PWHT after Hydro

[Mickey Brown]

Okay in B31.1 Section 137.1.5 Says hydrostatic testing SHALL be done after all NDE and PWHT. However because items were not mapped or tracked correctly there were some gamma plugs that got welded in and never PWHT before hydro. Once theses were found they were hydro'd, now my question is Do we have to hydro again?

All of this is on nonboiler external piping.
Section 137.8.3 says that we can do seal welds and welded attachments without re-doing our hydro. Now this make no mention of excluding any material class. Anythime you weld to P91 material you are required per table 132.2 to post weld. Knowing this would it be fair to say that PWHT after hydro does not invalidate the hydro?

I know this isn't the desired pratice, I'm just looking for the path forward.

 

[KevinNZ]

Hydro tests are not compulsory for NBEP have look at when it not required. 137.1.5 says if you are doing one then it needs to be after PWHT.

 

[metengr]

You can attempt to plead your situation with the owner per below

137.3.2 Nonboiler External Piping. All nonboiler
external piping shall be hydrostatically tested in accordance
with para. 137.4. As an alternative, when specified
by the owner, the piping may be leak tested in accordance
with para. 137.5, 137.6, or 137.7. Lines open to
the atmosphere, such as vents or drains downstream of
the last shutoff valve, need not be tested.

Also...

137.8.3 If repairs or additions to nonboiler external
piping are made following a test, the affected piping
shall be retested in accordance with the provisions of
para. 137.3.2. However, a system need not be retested
after seal welding or after attachments of lugs, brackets,
insulation supports, nameplates, or other nonpressure
retaining attachments provided
(A) the attachment fillet weld does not exceed 3⁄8 in.
(10.0 mm) thickness or, if a full penetration weld is used,
the material attached does not exceed the nominal thickness
of the pressure retaining member or 1⁄2 in. (12.0 mm),
whichever is less
113
(B) welds shall be preheated as required by para. 131
(C) welds shall be examined as required by
Table 136.4
(D) seal welds shall be examined for leakage after
system startup

 

[Mickey Brown]

I presented it to the client. I presented it that 137.1.5 gives the sequence that will be followed due to the risk of hydroing something with unknown stress that could fail during the test. We are already past that point and we know it has the pressure retaining capabilities that the last part of 137.1.5 refers to.
My stance was we had a successful hydro however it was later discovered that we had P91 material that was never PWHT.
The fact that we are post weld heat treating after hydro does not effect the test since code allows you to do work after hydro with out retesting that would require a PWHT.
The client has somewhat agreed and is requesting the results from the hardness and PT test that we are doing.