failed hydro then pneumatic test as record

[eyec]

an ASME pressure vessel is hydro'd and leaks were found and repaired. instead of redoing the hydro a pneumatic pressure test was performed and used as the pressure test of record - is that allowable?

also, how does this square with ASNT?

TIA

 

[JohnGP]

Not sure what pressures you are talking about, but in my present facility it is hard enough to obtain approval for any pneumatic pressure test, but would be downright impossible to consider doing a pneumatic test after a failed hydrostatic test.

I've not answered your question, but the situation you describe would scare me.

 

[vesselfab]

ANST?

My shop would not allow it at all. Not sure what the AI would say.

I would never have thought to ask him the question.

 

[SnTMan]

well, I could maybe see it if it was a gasketed joint leaking, but otherwise not.

I'd say if the AI allows it, its allowed.

Regards,

Mike

 

[TJOrlowski]

Our shop would never allow that either, nor would we substitute acceptable test criteria without first clearing it with the customer. It sounds like the shop did not feel like taking the time to hydro again after repairing the leak.

I would ask for a copy of their NCR (make sure it has the disposition with AI sign-off). Then ask for their pneumatic test procedure, and actual test documentation, to make sure it conforms to UG-100.

-TJ Orlowski

 

[eyec]

as for my ASNT comment, under NDE - if a failure or reject is discovered by a specific method, then it must be re-examined by that method that discovered the failure/reject.

isn't a hydro an NDE method?

further, if the hydro is successful and a pneumatic test does not follow then i would consider that improper procedures. that is like - we'll do it this way and if it doen't work we'll do it that way!

 

[JohnGP]

Well ASME allows a pneumatic test to be undertaken instead of a hydro, but where a hydro is impractical (design or support issues, or remnant water cannot be tolerated) - see UG-100. The fact that the vessel was first hydro'd seems to suggest water was not a problem though.

The other thing is that the pneumatic test is at a lower pressure than the hydrostatic pressure test. Seems like cheating a bit there.....

Was this signed off by an AI?

 

[eyec]

UG100 was mentioned but water was not the reason for not re-doing the hydro - the drying out (heating process) was the reason for the change to pneumatic. not sure but i don't think UG100 is applicable.

besides could'nt dry air be used to dry out the area of repairs and then re-do the hydro.

 

[GenB]

ayec, you did not post what type of leak was found.
if it was just a pinhole in a porous weld, acceptable to put a weldpass and pneumatic re-test, it the hydro failed:
crack or other serious discountinuity, then a re-hydro is imperative.
genblr

 

[eyec]

the leak was in a weld. not sure of the severity as i was not present during the hydro.

 

[TJOrlowski]

There are two questions:

1) Was the U-1 signed by an AI?

2) Was a test method specified on the drawing?

-TJ Orlowski

 

[eyec]

the unit is not completed (requires other components) so i do not think the U1 has been completed yet.

will find out next week the answers to both questions.

 

[JR97]

eyec,

Hydrotest is not considered a non-destructive test (even if it doesn't leak!). Hydrotest and pneumatic tests are proof tests. A round-about way of demonstrating above, is Code requires NDE certifications be per ASNT SNT-TC-1A. SNT-TC-1A has many different NDE methods but nothing about hydrotest or pnuematic test.

JR97

 

[eyec]

JR97
thanks for that info.