Coating & Lining of Tanks

PAINTING — COATING AND LINING OF STORAGE TANKS

FEBRUARY 1993

EGE 35-B-2 — 1993

PAGE 1 OF 32

TABLE OF CONTENTS 1. 2. 3.

4.

Scope References General 3.1 General Requirements 3.2 Exterior Surfaces 3.3 Interior Surfaces 3.4 Chemical Exposure 3.5 Seam Sealing 3.6 Painting Safety 3.7 Nonferrous Surfaces Tank Exteriors 4.1 Surface Preparation 4. 2 P Prrime Coats 4.3 4.3 Ma Main inte tena nanc nce e Pain Painti ting ng

5.

6. 7. 8.

4.4 Special Service Conditions Tank Interiors 5.1 Need For a Lining 5.2 Use of Tank Linings 5.3 Types of Linings 5.4 Lining Selection 5.5 Surface Preparation 5.6 Lining Application 5.7 Lining Thickness 5.8 Lining Inspection Tank Identification and Marking Mobil Trademark Coating Index and Lining

1. SCOPE This Guide covers protective coating systems systems for storage tanks. This Guide does does not include painting procedures proc edures f or chemical exposures. For any other tank service service not discussed in in this Guide, recommendations shall be obtained from f rom Mobil Technology Company (MTC), Facilities Group. 2. REFERENCES The f ollowing publications publications form a part part of this Guide. Unless otherwise specified herein, herein, use the latest edition. Mobil Engineering Guides EGE 35-B-1 EGE 35-B-10 EGE 35-B-80 EGS 1060 EGS EGS 266 266

Painting — General Requirements Painting — Manufacturing Facilities Painting — Seam Sealing of Riveted or Bolted Tanks Cathodic Protection of Aboveground Storage Tanks Exi Existing ting Tank Tank Inspe nspect ctiion, on, Repa Repaiir, Alte Altera rattion, on, and and Tes Testing ting

API (American Petroleum Institute) Recommended Practices RP 2003 RP 652

Protection Against Ignitions Arising Out of Static, Lightning, and an d Stray Currents Lining Lining of Aboveground Aboveground Petroleum Storage Tank Bottoms

Code of Federal Regulations 29 CFR CFR 1910 1910

Title Title 29, Part Part 191 1910: 0: Occupa Occupati tiona onall Safet Safety y and Hea Health lth Admini Administ strat ratio ion n (OSHA) Standards (Labor)

MOBIL ENGINEERING GUIDE EGE 35-B-2 — 1993

PAGE 2 OF 32

FEBRUARY 1993

SSPC (Steel Structures Painting Council) Publications PA 2 VIS VIS 1

Measu easure remen mentt of Dry Dry Pai Paint Thickn Thicknes ess s with Magne agneti tic c Gag Gages es Visu Visual al Stan Standa dard rd for for Abr Abras asiive Bla Blast st Clea Cleane ned d Ste Steel el

Steel Structures Painting Manual, Volume 2, Systems and Specifications SP 1 SP 3 SP 5 SP 6 SP 7 SP 10

Solvent Cleaning Power Tool Cl Cleaning White Metal Blas last Clea leaning Comm mme ercial Blas last Clea leaning Brush-off Bl Blast Cl Cleaning Nearear-Wh Whiite Blas last Clea Cleani ning ng

NACE (National Association of Corrosion Engineers) Standards RP02 RP 0287 87 TM01 TM0175 75

Fiel Field d Mea Measu sure remen mentt of Surf Surfac ace e Pro Profi file le of of Abr Abras asiive Bla Blast st Clea Cleane ned d Steel Surfaces Using a Replica Tape Visu Visual al Sta Stand ndar ard d for for Sur Surfa face ces s of of New New Ste Steel el Cen Centr triifuga fugally lly Blas Blastt Cleaned with Steel Grit and Shot

3. GENERAL 3.1 3.1

Gen General eral Requi equire reme ment nts s

The procedures followed in the painting of storage tanks shall be in accordance with the requirements of EGE 35-B-1 35-B-1 for for exposure exposure environmen environment, t, surface preparation, preparation, application, applicat ion, and inspection. inspect ion. For any other tank service not discussed by this Guide, recommendations shall be obtained from the MTC Facilities Group. The terms for exposure conditions, as used in this Guide and in project specifications, are defined in this Section in order order of severity. They are: are: (a) Mild Exposure — Exposure — Areas where surfaces normally are subjected to very low humidity. Interiors of buildings and enclosures are generally considered to be subjected to mild exposure conditions. (b) Normal Exposu re re — Areas — Areas where surfaces are subjected to normal relative humidity (30 percent to 65 percent) and no chemical environment. (c) Severe Exposure — Areas where surfaces usually are moist or are exposed to condensation, frosting, sporadic water immersion, or high relative humidity (greater than 65 percent). (d) Chemical Exposure — Exposure — Areas where surfaces are exposed to liquid spillage or chemical vapors that have a detrimental effect on the surface material. 3.2 3.2

Ext Exterio eriorr Su Surfac rfaces es

The method of surface preparation, minimum number of coats, minimum dry-film thickness, colors, and types of paint used for shop and field painting shall be in accordance with the requirements of Sections 4 and 8 and Table Tables s 1 and 2 of this Guide Guide and and with the exposure conditions given in the project specifications. s pecifications. Maintenance painting shall conform to the requirements of this Guide, Sections 4 and 8; EGE 35-B-1, Section 8; and/or the project specifications, which stipulate exposure conditions. EGE 35-B-10, Tables 1 through thr ough 3, include descriptions of coating systems available for fire protection equipment. OSHA requirements (29 CFR 1910) or other applicable code or standard for safety colors shall be followed.


