Hydrotesting of ASME SEC VIII Div.2 vessel repair under NBIC 1

[qualitypro]

We have a major repair to be undertaken under NBIC to reweld the dished end to the shell of a ASME div.2 stamped HX in the field. The joints to be repair welded in the field are 6" and 3" in thickness. The HX has a design of 3000 psig. The original code of construction required a shell side and tube side hydro to be done at the shop and this was completed. Per NBIC can the field repair welds joints be 100% NDRE in lieu of a pressure test at 1.5 x design?

 

[TGS4]

What clause in NBIC would make you think that you could skip the pressure test?

Also, what’s the year of the original Code of Construction?

 

[fleischfresser]

I assume you mean the original Code of Construction is ASME Section VIII Div. 2.

NBIC Part 3, Para 4.4.1a)1) require for hydro test: Pressure tests shall be conducted using water or other liquid medium. The test pressure shall be the minimum required to verify the leak tightness integrity of the repair. The test pressure shall not exceed the maximum liquid test pressure of the original code of construction.

That means the minimum Test pressure for hydro test acc. to ASME VIII/2, para 8.2.1(a) is 1.25*MAWP*St/S (and not 1.5*MAWP) and shall not exceed the test pressure calculated acc. to para. 4.1.6.2 if design by rules was used.

NBIC Part 3 para 4.4.2 c) state: NDE may be conducted when contamination of the pressure-retaining item by liquids is possible or when pressure testing is not practicable. Concurrence of the owner shall be obtained in addition to the Inspector, and where required, the Jurisdiction.

In addition you must met the requirements of NBIC Part 3, para 3.3.5 (Repair Plan).

That means the repair must be accepted by the AI, the certifying Engineer, the owner and the jurisdiction. Therefor you need very good arguments to be able to do without the hydro test - I don't see any.

Regards - Juergen

 

[TGS4]

Yes - I was wondering what is the year/edition of VIII-2 that the vessel was originally built to.

I think that you are going to have a difficult time convincing the AI, your UDS Certifying Engineer, your MDR Certifying Engineer, the owner, and the jurisdiction to all sign-off on NDT in lieu of a pressure test. is there any situation that you have that would make the test "impracticable"?

 

[qualitypro]

@TGS4- the original construction code is 2019 edition

 

[Christine74]

I also don't expect that your AI will entertain this but here are two NBIC Interpretations that may or may not be relevant:

INTERPRETATION 98-38
Subject: NDE in Lieu of Pressure Test
Edition: 1998
Addendum: 1999
Question: Would the desire to save time and/or expense constitute pressure testing as not being practicable?
Reply: No. The determination of "practicable" is based on technical consideration of the nature and scope of the alteration activity.


INTERPRETATION 01-40
Subject: Use of VT when Pressure Test Is Not Practicable
Edition: 2001
Addendum: 2003
Question: If pressure testing is not practicable and if concurrence of the owner, Inspector and jurisdiction is obtained where applicable, may the Visual Testing (VT) NDE method be used to satisfy the NBIC requirement?
Reply: Yes.


-Christine

 

[qualitypro]

@ Christine74, thanks for sharing these cases. I am not sure if the Owner will concur with the approach of not doing a pressure test after the repair.
Also, I would like to know if a ASME VIII Div.2 vessel shop hydrotested at about 5000 psig,approved and stamped by the shop manufacturer's AI can be subjected to a rehydrotest in the field as part of the associated piping system circuit. The field piping joints are directly buttwelded onto the vessel nozzles and the customer is not inclined to have flanged joints or golden welds as we are dealing with high pressure critical toxic systems. Are there specific code requirements to be followed and are Code cases available that support this case? If so, what are the precautions to be taken per design code.

 

[qualitypro]

@fleischfresser, @TGS-4.. thanks for your responses. I dont think the owner is going to accept the repair without a pressure test.