ASME B31.3 Leak Tests
ASME B31.3 Leak Tests
(OP)
If a flanged valve is replaced, in kind, on an existing B31.3 process piping system, would this installation require a full hydrostatic test? Or is a service test sufficient.
No welding is performed and the valve was pressure tested by the manufacturer, documentation is available.





RE: ASME B31.3 Leak Tests
From the looks of it you will be stuck with the same test originally performed on the system.
Just my two cents worth.
A question properly stated is a problem half solved.
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RE: ASME B31.3 Leak Tests
In my non-inspector opinion this isn't a repair of pressure piping. You're swapping out a valve. The piping is unchanged.
If you were to swap out a pump casing for an equal pump casing, would you hydro the suction and discharge lines that flange up to the pump? Same concept, except the pressure change is reversed.
On the other hand, I've seen more than a few valves delivered with leaks even though they were tested by the name-brand, made-in-the-USA manufacturer.
- Steve Perry
RE: ASME B31.3 Leak Tests
But, if it is an old valve, then you need the service pressure test to verify you've done the repair (or removal and installation) properly. Here, present to the inspector the previous hydro test cert's, and plan on a service (operational) pressure test.
Don't try to make your case without the documents and pressure test data actually in hand however.
RE: ASME B31.3 Leak Tests
So the way I read it, in this instance it is possible for the Owner to specify a Service Test and the requirements of 4.4 and 5.2.
Correct?
RE: ASME B31.3 Leak Tests
RE: ASME B31.3 Leak Tests
No, a hydrotest is not required if the line had received an initial hydrotest.
Your rationale above is sufficient.
RE: ASME B31.3 Leak Tests
I'm assuming this is a line that was already in service (hence changing out a valve)
Depending on the service and specification requirements a hydro test would be an unnecessary cost (flushing prior to testing, additional blind installations, removal of test medium, air/steam blows,corrosion inhibitor drying, etc..)
Add all these things together and it can get expansive real quick. If your inspector is really worried about the flanges leaking try a "closure boltup" have him present to inspect the flange faces and witness the torques.
If the inspector still insists on a Re-Hydro , I foresee him looking for a new job in the near future.