Fitting and Tubing Inspection_Chim Sao WHP

8/7/2019 Fitting and Tubing Inspection_Chim Sao WHP

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VIET MY TRADING SERVICES CONSTRUCTION CO., LTD

Chim Sao WHP visit report

Overview

Chim Sao Offshore Platform ProjectOperator: Premier Oil UKWater Depth: 115 m / 380 ftClimate: TropicalRegion: South East AsiaCountry: Vietnam

Discovered in 2006, Chim Sao, formerly Blackbird, is located on Block 12W and 12E in 377 feet (115meters) of water, around 248 miles (400 kilometers) southeast of Ho Chi Minh City, offshore Vietnam.The Chim Sao wellhead platform (WHP) jacket has been loaded out and in place in July 2010 and tocommence production on July 1, 2011.

Viet My (Swagelok Vietnam) was supplying Fittings (SS316), Tubing (SS316/316L) and Valves (SS316)for this project.

Background Information - Corrosion Issue

We were told after Chim Sao wellhead platform was put in place 4 -5 months later external corrosionstain occurs on Instrument tray, Bracket, Bolts and Nuts, Fitting, Tubing and Valves, sizes ¼” , 3/8”, ½”and 1” in instrumentation system:

We were contacted to help provide feedback on the corrosion and suggestion to address this issue.

Our team consists of Mr. Prapas Lamphuoc- Sales Account Manager, Mr. Nguyen Duc Thien-SalesEngineer visited the platform on February, 15th 2011.

Upon arrival at the Offshore Platform we were met by Mr. Gerry and was brief about what we can do andwhat he need from us regarding visual inspection. He assigned Mr. Dat -Mechanical Engineer, PTSCM&C and Mr. Viet - Technical Engineer, PV Trans (Premier Oil’s sub-contractor) to go with us around the

platform.

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We spent a total of half a day onboard Chim Sao WHP and we inspected the following areas:

1. Chemical Injection line

2. Water injection line

3. Hydraulic line

Customer comment and request

The comment and question customer asked us is:

1. All tubing system are SS316.

2. Fittings and tubing are SS316, why did green color stain appear on surface. They understandgreen color stain only appear on copper material.

3. Is there some solution that we can recommend to them to prevent reoccurrence, or at least inhibitreoccurrence to some degree?

Investigation Methods

Visual inspection of the corrosion component at Chim Sao wellhead platform. Photos were taken on for component before and after wiping with clean cloth. Our focuses are on Tubing, Tube Fitting and Valves

Observation

• The system is currently not in operation.

• The systems were located in an open area and exposed to high humidity (Water droplets and saltstain appear at all surface of components)

• What we see:

o “Brown color stain” or “Green color stain” on all uncoated component surfaces.

o When we wipe some of the stain came off but the external surface still revealed some

corrosion attack.

o The surrounding parts which were painted or coated (Grease), were found to be without

stain.

o Temperature in the surrounding area is normal but with strong wind.

o Water droplets and salt stain appear on uncoated component surface.

Summary

Visual Inspection reveal 2 kind of stains existing on component surfaces:

1. Brown color stain were found on fittings, tubing and valves surface which are located at

the Chemical Injection line and Hydraulic line. To determine whether the stains are actualcorrosion wipe the stains. Some component surface stain disappear, but some stain remain(reduce).

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Picture 3. Chemical injection Line – SS316 material fitting and fitting ½” & 1” Before wipe

Picture 4. Chemical injection Line – SS316 material fitting and fitting ½” & 1” After wipe

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Picture 5. Before wipe, water droplet on tubing ½” OD surface

Picture 6. Chemical injection Line – SS316 material tubing ½ ” OD After wipe

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Picture 7. Chemical injection Line – SS316 material tubing ½ ” OD Before wipe

Picture 8. Chemical injection Line – SS316 material tubing ½ ” OD After wipe

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Location – Hydraulic Line (second level above sea water)

Picture 9. Hydraulic Line

Picture 10. Hydraulic Line

Hydraulic lines are located at high levels which are difficult access without ladder or scaffolding. Assuch we were not able to clean the component and show the differences.

