SPExSPE
SPExSPE
(OP)
Hi all,
Does somebody has such experiences which is requested SPExSPE seats?
Thanks.
Does somebody has such experiences which is requested SPExSPE seats?
Thanks.
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RE: SPExSPE
Not 100% sure excactly what you mean, but SPE X SPE seated valve is common and in use for many applications not requiring double barriere. Can also refer to it as a DBB.
To be able to give you a good answer i need to know the purpose of the valve
RE: SPExSPE
If I've understood this right, SPE x SPE does not count in anyone's books as a DBB as there is no second block, for which you need one DPE seat at least. Even then lots of people / companies don't accept DPE ba;; valves as a DBB - see plenty of debate on this forum on this point.....
The question isn't very clear, but I agree with you - this is basically a standard ball valve able to seal in a single seat in both directions, but no need for a body pressure relief.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: SPExSPE
Be sure not to confuse DBB and DIB. For a DIB you need a second block ( e.g double piston downstream for trunnion ball).
You can choose to use a DPE x DPE or SPE X DPE dependent on what you need the barriere for.
A DBB valve has 2 seating surfaces to have seat sealing against pressure from both upstream and downstram the valve (SPE X SPE). This gives you only a single barriere, not double. If you need a double barriere, there is a need for a DIB valve.
For a DIB valve there is also a need for cavitydrain valve to verify the upstream barriere.
RE: SPExSPE
RE: SPExSPE
RE: SPExSPE
So, if you pressurize the cavity with the nozzles unde atmospheric pressure, the maximum inner pressure will be 0,33 x design pressure because at this time of test you do not have the pipeline back pressure.
The API 6D does not makes mandatory the use of a bleed on cavity. You have to ask it during purchase order.
RE: SPExSPE
RE: SPExSPE
RE: SPExSPE
Query on your statement, "A DBB valve has 2 seating surfaces to have seat sealing against pressure from both upstream and downstram the valve (SPE X SPE). "
For a valve to have a DBB function, is it a requirement to have both pressures on upstream and downstream? What if pressure on downstream is equal to zero?
Cheers,
RE: SPExSPE
Cheers,
John
RE: SPExSPE
RE: SPExSPE
The SPE seats are designed to reliev overpressure in the cavity (as Roberto1956 are stating).
My main point is to clarify the confusion between a DBB and DIB (as also Markgood mention), as i see that alot working with valves in the plant. Many people think it is always safe to work downstream a valve as long as the valve is classified as DBB.
RE: SPExSPE
DPE x DPE = DIB-1 (Two positive blocks regardless which side pressure is on. Seats cannot self-relieve themselves. External DTR required.)
SPE x DPE (or DPE x SPE) = DIB-2 (Two positive blocks with pressure from DPE side of valve. Only one positive block with pressure from SPE side of valve. SPE seat can self-relieve itself.)
DIB-2 is the style of API6D valve becoming the norm for many operation groups in the pipeline industry.