

TIB Chemie

Protegal 32-10

Polyurethane

135

150 V/Mil

Black

5

Yes

Yes

TIB Chemie

Protegal 32-10RG

Polyurethane

180

150 V/Mil

Black

5

Yes

Yes

TIB Chemie

Protegal 32-50RG

Polyurethane

180

150 V/Mil

Red

5

Yes

Yes

Valspar

Valpipe 100

Polyurethane

160

125 V/Mil

Gray

5

Yes

Yes

Madison Chemical

Corropipe 2TX

Polyurethane

140

200 V/Mil

Black

5

No

No

Reilly Tar & Chemical

#230 A Enamel

Coal Tar Enamel

140

Black

6

No

No

Raychem

Flexclad

Black

3

No

No

Yellow

3

No

No

Canusa

Wrapid-Tape

Applied Tape

Applied Tape

1250


1250


1250


135

135

Tapecoat

10/40W

Cold-Applied Tape

120

8,000 V

Black

2

No

No

Tapecoat

H-50

Cold-Applied Tape

120

6,500-8,500 V

Black

2

No

No

Tapecoat

CT

Cold-Applied Tape

120

7,000 V

Black

2

No

No

Polyguard

RD-6

Cold-Applied Tape

120

3,000-5,500 V

Black

2

No

No

Polyken

900 Series

Cold-Applied Tape

120

10,000 V

White

2

No

No

Denso

HT

Petrolatum Tape

120

Wet Spronge Jeep

Brown

2

No

No

Trenton

#1 Wax Tape

Petroleum Wax Tape

120

Wet Spronge Jeep

Brown

2

No

No

Chevron Corporation

900-47

September 1996


Coatings Manual

Fig. 900-30 Standards for Surface Preparation Description

SSPC

NACE Internt'l

Short

SP 1

—

Solvent Cleaning

SP 2

—

SP 3

—

SP 5

Foreign Standards Long

Canadian

Swedish

British

Removal of oil, grease, dirt, soil, salts, and contaminants by cleaning with solvent, vapor, alkali, emulsion, or steam.

—

—

—

Hand Tool Cleaning

Removal of loose rust, loose mill scale, and loose paint to a degree specified, by hand chipping, scraping, sanding, and wire brushing.

31 GP-401

St. 2 (Approx.)

—

Power Tool Cleaning

Removal of loose rust, loose mill scale, and loose paint to degree specified, by power tool chipping, descaling, sanding, wire brushing, and grinding.

31 GP-402

St. 3

—

NACE #1

White Metal Blast Cleaning

Removal of all visible rust, mill scale, paint, and foreign matter by blast cleaning by wheel or nozzle (dry or wet) using sand, grit, or shot. (For very corrosive atmosphere where high cost of cleaning is warranted.)

404 Type 1

Sa. 3

BS 4232 First Quality

SP 10

NACE #2

Near-White Blast Cleaning

Blast cleaning nearly to white metal cleanliness, until at least 95% of each element of surface area is free of all visible residues. (For high humidity, chemical atmosphere, marine or other corrosive environment.)

—

Sa. 2-1/2

BS 4232 Second Quality

SP 6

NACE #2

Commercial Blast Cleaning

Blast cleaning until at least two-thirds of each element of surface area is free of all visible residues. (For rather severe conditions of exposure.)

31 GP-404 Type 2

Sa. 2

BS4232 Third Quality

SP 7

NACE #4

Brush-off Cleaning

Blast cleaning of all except tightly adhering residues of mill scale, rust, and coatings, exposing numerous evenly distributed flecks of underlying metal.

31 GP404 Type 3

Sa. 1

Light Blast to Brush Off

SP 8

—

Pickling

Complete removal of rust and mill scale by acid pickling, duplex pickling, or electrolytic pickling. May passify surface.

—

—

—

•

Plastic coatings swell and eventually fail under prolonged exposure to hydrocarbons.

•

Hydrocarbons attack and dissolve the soft adhesive that holds plastic coatings to the pipe. Typically, soft adhesives have a lower resistance to hydrocarbon than the plastic jacket.

Ultraviolet (UV) Resistance. While all coatings degrade in sunlight, there are some practical solutions: •

September 1996

To prevent degradation of coatings on pipes that are stored outside, whitewash the coatings if they have poor UV resistance.

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Consult the manufacturer of the coating for recommended procedures for UV protection and for help with determining the condition of coated pipe already stored outside. If the degree of degradation is unknown in a stack of pipe, use unexposed pipe; as only the top and outside joints are exposed to UV rays. •

Plastic coatings, such as extruded and tape wrap, degrade in the sun, hardening and often splitting. Thermal expansion-and-contraction problems occur because plastic expands much more than steel.

•

FBE coatings chalk in sunlight, but the chalk protects the coatings. Millage loss is only a problem when rain and wind remove the chalk steadily for a long time. FBE coatings can also blister if stored too long in hot, humid climates such as is found in the Gulf Coast.

For information about the outdoor storage life and UV resistance for external pipeline coatings, see Figure 900-31. Resistance to Mechanical Damage. Coated pipe is subject to damage during handling, shipping, installing, or servicing. As a result, consider taking these preventive measures: •

Make the coating thicker to improve its resistance to mechanical damage.

•

Handle coated pipe with padded equipment, and stack and ship it with rubber spacers between each pipe. Set the spacers to separate the pipe far enough so that gravel and cinders thrown up from the road or rail tracks are not caught between pipes and abrade the coating.

•

Consider wrapping the pipe in plastic or installing pillowed supports.

•

Store the pipe on sand wind-rows and cover it with tarps.

See Section 921 of this manual, Selection, for information regarding Rock Protection. Cathodic Shielding. When a coating separates from a cathodically protected pipe, it can shield the pipe from the protection of the cathodic current. Significant localized corrosion occurs where earth or water (or both) becomes trapped between the separated coating and the pipe's surface. The current from cathodic protection does not increase to give a warning. The only way to determine the amount of corrosion on a cathodically shielded line is with metal-loss inspection tools which detect changes in the thickness of the pipe's wall. Note the following about cathodic shielding:

Chevron Corporation

•

Tape wraps are most susceptible because water has a greater chance of penetrating the overlaps (often poorly bonded and susceptible to soil stresses) and because they have high electrical resistivity.

•

Water can seep under continuous, extruded plastic coatings at field joints or mechanically damaged areas.

900-49

September 1996


Coatings Manual

Fig. 900-31 Pipe Storage and Ultraviolet (UV) Resistance Generic Type

Trade Names

Resistance

Storage Limit (Years)

Remarks

Asphalt Mastic

Somastic

Poor

1

Protect from sunlight.

Coal Tar Enamel

Reilly Tar and Chemical

Poor

1


Coal Tar Epoxy

International Tarset Maxi-Build 7080

Good

1

—

Cold-Applied Tapes

Tapecoat 10/40W, H-50, and CT Polyguard RD-6, Polyken 900 series

Poor

—

Normally applied in ditch and immediately buried.

Crosshead-Extruded Plastic with Asphalt Mastic

Bredero Price Entec Plexco Plexguard Shaw Yellow Jacket and Black Jacket

Fair

1

Fair except for Plexco Plexguard, which may be poor.


3M 206N and 226N Nap-Gard 7-2501 and

Excellent

2

Excellent except in hot, humid sea atmospheres where blistering of coating occurs.

7-2504 (Gold) Lilly Pipeclad 1500 Valspar-D1003LD Heat-Applied Tapes

Canusa Wrapid Tape Raychem Flexclad

Poor

—

Normally applied in ditch and immediately buried.

Multi-Layer Extruded Plastic with FBE Primer

Elf Atochem Du Val Himont Mapec, Du Pont Canada

Excellent

2

—

Petrolatum Tapes

Denso MT

Good

—

Use as an atmospheric pipe coating.

Polyester Epoxies

Master Builder's Oilcote Flakeline 251

Excellent

—


Polyurethanes

TIB Chemie Protegal UT32-10 Valspar Valpipe 100

Excellent

—


Radiation Cross-Linked HeatApplied Tapes

Raychem Rayclad 120

Poor

1


Side-Extruded Polyethylene with Butyl Rubber Mastic

Bredero Price Pritec

Excellent

1

—

Thermoset Epoxies

Hempel Nap-Wrap Epoxy 8553

Excellent

—


Wax Tape

Trenton #1 Wax-Tape

Good

—


•

The adhesive strength of FBE (also a continuous coating) is greater than its cohesive strength, resulting in complete rupture of the film rather than disbonding[1].

