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Thickness Range when CVN is involved - AWS D1.1

Thickness Range when CVN is involved - AWS D1.1

Postby laurudolphy » Thu Dec 12, 2013 4:07 pm

Dear friends,

A 25 mm plate coupon was used to qualify welding procedure with CVN test requirement. Therefore the qualified thickness range is:
Plate thickness range 3 mm to unlimited when CVN is not involved (Table 4.2, Section 1).
Plate thickness range 16 mm to unlimited when CVN is involved (Table 4.6, variable 2).

A suggestion was put up to me by somebody regarding that qualification:
Weld another test coupon with thickness less than 6 mm using the same WPS doing only CVN test and incorporate the report of the present CVN test into the original PQR. By virtue of this second CVN test, write another WPS and the thickness qualified would be from 3 mm to unlimited with CVN (Table 4.6, variable 2) provided that all other essential and supplementary essential variables apply.

Is this acceptable? My answer was NO, as the second coupon does NOT conform to the "ORIGINAL TEST" as specified in clause 4.36.3 of AWS D1.1: "When CVN testing is a requirement, a PQR with CVN tests and a qualified WPS are required. Either a new PQR shall be prepared or if a PQR exists which satisfies all requirements except for CVN testing, it shall be necessary only to prepare an additional test weldment with sufficient material to provide the required CVN test specimens. A full or partial (as noted above) test plate shall be welded using a WPS which conforms to the original “test” if applicable and the limits of Tables 4.1, 4.2, and 4.5, plus those supplementary essential variables applicable only to CVN testing (Table 4.6). A new or revised PQR shall be prepared and a new or revised WPS written to accommodate the qualification variables for CVN testing."

Request you to share your thought.

Thanks
laurudolphy
 
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Re: Thickness Range when CVN is involved - AWS D1.1

Postby techupon » Sat Dec 14, 2013 10:50 am

Weld another test coupon with thickness less than 6 mm using the same WPS

Laurudolphy,

The above statement is not correct because you cannot weld thickness less than 16 mm with the original WPS when CVN test is required. So, your interpretation is correct since the WPS for welding the second test coupon doesn't conform to the original WPS basically in terms of thickness.

regards,
techupon
techupon
 
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Re: Thickness Range when CVN is involved - AWS D1.1

Postby laurudolphy » Sun Dec 15, 2013 3:16 pm

Thanks Teckupon, for your confirmation.
Regards
laurudolphy
 
Posts: 51
Joined: Wed Aug 14, 2013 1:19 pm

Re: Thickness Range when CVN is involved - AWS D1.1

Postby mawsamit » Fri Jan 10, 2014 6:08 pm

Dear Laurudolphy and Techupon,

As per my interpretation of section 4.36.3 you can weld another test coupon with thickness less than 6 mm based on the existing PQR since the qualified thickness range is 3 mm to unlimited. Then you shall perform impact test to test specimens taken from that coupon as per AWS D1.1 requirements and provided that the results are acceptable, the extended procedure qualification will qualify for thickness as per the variable 2 of table 4.6 (3 mm to unlimited). The key point is that you are to weld a test coupon so as to perform impact test and not a production welding with impact test requirements (the qualified thickness range of the former is 3 mm to unlimited and of the latter 16 mm to unlimited).

Please let us have your opinion

Thanks,
mawsamit
mawsamit
 
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Re: Thickness Range when CVN is involved - AWS D1.1

Postby laurudolphy » Sun Jan 12, 2014 4:17 pm

Thanks Mawsamit.

Can you please explain what is the meaning of statement "using a WPS which conforms to the ORIGINAL TEST" that referred in clause 4.36.3 ?

When you say that this 16 mm is only when impact test is required for production weld, do you mean that when we don't do impact test during the preparation of the PQR, we can still perform production welds with thickness 16 mm and above when impact test is required ?
laurudolphy
 
Posts: 51
Joined: Wed Aug 14, 2013 1:19 pm

Re: Thickness Range when CVN is involved - AWS D1.1

Postby techupon » Mon Jan 13, 2014 4:02 pm

Mawsamit,

To my opinion the code is clear since it clarifies in clause 4.36.3 that among others the WPS for the preparation of CVN test coupon shall conform to the table 4.6. As per the variable 2 of table 4.6 you cannot weld thickness less than 16 mm with the original WPS.

regards,
Techupon
techupon
 
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Re: Thickness Range when CVN is involved - AWS D1.1

Postby Logosweld » Tue Jun 10, 2014 9:28 am

CVN requirement now a days become mantatory for particularlu Oil and Gas industries.
Logosweld
 
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Location: India


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