Steam service PSVs testing on Air Test Stand

[nasim123]

Dears

ASME SECTION VIII D1 2009, UG-136(d)(4) states " Necessary corrections for differentials in popping pressure between steam and air shall be established by the Manufacturer and applied to the popping point on air."

Is it mandatory to make the CDTP corrections while testing the Steam service pzvs in Air Test stand?

Your comment/advice pls.

 

[The Obturator]

nasim123 It can vary between manufacturer. I do know that for some manufacturers, and provided the valve had a suitable open bonnet (not only vented), no temperature correction was applied. This was due to the valve expected to get natural heat venting around the spring area. You will note however, that ASME states that all steam service safety valves should be set on steam where possible.

Per ISO, only the term Safety Valve is used regardless of application or design.

 

[CKchi]

Hi Nasim 123, Typically you should be able to get both CDTP value and Set pressure value from the PSV datasheet/ tag. When you test the PSV on the test bench, you only need to refer to the CDTP value.
But if the PSV is not originally designed for your steam service and now you want to use it on steam, you need to get the new CDTP value from valve manufacturer with providing them your set pressure and temperature at least.