Note Adhesive strength means metal to coating; cohesive strength means coating to coating. Cathodic Disbonding. Excessive currents can cause free hydrogen to form at holidays. Hydrogen bubbles form on and break away from the exposed pipe metal,

September 1996

900-50

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Coatings Manual


exerting high pressure between the coating and the metal. Pressure occurring under the edges of a damaged coating disbonds the coating from the pipe, exposing more metal. This phenomenon causes the rapid disbonding of an otherwise good coating. Note Excessive current are amounts that exceed the hydrogen-over-voltage potential. Note Holidays are minor areas of damage—breaks or flaws—in an applied coating. Run a laboratory test to determine the relative resistance of a coating to cathodic disbonding. While it is often difficult to relate laboratory results to field conditions, this particular test is an excellent tool for judging whether or not some coatings, such as FBE, have been applied properly. Example: A 24-hour, 150°F test for cathodic disbonding of FBE provides a good, quick check for undercure, under thickness, surface contamination, and poor surface preparation. Problems with the coating process show up as a sudden increase in the amount of coating that disbonds during the test. See also Section 6.0 of Specification COM-MS-4042.

Construction Factors Impact Resistance. Pipe coatings with high impact resistance are less likely to be damaged during transportation and construction. In general, resistance to impact decreases in this order: 1.

Extruded plastics with hard adhesives

2.

FBE

3.

Extruded plastics with soft adhesives

4.

Asphalt mastics

5.

Coal-tar enamel

Flexibility in Cold Weather. Coated pipe is sometimes bent in the field in weather conditions that make coatings more brittle. The Canadian Standards Association (CSA) Pipe Bend Test shows that FBE and extruded-plastic coatings with hard adhesives have the widest temperature range during construction of all pipe-coating systems. Both FBE and extruded-plastic coatings with hard adhesives pass the CSA Pipe Bend Test as they can survive bending during typical Canadian winter weather. Coal-tar enamels can, however, soften in warm weather and fail during the field-bending process. Field Repair. Some pipe coatings are harder to repair in the field than others. FBE is the easiest to patch. While extruded plastics with hard adhesives can be difficult to repair, manufacturers are making progress with these coatings. For information about recommended field repair methods, contact CRTC’s coating specialists (listed in the Quick Reference Guide) or review pipe-coating specifications.

Chevron Corporation

900-51

September 1996


Coatings Manual

Limitations of Temporary Storage. Most pipe coatings have maximum storage limits depending on the climate of the storage area. Storage is usually a problem only if the pipe is coated and stored for longer than one year before construction starts. Climate during Construction Project. The climate during the construction project may affect coatings. •

Some coatings, such as coal-tar enamels and asphalt mastics, become soft and difficult to handle during hot weather.

•

See Flexibility in Cold Weather (above).

•

Some field-applied coatings have temperature dependent cure times.

Construction Methods during Project. Coatings for pipe laid in the ditch need to be less abrasion resistant than coatings for pipes used in trenchless construction techniques such as slick-bore, drilled, or pushed methods.

Application Factors The application factors that most often affect coating decisions are cost, site, and field support from the manufacturer and coatings applicator. Cost. The following project components affect cost: • • • • • • •

Size of project Coating materials Surface preparation Application Transportation Girth-weld coating (field joints) Field repairs

Balance the costs of the initial installation against the reliability expected. •

Select premium-quality coatings where failures are especially costly (e.g., subsea, congested areas, hard-to-access lines, and lines where leaks are intolerable).

•

Consider that less-expensive coatings are generally poorer in quality and tend to fail prematurely, resulting in higher maintenance costs and possible early corrosion failure of the line.

In Figure 900-32, there is a list of approximate costs for the various pipeline coatings. The cost of transporting pipe from the mill to the ditch can become significant for heavier coatings such as coal-tar enamels and Somastic. Site. While shop-applied coatings are inherently of higher quality than field-applied coatings, their handling costs are generally higher, and they are susceptible to shipping damage. For large coating projects, consider setting up portable coating plants near the job site to reduce costs, time, and potential shipping damage. You should also ensure

September 1996

900-52

Chevron Corporation

Coatings Manual


Fig. 900-32 Costs (1988)—External Pipeline Coatings Material(1) Cost/Ft2 $

Coating (3)

Total Applied Ft(2)

Comments

(4)

10 ¾" OD 0.219" wall; 12 mil min. coating thickness

—

(4)

0.41


—

0.36(4)


—

—

(4)


—

—

0.52-0.56

KLMR line bid range, 16 mil avg., 14 mil min. of polyethylene, 18" OD, 0.250" wall, 80,000 feet of pipe

—

0.42-0.48

KLMR line bid range, 10 mil adhesive, 40 mil of polyethylene, 18" OD, 0.250" wall, 80,000 feet of pipe

(Plexco P.E)

—

0.39

12

(Plexco P.P)

—

0.42

12

Coal Tar Enamel

—

0.45-1.00

Liquid Epoxies (Thermosets)

0.66

—

For 20 mils

0.80-0.90

—

Does not account for overlap

1.40

—


2.00

—

30./weld

—

Includes delivery, cleaning, and application

Protegal 3210

6.00

—

25 mils

Denso Tape

0.65

—


Porter Tarset

0.24

—

16 mils

Hempel

0.66

—

20 mils

Fusion Bonded Epoxy (FBE) — —

Extruded Plastic

—

0.38

0.38

(Pritec brand)

Tape Wrap; < 140°F Raychem Hotclad

Wide variation is due to application and locale. The $1.00/ft2 is for the Richmond Effluent Project, 5960 feet of 36" OD pipe

Field Coating of Weld Joints Shrink Sleeves FBE Valves and Fittings

Epoxy 8553 (1) Costs in this column where obtained from applicators without consideration of job size. These numbers do not take into account the cost of labor, surface preparation and plant location. (2) See Company's Cost Estimating Manual for additional cost information. (3) Material costs on small project of 16 mils; add 5 percent of cost for additional mils over 16. (4) Mesquite project; 168 miles of pipe.

that the pipe receives proper surface preparation and is neither dirty nor corroded when the coating is applied.

☞

Caution Consider over-the-ditch applications only when refurbishing old lines that cannot be taken out of service or for new lines at remote locations. Field Support from Manufacturer and Coatings Applicator. If construction delays occur due to coatings problems, determine the level of field support received from the manufacturer or coatings applicator or both.

Chevron Corporation

900-53

September 1996


Coatings Manual

Inspection Refer to the coating specification for information about inspecting a given pipeline coating.

930 Internal Pipeline Coatings Pipe is coated on the inside to prevent corrosion or to increase the efficiency of flow by reducing losses from friction. There are other alternatives—cement and plastic linings—which are critiqued as a comparison to coatings in Figure 900-33 Internal Coating/Lining Alternatives for Pipelines. Fig. 900-33 Internal Coating/Lining Alternatives for Pipelines Material

Recommended Services

Advantages

Limitations

Approximate Cost(1)

Cement Lining

Produced water Salt water Almost always for new lines

Thick, usually very reliable against water corrosion

Joints are potentially a weak link, not good in many chemicals Min. pipe diameter: 2-3 inches Temp. approx. 250°F Pressure approx. 5,000 psig. Velocity approx. 10 fps

Shop = $1.60/ft

Plastic Liner (shop-applied)

Process chemicals

Excellent corrosion resistance to a variety of services

Typically comes in 20-ft flanged lengths Flange joints can leak Pipe diameter 1-16 inches Temp. approx. 200°F (PPL) to approx. 500°F (Teflon)

Include pipe and flanges = $80/ft (PPL) to $300/ft (Teflon)

Plastic Liner (field-applied) (HPDE)

Produced water Salt water New existing lines

Very reliable Very few joints Can salvage existing lines

Pipe diameter 3-16 inches (but larger sizes can be done) Temp. ± 200°F

$9.20/ft

Coatings (shop-applied)

Produced water Salt water Flow friction reduction

Fair to good corrosion resistance

Joints are potentially a weak link Relatively thin film (may give shorter, less reliable life)

Coatings (field-applied)

Produced water Salt water Flow friction reduction New or existing lines

Fair to good corrosion resistance

Good chance of field foul-ups Spotty history of quality control Relatively thin film (may give shorter, less reliable life)

(1) Except as noted, costs are for lining an 8-inch pipe at the shop location. Pipe costs extra. Costs are for rough comparative purposes only.

Note For detailed information about lining pipelines, see also the Company's Pipeline and Piping Manuals. Shop- or mill-applied coatings control corrosion of known aggressive systems or help reduce friction. Field-applied coatings primarily extend the service life of pipelines by preventing additional damage from corrosion. If internal damage from corrosion results in an unacceptable operating pressure, replace the pipeline or install a plastic liner to increase the pipeline's maximum operating pressure (MOP).