PAGE 2 OF 32

FEBRUARY 1993

SSPC (Steel Structures Painting Council) Publications PA 2 VIS VIS 1

Measu easure remen mentt of Dry Dry Pai Paint Thickn Thicknes ess s with Magne agneti tic c Gag Gages es Visu Visual al Stan Standa dard rd for for Abr Abras asiive Bla Blast st Clea Cleane ned d Ste Steel el

Steel Structures Painting Manual, Volume 2, Systems and Specifications SP 1 SP 3 SP 5 SP 6 SP 7 SP 10

Solvent Cleaning Power Tool Cl Cleaning White Metal Blas last Clea leaning Comm mme ercial Blas last Clea leaning Brush-off Bl Blast Cl Cleaning Nearear-Wh Whiite Blas last Clea Cleani ning ng

NACE (National Association of Corrosion Engineers) Standards RP02 RP 0287 87 TM01 TM0175 75

Fiel Field d Mea Measu sure remen mentt of Surf Surfac ace e Pro Profi file le of of Abr Abras asiive Bla Blast st Clea Cleane ned d Steel Surfaces Using a Replica Tape Visu Visual al Sta Stand ndar ard d for for Sur Surfa face ces s of of New New Ste Steel el Cen Centr triifuga fugally lly Blas Blastt Cleaned with Steel Grit and Shot

3. GENERAL 3.1 3.1

Gen General eral Requi equire reme ment nts s

The procedures followed in the painting of storage tanks shall be in accordance with the requirements of EGE 35-B-1 35-B-1 for for exposure exposure environmen environment, t, surface preparation, preparation, application, applicat ion, and inspection. inspect ion. For any other tank service not discussed by this Guide, recommendations shall be obtained from the MTC Facilities Group. The terms for exposure conditions, as used in this Guide and in project specifications, are defined in this Section in order order of severity. They are: are: (a) Mild Exposure — Exposure — Areas where surfaces normally are subjected to very low humidity. Interiors of buildings and enclosures are generally considered to be subjected to mild exposure conditions. (b) Normal Exposu re re — Areas — Areas where surfaces are subjected to normal relative humidity (30 percent to 65 percent) and no chemical environment. (c) Severe Exposure — Areas where surfaces usually are moist or are exposed to condensation, frosting, sporadic water immersion, or high relative humidity (greater than 65 percent). (d) Chemical Exposure — Exposure — Areas where surfaces are exposed to liquid spillage or chemical vapors that have a detrimental effect on the surface material. 3.2 3.2

Ext Exterio eriorr Su Surfac rfaces es

The method of surface preparation, minimum number of coats, minimum dry-film thickness, colors, and types of paint used for shop and field painting shall be in accordance with the requirements of Sections 4 and 8 and Table Tables s 1 and 2 of this Guide Guide and and with the exposure conditions given in the project specifications. s pecifications. Maintenance painting shall conform to the requirements of this Guide, Sections 4 and 8; EGE 35-B-1, Section 8; and/or the project specifications, which stipulate exposure conditions. EGE 35-B-10, Tables 1 through thr ough 3, include descriptions of coating systems available for fire protection equipment. OSHA requirements (29 CFR 1910) or other applicable code or standard for safety colors shall be followed.

MOBIL ENGINEERING GUIDE FEBRUARY 1993

PAGE 3 OF 32

EGE 35-B-2 — 1993

Lead-based paints paints shall not be applied to the exterior surfaces of storage st orage tanks. 3.3 3.3

Inte Interi rio or Su Surfac rfaces es

The method of surface preparation, minimum number of coats, recommended dry-film thickness, and types of paint used shall be in accordance with the requirements of Sections 5 and 8 of this Guide. 3.4 3.4

Chemi emical cal Exp Exposure sure

This Guide does not include painting procedures for chemical exposures. exposures. Painting recommendations recommendations for all such environments shall s hall be obtained from Mobil Technology Company, Company, Facilities Group. 3.5

Seam Se Sealing

When seam sealing of riveted or bolted tanks is necessary because of leakage at seams, the requirements of EGE 35-B-80 shall apply. 3.6 3.6

Pai Painting Safe Safetty

All painting painting shall shall be accomplished in accordance accordance with local governmental governmental regulations regulat ions.. Blastin Blas ting g is considere cons idered d hot work. Any storage storage tank to be blast cleaned requires approval from the local safety saf ety group. Compliance with safety measures measures outlined outlined in API RP 2003 2003 and with plant plant safety rules is required when storage s torage tanks are blast cleaned while in service. 3.7 3.7

Non Nonferr ferrou ous s Surf Surfac aces es

Galvanized or aluminum surfaces shall not normally be painted unless safety color code markings are required. required. Galvaniz Galvanized ed surfaces surfaces may be be painted painted where where previous previous experience indicates indicate s the t he need exists. exists . Tables 1 and 2 cover painting requirements for galvanized surfaces. 4. TANK TANK EXTER EXTERIO IOR RS 4.1 4.1

Surf Surfac ace e Prep Prepar arat atio ion n

4.1.1 Abras Ab rasive ive blast blast clean cleaning ing is the preferred preferred method method of of surface surface prepa preparatio ration n and and shall shall be used used except except in hazardous areas where blast cleaning is not permitted.


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FEBRUARY 1993

TABLE 1 EXTERIOR EXPOSURE MILD AND NORMAL EXPOSURE CONDITIONS (Note 4) (Colors are an approved part of the Mobil Identity Program.) Prime Coats (Note 1)

Surface Preparation

First Coat

Second Coat (Note 2)

Finish Coats (Notes 1 and 5)

Remarks (Note 3)

Color

CONE-ROOF AND DOME-ROOF TANKS Power tool

Nonlead primer

Nonlead primer

Volatile products: Gasoline, MTBE, naphtha, solvents, etc. Roof and shell courses (includes fittings): Tank white a alkyd (2 coats)

White

Nonvolatile distillates: Diesel oil, heating oil, etc. Roof and shell courses (includes fittings): Alkyd enamel (1 coat)

Mobil Beige

a. One spray coat of high-build alkyd tank white may be substituted for two coats of tank white alkyd.

or Commercial blast

Epoxy mastic

Residual black oils: Bunker C, No. 6 fuel, road oil, etc. Entire tank (including fittings): Alkyd enamel (1 coat)

Black

HORIZONTAL TANKS Power tool

Nonlead primer

Nonlead primer

Volatile products: Propane, butane, LPG, etc. Tank and fittings: Tank white a alkyd (2 coats)

White

Nonvolatile products: Lube oil, diesel oil, etc. Tank and Fittings: Alkyd (1 coat)

Mobil Beige

Legs, bases, saddles: All products Metal: Alkyd (1 coat) Concrete: Do not paint.

