the problem exists only with WAFER type butterfly valves, which have to be installed inbetween flanges (like a gasket).
LUG type butterflies have through threaded holes (except the ones adjacent to the stem which are blind holed) which means you can bolt either end independently.
Danlap, thanks for your point of view.
Allow me to disagree on your statement "Seat leakage acceptance criteria is always measured on the downstream side as per API 6D/API598/ISO5208/50 mm³/s x DN".
This is not true, in fact API 6D clearly states:
Checking leakage downstream is only allowed...
Danlao, this is a production test, 10% sampling and we are using 50 mm³/s x DN as allowable leakage, but this is not my point.
the concern i am raising to the valve manufacturer is the following:
if they are detecting the seat leakage through the body cavity during the ambient temperature...
We have a number of cryogenic TMBV's, 3x2 class 150, lip seals, PCTFE seats.
Seat configuration is SPE-DPE.
Valves have been tested 100% at ambient temperature according to API 6D (leaks detected through body cavity, DPE seat tested in both directions) with no leaks.
The problem is that BS6364...
a customer is asking me to repeat the shell test on all my trunnion mounted ball valves, for the simple reason that during the seat test we are removing the cavity vent device and putting it back
now this is something new to me
API 6D asks for checking seat leakage through cavity drain or...
Sorry for the weird question here.
Usually, when customers ask us to test RTJ valve with oval ring gaskets (to test RTJ groove integrity) we test it out of bench with blind RTJ flanges (full end thrust test).
Would it be possible to do the same thing on a vertical hydraulic testing bench...
also please note that UT requires a regular shapes and smooth surfaces to be correctly read by the operator, that is why UT is not performed on castings.
in my experience i've seen this terminology "high integrity seals" referred to thermoplastic seals (lip seals) which are intrinsically resistant to explosive decompression, unlike elastomers.
but again, this is interpretable in so many ways.
i looked at it, unfortunately the cap is not on the BOM (probably because it's a loose item)
i'm waiting for an answer from factory but i was curious to know your opinions!
hello, please take a look at the attached picture.
this cap is used as a mechanical stop in lever operated ball valves (it's got no "structural" duty as it's not subject to loads)
seems clear to me that's a casting (CS or cast iron) but i'm not sure if the material is also coated in some way...
Muktiadi, i think the answer is much simpler.
He should use FCI 70-2 for seat leakage tests, for the simple reason that API 598 / API 6D allowable leakages are meant for shut-off valves, therefore much more restrictive than FCI 70-2. Control valves are meant for control, not shut-off.
As for...
elastomers seats are not suitable for pressure classes 900 & higher. they will extrude in short time.
there is no need to go metal-to-metal
go with a high strength thermoplastic material like DEVLON-V or PEEK
obviously i am supposing your fluid is clean