September 1996

900-54

Chevron Corporation

Coatings Manual


931 Shop-applied Internal Pipeline Coatings This section discusses the following issues regarding shop-applied internal pipeline coatings: • • • • •

Quality control Coatings selection Surface preparation Application Inspection

Quality Control Specifications. Although the Company does not have a specification for internal pipeline coatings, information is available from CRTC specialists in M&EE. Coating Quality. If holidays occur, you should not repair FBE coatings and liquid coatings with a primer but you must burn the material off and recoat. You can patch FBE and liquid-epoxy coatings that do not have primers by following the manufacturers' recommendations. If the specification requires a 100-percent-holiday-free coating, the coatings applicators must make the pipe smooth enough, clean enough, and capable of being coated to this requirement. The Company's representative is responsible for specifying proper surface preparation.

Coatings Selection As liquid coating systems need a furnace bake, there is no known method to apply them to internal weld joints; therefore, there are two, basic, internal coating systems: heat-cured powder and baked-on liquid. Heat-cured Powder. The heat-cured powder is a thermosetting resin, applied by FBE process, with or without primer. Typically, select unprimed FBE for environments requiring improved flow efficiency or having mild internal corrosion, and primed FBE for environments with severe internal corrosion. Baked-on Liquid. Baked-on liquid may be epoxy, epoxy-phenolic, or possibly a polyurethane. For fresh water, saltwater, and production water at temperatures up to about 150°F, select straight epoxies such as O'Brien NapGard, Scotchkote 134, Scotchkote 206N, and Scotchkote 150. For very corrosive environments with higher temperatures (200°F to 400°F), choose epoxy-phenolic or epoxy-modified phenolics. Note

Phenolics tend to be brittle and will crack when bent.

For internal coating of girth welds in the field, the Company typically chooses Scotchkote 206N because it cures in less than one minute from the residual heat of the weld joint.

Chevron Corporation

900-55

September 1996


Coatings Manual

The range for field-and-mill application of FBE is a 25- to 48-inch diameter and up to a maximum wall thickness of 0.750 inches.

Surface Preparation All pipe needs the same surface preparation: cleaning and abrasive blasting, followed in some cases, by priming. Cleaning. Chemical treatment is the best cleaning method, but costly disposal is a factor. Thermal burnoff at 600°F to 800°F is particularly important for a heavy mill scale/rust. Abrasive Blasting. Suitable abrasive is necessary to obtain the desired anchor profile and a white metal (SSPC SP5) finish. Finish is checked visually with a highintensity light. Priming. In water service, internal FBE does not usually require a primer; however, you should alert the coatings manufacturer if the water is aggressive (contains CO 2 or H2S, is hot, or at high pressure).

Application See the list of current contractors in the Quick Reference Guide.

Inspection Virtually all shops inspect and test internally coated pipe, for holidays, adhesion, and bends. Holidays. The inspector checks 100 percent of the coating against an agreed-upon standard (e.g., 100 percent holiday free, or 4 holidays maximum per length of pipe). Typical voltage is 100 to 125 volts per mil of coating thickness. Adhesion. Typically, the inspector cuts an x pattern into the coating and prods it with a knife to check adhesion. The inspector conducts the test every two hours on the weld cutback area of a section of pipe that is left deliberately unmasked for this test. Bends. Typically, once per shift, often at a cool temperature, the inspector tests the flexibility of the coating by bending a strip of coated metal over a specified mandrel and checks it for holidays and cracks.

932 Field-applied Internal Pipeline Coatings Liquid epoxy is the only internal coating that the Company field applies (in situ), generally for one or more of the following reasons: • • •

To prolong the life of a line For product purity To reduce friction loss

Brands of field-applied, internal pipeline coatings include Hempel 233U, Hempel 458U, Sigma In-Situ Pipecoating 15, Sigmaguard HTR.

September 1996

900-56

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Factors affecting field-applied coating are its limitations, the coating contractors and applicators, acceptable brands, surface preparation, application, and inspection.

Limitations Field application of internal pipeline coatings is less likely to produce pinhole-free coatings than shop-applied systems. Field application is also unsuccessful with slip-on flanges because the ID discontinuity at the pipe ends causes excess coating deposits which rapidly disbond in shingles to plug the line or create a site for corrosion.

Coating Contractors and Applicators Select coating contractors and applicators carefully because they can have a profound affect on the success of a project. Improperly applied coatings may result in inadequately protected lines, delays in returning the line to service, and complete loss of the line. Before choosing a coatings applicator, review in detail the work history (resume) of the foreman and personnel proposed for the job. See the list of contractors who field-apply pipeline coatings in the Quick Reference Guide.

Acceptable Brands Sigma Coatings In-Situ Pipecoating 15 and Hempel 233U have longer pot lives, but Sigmaguard HTR and Hempel 458U have better high-temperature resistance. All products have the same chemical resistance. Note For more detailed background on field-applied coatings, see the references at the end of this section [16, 17, 18, 19, 20, 21].

Surface Preparation Prepare an internal steel pipe by cleaning it in one of two ways: • •

Inhibited acid Abrasive blasting

Existing pipelines may also require initial cleaning by scraper pigs and with solvents.

Application See list of current contractors for pipeline coatings in the Quick Reference Guide.

Inspection Compared to shop-applied internal coatings, inspection of field-applied internal coatings is relatively crude. The inspector often visually examines a flanged, removable spool located near the middle of the line and also tests it for holidays and thickness. Video cameras allow full-length inspection of the line for pipe sizes as small as 10 to 12 inches in diameter.

Chevron Corporation

900-57

September 1996


Coatings Manual

933 Weld-joint Application & Inspection In Figure 900-34, Properties of Internal Pipeline Coatings, a method of weld-joint protection is recommended for each coating system, where applicable. Fig. 900-34 Properties of Internal Pipeline Coatings System

Recommended Services

Advantages

Limitations

Weld Joint Protection

Shop-Applied Heat-Cured Powder: Epoxy with Primer

Sour water Wet sour gas (CO2 up to 10%) Inspection and disposal wells

Good corrosion resistance

Resistant to low concentrations of H2S Girth weld cannot be coated

Mechanical joints

Epoxy without Primer

Produced water Fresh water Salt water (CO2 up to 10%)

Can coat girth weld with crawler Fair corrosion resistance

Low resistance to H2S

≥ 8-inch pipe diameter: crawler < 8-inch pipe diameter: mechanical joints

Sizes up to 20 inches: very low flexibility Temp. ± 150°F Cannot repair holidays

Mechanical joints

Cannot bend Maximum pipe diameter: 20 inches Temp. ± 400°F Cannot repair holidays

Mechanical joints

High chance of foul-up if wrong contractor has job

Does not apply

Baked Liquid: Epoxy

Produced water Fresh water Salt water

Epoxy-Phenolic

Sour water Wet sour gas (CO2/H2S)

Good corrosion resistance

Field-Applied In situ: Liquid Epoxy

Sour water Produced water Fresh water Salt water Flow friction reduction Gas lines

Good corrosion resistance High temp. service (+200°F) Extends serviceable life of existing line

Application The crawler is the method for applying internal pipeline coating systems. Mechanical joints are also available as an alternative for 2- to 12-inch-sized pipes. Crawlers. A self-propelled, in-line tool that performs a task under remote control, the crawler works in either field or shop. For the latter, that means that the shop can join pipe lengths to reduce the number of field-welded joints. Currently, the minimum pipe diameter for a crawler is ten inches. Some of the crawler's coating tasks are as follows:

September 1996

•

For non-primed FBE internal coatings, crawlers clean and coat the girth welds.

•

After welding, an abrasive-blasting crawler travels through the pipe to clean the cutback area of weld splatter slag and to degloss the powder.

900-58

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Coatings Manual


•

An induction coil, applied to the pipe's exterior, heats the girth weld area and a powder-coating crawler then travels through the pipe.

There are basically two circumstances under which shop or field coatings applicators cannot use a crawler: • •

The pipe requires a liquid primer or coating The pipe diameters are less than ten inches

Mechanical Joints. One alternative to the crawler is mechanical joints. There are at least a dozen mechanical joint systems that provide a continuous internal seal. Some, such as Crimp-Kote from Tuboscope Vetco International, are fully mechanical interference-fit joints. Some are elaborate mechanical sleeve systems, which may include welding. Most require special equipment for field installation. Mechanical joints are usually available in 2- to 12-inch sizes.

