PWHT Delay After Finishing Welding of (A387 Gr11 Cl2) Material According to B31.3

[TOMMY2010]

Dear Members,
Hope you are all well!

I am facing a situation where we already have done welding of two joints (φ24" | thickness of 18mm | Material. A387 Gr11 Cl2) which is a in process piping job according to B31.3.
What happened that one of my colleges already did all checks during welding according to our WPS.
Fit-Up--> Preheating --> Welding --> In the last step for this alloy material he was supposed to go with PWHT after welding but he didn't as our client told him verbally not to go with PWHT till he makes volumetric NDT with UT before PWHT. Also, The line has a refractory lining and it will complicated to run through cutting and rewelding.

For some technical issues, The NDT team which will proceed for the job came after 3 days of the welding finished. and now the client is complaining for the long time ( More than 1 day they said without mentioning a reference for that speaking ) it takes before the NDT team did the inspection and they wanted those joints to be cut !!

1. Is our client right for that and is there any reference for his speech ?
2. Is it actually a problem or not and
3.Is there any reference that might help in making a good decision in this situation?

Appreciating your time and help,
Thanks and regards.

 

[DekDee]

Firstly, if it is not written down it never happened. Never take verbal instructions that may cost you a lot of money.
Secondly, politely ask the client to reference where in B31.3 it says PWHT must be performed within 1 day

 

[david339933]

What does your WPS say in regards to preheat maintanence?..What does your client specs say in regards to preheat maintanence?
For B31.3 see 330.2.2

 

[gtaw]

Interesting. The carbon equivalent for this material is on the high side indicating an increased tendency to experience delayed cold cracking due to the presence of hydrogen related to welding. A reduced lag time between welding and PWHT reduces the probability of delayed cold cracking by reducing the hardness, residual stress, and permitting the hydrogen to effuse from the weld and HAZ.

There is an issue due to the need to perform NDE before PWHT, but that could have been mitigated by planning and scheduling the NDE at the proper time.

In many cases, welding standards prefer a delay in the NDE to permit any delayed cold cracks to propagate thereby increasing the probability of detection should they occur. The probability of developing delayed cold cracks is reduced as time passes, but any cracks that do develop shortly after the welds cool will propagate and be easier to detect with the passage of time. It takes time for the delayed cold crack to initiate and grow to a detectable size. So, delay the NDE so that sufficient time passes to allow the crack to occur if it is going to crack or immediately perform the PWHT to mitigate the conditions that cause delayed cold cracking to occur.

What has been stated by the other folks on this thread is reasonable as well; where are the requirements mentioned by the Owner's rep. stated? Verbal orders holds as much water as a sieve unless it is immediately commemorated in writing.

Best regards - Al

 

[TOMMY2010]

@DekDee,
- A great approach that I will use of course, Thx for your time and thx for you advice.

@david339933,
- on our WPS, Its clearly stated that preheat temperature shall be maintained. (Preheat Maintenance | Yes)
- The time of application of PWHT or this delay between Welding and PWHT is not mentioned in our client specs and I already checked it seeking for something that may be help but nothing is indicated relating this subject and actually I don't know if its good thing that will be in our favor or no.
- B31.3 see 330.2.2 I will recheck again if I could find something I didn't see before.
- I am really grateful for your time and reply.

@GTAW.
- In depth approach that is somehow clear like glass but does it mean that if till the time of NDT there is no cold cracks happened, then we are ok ? Only cold crack is our concern here ?
- The time of application of PWHT or this delay between Welding and PWHT is not mentioned in our client specs and I already checked it seeking for something that may be help but nothing is indicated relating this subject and actually I don't know if its good thing that will be in our favor or no.
- Thx for your time, advice which I really appreciate.

 

[david339933]

"Yes" for Preheat maintenance on the WPS is not the end of the world...it is non-essential. If the client specs don't mention preheat maintenance, I would refer them to 330.2.2.

SA-387-11 C2 is a P4 material.

330.2.2 - After welding commences, the minimum preheat temperature shall be maintained until any required PWHT is performed on P#3,4,5A,5B,6 and 15 E except when the following conditions are satisfied:
(b) - For P#s 3,4 and 5A materials, the weld allowed to cool slowly to room temperature.

That being said, your client may state that they approved the WPS because preheat maintenance was included.

 

[DekDee]

I think you need someone higher up the food chain to get involved as this is contractual.

341.3.1
(a) For P-Nos. 3, 4, 5A, 5B, 5C, and 15E materials, examinations
shall be performed after completion of heat treatment.

If you had programmed PWHT after welding and programmed NDT after PWHT then you are code compliant.
If the Client wants additional NDT (which you hadn't programmed for)done before PWHT (and it isn't in the contract specs) then any problems that may occur are the Clients responsibility.

 

[weldstan]

Clients have often required NDE to be performed before and after PWHT. If the Client did not specify such in its Contract specifications, it should have been done as a cost addition. NDE after PWHT as required by B31.3 will reveal delayed cracking, usually occurring in less than 72 hrs. There is no requirement in B31.3 to perform PWHT of this alloy within 24 hrs. of weld completion and if not defined in the Contract specifications the Client is liable for additional costs of compliance. This appears to be the whim of the Client's Inspector but ask him to justify his requirements by quoting Contract requirements for such. Finally it is up to your project management to interact with the Client's project management to resolve the issues,

 

[Dhurjati Sen]

The client could have their own standard that would supersede all construction codes. If they have one, look there first.

I hope you have wrapped the weld joints with ceramic fibres etc to ensure that the welds have cooled slowly to ambient. If yes, highlight this to the client and ask for a go ahead for PWHT.

Still the client does not agree!

Ask the client for any other NDEs like replica, hardness etc at your cost that would satisfy them.

Cutting and rewelding is not an option.

DHURJATI SEN

 

[0707]

If the material after welded, was not involved in ceramic fiber to cool slowly your client is right!

luis