Black

See remark (a).

or Commercial blast

Epoxy mastic

OPEN-TOP, FLOATING-ROOF TANKS: ROOF AND STIFFENING RINGS (WINDGIRDERS) Power tool

Epoxy mastic

Epoxy mastic (1 coat)

White

High-build epoxy (1 coat)

White

b

b. Windgirder shall be same color as shell.

or Near-white blast

Epoxy zinc rich

None

OPEN-TOP, FLOATING-ROOF TANKS: SHELL Power tool

Nonlead primer

or Commercial blast

Nonlead primer

Upper-courses (includes fittings): a Tank white alkyd (2 coats) or alkyd (1 coat)

Epoxy mastic

TABLE 1 — Contd

White or Mobil Beige

See remark (a).


EGE 35-B-2 — 1993

PAGE 5 OF 32

Prime Coats (Note 1)

Surface Preparation

First Coat

Second Coat (Note 2)

Finish Coats (Notes 1 and 5)

Color

Remarks (Note 3)

SPHERES AND SPHEROIDS Power tool

Nonlead primer

Nonlead primer

Shell: Tank white alkyd a (2 coats)

White

Spheroid skirt: Alkyd

Black

See remark (a).

or Commercial blast

Epoxy mastic

Sphere legs:

Fireproofed— prime paint should be compatible with fireproofing.

TANK ACCESSORIES: ALL TANKS Commercial blast

Nonlead primer

Nonlead primer

Platf orm, walkways, handrails, stairs, ladders, ladder cages, bridges: Alkyd gloss enamel (2 c coats)

Lemon Yellow

c. Platf orms, etc., may be left unpainted if galvanized.

or Epoxy mastic

Tank valves, gage supports: Same as tank background. Piping: Alkyd (1 coat)

Mobil Beige

GALVANIZED SURFACES Solvent clean and brush blast

Metal primer

None

Platforms, walkways, handrails, stairs, ladders, ladder cages, bridges: Alkyd enamel

Lemon Yellow

NOTES TO TABLE 1: 1. 2. 3. 4. 5.

For specific recommendations on paint type, see Tables 6 and 7. For mild exposure conditions, the second prime coat may be omitted. Superscript letters (a, b, c) used throughout the Table refer to the remarks in this column. See Paragraph 4.3 for maintenance painting requirements. On roofs painted white, an area 0.6 m (2 ft) in diameter surrounding gage hatches shall be painted black with one coat of an alkyd paint, such as Valspar V20-J-5 or equivalent.


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FEBRUARY 1993

TABLE 2 EXTERIOR EXPOSURE SEVERE EXPOSURE CONDITIONS (Colors are an approved part of the Mobil Identity Program.) Prime Coats (Note 1)

Surface Preparation

First Coat

Second Coat

Finish Coats (Notes 1, 4, and 5)

Remarks (Note 2)

Color

CONE-ROOF AND DOME-ROOF TANKS Near-white blast

Epoxy zinc rich

None

Volatile products: Gasoline, MTBE, naphtha, solvents, etc. Roof and shell courses: Highbuild epoxy (1 coat)

White

Nonvolatile products: Diesel oil, heating oil, etc. Roof and shell courses: High-build epoxy (1 coat)

Mobil Beige

Residual black oils: Bunker C, No. 6 fuel, road oil, etc. Entire tank (includes fittings): Highbuild epoxy (1 coat)

Black

HORIZONTAL TANKS Near-white blast

Epoxy zinc rich

None

Volatile products: Propane, butane, LPG, etc. Tank and fittings: High-build epoxy (1 coat)

White

Nonvolatile products: Lube oil, diesel oil, etc. Tank and fittings: High-build epoxy (1 coat)

Mobil Beige

Legs, bases, saddles: All products Concrete: Do not paint. Metal: High-build tank lining epoxy (1 coat)

Black

OPEN-TOP, FLOATING-ROOF TANKS: ROOF AND STIFFENING RINGS (WINDGIRDERS) Power tool

Epoxy mastic

Epoxy mastic (1 coat)

White

High-build epoxy (1 coat)

White

or Near-white blast

Epoxy zinc rich

None

OPEN-TOP, FLOATING-ROOF TANKS: SHELL Near-white blast

Epoxy zinc rich

None

Upper-courses (includes fittings): High-build epoxy (1 coat)

White or Mobil Beige

a

a. Windgirder shall be same color as shell.


EGE 35-B-2 — 1993

PAGE 7 OF 32

TABLE 2 — Contd Prime Coats (Note 1)

Surface Preparation

First Coat

Second Coat

Finish Coats (Notes 1, 4, and 5)

Color

Remarks (Note 2)

SPHERES AND SPHEROIDS Near-white blast

Epoxy zinc rich

None

Shell: High-build epoxy (1 coat)

White

Spheroid skirt: High-build tank lining epoxy (1 coat)

Black

Sphere legs:

Fireproofed— prime paint should be compatible with fireproofing.

TANK ACCESSORIES: ALL TANKS Near-white blast

Epoxy zinc rich

None

Platform, walkways, handrails, stairs, ladders, ladder cages, bridges: High-build epoxy (1 b spray or 2 brush coats)

Lemon Yellow

b. Platforms, etc., may be left unpainted if galvanized.