Inspecting Internal Pipeline Coatings Inspection varies with the coating material and the application method. For information about inspecting internal pipeline coatings, contact CRTC's specialists listed in the Quick Reference Guide.

940 References

Chevron Corporation

1.

O'Carroll, B. M., “The Performance of Pipe Coatings in Relation to Cathodic Protection,” 5th International Conference on the Internal and External Protection of Pipes, Innsbruck, Austria, October 25-27, 1983.

2.

Materials Laboratory Report, 150°F Cathodic Disbondment Tests of Pipeline Coatings, C.A. Shargay, September 17, 1982, File No. 6.55.5.

3.

Article, What's New in Distribution/Transmission Pipeline Coatings, Ron Sloan.

4.

Materials Laboratory Report, Rangley CO2 Pipeline Coating Tests, J. H. Kmetz, File: 6.55.75, December 21, 1984.

5.

Davis, J. A. and Thomas, S. J., “Properties and Application Procedures for Polyethylene Tape Coating Systems,” Pipeline, April 1985, p. 6.

6.

Materials Laboratory Report, Sudan Pipeline Coatings - Tape Wrap Tests, L. J. Klein, File 6.55.50.

7.

Materials Laboratory Report, Aramco Mastic Tape Tests, Final Report, C. A. Shargay, File 6.55.50, April 27, 1983.

8.

Choate, L. C., “New Coating Developments, Problems, and Trends in the Pipeline Industry,” Materials Performance, April 1975.

9.

O'Donnell, John P., “Coal-Tar Enamel Resins: Most-Preferred Pipe Coating,” Oil and Gas Journal, July 6, 1981.

900-59

September 1996


Coatings Manual

10. Ward, D. K., Moore, D. E., and Hawkins, P. J., “External and Internal Pipeline Coatings in the Arabian Gulf Area,” 5th International Conference on the Internal and External Protection of Pipes, Innsbruck, Austria, October 25-27, 1983, Paper C3. 11. Chevron Pipe Line Company Memo, Field Joint Coatings from P. T. Groff to R. G. Lueders, July 1, 1987. 12. Memo to CRTC File, Bakersfield Experience with Extruded Plastic Control Pipe, E. H. Niccolls, File 6.55.15, May 24, 1990. 13. Materials Laboratory Report, KLM Pipeline Reclamation Trial Coatings, K. K. Kirkham, File 6.55.15, January 4, 1984. 14. Materials Laboratory Report, KLM Pipeline Reclamation Trial Coatings, B. J. Cocke, File 6.55.15, October 25, 1983. 15. Materials Laboratory Report, Hot Subsea Pipeline Coatings Disbonding Tests, N. E. Daley, File 6.55.30, December 27, 1988. 16. E.H.Niccolls, InSituInternalPipelineCoatings, Materials Laboratory File N28.15, July 17, 1981. 17. S. E. Pfeiffer, “Fusion Bond Coated Girth Welds, External/Internal,” Corrosion 83 Paper 117, NACE International. 18. P. J. Bryant, “Internal In-Place Pipe Coating,” Pipeline Gas Journal, Volume 214, Pages 17-18, February 1987. 19. S. V. Daily, “An Alternative Surface Preparation Procedure for the Application of Internal In-Situ Pipeline Coating,” Corrosion 88 Paper 308, NACE International. 20. S. Selinek, “In Situ Internal Coating of Pipelines—North Sea Experience,” Corrosion 90 Paper 254, NACE International. 21. R. E. Carlson, Jr., “Internal Lining of Pipeline Weld Joints,” Material Performance, Volume 31, Number 9, pages 46-49, September 1992. 22. Dr. J. M. Leeds, “A High-temperature (120°C) Gas Pipeline CoatingRefurbishment Programme, Using High-solids Epoxy,” Pipeline Risk Assessment, Rehabilitation and Repair Conference, Houston, Texas, May 20-23, 1991. 23. P. Barrien, S. E. McConkey, M. A. Trzecieski, “Coating Evaluation Program for 116°C Service Temperature,” Corrosion 84 Paper # 358, NACE International, New Orleans, Louisiana, April 1984. 24. John Bethea and Adel Botros, “A New Approach to Fusion Bonded Epoxy Coatings for Pipeline Protection,” API Pipeline Conference, April 1994. 25. NAPCA Bulletin 1-65-91, “Recommended Specification Designations for Coat Tar Enamel Coatings.”

September 1996

900-60

Chevron Corporation

Coatings Manual


26. NAPCA Bulletin 2-66-91, “Standard Applied Pipe Coating Weights for NAPCA Coating Specifications.” 27. NAPCA Bulletin 3-67-91, “External Application Procedures for Hot Applied Coal Tar Coatings to Steel Pipe.” 28. NAPCA Bulletin 6-69-90-1, “Suggested Procedures for Hand Wrapping Field Joints Using Hot Enamel.” 29. AWWA Standard C-203, “Coal-tar Protective Coatings and Linings for Steel Water Pipelines - Enamel and Tape Hot Applied.” 30. AWWA Standard C-213, “Fusion-bonded Epoxy Coating for the Interior and Exterior of Steel Water Pipelines.”

Chevron Corporation

900-61

September 1996

Quick Reference Guide Contents

Page

Introduction

QR-2

Company Contacts

QR-3

CRTC’s Coatings Specialist Facilities for Analyzing Lead in Coatings Coating Manufacturers Suppliers Steps to Coating System Selection

QR-7

System Number Selection Guide

QR-8

Atmospheric Coatings for On- & Offshore Coatings for Concrete Coatings Under Insulation & Fireproofing Internal Vessel Coatings Coating Compatibility Chart

QR-11

Coating System Data Sheets

QR-12

Available System Data Sheets System Data Sheets Acceptable Brands by Generic Classification Acceptable Brands by Manufacturer

Chevron Corporation

QR-1

May 1998

Introduction

Coatings Manual—Quick Reference Guide

Introduction This Quick-Reference Guide from Chevron’s Coatings Manual has been designed to give you easy access to the selection process for certain types of coating projects: •

Atmospheric (both on- and offshore)

•

Concrete (mild environment only)

•

Internal vessel

•

Under insulation and fireproofing

By following the coating selection process, you will find a system data sheet which details the specifications and approved manufacturers for the coatings that fit your project. (See sample system data sheet below.) The design of the data sheet simplifies your preparation of a selection-and-specification package for a coating contractor: just photocopy the appropriate data sheet(s) and specification(s). Sample of a System Data Sheet Coatings Manual

Chevron Corporation

SYSTEM DATA SHEET

Two-Component Systems Self-Cured Inorganic Zinc | High-Temperature Silicone Surface Prep:

SSPC-SP10 (NACE No. 2) Near-white blast finish.

2.4

Touch Up: Use pure silicone topcoat only, two coats.

Anchor Pattern: 1.5 - 2.5 mils Total DFT (min) 4.5 mils Coat, Generic Classification, DFT

PRIMER Self-Cured Inorganic Zinc - Solvent Reducible 2.0 - 3.0 mils DFT

Manufacturer Ameron Ameron Ameron Carboline Carboline Dampney Devoe Hempel Hempel International PPG Industries Sherwin Williams Sherwin Williams Sigma Valspar

Product Designation Dimetcote 21-9 Dimetcote 6 Dimetcote 9 Carbozinc 11 Carbozinc 11 HS Thurmalox 245C Silicone Zinc Dust Primer Catha-Coat 304V Galvosil 1570.3 Galvosil 1578 Interzinc 311 Metalhide 1001 Primer 97-673/97-674 B69VZ1/B69VZ3/B69D11 Zinc Clad II B69V11/B69D11 Tornusil MC 58 7558 V13-F-12

VOC (G/L)

By Max Svc Temp

• 293 500 506 515 • 264 413 • 336 • 340 520 530 397 • 312 462 528 • 324

» Keep inorganic zinc silicate mixed, using agitated pot while applying.

TOPCOAT Silicone - High Temp Rated to 700°F 1.5 - 2.5 mils DFT

Ameron Carboline Dampney Devoe Hempel Hempel International PPG Industries Sherwin Williams Sherwin Williams Sigma Valspar

PSX 892HS Thermaline 4631WB Thurmalox 230C* HT-12 5690 5691 Intertherm 230 Pittherm High Heat Silicone Aluminum 100-A-518 Black 880-B-001 Sigmatherm 5267 37-A-1

• 324 • 108 360 572 400 586 612 554 420 514 600 599

» Non-catalyzed silicones remain tacky until exposed to heat above 300°F to 400°F. * Thumalox 230C topcoat will go over ONLY Thurmaloc 245C Silicone Zinc Dust Primer.

