Define an Examination Lot per ASME B31.3

[WDSeng]

Hello Everyone,

I am working with an ASME code fab shop that is fabricating and testing a few small piping systems (8 butt welds each) per ASME B31.3. The pipe fab shop and I have a difference in opinions on what defines a lot.

Per ASME B31.3-2014 para 341.4.1(b)(1), "not less than 5% of circumferential butt and miter groove welds shall be examined fully by random radiography in accordance with para 344.5 or by random ultrasonic examination in accordance with para. 344.6. The welds to be examined in each designated lot shall include the work product of each welder or welding operator whose welds are part of the lot."

ASME B31.3 Para. 344.1.3 note 1, "A designated lot is that quantity of piping to be considered in applying the requirements for examination in this Code. The quantity or extent of a designated lot should be established by agreement between the contracting parties before the start of work. More than one kind of designated lot may be established for different kinds of piping work. See Pipe Fabrication Institute Standard ES-48, Random Examination, for examples of lot selection.”​

Per 341.4.1(b)(1), there is minimum examination required for each designated lot. Para 344.1.3. states the "designated lot should be established between the contracting parties". The fab shop is stating that they do not need to provide 5% RT on my job because they have achieved at least 5% RT based on overall manufacture (some fabrications require 100% RT). This doesn't make sense to me that they use RT from other fabrications towards minimum requirements on my fabrication. I would like your feedback on whether their interpretation of a lot is appropriate and in accordance with ASME B31.3.

Thanks in advance for your input.

 

[metengr]

What did you specify in your contract specification????

 

[XL83NL]

I understand your question metengr, but would the fab shop even be allowed to reach 5% over a scope of work that does not include that of the OP?

 

[metengr]

Hi XL83NL;
No.

 

[WDSeng]

metengr,

Contract specifications are still being developed. When minimum required examination was not listed then questioned we were told those requirements would be met by overall manufacturer not per this single contract. This raised a red flag with me.

Let's say we have contracts A, B and C with this fab shop to build different piping systems for 3 different end users. Does their stance hold true if they use RT from contract A (100% RT) for Contract C (5% RT). It still doesn't make sense to me.

Thanks.

 

[weldstan]

To answer your last question, No. You may not use the 100% RT form Contract A to meet Contract C. Each contract lot is independent from another contract.

 

[DekDee]

" The quantity or extent of a designated lot should be established by agreement between the contracting parties before the start of work."

If you have let them start work without clarifying this requirement you may be chasing your tail for a while.
Good luck,
Cheers,
Shane

 

[david339933]

Agree 100% with Weldstan - Cannnot use Contract A NDE to cover any other contracts.

344.1.3 states 100% examination as - "complete examination of all of a specified kind of item in a designated lot of piping."
So if all circ seams are required to be RT'd in Contract A (100%) then that is a lot of piping.

I would tell them....If they are considering all contracts to be one single lot.....they are in violation of contract A which requires 100% NDE of the entire lot....might change their tune.

 

[DekDee]

Interpretation: 3-5
Subject:
Date Issued:
File:
Progressive Examination
May 29, 1984
B31-84-009
Question: In applying the ANSI/ASME B31.3 requirements for progressive examination in 336.5.4,
random radiography is specified within "a designated lot" of piping. Is it permissible to include
piping from more than one owner in "a designated lot"?
Reply: No.

If your "end-users" are the "owners" then it is quite clear the contractor cannot combine contracts A, B & C

Cheers,
Shane

 

[WDSeng]

Thanks everyone, I appreciate your feedback. I will touch base with the supplier and let you know the outcome.