Tank valves, gage supports: Same as tank background. Piping: High-build epoxy (1 coat)

Mobil Beige

GALVANIZED SURFACES Solvent clean and brush blast

Epoxy mastic

None

Platforms, walkways, handrails, stairs, ladders, ladder cages, bridges: High-build epoxy

Lemon Yellow

NOTES TO TABLE 2: 1. 2. 3. 4. 5.

For specific recommendations on paint type, see Tables 6 and 7. Superscript letters (a, b) used throughout the Table refer to the remarks in this column. See Paragraph 4.3 for maintenance painting requirements. On roofs painted white, an area 0.6 m (2 ft) in diameter surrounding gage hatches shall be painted black with one coat of an alkyd enamel, such as Valspar V20-J-5, or equivalent. If a high gloss is required for aesthetics or it is the normal practice of the plant to finish coat tanks with a high gloss, the epoxy finish coat shown above can be topcoated with a urethane enamel, such as Valspar 40 series, or equivalent (in the appropriate color).


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FEBRUARY 1993

4.1.2 A "silica-free" abrasive material shall be used. Personnel performing the work shall wear proper air breathing and safety equipment. A "grit" abrasive is preferred to a "shot" abrasive. A "grit" abrasive will give a better anchor pattern for coating than will a "shot" abrasive. 4.1.3 Where the existing paint system is red lead/alkyd and blast cleaning is not permitted, hand tool cleaning, hand sanding, or chemical rust removal compounds may be specified. The prime coat and the method of application shall be compatible with the surface preparation. Environmental regulations should be observed when removing lead-based paints. Removal of lead-based products should be done in accordance with all appropriate laws and regulations. For minor repairs to a red lead/alkyd system, spot blasting and priming with a compatible nonlead-based primer should be conducted. Removal of the entire lead-based system should be considered. 4.2 4.2.1 2.

Prime Coats All steel tank surfaces shall be primed in accordance with the requirements shown in Tables 1 and

4.2.2 An epoxy mastic primer can, with Mobil approval, be used as a primer over marginally prepared steel surfaces. The epoxy mastic primers such as Valspar Alumapoxy (V75-A-1) and Valspar Val-Chem Epoxy Mastic (V75-W-9, V75-D-7), or equivalent, can be topcoated with a high-build epoxy. 4.3

Maintenance Painting

It is acceptable to utilize the same generic coating system for maintenance painting of an existing painted surface. However, it is generally best to perform maintenance painting prior to damage to the existing primer. EGE 35-B-1, Section 8, shall be referred to when deciding the coating requirements for maintenance painting. 4.3.1 The surface to be painted shall be cleaned by blasting, power tools, hand tools, or solvents, or by a combination of these. All grease, oil, dirt, foreign matter, and rust — as well as loose, cracked, brittle, or nonadhering paint — shall be removed. 4.3.2 New prime and/or finish coatings shall be checked or tested for compatibility with the paints they are to cover to ensure that the existing coating will not lift or wrinkle. Compatibility between paints of various manufacturers should be considered prior to paint selection. The MTC Facilities Group should be contacted for guidance on compatibility. 4.3.3 When the existing coating is the alkyd system (Table 1), the maintenance painting primer shall be an epoxy mastic, such as Valspar V75-W-9 or equivalent. The topcoat shall be either a high build epoxy such as the Valspar V89 Series or equivalent or a urethane enamel such as Valspar V40 Series or equivalent. 4.3.4 When the existing coating is the zinc-rich epoxy/epoxy system (Table 2), the maintenance painting primer shall be an epoxy mastic such as Valspar V75-W-9 or equivalent. The topcoat shall be either a high build epoxy such as the Valspar V89 Series or equivalent or a urethane enamel such as Valspar V40 Series or equivalent. 4.4

Special Service Conditions

4.4.1 Painting of roofs and shells of insulated or fireproofed tanks shall be done as follows. Temperatures shown below relate to actual metal surface temperature.


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EGE 35-B-2 — 1993

(a) Up to 110ºC (230ºF) — Commercial blast clean the surface and topcoat with two coats of a phenolic alkyd zinc phosphate primer such as Valspar Chromox Primer (V13-R-28), or equivalent. When, for safety reasons, blast cleaning is not permitted, a good power tool cleaner can be substituted. An alternative system includes the preferred blast cleaning with a coat of an epoxy mastic such as Valspar V75 Series, or equivalent. (b) From 110ºC to 180ºC (230ºF to 355ºF)  Commercial blast clean the surface and topcoat with one coat of an inorganic ethyl silicate such as Valspar MZ-7 Inorganic Zinc Rich (13-F-12), or equivalent. 4.4.2 The coating of refrigerated and insulated single-wall tanks down to a service temperature of 18ºC (0ºF) shall be achieved by application of an epoxy zinc such as Valspar MZ-4 (13-F-4), or equivalent. 4.4.3 Uninsulated hot product storage tanks operating in the 66ºC to 177ºC (150ºF to 350ºF) range shall be primed with one coat of an epoxy zinc rich such as Valspar MZ-4 (13-F-4), or equivalent, applied over a white metal blast-cleaned surface. The finish coat shall be a silicone/acrylic such as Valspar Heat-Resisting Silicone/Acrylic (V37-F-209), or equivalent. 4.4.4 The use of a coating on the underside of a tank bottom is not permitted, unless approval has been obtained from MTC Facilities Group. 5.

