Soft Iron Gasket

[Krishnnaa26]

Dear All

Can anyone share information on selection and field experience of soft iron gaskets in subsea pipelines in wet crude/gas, gas lift and treated seawater injection services.

Krishnnaa26

 

[LittleInch]

They will corrode rather quickly.

Need a bit more information. Any CO2?

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[Krishnnaa26]

Thank you Little Inch.

Yes, CO2 in the range of 4-5 mol% and H2S is in the range of 0.3-0.35.

 

[Krishnnaa26]

missed to add that the preliminary corrosion assessment resulted in corrosion rates of ~0.1gmm/year for wet crude, 0mm/year for wet gas and ~0.05mm/year in gas lift lines.

 

[LittleInch]

You missed the issue of seawater corroding the gaskets from the outside....[tt][/tt]

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Also: If you get a response it's polite to respond to it.

 

[Krishnnaa26]

understand that, CP will be there by means of sacrificial bracelet anodes. I missed to add it thinking that it is like default condition.

 

[LittleInch]

The ability of CP to get into the crevices where the gaskets are is limited though.

It still seems like a wholly bad idea to me.

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[Krishnnaa26]

As per Section 9.4.1 of EEMUA 194 is indicating that CP covers the gaskets adequately.
Section 9.2.2.2 indicating that crevices formed by bolt and bolt hole are also covered adequately.

 

[LittleInch]

Well go ahead then and if you're still good after 10years job done ok.

It's not something I would do and for the incredibly small cost difference why are you taking the risk?

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[EdStainless]

So there is zero water in this oil?
I can't imagine that, and the pH of that water will be low with that much CO2.

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P.E. Metallurgy, consulting work welcomed

 

[LittleInch]

4-5% CO2 and only miniscule corrosion rate?

Are you sure? Something doesn't sound right there

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Krishnnaa26]

well, I think it is due to the H2S content present in the production fluids crude and gas. The FeS layer could be reducing the corrosion rate.
The wet crude is having water content during mid to tail end life.

 

[1503-44]

Even better.

Don't worry about mid and tail life, the iron won't last that long.

 

[Krishnnaa26]

Many thanks to all.

Personally, my choice will be Alloy 625 gaskets with Alloy 625 WOL in gasket grooves in view of the subsea service. I am trying to look for examples of successful field experience with soft iron gaskets.