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Hydro Re-Test

Hydro Re-Test

Hydro Re-Test

(OP)
If an existing piping system was designed and built to a piping specification of 265 psi at 100F.  Then given a operating pressure of 40 psig and hydro tested to 60 psig.  Would the line have to be re-hydroed if the operating pressure needed to be increased to 150 psig?  If it does need to re re-hydroed can you please reference the code?

RE: Hydro Re-Test

It depends on why you de-rated it.  If it was de-rated because of loss of pipe wall, then yes you have to re-test.  If it was de-rated because some component with a 40 psig MAWP was added and subsequently removed, then maybe not.  This is a case where documentation is absolutely key.

David

RE: Hydro Re-Test

Have to disagree with zdas. ANY use at a steady state pressure over 40 psig will require a retest.  There is no apparent rerate.  Some codes limit MAOP by a factor ,<< 1, of the lowest TEST pressure at any point along the pipe, no matter if all component's ratings are even 100 times higher than that.

YES! given the information you have (and have not) supplied, I'd say that it must be tested to a minimum test pressure of probably 187.5 psig and maybe up to 225 psig, depending under which code, and maybe even where in the system the pipe is located.  Some codes have area class design factors.

No references until you state which code.

What would you be doing, if you knew that you could not fail?

RE: Hydro Re-Test

I would want to know why it was rehydrotested at 60 psig, that's a big decrease from the original 265 psig design pressure and simply lowering the operating pressure does not require the system to be hydrotested in itself.

RE: Hydro Re-Test

TD2K, this does not say that it was "REhydrotested".  It says it was "given" an "operating pressure" of 40 and tested to 60. That would subsequently (and commonly) establish an MAOP of 40 based on that test pressure having been done at 60 and divided by a test-to-MAOP factor of 1.5  Why that was done might be a curiosity, but not really revelant to the proposal to uprate to 150 at this time.

 

What would you be doing, if you knew that you could not fail?

RE: Hydro Re-Test

Agree with BigInch.

RE: Hydro Re-Test

Just noticed that the title of the post does mention "re" test, so perhaps there is some ambiguity, but still it is not (yet) relevant to the question as it is written.

What would you be doing, if you knew that you could not fail?

RE: Hydro Re-Test

I just re-read it too and the first time I read that it had been tested to 265 psig and then de-rated to 40 psig.  After reading it again, the only test seems to have been 60 psig.  In that case I was wrong and you have to test to re-rate.  

The way I read it the first time you probably wouldn't have had to re-test.

David

RE: Hydro Re-Test

If the ONLY hydrotest of the line is at 60 psig then I agree it needs to be hydrotested if they want to increase the operating pressure to 150 psig. I took the 'design and built to 265 psig' in mean it was hydrotested accordingly to support that design pressure but if that's not correct then I agree with BigInch's interpretation.

The OP really needs to supply some more details.  Pretty hard to supply code references without knowing what code this piping was designed to.

RE: Hydro Re-Test

(OP)
To clarify the only hydro test on the line was at 60 psig.  It was not documented why the line was not hydroed at 1.5X the design of 265 psig.

Thank you for the quick responces.

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