TANK INTERIORS

5.1

Need For a Lining

The need for an internal tank lining in an aboveground storage tank is based upon several considerations. These include: Internal corrosion prevention. Product cleanliness. Alternate services and upset conditions. Federal, state, and local regulations. 5.2

Use of Tank Linings

The proper selection and application of tank linings can prevent internal corrosion of the steel tank bottom, tank shell, and/or the underside of the tank roof. The external surfaces of the tank are protected from corrosion by means of coatings for the tank shell and roof as covered by Section 4 of this Guide. The external or underside surfaces of the tank bottom are protected from corrosion by means of cathodic protection as covered in EGS 1060. 5.2.1

Tank Bottom Linings

Generally, most products stored in tanks are not corrosive to steel. In many cases however, corrosive conditions such as accumulation of water or sludge occur on the bottom, causing the need for a tank bottom lining. A more detailed discussion of tank bottom corrosion mechanisms can be found in API RP 652. Tank bottom linings shall be utilized for situations where product contamination could result if corrosion occurs (i.e., jet fuel, etc.). Also, tank bottom linings shall be used when water accumulation that will cause corrosion is expected (i.e., crude oil, etc.) and/or where the product stored is corrosive to the tank bottom steel.

MOBIL ENGINEERING GUIDE EGE 35-B-2 — 1993 5.2.2

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FEBRUARY 1993

Tank Shell Linings

Generally, most products that will come in contact with the shell are not corrosive to steel. However, corrosion can occur on the shell above the liquid level when the product stored contains sulfur compounds that can combine with moisture condensation to form corrosive acids. Also, only limited corrosion would be expected on the tank shell where the surface will remain in constant contact with the stored product. Tank shell linings shall be utilized for situations where product contamination could result if corrosion occurs (i.e., jet fuel, etc.), the stored product is corrosive to the tank steel, and/or for tanks storing sulfur-containing products that can combine with moisture condensation to cause a corrosive environment. 5.2.3

Tank Roof Coating

Generally, most products that will come in contact with the tank roof underside are not corrosive to steel. However, corrosion can occur on the fixed roof tanks where the product stored contains sulfur compounds that can combine with moisture condensation to form corrosive acids. Also, only limited corrosion would be expected on the underside of steel floating roofs where the surface will remain in constant contact with the stored product. Tank roof underside coatings shall be utilized for fixed roof tanks where product contamination could result if corrosion occurs. Also, coatings shall be used for situations where stored product contains sulfur compounds that can cause corrosion of the tank roof underside (i.e., crude oil, marine diesel, etc.). 5.2.4

Tank Lining Considerations

Tanks may have design and fabrication features that would make the application of a lining impractical or that would seriously jeopardize the integrity of a lining. For example, internal steam coils, which are used to heat a product to maintain a desirable viscosity, limit accessibility to the tank bottom during surface preparation and application of the lining. As a result, a good quality installation may be difficult to achieve. In service, steam coils create local areas where the temperature can be much greater than that of the bulk product. The resulting thermal effects on a tank bottom lining may cause localized failure by blistering or by cracking. 5.3

Types of Linings

Tank linings can be divided into two classes: thin films, 500 µm (20 mil) or less, and thick films, greater than 500 µm (20 mil). The thin-film linings can be applied to the tank bottom, tank shell, and/or roof underside. The use of the thick-film linings other than the glass flake polyester are typically limited to application to the tank bottom. Linings may be applied to the tank internals when they are first constructed or they may be installed after some period of service. 5.3.1

Tank Bottom Linings

Thin-film linings can be applied to new tanks and to tanks that have experienced minimal bottom corrosion. Typically, thick-film linings are only used when a tank bottom has suffered severe corrosion. Information on minimum allowable tank bottom thickness is covered in EGS 266. Tank bottom linings generally cover the entire tank bottom and extend 450 to 600 mm (18 to 24 in.) up the tank shell. The design of the lining should follow the manufacturer's recommendations. Thin-film linings are generally applied in two or three coats to achieve the desired dry-film thickness. For thick-film linings,


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EGE 35-B-2 — 1993

one to four coats may be required to obtain the desired lining thickness. Thick-film or thin-film linings should not be used to prevent tank bottom leakage due to continuing soilside corrosion. 5.3.2

Tank Shell Linings

Thin-film linings are used most often to protect the shell against corrosion. They do not have to be the same lining material used to coat the tank bottom but must be chemically resistant to the stored product. Also, the tank shell lining must be chemically compatible with the tank bottom lining since the shell lining may be used to overcoat the bottom lining up to 450 to 600 mm (18 to 24 in.) of the tank shell. The only thick-film lining that can be used for the tank shell is the glass flake reinforced polyester type materials. 5.3.3

Tank Roof Coatings

Thin-film coatings are used to protect the roof underside from corrosion. The coating used should be compatible with the product stored in the tank. The same coating used for the tank shell and/or tank bottom is generally acceptable for the tank roof. 5.4

Lining Selection

Once it has been determined that a lining will be used, the type of coating can be determined from Tables 3 and 4. Table 3 presents the types of linings that can be selected and Table 4 shows typical dry-film thickness and temperature limitations of the particular coating type. The information in Tables 3 and 4 is industry accepted. The chemical compatibility, dry-film thickness, and temperature limitations for any paint product should be confirmed by the paint manufacturer prior to product use.


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FEBRUARY 1993

TABLE 3 COATING SELECTION (Note 1) Coating Reference Number (Note 2) Service

Thin-Film Coating

Thick-Film Coating

1,2 1,2,3 1,2,3 1 1,2 1,2 1 1 1

4,5,6,7 4,5,6,7 4,5,6,7 4,5,6 4,5,6,7 4,5,6,7 4,5,6 4,5,6 4,5,6

Potable water Utility water Wastewater Demineralized water Crude oil Fuels (low aromatic) Fuels (high aromatic or with MTBE) Ethanol MTBE NOTES: 1. 2.

The actual choice of possible products should be based on specific operating con ditions, economics, availability of produ cts, and qualified applicator, among other factors. Refer to Table 4 for the description of the coating reference numbers.

TABLE 4 TYPICAL COATING SYSTEMS Typical Total Dry-Film Thickness (DFT) µm 1. 2. 3. 4. 5. 6. 7.