• VOC at or below 340 g/l is the anticipated regulatory limit. Check local standards for current VOC limits. Consult manufacturer's product data sheets for specific details about applying any coating. May 1998

Last Update:

5/15/98

Page 15

Note The system data sheets outnumber the references to coating systems in the selection criteria because Chevron has many coating systems in use. Do not choose a coating system unless you have been directed to do so by following either: •

The selection guide in this publication.

•

Instructions from one of the Company’s coating specialists or a coating manufacturer.

Also included in this Guide, the Coatings Compatibility Chart is a resource for projects involving maintenance coatings. For questions about the Guide, contact the CRTC specialists listed on the Contacts page.

May 1998

QR-2

Chevron Corporation


Introduction

Company Contacts CRTC’s Coatings Specialist Rich Doyle

CTN 242-3247

Atmospheric, Concrete, Internal Vessel Coatings, Downhole Tubular Coatings, Pipeline Coatings

Other Company Contacts Corporate Identity Colors

Company Identity Center, Corporation Public Affairs Department—CTN 894-0260

Chevron Color Chips

Additional copies from Technical Standards—CTN 242-7241

CRTC Environmental Resource

CTN 242-5696

CRTC Mat'ls & Equip. Engineering

CTN 242-3247

Facilities for Analyzing Lead in Coatings Clayton Environmental Consultants

800/294-1755

22345 Roethel Drive

Novi

MI

48375

Forensic Analytical Specialties

800/827-3274

3777 Depot Road, Suite 409

Hayward

CA

94545

Coating Manufacturers Manufacturers of Atmospheric and Internal Vessel Coatings Ameron

714/529-1951

201 North Berry Street

Brea

CA

92621

Ashland Chemical

800/643-1234

1851 E. First Street, #700

Santa Ana

CA

95705-4017

Carboline

314/644-1000

350 Hanley Industrial Court

St. Louis

MO

63144

Ceilcote

216/831-5500

23700 Chagrin Boulevard

Cleveland

OH

44122

Dampney Company, Inc.

617/389-2805

85 Paris Street

Everett

MA

02149

Devoe

502/897-9861

4000 Dupont Circle

Louisville

KY

40207

Dudick

216/562-1970

1818 Miller Parkway

Streetsboro

OH

44241

Glidden

216/344-8000

925 Euclid Avenue

Cleveland

OH

44115

Hempel

713/672-6641

6901 Cavalcade

Houston

TX

77028

International

800/525-6824

P. O. Box 4806

Houston

TX

77210-4806

PPG (Attn Dave Landry)

713/944-8550

P. O. Box 5772

Pasadena

TX

77502

Sherwin Williams

800/321-8194

101 Prospect Avenue NW Corporate Offices

Cleveland

OH

44115

Sigma

504/347-4321

1401 Destrehan Avenue

Harvey

LA

70058

Southern Coatings

800/845-0487

P.O. Box 160

Sumpter

SC

29151

Tempil

908/757-8300

2901 Hamilton Boulevard

So. Plainfield

NJ

07080

Valspar

800/638-7756

1401 Severn Street

Baltimore

MD

21230

Wisconsin Protective Coatings

414/437-6561

614 Elizabeth Street

Green Bay

WI

54302

Manufacturers of Concrete Coatings Dudick (Attn: Customer Service)

800/322-1970

P.O. Box 2550

Streetsboro

OH

44241

KCC Corrosion Control Co. (Attn: Sales Engineer)

800/395-5624

4010 Trey Road

Houston

TX

77084

Master Builders (Attn: Technical Support)

800/821-3582

23700 Chagrin Boulevard

Cleveland

OH

44122-5554

Sauereisen (Attn: Technical Service)

412/963-0303

160 Gamma Drive

Pittsburgh

PA

15238-2989

Sentry Polymers (Attn: Technical Support)

800/231-2544

P.O. Box 2076

Freeport

TX

77541

Chevron Corporation

QR-3

May 1998

Introduction


Sika (Attn: Technical Service)

800/933-7452

12767 E. Imperial Highway

Santa Fe Springs

CA

90670

Stonhard

800/854-0310

1 Park Avenue

Maple Shade

NJ

08052

Wisconsin Protective Coatings (Attn: Technical Service)

414/437-6561

614 Elizabeth Street

Green Bay

WI

54308-8147

TX LA LA

77060

Manufacturers of Pipeline Coatings 3M

Albert Schupbach

512/984-5683

Canusa

Ben Medley Hank Reuser

713/367-8866 713/974-7211

Carboline

John Montle

314/644-1000

Denso

(Carboline markets) 713/821-3355

DuVal

Trevor McClery

416/284-1681

DuPont Canada

Jamie Cox

416/338-3764

Elf Atochem

Igor Leclere

215/419-5610

Hempel

Michael Bentkjaer

713/672-6641

Lilly

Mark Schaneville

334/365-9454

Montell (Himont)

Ed Phillips

302/996-6236

OBrien Nap-Gard

John Bethea Sherill Miller

713/939-4000 713/939-4000

Polyguard

Bob Nee

918/749-3634

Polyken

Grover Marshall Bob Hayes

918/627-3635 510/284-1515

Power Marketing Group

James Power

303/741-3993

Raychem

Shiv Kumar Walt Greuel Joseph Merket

619/482-8306 619/482-8302 415/361-4095

Reilly Coal Tar

John Johnson

317/247-8141 (ext. 6771)

Sigma Coatings

Lou Cucker

800/221-7978

Tapecoat

John Ward

704/896-7803

Trenton

Thomas Weber

713/556-1000

Valspar

Trevor McClery

416/284-1681

Manufacturers of Pipeline Coating Applicators Bayou Pipe Coating Co

713/591-1614 (F) 713/591-0284

450 N. Sam Houston Parkway East #232 Plants:

Houston Baton Rouge New Iberia

Bredero Price International, Inc. (Domestic USA)

713/ 974-7211 (F) 713/260-4500

7211 Regency Square Bl. St. 104 Houston Plants: Fontana Harvey Pearland

TX CA LA TX

77036

Bredero Price International, Inc. (Foreign)

713/999-2600 (F) 713/999-6189

250 North Belt, Suite 220 Plants:

TX

77060

May 1998

QR-4

Houston Australia Indonesia Malaysia Nigeria Scotland Singapore U.A.E.

Chevron Corporation


Introduction

Commercial Coating Services, Inc. (CCSI)

409/539-3294 (F) 409/539-3073

Post Office Box 3296 Plants:

Conroe Bakersfield Conroe

TX CA TX

77305-3296

Commercial Resins Co.

918/438-6522 (F) 918/437-5410

2001 North 170th East Avenue Plants:

Tulsa Napa Valley Tulsa

OK CA OK

74116

Compression Coat, Inc.

713/353-8597 (F) 409/756-8599

3513 N. Frazer Conroe Plants: Uses portable equipment

TX

77303

Energy Coatings Co. (Encoat)

Now Bredero Price International, Inc.

Shaw Pipe, Inc.

713/367-8866 800/SHAW PIPE (800/742-9747) (F) 713/367-4304

TX

77380-1038

2408 Timberloch Place, Bldg C-8 The Woodlands Plants: Australia Canada New Iberia

LA

Suppliers Suppliers of Coated Tubing and Accessories Baker Hughes Tubular Service

(USA: Now owned by ICO, Inc.) (Overseas: Now owned by Tuboscope Vetco International)

Tuboscope Vetco Int’l

713/799-5100 (F) 713/799-5183

P. O. Box 808

Houston

TX

77001

ICO, Inc.

713/872-4994 (F) 713/872-9610

100 Glenborough, Suite 250

Houston

TX

77067

Shield Coat, Inc.

504/879-3539 (F) 504/868-3173

Station 1, Box 10185

Houma

LA

70363-5990

Midland

TX

79702

Great Bend

KS

67530

Suppliers of Cement Linings Permian Enterprises, Inc. (now owned by ICO Inc.)

915/683-1084 (F) 915/683-1319

P. O. Box 2745

Suppliers of Fiberglass Linings Rice Engineering Corp

800/533-5480 316/793-5483 (F) 316/ 793-5521

1020 Hoover

Suppliers of PVC Linings Rice Engineering Corp

800/533-5480 316/793-5483 (F) 316/ 793-5521

1020 Hoover

Great Bend

KS

67530

Sealtite

800/835-0133 (F) 316/331-6832

P. O. Box 965

Independence

KS

67301

Chevron Corporation

QR-5

May 1998

Introduction


Suppliers of Pipeline Coatings Canusa

713/367-8866 (F) 713/292-8571

2408 Timberlock Pl., Bdg C-8

The Woodlands

TX

77380-1038

Denso North America Inc.

