00-SAIP-74

Insp nspe ect ction ion Proc roce edur dure e 00-SAIP-74 1 August 2009 Inspection of Corrosion under Insulation and Fireproofing Document Responsibility: Inspection Engineering Standards Committee

Saudi Saudi Aramco Desk DeskTop Top Standards Standards Table Table of Cont ents

1 2 3 4 5 6 7 8

Scope............................... Scope............................................. ........................... ............... .. 2 References................................ References.................. ........................... .................... ....... 2 Definitions........................... Definitions........................................ .......................... ............... 3 Responsibilities........................... Responsibilities............. ........................... ................... ...... 3 Susceptible Systems for CUI........................ CUI.......................... 4 Common Locations of CUI in Susceptible Systems.............................. Systems........................................... .......................... ............... 5 Guidelines for Inspection Program of CUI..... 6 Inspection for Corrosion Under Fireproofing (CUF).................... (CUF)................................. ............. 7

Previous Issue: 31 July 2004 Next Planned Update: TBD Revised paragraphs are indicated in the right margin Primary contact: Kakpovbia, Anthony Eyankwiere on 966-3-8747226 Copyright©Saudi Aramco 2009. All rights reserved.

Page 1 of 8

Document Responsibility: Inspection Engineering Standards Committee Issue Date: 1 August 2009 Next Planned Update: TBD

1

00-SAIP-74 Inspection of Corrosion under Insulation and Fireproofing

Scope This SAIP provides guidelines to inspection personnel on the development of an inspection program for corrosion under insulation (CUI) and corrosion under fireproofing (CUF) for plant facilities. Inspection for CUI includes insulation for cold and hot services in piping systems, pressure vessels and tanks.

2

References The following documents are to be used as reference for this procedure. 2.1

Saudi Aramco References Saudi Aramco Engineering Procedures SAEP-20

Equipment Inspection Schedules

SAEP-1135

On-Stream Inspection Administration

Saudi Aramco Engineering Standard SAES-N-001

Basic Criteria, Industrial Insulation

Saudi Aramco Inspection Procedure 00-SAIP-75

External Inspection

Saudi Aramco Standard Drawings

2.1

AA-036911

Insulation Details for Hot Piping

AA-036912

Insulation Details for Hot Vessels

AA-036913

Sht 1 Insulation Details for Cold Piping

AA-036913

Sht 2 Insulation Details for Cold Vessels

AC-036915

Details Fireproofing for Column and Vessel Skirts

Industry Codes and Standards American Petroleum Institute API-510

Pressure Vessel Inspection Code: Maintenance Inspection, Rating, Repair, and Alteration

API-570

Inspection, Repair, Alteration, and Re-rating of in-Service piping systems

API-653

Tank Inspection, Repair, Alteration, and Reconstruction

Page 2 of 8



National Association of Corrosion Engineers NACE RP0198

3

The Control of Corrosion Under Thermal Insulation and Fireproofing Materials- A systems Approach

Definitions Corrosion Under Insulation (CUI): CUI is an external corrosion which takes place as a result from the collection of water in the annu lus space between the insulation and the metal surface. Sources of water may include rain, water leaks, humidity condensation, cooling water tower drift, deluge systems and steam tracing leaks. It is a localized form of corrosion that occurs if certain operating conditions are met. It also includes chloride stress corrosion cracking of austenitic stainless steel under insulation. Susceptible Systems for CUI : Equipment and plant facilities that have greater tendency to become damaged by corrosion under insulation (CUI), due to its construction materials, process operating parameters or its geographical location (i.e. offshore or onshore as defined by SAES-H-001.) Vulnerable Location: are locations within susceptible systems for corrosion under insulation that, due to its geometrical shape or insulation con dition, will be damaged by CUI more than other locations. The inspection program for corrosion under insulation shall monitor these locations which will represent the general condition o f the insulated facility.

4

Responsibilities 4.1

4.2

The inspection unit supervisor shall be responsible for: 4.1.1

Assuring that an inspection programs for inspection of corrosion under insulation (CUI) and inspection for corrosion under fireproofing (CUF) are established and all susceptible systems for corrosion under insulation are being inspected and monitored.

