This article explores a few aspects around the concept of welding procedure qualification on a pipe test coupon. Is the full circumference of pipe necessary for qualifying the procedure? Does the answer change if we are talking about a welding performance qualification?
Consider the following question asked in Interpretation IX-19-11.
“Question: A groove weld procedure qualification is welded using a pipe test coupon that represents only a portion of the full circumference of the pipe. Is it required that a groove weld procedure qualification pipe test coupon represent the complete pipe circumference when the coupon is of a sufficient size to permit removal of the required test specimens?”
For procedure qualifications, the full circumference of the pipe need not be included in the test coupon. Article II (of Section IX) does not require full circumference, and only wants all tests to be covered. So, the size of the coupon must be sufficient to carve out all test specimens. Hence, the answer to the question has been given as ‘No’, by the Committee.
In fact, the inquirer need not even undertake the bother of using a pipe test coupon. Using a plate test coupon would be acceptable too. Qualification in plate also qualifies for pipe welding and vice versa. These exact words appear in QW 211.
However, would it be alright to use such a test coupon as described in question for welder performance qualification?
No. QW 302.2 specifies that the coupon “shall include the entire circumference for pipe(s)…”. QW 302.2 is for coupons tested through volumetric NDE.
What if the coupon is tested through mechanical tests? Would it be alright to use such a coupon for qualifying the welder/welding operator?
QW 302.1 (for mechanical tests) does not specify that full circumference is required when using a pipe test coupon. So it would seem that the coupon described in the question can be used. However, it holds to reason that – in pipe coupons, the performance qualification tests the ability of the welder to work around the outer diameter of the pipe (pipe OD being an essential variable for welder performance).
If the test coupon comprises only part of the circumference, it does not do justice to the qualification being pursued. Hence, in the opinion of the author of this article, for welder performance qualifications involving pipe test coupons – tested through volumetric NDE or mechanical tests, only full circumference coupon(s) should be used.
So this was all about this subject. Please do leave your observations in the comments section below.
See More:
Practice Case 6 – Backing For Welding Procedure Qualification