Recommended ring gasket material for sour (h2s) service

[engr2GW]

Hi all,

welding flow lines in a sour service (100ppm to 20,000ppm) and ensuring that:
a. low hydrogen electrodes are used
b. WPS passes NACE Vickers hardness test
c. C.E for pipe materials are not too high...(is 0.45 too low???)
d. pre-heat when possible
e. insulation of weld after welding to delay cooling and leave more time for H to leave the weld
Additional questions are:
1. Is PWHT necessary for every weld?
2. Are there recommendations for ring gaskets for this kind of service?

Thank you.

 

[brimmer]

I would go with Teflon for gasket material (often CO2 present in gas with H2S). Could possibly get away with Viton depending on other constituants in gas.

I would complete PWHT for every weld, whether it is necessary or not you might get varying opinions. Hopefully you have a weld spec, it is your risk or procedure to take. I would say what you do for one weld, you should do for all.

 

[Duwe6]

Teflon does not work for a Ring Gasket on a RTJ - ring-type joint. No resielincy(sp), it flows under pressure.

Check with Flexitallic. They sell RTJ gaskets and are pretty expert in whak can be used where.

 

[austsa]

mysarah,
Need for pre- or post-weld heating depends on pipe material, wall thickness and minimum temperature. CE of 0.45 is not low at all.
austsa