PSL 3G

[Michael C]

I'm in a bit of an argument with a veteran engineer. He's claiming all model M gate valves should be able to hold natural gas presser without leaking, I disagree. I'm telling him I've done PSL 3G test on model Ms before and they definitely leak under gas pressure. Can someone please confirm which one of us is right please? We keep going around in circles with this argument but I feel he's being stubborn. Also what does the G in PSL 3G stand for?

 

[SSCon]

The "G" means it passes gas testing.

 

[Michael C]

That's what I was telling the engineer it has to do with the GAS test , and I think he knows that too but doesn't want to admit his mistake. He' a good and very knowledgeable man, but stubborn as a mule.

 

[jmec87]

Yes, as SSCon has stated, the "G" means that the valve has passed gas testing (body, seat, and and possibly backseat - see API 6A 21st Ed. 11.3) as part of the factory acceptance testing. It does not guarantee that a used valve will pass a gas test.

Based on the current Cameron / SLB brochure, it looks like the model M valves are not typically available in 3G - see page 45 at the link below:

https://www.slb.com/-/media/files/sur/brochure/surface-overview-br.ashx

 

[Michael C]

Thank you jmec87

 

[jbeckhou]

The original type m was intended to only seal downstream. The upstream seat pocket has a non-sealing seat assembly which allows pressure to bypass the upstream seat and equalize throughout the valve body and only seal against the downstream seat. The handwheel is used to torque down the gate, jam-tight. The sealing action is mechanical not pressured energized. I've never seen it test gas but I would think it would be able to pass a gas seat test. The bonnet and stem aren't designed to backseat.



Petrotrim Services, LLC

http://www.petrotrim.com

 

[LittleInch]

Another AI post?

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