Epoxy phenolic (Note 2) Epoxy (Note 2) Coal tar epoxy (Note 2) Glass flake reinforced Vinyl ester reinforced Polyester reinforced Epoxy reinforced

250 250 300 750 1250 1250 1250

— — — — — — —

Temperature Limits (Note 1)

(mil) 350 350 400 1000 2750 2750 2750

10 10 12 30 50 50 50

— — — — — — —

14 14 16 40 110 110 110

ºC 82 — 104 60 — 71 49 — 66 66 82 — 93 49 — 60 60 — 71

NOTES: 1. 2.

The temperature limit refers to the actual temperature the lining will or could be subjected to. See Tables 6 and 7 for examples of acceptable products.

ºF 180 — 220 140 — 160 120 — 150 150 180 — 200 120 — 140 140 — 160


5.5

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EGE 35-B-2 — 1993

Surface Preparation

5.5.1 Interior surfaces to be painted shall be prepared by blast cleaning to a near-white metal specification (SSPC SP 10) or to a white metal blast clean specification (SSPC SP 5) depending on the requirement of the coating chosen. 5.5.2 Welds should be inspected before and after blast cleaning. All sharp edges and protrusions should be ground to provide a smooth surface that can be completely and uniformly covered with the lining material. Sharp edges and protrusions may be caused by such things as weld spatter, sharp weld crests, undercutting of the weld, arc burns, erection clips, plate joints, burrs, and gouges. Chipping, followed by grinding, can be used to remove sharp edges. Early lining failure can result if sharp edges and protrusions are not properly removed. A suggested minimum radius of 3.2 mm (0.125 in.) for grinding work should be considered 5.5.3 The surface preparation abrasive should be selected to produce the necessary surface profile for the lining to be applied. The coating manufacturer’s recommendation for surface profile must be achieved in order to optimize the mechanical adhesion of the lining to the steel tank bottom. The surface profile required for linings is typically 3 7 to 63 µm (1.5 to 2.5 mil) and generally increases with the thickness of the lining. 5.5.4 Abrasive blasting should not be performed if the temperature of the steel surface is less than 3ºC (5ºF) above the dew point or if the relative humidity is greater than 80 percent. The surface to be coated should have the specified surface preparation at the time the lining is applied. If the surface is degraded or contaminated subsequent to surface preparation and prior to lining application, the surface should be restored before lining application. Since freshly blasted surfaces are subject to immediate corrosion, particularly in areas of high humidity or salt atmospheres such as marine environments, no more surface shall be blast cleaned than can be prime coated before visible or detrimental rerusting occurs. Blasted surfaces shall be prime coated no later than at the end of the same workday. To eliminate the problem of high humidity, use of dehumidification equipment should be considered. 5.5.5 The abrasive and compressed air supply used for abrasive cleaning of tank internal surfaces should be f ree of contaminants such as water-soluble salts, dirt, clay, oil, and grease. If present in the blasting abrasive, small amounts of these contaminants may be delivered to the steel surface during the cleaning operation. These contaminants will reduce the useful life of the lining. 5.6

Lining Application

The application of a lining shall be in accordance with manufacturer's recommendations. Manufacturer's requirements on temperature and humidity during application shall be followed. 5.7

Lining Thickness

Insufficient film thickness will not provide adequate coverage for protection. Excessive film thickness can compromise coating adhesion and film integrity. The lining thickness shall be in accordance with the lining specification and manufacturer's recommendations. 5.8

Lining Inspection

The lining work shall be inspected during application and upon completion of the work.


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FEBRUARY 1993

5.8.1 All inspectors should be either NACE certified or persons who have demonstrated a thorough knowledge of coating and lining practices. 5.8.2

Surface cleanliness and profile shall be verified prior to application of any coating.

SSPC VIS 1 provides reference photographs and NACE TM0175 provides steel reference panels sealed in clear acrylic plastic that may be used to visually assess surface cleanliness. NACE RP0287 provides a method of measuring surface profile. Other types of profile comparators are available from SSPC and coating instrument suppliers. 5.8.3 Soon after coating application, wet-film thickness measurements should be made. After the coating has cured sufficiently to allow handling, dry-film thickness measurements should be made in accordance with SSPC PA 2. Visual examination of the coating shall be conducted after curing. Particular attention should be given to note the presence of surface irregularities, such as runs, sags, alligatoring, foreign material, dirt, etc. 5.8.4 The integrity of all coating surfaces shall be verified by using an acceptable low-voltage, wet-sponge holiday detector, such as the Tinker Rasor Model M-1, Elcometer Model DG-2150, or their equivalents. Any pinholes or other defects detected shall be marked and subsequently repaired to yield a defect-free surface. 6.

TANK IDENTIFICATION AND MARKING

6.1 Identification numbers shall consist of numerals in the standard Mobil Alphabet (see Figure 1) painted on a background disk. The colors, sizes, spacing, and location of the numerals and background shall conform to the requirements given in Paragraphs 6.1.1 through 6.1.4. 6.1.1

Colors

(a) For Tank Shells Painted Mobil Beige or Black  Numerals shall be Century Red (Valspar Coating V20-R-101 or equivalent) on a White (Valspar Coating V20-W-2 or equivalent) disk. (b) 6.1.2

For Tank Shells Painted White  Numerals shall be White on a Century Red disk. Sizes

When the tank identification numerals contain several digits, their height shall be reduced to fit attractively into the background disk. Numerals shall be sized in accordance with tank heights, as follows: (a) For tanks 9 m (30 ft) and more in height (read "diameter" for "height" of spheres and horizontal tanks), all three-digit numbers shall be three-eighths of their background disk diameter in height. When practical, numerals shall be 900 mm (36 in.) high, and the background disk shall be 2.4 m (8 ft) in diameter. All four-digit numerals shall be one-quarter of their background disk in height. (See Figure 4 for typical layout.)


