This article discusses an example of two different performance qualifications in a single coupon. Both the portions are welded by the same welder. The difference between the two portions is that of welding position: one portion is welded in 2G position, while the other in 4G. How are the qualified weld thickness and position to be reckoned in such cases?
Consider the following question asked in Interpretation IX-17-12.
A welder prepared his performance qualification test coupon using a 20 mm thick plate. He deposited 10 mm thick in the 2G position, and deposited the next 10 mm in 4G position, in the same coupon. The questions asked were as follows:
Is this welder qualified to deposit unlimited thickness in each of the flat, horizontal and overhead positions?
The answer given in the Interpretation was No. Let’s see why.
Welding position is an essential variable for welder performance qualifications. So, each portion of the test coupon, that is – the one welded in 2G position, and the one welded in 4G position – has to be reckoned as a separate qualification.
In view of the same, the 10 mm thick 4G qualification only qualifies the welder to deposit up to 20 mm thickness (not unlimited), in flat and overhead positions, while the 10 mm thick 2G qualification qualifies the welder to deposit up to 20 mm thickness (not unlimited), in flat position only.
The inquirer asked another question in the Interpretation. Can this welder deposit weld thickness up to a maximum of 20 mm in each of the flat, horizontal and overhead positions?
This is a no-brainer. As explained above, he is perfectly eligible to do so. The Committee responded likewise as well in reply to the aforementioned Interpretation. The interpretation can be found on the ASME’s online Interpretations database.
The welder’s eligibility to deposit twice (2t) the thickness welded in test coupon comes from QW 452.1 (b), while the eligibility for positions is governed as per QW 461.9. As per QW 461.9, a welder qualified with 4G position can weld in both flat and overhead positions.
Now, in flat positions alone – is this welder qualified to deposit unlimited thickness? The inquirer has not asked this question, however, the question is worth pondering over.
Why would this question arise?
4G position qualifies a welder to weld in 1G position as well, and so does 2G. The total deposition thickness with both these positions in the test coupon is 20 mm, which is more than the 13 mm required for qualifying a welder for unlimited thickness.
So is the welder qualified to deposit unlimited thicknesses in production jobs? Is this consistent with Section IX rules?
No, it is not. Like we discussed above, position is an essential variable for WPQs, and the 1G weld and the 4G weld must be reckoned as two different qualifications. The deposited thickness in each of these qualifications is only 10 mm (and not 13 mm).
At any given time, only one qualification can be reckoned to determine the welder’s eligibility to make a weld. Hence, this welder is not qualified to deposit unlimited thickness in flat position, or in any other position.
So this was about how to reckon qualified weld thickness and position in welder qualification. Would you like to add something? Do share your thoughts in the comments section below.