Do you hydrotest a MOV (this one is a ball valve)? 2

[NGil]

I "inherited" a job in which the purchase order required hydrotesting for Motor Operated Ball Valves. Now I’m wondering, and therefore the question: Do you hydrotest an MOV? Does anybody have an answer? Thanks

 

[JimCasey]

The same way you test a manual valve.

Open the valve about 50%, Put it in the tester, fill it with water until the overflow runs clear and free of bubbles. Valve off the overflow and engage the HP Pump. Run the pressure up to the ASME B16.34 test pressure for the material and class of the valve. Hold it there and watch for leaks-usually at least a minute, sometines 5 minutes. Long enough to be sure that the valve has full integrity.

Thn run the seat leak test. FCI 70.2 has the procedure: Close the valve and pressurize one side to 50 psi. Measure any leak flow. cc/minute or bubbles per minute, depending on the leak class to be met. Calculate the allowable leakage for the specified class and compare the observed leakage to the allowable leakage to determine if the valve passes. It may be appropriate or necessary to repeat the seat leak test with the pressure in the other direction.

It is dangerous and foolish to run the hydro test with air instead of water. The seat leak test may be run with air or N2.

 

[itsmoked]

Hi Jim.
Thanks for the clear explanation.

I take it the hydro test precedes an air bubble leak test to rule out a structural problem before getting a gas into the picture?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[JimCasey]

..>>I take it the hydro test precedes an air bubble leak test to rule out a structural problem before getting a gas into the picture? <<..

Yeah, that, and a pressure boundary flaw could show up as a seat leak and cause you to waste a lot of time reworking the seat before you realized that you had a flawed casting.

In case you were wondering, partially opening the ball allows the cavity between the seats to pressurize so you're not testing the pressure integrity of the bore of the ball (if full open) or of just one end of the valve (if full closed).

 

[itsmoked]

I wasn't .. But I should've!
Thanks again.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[NGil]

Thanks Jim.
NG

 

[JLSeagull]

For a ball valve I would consider API 598 instead of FCI 70.2.