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EGE 35-B-2 — 1993


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FEBRUARY 1993

(b) For tanks less than 9 m (30 ft) in height (read "diameter" for "height" of spheres and horizontal tanks), the height of all numerals shall be one-third of the disk diameter (when practical) and the disk diameter shall be one-quarter of H. NOTE: Definitions of H for: Horizontal tanks and spheres  the diameter of the tank or sphere. Dome-roof tanks  the vertical distance from the tank bottom to the line of transition of shell to roof. Cone-roof, open-top  the vertical distance from the tank bottom to the top angle of the shell.

(c) For tanks with a height-to-diameter ratio greater than 1.5:1, disks shall be one-half the diameter of the tank but not less than 1.2 m (4 ft) or more than 2.4 m (8 ft) in diameter. Disks shall be positioned with their centerlines at two-thirds the tank height, but not more than 3 m (10 ft) below the top of the shell. 6.1.3

Spacing

A grid system over the numerals is illustrated in Figures 2A through 2E. The grids are composed of 75 mm (3 in.) squares when the numerals are 900 mm (36 in.) high. For other numeral heights, the square grid over the numerals should be used as a guide for enlargement to the desired size. If suitable equipment is available, it is preferred that the numerals be enlarged photographically or by optical projection. The spacing between numbers shown in Figures 2A through 2E is not the spacing specified in Table 5. In Table 5, where the proper spacing between numerals is given, a unit of spacing is equal to the grid spacing of Figures 2A through 2E. The first numeral is found in the left-hand column and the following numeral is found across on the top line. TABLE 5 NUMERICAL SPACING UNITS FOLLOWING NUMERAL

0

1

2

3

4

5

6

7

8

9

0

1

1/2

1/2

1/2

1/2

1

1

1/2

1/2

1/2

1

1

1

1

1

1

1

1

1

1

1

2

1/2

1

1

1/2

1

1/2

1/2

1/2

1

1/2

3

1

1

1

1

1

1

1

1/2

1

1/2

4

1

1/2

1

1

1

1

1

0

1

1/2

5

1

1/2

1/2

1

1

1

1

1/2

1

1

6

1

1/2

1/2

1

1

1

1

0

1

1/2

7

1/2

1

1/2

1/2

1/2

1/2

0

1

1/2

1/2

8

1/2

1/2

1

1

1

1

1

1/2

1

1/2

9

1

1

1

1

1/2

1/2

0

1/2

1/2

1


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EGE 35-B-2 — 1993

Example  To make up the number 472: The spacings between 4 and 7, and 7 and 2 are needed. Find 4 in the left column and read across to the column headed by 7. The unit answer is 0. To space 72, find 7 in the left column and read across to the column headed by 2, which shows a unit space of 1/2. The spacing units are measured from the extreme left- and right-hand edges of the numerals, as shown in Figure 3. 6.1.4

Location

(a) Horizontal Tanks  The identification number shall be located on one of the tank heads with the disk centerlines concentric to the head axis. (b) Spheres  The horizontal centerline of the disk shall be along the horizontal axis of the spheres. (c) Dome-Roof Tanks  The distance of the horizontal centerline of the disk below the line of transition of the shell to the roof of the tank shall be 3 m (10 ft) for tanks 9 m (30 ft) and more in diameter and onethird H for tanks less than 9 m in diameter. (d) Cone-Roof and Open-Top Tanks  The distance of the horizontal centerline of the disk below the top of the tank shell shall be 3 m (10 ft) for tanks 9 m (30 ft) and more in diameter and one-third H for tanks less than 9 m in diameter. The location of primary identification numbers on tanks within a group should be consistent; that is, all identification numbers should face the tank farm road. Where desirable from an operational standpoint, a second identification number of the same size may be located where convenient. Smaller secondary numbers (where required) may be located on the tank at suction lines or fill lines, or both. A white disk, 300 mm (12 in.) in diameter with 100 mm (4 in.) high Century Red numbers, shall be centered between the suction and discharge lines when they are close together. When these lines are widely separated, the disk shall be centered above a single line midway between the top of these lines and the top of the black bottom band or top of first shell course. 6.2 Certain structural aspects of the tank, such as excessive height-to-diameter ratio, the location and number of stiffening rings on an open-top tank, or the height of the vertical shell section of a vapor-dome tank, may preclude the sizing and location of the identification number as specified in Paragraph 6.1. In this case, the identification number shall be proportionately reduced in size and located to suit the tank condition. In a battery of such tanks, the modifications shall be consistent. For a neat appearance, the individual identification marks shall be aligned with regard to height. 6.3 A typical layout for a tank identification number located on a cone-roof tank 9 m (30 ft) or more in diameter is shown in Figure 4. The general principles regulating the layout of the numerals and disk shall apply to all types of tanks. 6.4 Should additional identification be required by local authorities, characters shall be in the standard Mobil Alphabet (see Figure 1), and the color system shall comply with Paragraph 6.1.1.


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EGE 35-B-2 — 1993


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EGE 35-B-2 — 1993


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EGE 35-B-2 — 1993


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Tank Diameter Greater Than 9 m (30 ft)

FEBRUARY 1993


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EGE 35-B-2 — 1993

6.5 Storage tanks shall be inscribed with the date of painting and/or cleaning. Letters and numerals shall be painted on the tank in red with an alkyd enamel such as Valspar V20-R-101 Bulletin Coating or equivalent, 25 mm (1 in.) high, with 3 mm ( 1/8 in.) stroke characters. Inscriptions shall be as follows: (a) "SHELL PAINTED (date) " shall be painted on the shell 200 mm (8 in.) above the edge of the manhole cover closest to the product inlet and outlet nozzles. The inscription shall straddle the vertical centerline of the manhole. (b) "ROOF PAINTED (a). (c) "CLEANED centerline.

(date) (date)

(d) "INTERIOR LINED Item (b).