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2. Green color stain were found on fittings and tubing surfaces of the Water Injection line only.

We wipe the stain with clean cloth. We found the stain to be more difficult to remove.However those stain that was remove show dark gray surface.

Location- Water Injection Line (first and second level above sea wa

Picture 11. Water Injection system, Green Color stain on Tubing and Fitting

Picture 12. Water Injection system, Green Color stain on Tubing and Fitting

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Picture 13. Green Color Stain on tubing (Material?) and fitting (Monel) 3/8” OD

Picture 14. Water Injection line tubing (Material?) ½” OD Before wipe

Picture 15. Water Injection line tubing (Material?) ½” OD After wipe

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Picture 18. Green Color Stain on tubing (Material?) and fitting (Monel) ½” OD Before wipe

Picture 19. Green Color Stain tubing (Material?) and fitting (Monel) ½” OD Before wipe

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Picture 20. Green Color Stain on tubing (Material?) fitting (Monel) ½” OD After wipe

Our comment and Suggestion:

1. We confirm that both Chemical Injection line and Hydraulic Line are of SS316/SS316L (Sandvikprint on the tubing surface and Swagelok marking on Tube Fittings). However, the Water Injectionline tubing cannot be confirmed as we cannot see any printing on the tubing surface. We suspectthe fittings are Monel material, an alloy of nickel and copper. You can tell from the marking of theparts, for example, the nuts marked Swagelok-MSNA are nuts made from Monel and have heatcode SNA. It is typical for Monel to develop a greenish scale.

Monel does not necessarily have the best resistance to pitting and crevice corrosion resistance.

Since we are not sure what materials were used for the tubing, we suggest you check your recordto identify the material used. Cleaning is recommended, please see suggestion below.

Alternatively, you may want to look at Alloys 6Mo and 2507 which are better corrosion resistant to

seawater environment.

2. The "Brown Color rusted" on Chemical Injection line and Hydraulic line (SS316 parts) were most

likely contaminated with iron that may have come from different sources, for example, cutting,grinding, and blasting of structural parts of the platform. As soon as "free iron" accumulates on astainless steel surface, it will oxidizes to form a brownish deposit, giving the stainless steel arusted appearance.

From our visit we suggest the following step:

• Clean – To identify extend of the corrosion and prevent the spread of corrosion.

• Protect - Prevent the spread of corrosion.

• Change to compatible material.

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Cleaning

It is very important that stainless steel be kept clean. Regular cleansing with water is important,and if the cleansing is done with seawater than a fresh water rinse is recommended. The

customer should consider cleaning the tubing and fittings. There are many cleaning products inthe market . Please refer to British Stainless Steel Association recommendation for StainlessSteel as below:

Mild staining or surface 'bloom' Mild-non scratching domestic cleaning creams or polishes can be used.These usually contain calcium carbonate, withsurfactant additions. 'Jif' kitchen cream cleaner (Lever Brothers Ltd) is an example of such aproduct.Domestic stainless steel cleaners, which maycontain citric acid can also be used. Shiny Sinks -

(Home Products Ltd) is an example of such aproduct.

Moderate rust staining Phosphoric acid cleaners can be effective if sufficient time and care is taken, with minimal riskof etching the surface.Alternatively, dilute nitric acid should remove smallamounts of embedded iron and will helprepassivate the cleaned surface.

More severe rust staining Nitric / hydrofluoric acid pickling preparations

should remove more embedded iron than nitric acidalone.Surface etching is likely and so completerestoration to the original finish and surface texturemay not be possible.If these preparations are left on stainless steelsurface too long, pitting can be caused. There is alimit to what can be achieved.Although contamination may be removed, thesetreatments will not remove any pitting associatedwith severe staining.In such cases mechanical grinding may have to beconsidered to 'bottom-out' the pits which means

that a complete restoration of the surface will thenbe needed.

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Protect

Picture 21. Cover with Plastic to protect from sea water

Picture 22. Cover with Grease on Valve handle

This report is written by Prapas Lamphuoc, Nguyen Duc Thien, Andrew BT Wong

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Fitting and Tubing Inspection_Chim Sao WHP