PWHT of Temporary B31.1 Welded cap

[Gapinspect]

We need to weld a temporary cap (P1) to a (P4) pipe for a shop hydro-test of a spool piece. The only qualified weld procedure we have requires PWHT. Is there any exemption/code case/interpretation that allows us to perform the weld, perform the hydro, and cut out the weld. All without PWHT?

Thanks in advance

 

[LittleInch]

Remove the word "temporary" from your question and then think again. Once you pressurise something the word temporary should be banned as it leads to exactly this sort of thing - a desire to do somehting different or miss something out from what you would do if it was "permanent". Are you going to stand next to that cap when you hydro the spool or do you expect someone else to do it??

In these sort of situations always think about what you would tell the widow / police / court if it failed - Oh we didn't bother doing it properly because it was only "temporary" - doesn't sound like a good excuse to me...

Sorry for comong over all heavy, but I've seen this too many times and I'm on a mission to get rid of it wherever I can.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Gapinspect]

LittleInch thank you for your personal opinion. And although I do agree with you it is not much help in answering my question. So again, Is there any exemption/code case/interpretation that allows us to perform the weld, perform the hydro, and cut out the weld. All without PWHT?

 

[DekDee]

LittleInch,
You need to be very careful launching a personal crusade based on your personal opinion (no matter how noble the crusade may be).
I personally agree with your feelings but certain codes do not even require PWHT for P4 materials in certain circumstances.

GapInspect,
You do not nominate a code / standard or pipe wall thickness.

Hypothetically, you are asking about B31.1 and your pipe wall thickness is greater than 1/2" (13 mm) - that 13 mm is critical because that is your only exception to PWHT (that I can find).

This is from B31.1
122.10 Temporary Piping Systems
(F) Where temporary piping has been installed and
it does not comply with the requirements of this Code
for permanent piping systems, it shall be physically
removed or separated from the permanent piping to
which it is attached prior to testing of the permanent
piping system and prior to plant startup.

This clause is applicable to temporary piping installed for flushing and cleaning but it is also applicable to your situation - if it doesn't comply with permanent piping it must be removed before the pressure test.

Regards,
DD

 

[LittleInch]

Ok, answering posts late at night might not be the best idea in the world, but as both of you actually agree with me I am struggling to see why you don't take it in the spirit it is intended.

Gapinspect, I fully understand why you're trying to see if there is some easy way to do this, but you really need to ask your welding inspector / engineer as regardless of what we say it is him that would have to sign off on this.

In reality it will probably be ok and if you put in place procedures to eliminate personnel from the test location whilst the spool is under test and / or put guards in place in the unlikely event of failure of that weld then you can demonstrate that you have done all that is reasonable to prevent harm to people. Who you justify this to I can't say, but I would go with that approach rather than the mechanical argument.

I'm sorry if my approach was a bit OTT, but I truly feel that we all need to stand up and be counted when we see something we think is an unsafe practice.



My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[jbeckhou]

LittleInch 100% correct. If you do not have a QWP, get one.

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