ASME B16.34 / Body Minimum Wall Thickness

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ASME B16.34 interpretations - Docstoc

There will be several inside diameters of interest:
1) Inlet connection inside diameter.
2) Seat (orifice or opening) diameter.
3) Outlet passage inside diameter.

The flow capacity of the valve is most closely governed by (2); the other ID's will be larger:
1) The inlet pipe ID should be > the seat diameter; the valve ID will match the pipe OD.
2) The valve disk or plug will be somewhat larger diameter than the seat opening.
3) The annular area around the disk/plug needs to be >= the seat opening area.

The wall thicknesses of these areas depend on the pressure of the fluid, as well as the pressure exerted by the pipes screwed into the valve. Finally, this will determine the OD's of the various valve sections.

That is about as short and sweet as I can make it, without writing a book.

Thank you so much!!! for your answer!!!

May I think that

For the purpose of determining the wall thickness tm, the inside diameter, d is

diameter of seat(nozzle) at safety relief valve

right???

No. The wall thickness depends on the different ID at each different location, together with the pressure that will be encountered at each different location.

The size of any safety valve is a function of the volume and pressure of the vessel to be relieved, and the nature of the contents. Normally this will be determined by the Process Engineer in conjunction with the valve manufacturer prior to selection and purchase.