Pcm of piping material is higher Pcm of PQR qualified

[quatle]

hello everyone
I have one question is: when I qualify a PQR carbon steel A106 Gr.B pipe to pipe, the Pcm calculated in mill certificate is 0.245%. however, Pcm carbon (A106Gr.B) piping material show on mill certificate for fabrication in my project is 0.255%, what we can do in this case.

 

[DVWE]

What fabrication code are you using?

Pcm carbon equivalency typically does not apply in piping codes such as ASME B31.3

 

[quatle]

DVWE,

Code applicable is ASME B31.3, 2014. but client's specification required Pcm allowed plus 0.02%

 

[CWEng]

If your client allows the Pcm qualified plus 0.02%, you should be qualified up to 0.265%. Typically you would want to specify this maximum on your WPS, and purchase all materials to be welded accordingly. The pipe with 0.255% Pcm should be fine if this is the case.

 

[quatle]

CWEng,
my project is urgently, If I do a new qualify PQR with Pcm highest, it mean that project will delay. 35% purchase materials higher WPS. almost my project is CS (P nos 1).
pls advise how to do, new PQR qualify or other better solution for this case.
Clients specication is not specify for carbon equivalent applied material typical, I think Pcm only applied for 0.11%C and low alloy steel up to hight alloy

 

[CWEng]

Sorry, I'm really not sure what your last post is saying.

 

[DVWE]

but client's specification required Pcm allowed plus 0.02%

Pcm allowed by your client? Or Pcm qualified in the PQR?

 

[DekDee]

quatle,
Is your clients specification in English ?
If so copy and paste or type the exact wording of the clients requirements - you will get a much quicker response.
Half of the questions we see on this forum are from people who don't understand the requirement as written or have misinterpreted the requirement.
If your first language is not English it can sometimes be hard to fully understand client requirements if written in English (in some cases you cannot understand them even if English is your first language. LOL !!)
Cheers,
DD

 

[quatle]

DekDee

thank you for your support, English is my second language.

we can see the section of clients specification as below:

4.2. Essential Variables
4.2.1. Essential variables shall be those required by the applicable industry code (e.g., API 1104, ASME Section IX or AWS D1.1) and the additional variables in TABLE 1. Any deviation from these variables shall require a new weld procedure be qualified. All essential variable tolerances listed as percentage variations apply to the actual qualified mean values recorded for each pass.
4.2.2. Test pieces for welding procedure qualifications shall be in accordance with the referencing COMPANY specification and industry standard.
4.2.3. Test pieces for procedure qualification of carbon steel shall be selected from the higher range of carbon equivalents. All qualified procedures are based upon the carbon equivalent (Pcm) of the parent metal being defined as:

Pcm = C + Si/30 + (Mn+Cu+Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B
4.2.4. Procedures shall be qualified for welding production materials with a Pcm up to and including 0.02% higher than the qualification test material. Heat / ladle analysis may be used if approved by COMPANY when product analysis is not reported. Use of higher Pcm steels will require a new welding procedure qualification.

 

[DekDee]

quatle,
See the first response from CWEng.
Your 0.245% qualified plus the 0.02% allowed by the specification means you are all OK with fabrication material up to 0.265%,
Cheers,
DD

 

[DVWE]

Agree with DekDee and CWEng.

 

[quatle]

DekDee and CWEng

I'm sorry for put wrong the acceptable table in my exel summary file. re-correct WPS Pcm is 0.22% and purchase materials is 0.56% sample. almost the material are Flange and fitting.