Fusion bonded Epoxy pipes - Internall coated pipes - hydrostatic pressure

[Green white]

I have 24 in pipeline, Thickness is 0.5 in, service is water
the design pressure for this pipeline is 1800 psi
the hydrostatic pressure is 2250 psi (90% of SMYS)

if this pipe is internally coated with Fusion bonded Epoxy (FBE), can i hydro-test the pressure to 2250 ?
or i need to consider the internal coating ?

 

[LittleInch]

Internal coating of FBE has no impact on hydrostatic test.

You don't need to do anything different and can test to 2250.



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[Green white]

Thank you LITTLEINCH for your quick response

Do you agree with the opinion that the FBE coating process requires heating the line pipe to about 250°C, and this can cause ‘strain ageing’, which can increase strength and decrease yield strength to ultimate tensile strength ratio (‘Y/T’.

 

[LittleInch]

Never heard of that before.

That's not to say it doesn't happen but given that it has happened on the outside for countless millions of pipes you would have thought it would be more common and understood....

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[SJones]

It can do. The principal effect tends to be more on Charpy toughness/fracture toughness. End users’ specs sometimes ask for examination of strain ageing response in the pipe mill qualification testing programme.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[IFRs]

Question from an ignorant newbie: Will the epoxy follow the pipe expansion or will it crack or delaminate?

 

[SJones]

@IFRs - if it has been applied correctly, and the hydrotest is within normal parameters, no. The coating will have some flexibility, as demonstrated by bend tests, for example.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[LittleInch]

IFRS,

FBE costings are quite flexible and will withstand being cold bent, which is a max plastic strain of 2%. This is on top of any elastic strain.

The coatings undergo bend and pull tests to ensure they can withstand this.

when they (FBE / spray coatings) first came out ( prob 40+ yrs ago) there were examples of de-lamination and bubbling over time, but in recent years the application and techniques have improved to the point where I would guess 90% of pipes designed for ambient temp pipelines have an FBE coating plus then sometimes a further coating to protect them even more.

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