Expoxy lining on face of flange

[jtseng123]

Dear all,
We have CS vessels and tanks require internal epoxy lining. When equipment arrived at site, found the lining on the face of flange was damaged and needs to be redone.

Questions from field contractor is: Is it necessary to line on the face of flange? They claimed it is not required.

Anyway, if it is deemed required,
(1) how to check if the epoxy lining surface is good for gasket seating? It can not be circular laid like metal, so not knowing what kind of surface preparation for gasket after lining.
(2). What kind of special gasket shall be used ? (demin water, slop oil, and other corrosive service) (304SS spiral wound which requires high seating stress may damage the lining). The connecting piping is galvanized.

Please advise if anyone has experience.

 

[metengr]

I would discuss with the valve manufacturer, I have seen both - epoxy coated and uncoated flange surfaces. It depends on the valve manufacturer and service duty.

 

[SJones]

http://www.eng-tips.com/search.cfm?q=coating+of+flange+face&action=search

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

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

 

[r6155]

All damaged parts must be repaired, you paid original requirements.

According to this post and the last in 19 dec 2017 “allowable compressive stress due to bending”, the quality system in your company need a review.

Regards
r6155

 

[DekDee]

Have a look at the link S.Jones has provided - specifically the post by eadwine in Coating of Flanges.
Explains pretty well what is required.
Flange face is broken into 3 parts - you have not nominated which part is damaged on your flanges.
1/3 inside the raised face - requires repair if epoxy damaged.
1/3 - the actual Raised Face - does not require epoxy coating
1/3 - outside the raised face - does not require epoxy coating but if coated with epoxy and damaged will require repair

 

[SnTMan]

jtseng123, my experience with coated flanges is to use a composition gasket, often a full face design. It is often worthwhile to consult the coating manufacturer before getting too far down the design road.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[LittleInch]

If you epoxy line the sealing faces of a flange you will need some sort of soft compressible gasket like neoprene or rubber to avoid damaging the epoxy.

The alternative often used is to get the sealing surface and the first part of the bore faced with something like Inconel 625. The sharp corner on the flange is often very difficult to coat and frequently fails any sort of spark testing.

If you need epoxy coating then it is clear this is required for all surface exposed to the fluid. The issue with the sealing surface is that it's very difficult to determine where this starts and stops and also sealing can be affected by the coating.

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