Valve stem rating
Valve stem rating
(OP)
We have a butterfly valve with 6" 2500# Flanges. A working pressure of 3080 psig, a differential pres of 700 psi. Materials are 316SS. How do I determine the minimum class rating for the stem and bushing inside the valve? If you could point me to the right standard or provide guidance I would appreciate it. The working fluid is Nitrogen.





RE: Valve stem rating
I'm not sure if that is exactly what you mean.
RE: Valve stem rating
Therefore, the butterfly valve internal trim must have been "down-rated" in respect to the flanges (meaning that the differential pressure allowed across the closed valve is much less than the pressure allowed within the open valve as a shell), I guess...
In this case, I believe there are no official standards for disc and stem design (maybe something exists for design verification, once you have chosen dimensions, but probably also for this FEM simulation is better than simple calculation formulas...?), but you should ask the Manufacturer what design pressures they considered.
Hope this helps,
'NGL
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RE: Valve stem rating