" shall be painted 25 mm (1 in.) above the inscription given in Item " shall be painted on the manhole cover 150 mm (6 in.) above the

(date)

" shall be painted 25 mm (1 in.) above the inscription given in

The date in each inscription shall consist of the month and year only, and both shall be indicated in numbers; for example: 10-92. The particular paint product name descriptions shall also be included. 7.

MOBIL TRADEMARK

7.1 Tanks in prominent locations may have the Company trademark or logo (in the form of the word "Mobil") painted on their shells. The tank identification number shall be painted on the side opposite the trademark. In a given facility, the Mobil trademark shall be limited to one per side, or exposure, of that facility. 7.2 The Mobil trademark or logo shall be painted in Century Blue (Valspar Coating V20-B-101 or equivalent) and Century Red (Valspar Coating V20-R-101 or equivalent), in accordance with the grid and requirements shown in Figure 5. This trademark shall be painted only on Mobil Beige or White tanks. Size and location of the trademark shall be in accordance with the requirements of Figure 6. 7.3

For Company identity, the Mobil trademark should be painted only on cone-roof, or open-top tanks.

7.4 Certain structural aspects of a tank, such as an excessive height-to-diameter ratio, the location and number of stiffening rings on an open-top tank may preclude the sizing and location of the trademark as specified in Paragraph 7.2. In that case, the trademark shall be proportionately reduced in size and located to suit the tank condition. 8.

COATING INDEX AND LINING

8.1 Tables 6 and 7 key the generic coatings specified in this Guide and the acceptable dry-film thickness range per coat required for each product. The maximum dry-film thickness shall not be exceeded by more than 25 percent. 8.2 Tables 6 and 7 reference the use of Valspar Corporation paint products, or equivalents. Contact the MTC Facilities Group for acceptable equivalents. When a Valspar Corporation equivalent paint product is approved and used, the completion of the data form shown in Table 8 is required. Completed forms should be returned to the MTC Facilities Group. The information included in this form will be used to develop a performance data base to determine the effectiveness of a particular company’s products.


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FEBRUARY 1993

8.3 Compatibility between various manufacturers’ paints should be considered prior to paint selection. The MTC Facilities Group should be contacted for guidance on compatibility. 8.4 The generic coatings identified in this Guide are based on Mobil field experience. The MTC Facilities Group shall approve equivalence of manufacturers’ products that have not previously been adequately evaluated by Mobil.


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EGE 35-B-2 — 1993


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EGE 35-B-2 — 1993

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TABLE 6 UNDERCOAT INDEX Recommended Dry-Film Thickness

Generic Product

Examples*

m

mil

Color

Epoxy zinc rich

Valspar 13-F-4 or equivalent

50 to 75

2.0 to 3.0

Gray Green

Nonlead primer

Valspar 13-R-29 or equivalent

38 to 50

1.5 to 2.0

Orange

Metal primer

Valspar V89-W-71 or equivalent

50 to 75

2.0 to 3.0

White

Coal tar primer

Valspar V64-J-5 or equivalent

175 to 200

7.0 to 8.0

Dark Red

Tank lining high-build epoxy

Valspar V78-D-7 or equivalent

100 to 125

4.0 to 5.0

Light Buff

Epoxy mastic

Valspar V75-A-1 or equivalent

125 to 200

5.0 to 8.0

Aluminum

Epoxy mastic


125 to 200

5.0 to 8.0

White

Epoxy mastic


125 to 200

5.0 to 8.0

White

Phenolic alkyd zinc phosphate

Valspar V13-R-28 or equivalent

50 to 63

2.0 to 2.5

Red

Inorganic ethyl silicate

Valspar 13-F-12 or equivalent

75 to 100

3.0 to 4.0

Gray Green

Epoxy phenolic


125 to 150

5.0 to 6.0

White

________ *See Paragraph 8.4.


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FEBRUARY 1993

TABLE 7 FINISH COAT INDEX Recommended Dry-Film Thickness

Generic Product

Examples*

m

mil

Color

Alkyd enamel

Valspar V20-F-38 or equivalent

38 to 50

1.5 to 2.0

Mobil Beige

Alkyd enamel


38 to 50

1.5 to 2.0

Black

Tank white alkyd

Valspar 12-W-3 or equivalent

38 to 63

1.5 to 2.5

White

High-build alkyd tank white

Valspar 12-W-4 or equivalent

100 to 125

4.0 to 5.0

White

Epoxy mastic


125 to 200

5.0 to 8.0

White

Coal tar epoxy


200 to 250

8.0 to 10.0

Black

High-build epoxy


125 to 175

5.0 to 7.0

Black

High-build tank lining epoxy


125 to 175

5.0 to 7.0

White

High-build epoxy


100 to 175

4.0 to 7.0

Mobil Beige

High-build epoxy


100 to 175

4.0 to 7.0

White

High-build epoxy

Valspar V89-Y-21 or equivalent

100 to 175

4.0 to 7.0

Lemon Yellow

Epoxy mastic


125 to 200

5.0 to 8.0

Mobil Beige

Alkyd enamel

Valspar V20-B-101 or equivalent

38 to 50

1.5 to 2.0

Century Blue



EGE 35-B-2 — 1993

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TABLE 7 — Contd

Recommended Dry-Film Thickness

Generic Product

Examples*

m

mil

Color

Alkyd enamel

Valspar V20-R-101 or equivalent

38 to 50

1.5 to 2.0

Century Red

Alkyd enamel


38 to 50

1.5 to 2.0

White

Alkyd enamel

Valspar V20-Y-21 or equivalent

38 to 50

1.5 to 2.0

Lemon Yellow

Silicone acrylic


25 to 38

1.0 to 1.5

Gray

Urethane enamel

Valspar V40 Series or equivalent

38 to 50

1.5 to 2.0

Various

Epoxy phenolic


125 to 150

5.0 to 6.0

Light Buff


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