4.1.2

Ensuring a worksheet or logbook entry for a minor defect found by the CUI inspection program or corrosion under fireproofing (CUF) inspection program is issued.

The plant corrosion engineer shall be responsible for: 4.2.1

Identifying all locations in the susceptible systems that are vulnerable for corrosion under insulation.

Page 3 of 8



Commentary Note: The corrosion engineer should interface with the process engineer to identify all piping systems and plant equipment that are susceptible to corrosion under insulation. He should also verify that all existing insulation on piping or equipment is needed either for energy conservation or personnel protection. All unneeded insulation shall be removed and related drawings and documents should be updated.

4.2.2 4.3

5

Review all repair procedures and make sure that factors promoting corrosion under insulation are being eliminated if possible.

The area Inspection shall be responsible for: 4.3.1

Ensuring all susceptible systems for corrosion under insulation and fireproofing are identified and monitored by the OSI program as per SAEP-1135.

4.3.2

Ensuring appropriate inspection methods are used for each vulnerable location for corrosion under insulation and fireproofing as per the schedule.

4.3.3

Ensuring that all insulated lines in the plant were considered for inspection for corrosion under insulation program.

4.3.4

Performing inspection on the vulnerable locations for corrosion under insulation and fireproofing as per the schedule.

4.3.5

Initiating a work sheet for any major findings and a logbook entry for any minor findings.

4.3.6

Performing visual inspection as per 00-SAIP-75 guidelines.

Susceptible Systems for CUI 5.1

Piping Systems Insulated piping systems shall be included in an inspection program for corrosion under insulation if any of the followings conditions app ly: 5.1.1

Piping systems made of carbon steel and operating temperature between 25ºF (-4ºC) and 250ºF (121ºC).

5.1.2

Piping systems made of carbon steel and operating temperature above 250ºF (121ºC) or below 25ºF (-4ºC) but in intermittent service.

Page 4 of 8


5.2


5.1.3

Piping systems made of austenitic stainless steel and operate between 100ºF (38ºC) and 400ºF (204ºC).

5.1.4

Piping located in areas exposed to mist overspray from cooling water towers.

5.1.5

Piping systems located in areas exposed to steam vents.

5.1.6

Piping systems exposed to deluge systems.

5.1.7

Piping systems subject to process spills, ingress of moistures or acid vapors.

5.1.8

Deadlegs and protrusions from insulted piping that operates at different temperatures of the main line.

5.1.9

Steam traced piping systems that may experience tracing leaks, especially at tubing fittings beneath the insulation.

5.1.10

Piping systems with deteriorated coating and wrapping, damaged insulation cladding, or insulation that might be da maged by piping vibration.

Insulated Drums, Vessels and Heat Exchangers: Insulated equipment shall be inspected for corrosion under insulation if any of the following conditions apply:

6

5.2.1

Equipment operating between 25ºF (-4ºC) and 250ºF (121ºC).

5.2.2

Equipment operating above 250ºF (121ºC) or below 25ºF (-4ºC), but in intermittent operation.

5.2.3

Equipment protected by deluge water system.

Common Locations of CUI in Susceptible Systems 6.1

Common locations in piping systems as per API 570 and NACE RP0198: Piping systems susceptible to CUI as stipulated in 5.1 may have specific locations, which will be more vulnerable to CUI than the rest of the piping systems. 6.1.1

All penetrations or breaches in the insulation jacketing such as deadlegs (vents, drains, instrument tapping and similar items), pipe hangers and supports and steam tracing tubing penetrations.

Page 5 of 8


6.2


6.1.2

Irregular insulation surfaces such as valves and fittings.

6.1.3

Bolted-on shoes.

6.1.4

Terminations of insulation at flanges and other piping components.

6.1.5

Damaged or missing insulation jacketing or when the seams of the insulating jacketing are located on the top of horizontal piping.

