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Confused about ball valve pressure testing

Confused about ball valve pressure testing

Confused about ball valve pressure testing

(OP)
Hey
Greetings!
Firstly I have bought a Class 800 Socket welded three piece ball valve of CF8M material from a local purchaser.
Now I wanted to check if the purchaser has done proper testing of the valve according to API 598. And when I referred the standards the shell hydrostatic testing pressure should be 1.5 times cold working pressure for the given material from Table 2.2 (ASME 16.34), I found that the test should be done at around 1.5*132.4(approx)= 198.6 bar. Is that correct?
And if it is correct then what seat material should have been used while testing?
Because the material provided with the valve seat is PTFE and I have read that PTFE has 63 bar cold working pressure only. So is it that while testing at 198.6 bar PTFE will work correctly?
(P.S. I could have asked the purchaser directly but then its not learning RIGHT?)
Thanks in advance :)

RE: Confused about ball valve pressure testing

The shell hydrotest can be undertaken either with the valve in partially open (50%) position so that the pressure containing parts are exposed to pressure or without the valve ball or seals / seats.

Class 800 as noted before is a strange rating but if you use 132 as the rated pressure you're probably ok, so 1.5 times that for the shell PT is good.

Now that doesn't mean that the valve you buy is designed to seal at that pressure if the valve data sheet states max differential pressure is something different. In other words you can buy a class 800 valve that is only good for sealing up to 50 bar. The valve body won't break, but the seals might blow out if you put 100 bar across it. If you only are ever going to see say 10 bar or less, why pay more for a valve to seal at 132 bar when you don't need it to?

That lower max operating / differential pressure becomes your seat test pressure ( X 1.1 usually).

I don't know where you got 63 bar for PTFE, but may well be taken out of context. However the valve seat at best is only designed for 132 bar x 1.1. 198 bar is for the shell test ONLY, not the seat leakage test.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Confused about ball valve pressure testing

(OP)
Okay so if I want to do the shell testing that means I can do it at 198 bar pressure but without my seals/seats and all other valve trims except my body. Correct?
I mean what if I do it with whole valve assembled and at some 63 bar pressure I find leakage or the seals blow out then how am I supposed to test it because it hasn't reached 198 bar (calculated testing pressure for Cl800 CF8M material)?
P.S. I am trying to learn something here :)
Thanks in advance.

RE: Confused about ball valve pressure testing

Ok I'll try again.

You can test the shell with or without the ball etc. This test should be at 1.5 x rated pressure of the valve ( in your case a total of 198 bar)
If you test the shell with the ball and seats in place, the valve MUST be OPEN or at least 50% Open to prevent damage to the seats.

To test the seats you close the valve and test against one end or both ends.
What the seat test pressure is depends on what you have specified as the required Max pressure. In your case it appears to be a max of 63 bar, but I don't know where you got that figure from.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Confused about ball valve pressure testing

(OP)
okay I got it!
I will check the valve accordingly at 198 bar for shell test and 1.1 times the maximum pressure for hydrostatic seat leakage test.
Thanks for the help and you are really a true expert @LittleInch :)

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