713/821-3355 (F) 713/821-0304

18211 Chisholm Trail

Houston

TX

77060

DuPONT Canada, Inc. Modified Polymers Division

519/862-5700 (F) 519/862-5880

Albert Street

Corunna, Ontario

N0N 1G0 Canada

Elf Atochem

215/419-7000

2000 Market Street

Philadelphia

PA

19103-3222

North America Inc.

(F) 215/419-5305

Hempel Coatings (USA), Inc.

800/678-6641 (F) 713/674-0616

6901 Cavalcada

Houston

TX

77028

Kop-Coat Carboline Co.

314/644-1000 (F) 314/644-4617

350 Hanley Industrial Court

St. Louis

MO

63144-5199

Lilly Powder Coatings, Inc.

816/421-7400

1136 Fayette North

Kansas City

MO

64116

Pipe Clad Products Div

(F) 816/421-4563

3M Company

512/984-1800 (F) 512/984-3556

6801 River Place Boulevard

Austin

TX

78726-9000

Madison Chemical Industries, Inc.

905/878-8863 (F) 905/878-1449

490 McGeachie Drive

Milton, Ontario

L9T 3V5 Canada

Nap-Gard Pipe Coatings O’Brien Powder Products, Inc.

713/939-4000 (F) 713/939-4027

9800 Genard Street

Houston

TX

77041

Polyguard Products, Inc.

214/875-8421 (F) 214/875-9425

P. O. Box 755

Ennis

TX

75119

Polyken Technologies Kendall Co.

508/261-6200 800/248-7659 (F) 508/261-6271

15 Hampshire Street

Mansfield

MA

02048

Power Marketing Group, Inc.

303/741-3993 (F) 303/ 741-2548

6416 South Quebec St, Ste 41

Englewood

CO

80111

Raychem Corp., Ultratec Div.

619/482-8300 (F) 619/ 482-2813

1670 Brandywine Avenue

Chula Vista

CA

91911

Reilly Industries, Inc.

317/ 247-8141 (F) 317/248-6402

1500 South Tibbs Avenue

Indianapolis

IN

46241

Royston Laboratories, Chase Corp

412/828-1500 800/245-3209

128 First Street

Pittsburgh

PA

15238

Tapecoat Co., TC Manufacturing Co., Inc.

847/866-8500 (F) 708/866-8596

1527 Lyons Street

Evanston

IL

60201-3551

Valspar Inc.

416/284-1681 (F) 416/284-6549

645 Coronation Drive

West Hill, Ontario

M1E 4R6 Canada

Suppliers of Inspection Tools Paul N. Gardener Co., Inc.

954/946-9454 316 NE First Street (F) 954/946-9309 or -9375

Pompano Beach

FL

33060

KTA-Tator Inc.

412/788-1300

Pittsburgh

PA

15275

May 1998

115 Technology Drive

QR-6

Chevron Corporation


Introduction

Steps to Coating System Selection

Start

No

Type of Coating: Atmospheric Coating? Concrete Coating (Mild Environment)? Internal Vessel Coating?

Contact a CRTC Coating Specialist Yes

System Number Selection Guide Choose a system number by type of surface, service, voc units.

System Data Sheets

Locate the correct data sheet by system number

No Coating over an existing system?

Yes

No

Yes Compatibility Chart: Compatible?

Photocopy Coating System Fact Sheet. Attach to spec.

End

Chevron Corporation

QR-7

May 1998



System Number Selection Guide Note Pick a coating system number from one of the following tables then find that number in the System Data Sheets for Coating Systems. For coatings under insulation & fireproofing, see chart next page Atmospheric Coatings for On- & Offshore (1 of 2) Onshore Std

Type of Equipment

Hi Perf

Offshore

Code C/E: Vessels & Heat Exchangers Uninsulated below 200°F

2.2

3.1

3.1

Uninsulated to 200°F and steamed out

2.6

3.1

3.1

Uninsulated 200–600°F

N/R

2.4

2.4

Uninsulated 300-600°F

2.4

N/R

N/R

Uninsulated to 200°F

2.2

3.1

3.1

Wind girders

2.2

Floating roofs (Uninsulated)

2.6

3.1

N/R

Stairways & railings

2.2

Code D: Tanks

Code F: Furnaces Structural steel & platforms

2.6

2.6

Stacks, breeching, furnace body to 600°F

2.4

2.4

N/R Code G/K: Pumps, Turbines, Compressors & Drivers Uninsulated to 200°F

N/R

3.8

3.8


2.4

2.4

2.4

3.8

3.8

N/R

1.4

2.2

2.6

3.1

N/A

N/A

N/R

N/R

Motors N/R Externally insulated exhaust ducts Code J: Instruments Field instrument panels (steel) Weatherproof housings (steel)

3.1

Instrument tubing (stainless) N/R Instruments (galvanized or aluminum)

Code L: Piping (including Valves & Fittings)

May 1998

Uninsulated to 200°F

2.2

3.1

3.1

Uninsulated below 200°F steamed out

2.6

3.1

3.1


2.4

2.4

2.4

QR-8

Chevron Corporation



Atmospheric Coatings for On- & Offshore (2 of 2) Onshore Std

Hi Perf

Offshore

Concrete

N/R

N/R

N/R

Exposed steel, platforms, ladders, supports

2.2

3.1

3.1

Floor plate (smooth)

4.6

4.5

4.5

Galvanized floor grating repairs

1.6

1.6

1.6

Type of Equipment Code M: Structural

Galvanized stairways and railings

N/A

Jacket above splash zone; deck modules; boat landing

3.1

Jacket splash zone - structural members

4.2

Jacket splash zone - appurtenances

N/A

N/A

Risers, conductors: splash zone below 140°F not pressure treated

4.1

Risers, conductors: splash zone to 160°F

4.3

Risers, conductors: splash zones to 250°F

4.2

Code P: Electrical Equipment Galvanized or aluminum

N/R

N/R

N/R

Steel

2.2

3.1

3.1

Code R: Buildings and Control Houses (Exterior) Galvanized steel N/R

N/R

Steel

2.2

2.6

Wood

N/R

N/R

Masonry walls N/A

Code S: Miscellaneous Equipment Subsea completion equipment Standard: High Performance:

N/A

N/A

8.4 11.4

Coatings for Concrete Coating System by Exposure Item Oil/water Separator Secondary Containment

Temperature

Environment

< 140°F

Oil/water mixture

< 140°F

(2)

Hydrocarbons, caustics

dilute acids,

Physical Abuse

Continuous

Intermittent

Moderate(1)

20.1

N/A

(1)

20.2

20.2

20.1

20.1

Aggressive

20.3

20.3

(4)

N/A

20.2

Mild

Moderate(1) (3)

Equipment Foundations (1) (2) (3) (4)

< 140°F

(2)

Hydrocarbons , dilute acids, caustics

Mild

Moderate coating loss due to abrasion, light equipment wear. Possibility of impact on coating. Crude oil, jet fuel, gasoline, etc. Severe coating loss due to abrasion, heavy equipment wear. Definite potential for impact on coating. No coating loss due to abrasion, possible light foot traffic. No physical impact on coating

Chevron Corporation

QR-9

May 1998



Coatings Under Insulation & Fireproofing Substrate Carbon Steel

Temperature(1)

Exposure to Temperature

Coating System

Continuous

-50°F to 140°F

12.1

Continuous

140°F to 300°F

12.2

Cyclic (produce wet/dry conditions)

Stainless Steel

12.3

Continuous

Above 300°F

Do not coat

Special Conditions

Above 300°F

12.7

Continuous

-50°F to 140°F

12.4

Continuous

140°F to 300°F

12.5

Cyclic (produce wet/dry conditions)

12.6

Continuous

Above 300°F

12.7

(1) Actual temperature of steel not design temperature.

