Subsea valves with welding end
Subsea valves with welding end
(OP)
I am in process of writing subsea valve Spec with welding ends for manifold fabrication. So there probably are two contractors involved: valve manufacturer and manifold fabricator. Then how should I specify the FAT test in the valve Spec (no blind flange can be used for testing given the welding ends)? What is the typical work-around? The valve is pretty much specified along with 6A/17D. Thanks a lot.





RE: Subsea valves with welding end
With pup piece, you just make them longer than you need, weld a flange on, test it, cut the flange off and away you go. You then cut the pup piece to size.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Subsea valves with welding end
I do not think this statement is quite true based on the available evidence.
[It is relatively rare for a WE valve to be specified without a pup piece welded on during the valve manufacture]
It is also not consistent with my experience over the years I was still doing piping.
If you look at this web site >http://bonneyforge.com/resources/CSV.pdf< and scroll down to page 11 thru 14 you will see that all the gate valves come in Raised Face, RTJ Face and Butt Weld Ends all with the same end-to-end dimensions(L, L1 & L2) per valve size/rating. There is no indication that an extra Pup was added on.
prognosis: Lead or Lag
RE: Subsea valves with welding end
RE: Subsea valves with welding end
The dimensions of the valve are fixed, I agree, but as noted above by the OP, if you don't add a pup piece as part of YOUR data sheet / spec, then it becomes very difficult / impossible to test and, in reality, very difficult to actually install without risk of damage of seats (especially if these are soft seated) and issues about how to cut out or repair the weld if it fails NDT.
In addition, each valve then needs it's own WPS and test because it is a new material whereas if you supply the pipe pup that issue just goes away and becomes a valve supplier issue, not yours.
The only other possible way to test WE valves is to place them between seals and apply large forces to seal the ends whilst you test, similar to pipe mill pipe tests.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Subsea valves with welding end
RE: Subsea valves with welding end
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way