NACE MR0103 / SP4072 Interpass & PWHT Temperatures - P1 MATERIALS

[Geof]

I'm over my head here.

As far as I can find in either, 1125 +/- 25°F (i.e. 1100°F min) - 1 hour per inch / minimum of 1 hour is correct for standard P1 materials.
I have a customer (actually customer's customer's engineer in another county - so communication is difficult) who is stating it should be 1150-1200. This looks correct for martensitic stainless steels, but for C.S. is shows a minimum 1100°F - I can't find an exception.

And interpass: We specify 200° preheat & interpass for our MR0175 non-PWHT procedures, but do not require it when PWHT is to be applied in P-1 materials.

Am I off base? I don't think the requirements are correct, or perhaps they are just being more conservative, using someone else's specs, or using requirements from a different material.

 

[weldstan]

The increased PWHT temp. is not uncommon when in potential stress corrosion cracking environmemts. Increased stress relief does occur at the higher temp range.

 

[DVWE]

Reference API RP 582. Industry standard (at least in oil and gas) has gone towards 1175 +/- 25F for P1 base metals, and even higher at 1200 +/- 25F for P1 base metals in carbonate service.

Another industry standard for preheat is thickness driven for P1 base metals. 175-200 F is pretty standard for anything over 1", regardless of PWHT or not. Ref. ASME VIII, Div 1, non-mandatory appendix R and ASME B31.3.

The devil is in the details; she also wears prada.

 

[Geof]

Thanks,
This clears it all up, especially RP 582. Carbonates are even listed at 1200 to 1250 deg F.
I think we can still use our existing PQR's to write up a new WPS. The temperature increase on PWHT is only 50°. Hardness testing passed at the lower PWHT, so I don't believe a new PQR is necessary. I'll have to check to see if adding preheat is an essential variable, but we have two non-PWHT PQR's that we can list in the supporting PQR's.

 

[SJones]

Provided that the carbon equivalent values of the parent materials to be welded are within the essential variable limits.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[DekDee]

I am continually seeing Clients "wish lists" come into the equation and it drives me crazy.
If the contract documents state a code and a project specification then those are the governing documents - anything the Clients Welding Engineer "would like" to see is irrelevant if not covered in those documents.
I have been Clients Quality Rep on multiple projects where some "green" engineer has tried to enforce additional requirements because they liked them - have to explain the realities of life to them pretty bluntly.
Sorry for the rant.

 

[Geof]

DekDee - we're getting a lot of that. And wordsmithing of our standard documentation besides.

Just spoke with my CWI - turns out that we can't double up on PQR's i.e. one with PWHT but no Preheat, another with Preheat but no PWHT, to qualify a WPS with both.
Seemed logical, especially since the hardness testing passed with both procedures.
And...the 50°F increase: A change in PWHT temperature is an Essential Variable in Section IX.

So - redo from start.

 

[david339933]

You can't mix non-PWHT PQR with a PWHT PQR, unless you were looking for a WPS for both PWHT and No PWHT all in one...but the change in PWHT temperature is not an essential variable. You are still under the transformation temp.
You don't mention any impacts being applicable, so there is no reason you can't increase the pre-heat on the PWHT WPS.