6.1.6

Termination of insulation in a vertical piping.

6.1.7

Caulking that has hardened, has separated or is missing.

6.1.8

Bulges or staining of insulation or jacketing.

6.1.9

Low points in piping systems that have a known breach in the insulation system, including low points in long unsuppo rted piping runs.

6.1.10

Carbon or low-alloy steel flanges, bolting and other components under insulation in high-alloy piping systems.

6.1.11

UT measurement windows in the insulation jacketing.

Common locations of CUI in insulated vessels and tanks as per API 510, API 653 and NACE RP0198. Insulated vessels and tanks that are susceptible for CUI have locations that are more prone to CUI than the rest of the equipment. Examples of highly suspect areas include, but not limited to the following: 6.2.1

Stiffening rings and insulation suppport.

6.2.2

Areas around nozzles and manways.

6.2.3

Areas around protrusions; like lifting lungs and platforms supports. Commentary Note: If practical, these locations can be inspecteed internally by thickness measurements during equipment T&I in lieu of insulation removal or NDT.

7

Guidelines for Inspection Program of CUI Insulated equipment and piping systems shall be identified and ch ecked if they meet any of the criteria stipulated in this procedure for vu lnerability to corrosion under insulation. All equipment and piping systems susceptible for CUI, as per section 5 of Page 6 of 8



this procedure shall be inspected frequently through an inspection program structured as per this procedure. Inspection frequency shall be as per SAEP 20. Susceptible systems shall be thoroughly inspected visually. Visual inspection shall identify any sign of damaged insulation, jacketing or deviations from SAES-N-001 and Saudi Aramco standard drawing requirements as referenced in this SAIP. Bulges in the insulation have to be identified since they may be signs of corrosion under insulation. Any other sign of corrosion under insulation has to be identified through the external visual inspection. Commentary Note: It should be noted that CUI might take place without any sign of it on the external surface of the insulation. NDT may be used in lieu of insulation removal provided the method and extent of NDT is approved by Inspection Department.

Samples of the common locations of corrosion under insulation a s described in section 6 of this procedure and locations of damaged insulation found through visual inspection of the system shall be inspected by either NDT or insulation removal. Quantities of inspection samples are as shown in Table 1. Piping classification is per section 6.2 of API-570. All vessels and tanks are to be classified as class 1. Table 1 Class 1 2 3

% of locations found with damaged insulation to be inspected by NDT or insulation removal 75% 50% 25%

% of locations defined by section 6 of this procedure to be inspected by NDT or insulation removal 50% 33% 10%

If the inspection of the locations found significant corrosion under insulation, then the percentage of location selection should be increased. If the system is known to have a good coating system, or if the system has a good history from previous inspections for corrosion under insulation, then the percentage o f locations selected can be decreased 50% of the amounts given in Table 1.

8

Inspection for Corrosion Under Fireproofing (CUF) Fireproofing on static equipment and piping systems shall be considered as insulation. Equipment furnished with fireproofing shall be inspected for corrosion under fireproofing as per the guidelines of sections 5, 6 a nd 7 of this procedure. 8.1

For Static Equipment Skirts, Saddles and Elevated pipe Supports Thorough visual inspection shall be performed. Areas near moisture and water entry points shall be given more attention during inspection. Any crack in the Page 7 of 8



fireproofing shall be studied to find out if it is indicating an y sign of corrosion. Inspection windows might be made to verify an y external sign of corrosion under fireproofing. If corrosion is found then the fireproofing shall be removed to expose all corroded area. 8.2

For Structures and Pipe Racks Visual inspection shall be performed to find out an y external sign of corrosion under fireproofing. Inspection windows in form of horizontal stripes should be made if deemed necessary. They should intersect cracks at random locations. If corrosion is found, then all corroded area shall be exposed. If any NDT can be applied to inspect the equipment under fireproofing for corrosion, then inspection windows or stripes should not be made.

1 August 2009

Revision Summary Editorial revision to change the Primary Contact.

Page 8 of 8

00-SAIP-74

Recommend Documents