Internal Vessel Coatings High Temperature/Pressure

Non-Reinforced Thin Film

Reinforced Glass Flake

Laminate

Fresh Water

8.1

9.1

10.1

Demineralized Water

8.2

9.2

10.2

Potable Water

8.3

9.3

N/R

Salt Water & Brine

8.4

9.4

Produced Water

8.5

Crude Oil (sweet or sour)

High Temperature/ Cathodic

High Temperature/ Non Cathodic

11.2

11.2.1

10.4

11.4

11.4.1

11.4.2

9.5

10.5

11.5

11.5.1

11.5.2

8.6

9.6

10.6

11.6

11.6.1

11.6.2

Fuels (low aromatic)

8.7

9.7

10.7

Fuels (high aromatic)

8.8

9.8

10.8

Aromatic Hydrocarbon

8.9

9.9

10.9

Acetone

8.10

Ethyl & Methyl Alcohol

8.11

Services

High Pressure/ Non Cathodic

N/R

May 1998

QR-10

Chevron Corporation


Coating Compatibility Chart

Coating Compatibility Chart

Epoxy Mastic

Inorganic Zinc

Lacquer

Latex Emulsion

Phenolics

Polyamide Epoxy

Polyurethane

Silicone Alkyds

Vinyls

Vinyl Acrylic

Wash Primers

YES 3

N/R

YES 3

N/R

YES

N/R

YES

YES

YES

YES 3

YES 3

YES

YES

YES

YES

Amine Epoxy

N/R

YES 2

N/R

YES 2

N/R

N/R

YES

N/R

N/R

N/R

YES

YES 2

N/R

N/R

N/R

YES

Asphalt Mastic

YES

N/R

YES

N/R

YES

N/R

YES

N/R

YES

YES

N/R

N/R

YES

N/R

N/R

YES

Chlorinated Rubber

N/R

YES 3

N/R

YES 3

LTD

YES

YES

N/R

YES

YES

YES 3

YES 3

N/R

YES

YES

YES

Coal Tar Paints

N/R

N/R

N/R

N/R

YES

N/R

YES

N/R

YES

LTD

N/R

N/R

N/R

N/R

N/R

YES

Epoxy Mastic

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

YES

Inorganic Zinc

N/R

N/R

N/R

N/R

N/R

N/R

YES

N/R

N/R

N/R

N/R

N/R

N/R

N/R

N/R

N/R

Lacquer

N/R

YES 1

N/R

YES 1

N/R

N/R

LTD

YES

YES

N/R

YES

LTD

N/R

YES

N/R

YES

Latex Emulsion

YES

YES 3

YES

YES 3

YES

YES

YES

YES

YES

YES

YES 3

YES 3

YES

YES

YES

YES

Phenolic

YES

YES

N/R

YES

N/R

YES

LTD

YES

YES

YES

YES

YES

YES

YES

YES

YES

Polyamide Epoxy

LTD

YES

N/R

YES

N/R

LTD

YES

N/R

N/R

LTD

YES

YES

LTD

N/R

N/R

YES

Polyurethane

N/R

YES 2

N/R

YES 2

N/R

N/R

YES

N/R

YES

N/R

YES

YES 2

N/R

N/R

N/R

YES

Silicone Alkyd

YES

YES 3

N/R

YES 3

N/R

YES

YES

YES

YES

YES

YES 3

YES 3

YES

YES

YES

YES

Vinyl

N/R

N/R

LTD

N/R

LTD

N/R

YES

N/R

YES

N/R

N/R

N/R

N/R

YES

YES

LTD

Vinyl Acrylic

LTD

YES

N/R

YES

LTD

YES

YES

N/R

YES

LTD

YES

YES

YES

YES

YES

YES

Wash Primers

N/R

N/R

N/R

N/R

N/R

N/R

YES

N/R

N/R

N/R

N/R

N/R

N/R

N/R

N/R

N/R

Asphalt Mastic

YES

Amine Epoxy

Alkyd

Coating Being Applied

Alkyd

Coal Tar Paint

Chlorinated Rubber

Coating Being Overcoated

Notes: YES: Applied coating will not lift, wrinkle, blister; will have reasonable bond; check in field with a test patch. LTD: Some formulae are compatible; some not. Consult manufacturer. N/R: Not recommended 1 Durability and use depend on type of lacquer. 2 Must apply topcoat before coated surface has hardened. 3 Gloss on paint being overcoated must be removed by weathering or sanding. 4 Topcoat may blister if high-solvent topcoat applied too thickly, too quickly.

Chevron Corporation

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May 1998



Coating System Data Sheets Available System Data Sheets Primer Only Systems 1.1

Inhibited Alkyd (Primer Only)

1.2

Silicone Alkyd (Primer Only)

1.3

Self-Cured Inorganic Zinc–Solvent Reducible (Primer Only)

1.3.1

Self-Cured Inorganic Zinc–Water Reducible

1.4

Polyamide Epoxy (Primer Only)

1.5

Amine Adduct Epoxy (Primer Only)

1.6

Organic Zinc-Rich Primer for Galvanizing Repair

1.7

Vinyl Butyral Wash Primer

1.8

Epoxy Mastic–Surface-Tolerant Prime

1.8.1

Epoxy Mastic–Surface-Tolerant Primer–Aluminum Color Only

1.9

Temperature-Indicating Paint

Two-Component Systems

May 1998

2.1

Inhibited Alkyd | Alkyd Enamel

2.2

Inhibited Alkyd | Alkyd Enamel | Alkyd Enamel

2.3

Silicone Alkyd | Silicone Acrylic

2.4

Self-Cured Inorganic Zinc | High-Temperature Silicone

2.5

Self-Cured Inorganic Zinc | Silicone Acrylic

2.6

Self-Cured Inorganic Zinc | Polyamide Epoxy (High Build)

2.7

High-Temperature Silicone | High-Temperature Silicone

2.8

Manufacturer's Standard | Alkyd Enamel

2.9

Manufacturer's Standard | Alkyd Enamel | Alkyd Enamel

2.10

Manufacturer's Standard | Silicone Acrylic

2.11

Manufacturer's Standard | High-Temperature Silicone

2.12

Epoxy Mastic–Surface-Tolerant Primer | Polyamide Epoxy (Finish)

2.12.1

Epoxy Mastic–Surface-Tolerant Primer–Aluminum Color Only | Aliphatic Polyurethane

2.13

Epoxy Mastic–Surface-Tolerant Primer | Polyamide Epoxy (High Build)

2.13.1

Epoxy Mastic–Surface-Tolerant Primer–Aluminum Color Only | Polyamide Epoxy (High Build)

2.14

Polyamide Epoxy | Polyamide Epoxy

QR-12

Chevron Corporation



2.15

Epoxy Mastic–Surface-Tolerant Primer | Aliphatic Polyurethane

2.15.1

Epoxy Mastic–Surface-Tolerant Primer–Aluminum Color Only | Aliphatic Polyurethane

Three-Component Systems 3.1

Self-Cured Inorganic Zinc | Polyamide Epoxy (High Build) | Aliphatic Polyurethane

3.1.1

Self-Cured Inorganic Zinc | Polyamide Epoxy (High Build) | Aliphatic Polyurethane

3.2

Zinc-Rich Epoxy | Polyamide Epoxy (High Build) | Aliphatic Polyurethane

3.3

Self-Cured Inorganic Zinc | Vinyl Tie-Coat | Vinyl (High Build) | Vinyl (High Build)

3.3.1

Self-Cured Inorganic Zinc | Vinyl Tie-Coat | Vinyl (High Build) | Vinyl (High Build)

3.4

Zinc-Rich Epoxy | Vinyl (High Build) | Vinyl (High Buid)

3.5

Epoxy Mastic | Polyamide Epoxy (High Build) | Aliphatic Polyurethane

3.5.1

Epoxy Mastic—Aluminum Color Only | Polyamide Epoxy (High Build) | Aliphatic Polyurethane

3.6

(reserved for future use)

3.7

Manufacturer's Standard | Universal Primer | Polyamide Epoxy (High Build) | Aliphatic Polyurethane

3.8

Manufacturer's Standard | Universal Primer | Aliphatic Polyurethane

Specialty Coating Systems 4.1

Splash Zone Coating—Sprayable

4.1.1

Splash Zone Compound—Asbestos Free Rated to Cure Underwater

4.2

Monel Sheath for Splash Zones

4.3

Vulcanized Neoprene for Splash Zones

4.4

Polyamide Epoxy | Fireproofing | Polyamide Epoxy (High Build) | Aliphatic Polyurethane

4.5

Polyester Non-Skid | 20–30 Mesh Grit | Polyester Non-Skid

4.6

Epoxy Non-Skid | Grit | Epoxy Non-Skid

Non-Reinforced Thin Film Internal Coatings

Chevron Corporation

5.1

FDA-Approved Epoxy (Polyamide or Amine Cured) for Potable Water

5.2

Polyamide Epoxy (Thin Film) | Polyamide Epoxy (Thin Film)

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May 1998



5.3

Amine Adduct Epoxy (Thin Film) | Amine Adduct Epoxy (Thin Film)

