Seat leakage classes
Seat leakage classes
(OP)
Can the ANSI/FCI 70.2 (IEC 60534-4) control valve seat leakage classes be applied to ball valves? Well, OK, yes I know they can, but would a supplier/manufacturer supply/manufacture to such standards? Is there a standard specific for ball valves?





RE: Seat leakage classes
Hope this helps.
RE: Seat leakage classes
RE: Seat leakage classes
FCI 70.2 at least specified that you test on air or water at around 50 psi, and it strongly hints at how much leakage is allowed. It has no correlation to how much leakage you are going to get at operating pressure, though in any class except for class V. I think the Sierra club should pursue FCI for all the trees that have been killed in the printing of Class 1, which is absolutely and completely meaningless, exceeded in meaninglessness only by its uselessness.
MSS-SP61 is probably more appropriate for shutoff valves as is API 6D.
RE: Seat leakage classes
may be you'll find useful to consult the other posts about the issue in object within this forum:
- thread408-23297 ;
- thread408-76110 ;
- thread408-122060 ;
- thread408-135434 .
Hope this helps, 'NGL
RE: Seat leakage classes
John
RE: Seat leakage classes
Control valves because there primary function is to control are often not leak tight - the class rating is so that clients can specify a control valve which has also got a tight shut off capability.
This is not the same as Isolation valves - API598 does allow metal seated isolation valves to have a small amount of leakage across the seats but, soft seated valves are to have Zero leakage when tested.
Class VI is for soft seated control valves and does not specify zero leakage
RE: Seat leakage classes
A ball valve gets tighter with more differential across it.
Doesn't the standard also only go to 8"???
I can't count the number of times I've seen a 12" butterfly valve to class six tightness...
RE: Seat leakage classes
temperature. No visible leakage through the body or the disc or past the seat shall be allowed. Test duration shall not be less than shown in Table 4. I TABLE 4. SEAT TEST DURATION - see the standard.
John
RE: Seat leakage classes
I was a member of the API workgroup that made the latest revision to API 598. There are some important changes in the standard, so if you are working with any version prior to the current 8th edition (2004) you need to get the updated volume.
Greg Johnson
United Valve