Bellows in Bellows Sealed Nuclear Class Valve to ASTM A/B or ASME SA/SB?

[johcatrac]

Clauses NX-3515 in ASME III indicates bellows need not constructed to the requirements of the subsection if the bellows does not retain pressure and Design Pressure
is imposed on a required backup stem seal such as packing. But, a bellows in a bellows sealed valve is always retaining pressure - it is either seeing the upstream pressure or the downstream pressure. A reputed valve vendor supplied us the bellows material in ASTM B and when asked the question they reluctantly have agreed to change to ASME SB.
Does anyone on this forum have any insight into this?

 

[racookpe1978]

Depends on your application and where the bellow in question is used. Show the valve (and its bellows seal location around the stem ???)