5.4

Polyamide Coal Tar Epoxy | Polyamide Coal Tar Epoxy

5.5

Amine Adduct Coal Tar Epoxy | Amine Adduct Coal Tar Epoxy

5.6

Epoxy Phenolic | Epoxy Phenolic

Glass Flake Reinforced Internal Coatings 6.1

Polyamide Epoxy Glass Flake (Spray) | Polyamide Epoxy Glass Flake (Spray)

6.1.1

Polyamide Epoxy Glass Flake (Trowel) | Polyamide Epoxy Glass Flake (Trowel) | Glass Flake-Free Epoxy Resin Gel Coat

6.2

Amine Adduct Epoxy Glass Flake (Spray)| Amine Adduct Epoxy Glass Flake (Spray)

6.3

Isophthalic Polyester Glass Flake (Spray) | Isophthalic Polyester Glass Flake (Spray)

6.3.1

Isophthalic Polyester Glass Flake (Trowel) | Isophthalic Polyester Glass Flake (Trowel) | Wax Coat of Glass Flake-Free Isopolyester Resin

6.5

Vinyl Ester Glass Flake (Spray) | Vinyl Ester Glass Flake (Spray)

6.5.1

Vinyl Ester Glass Flake (Trowel) | Vinyl Ester Glass Flake (Trowel)

Laminate Reinforced Internal Coatings 7.1

Polyamide Epoxy Laminate

7.2

Amine Adduct Epoxy Laminate

7.3

Isophthalic Polyester Laminate

7.4

Bisphenol “A” Laminate

7.5

Vinyl Ester Laminate

Non-Reinforced Thin Film Coatings for Immersion Service

May 1998

8.1

Non-Reinforced Thin-Film Coatings for Fresh-Water Immersion Service

8.2

Non-Reinforced Thin-Film Coatings for Demineralized Water or Condensate Immersion Service

8.3

Non-Reinforced Thin-Film Coatings for FDA-Approved Potable Water Immersion Service

8.4

Non-Reinforced Thin-Film Coatings for Salt Water and Brine Immersion Service

8.5

Non-Reinforced Thin-Film Coatings for Produced-Water Immersion Service

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Chevron Corporation



8.6

Non-Reinforced Thin-Film Coatings for Crude Oil (Sweet or Sour) Immersion Service

8.7

Non-Reinforced Thin-Film Coatings for Fuel (Low-aromatic) Immersion Service

8.8

Non-Reinforced Thin-Film Coatings for Fuel (High-Aromatic) Immersion Service

8.9

Non-Reinforced Thin-Film Coatings for Aromatic-Hydrocarbon Immersion Service

8.10

Non-Reinforced Thin-Film Coatings for Acetone Immersion Service

8.11

Non-Reinforced Thin-Film Coatings for Ethyl & Methyl Alcohol Immersion Service

Glass Flake Reinforced Coatings for Immersion Service 9.1

Glass-Flake-Reinforced Coatings for Fresh-Water Immersion Service

9.2

Glass-Flake-Reinforced Coatings for Demineralized Water or Condensate Immersion Service

9.3

Glass-Flake-Reinforced Coatings for FDA-Approved Potable Water Immersion Service

9.4

Glass-Flake-Reinforced Coatings for Salt Water and Brine Immersion Service

9.5

Glass-Flake-Reinforced Coatings for Produced Water Immersion Service

9.6

Glass-Flake-Reinforced Coatings for Crude Oil (Sweet or Sour) Immersion Service

9.7

Glass-Flake-Reinforced Coatings for Fuel (Low Aromatic) Immersion Service

9.8

Glass-Flake-Reinforced Coatings for Fuel (High Aromatic) Immersion Service

9.9

Glass-Flake-Reinforced Coatings for Aromatic Hydrocarbon Immersion Service

Laminate Reinforced Coatings for Immersion Service

Chevron Corporation

10.1

Laminate-Reinforced Coatings for Fresh-Water Immersion Service

10.2

Laminate-Reinforced Coatings for Demineralized-Water or Condensate Immersion Service

10.3


10.4

Laminate-Reinforced Coatings for Salt-Water Brine Immersion Service

10.5

Laminate-Reinforced Coatings for Produced-Water Immersion Service

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May 1998



10.6

Laminate-Reinforced Coatings for Crude-Oil (Sweet or Sour) Immersion Service

10.7

Laminate-Reinforced Coatings for Fuel (Low Aromatic) Immersion Service

10.8

Laminate-Reinforced Coatings for Fuel (High Aromatic) Immersion Service

10.9

Laminate-Reinforced Coatings for Aromatic Hydrocarbon Immersion Service

High-Temperature/High-Pressure Coating Systems 11.1


11.2

Demineralized Water or Condensate Coatings Resistant to Temperature Gradients of 50°F & Compatible with Cathodic Protection

11.2.1

Demineralized Water or Condensate Coatings Resistant to Temperature Gradients of 50°F & Incompatible with Cathodic Protection

11.3


11.4

Salt Water & Brine Service Coatings Resistant to Temperature Gradients of 50°F & Compatible with Cathodic Protection

11.4.1

Salt Water & Brine Service Coatings Resistant to Temperature Gradients of 50°F & Incompatible with Cathodic Protection

11.4.2

Salt Water & Brine Service Coatings Resistant to Temperature Gradients of 50°F & Incompatible with Cathodic Protection

11.5

Produced Water Service Coatings Resistant to Temperature Gradients of 50°F & Compatible with Cathodic Protection

11.5.1

Produced Water Service Coatings Resistant to Temperature Gradients of 50°F & Incompatible with Cathodic Protection

11.5.2

Produced Water High Temperature/High Pressure Service Coatings Resistant to Temperatures to 180°F, Pressures of 1000 PSI & Incompatible with Cathodic Protection

11.5.2

Crude Oil Service (Sweet or Sour) Coatings Resistant to Temperature Gradients of 50°F & Compatible with Cathodic Protection

11.6.1

Crude Oil Service (Sweet or Sour) Coatings Resistant to Temperature Gradients of 50°F & Incompatible with Cathodic Protection

11.6.2

Crude Oil (Sweet or Sour) High Temperature/High Pressure Service Coatings Resistant to Temperatures to 180°F, Pressures of 1000 PSI & Incompatible with Cathodic Protection

Coatings Under Insulation & Fireproofing 12.1

May 1998

Under Insulation & Fireproofing—Non-Reinforced Thin Film Epoxy Coatings for Continuous Carbon Steel Temperatures -50°F to 140°F

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Chevron Corporation


12.2

Under Insulation & Fireproofing—Non-Reinforced Thin Film Epoxy Coatings for Continuous Carbon Steel Temperatures 140°F–300°F

12.3

Under Insulation & Fireproofing—Non-Reinforced Thin Film Epoxy Coatings for Cyclic Carbon Steel Temperatures that Produce Wet/Dry Conditions

12.4

Under Insulation & Fireproofing—Non-Reinforced Thin Film Epoxy Coatings for Continuous Stainless Steel Temperatures -50°F to 140°F

12.5

Under Insulation & Fireproofing—Non-Reinforced Thin Film Epoxy Coatings for Continuous Stainless Steel Temperatures 140°F–300°F

12.6

Under Insulation & Fireproofing—Non-Reinforced Thin Film Epoxy Coatings for Cyclic Stainless Steel Temperatures that Produce Wet/Dry Conditions

12.7

Under Insulation & Fireproofing—Non-Reinforced Thin Film Inorganic Coatings for Carbon Steel or Stainless Steel Temperatures Above 300°F

(Series 13 through 19 Reserved for Future Use) Concrete Coatings

Chevron Corporation

20.1

Epoxy Coatings for Concrete: Service Temperatures <140°F, Moderate Physical Abuse, Intermittent & Continuous Exposure

20.2

Epoxy Coatings for Concrete: Service Temperatures <140°F, Mild Physical Abuse, Intermittent & Continuous Exposure

20.3

Epoxy Coatings for Concrete: Service Temperatures <140°F, Aggressive Physical Abuse, Intermittent & Continuous Exposure

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May 1998

Appendix A. Conversion Charts

Chevron Corporation

A-1

Appendix A

Coatings Manual

A-2

Chevron Corporation

Coatings Manual

Chevron Corporation

Appendix A

A-3

Appendix B. Color Chips

(Not available in electronic format. Please find a paper copy of the manual in your facility, or chips may be obtained by contacting the Technical Standards team at CTN 242-7241.)

Chevron Corporation

B-1

January 1995

MANUAL - Coatings

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