This article explores the question of using a WPS qualified on a groove weld for tube-to-tubesheet welding, while using a welder qualified on demonstration mock-ups of QW 193. And vice versa, using a welder qualified on a groove weld for tube-to-tube sheet welding, while using a WPS qualified in accordance with QW 193. The article touches upon both the procedure as well as performance qualification for tube to tubesheet welds.
Consider the following question asked in Interpretation IX-16-14.
“Question: When the applicable Code Section does not require the use of QW-193 for tube-to-tube sheet demonstration mockup qualification tests, is it permitted for a welder, qualified on a groove weld test per QW-303.1 to perform tube-to-tubesheet welding on a Code item using a WPS qualified for tube-to-tubesheet welding in accordance with QW-193.1, provided the welds are within the limits of the welder’s qualified range?”
The performance qualification for tube-to-tubesheet welds is governed by QW 387, which is clear in stating that a mandatory use of QW 193.2 is necessary only if the applicable Code Section requires use of QW 193 for welding qualifications.
QW 387 also says that if the construction code does not invoke any specific qualification test requirements, then the performance qualification for tube-to-tubesheet welds can be done on a groove weld (or fillet weld, if the production joint is to be made with fillet) as per QW 303.1 (or QW 303.2), or as per the demonstration mock-ups as described in QW 193.2. Clearly, a choice has been given.
A similar stipulation appears in QW 202.6 for procedure qualifications too, for tube-to-tubesheet welds.
The question above is clear in that the applicable Code Section does not require use of QW 193. So, the welder qualified on a groove weld as per QW 303.1 is definitely permitted to weld the tube-to-tubesheet joints. The inquirer probably wants to ask whether the welder qualified on a groove weld can weld with a WPS qualified in accordance with QW 193.1.
In other words, is it necessary that a WPS qualified in accordance with QW 193 be used by a welder also qualified in accordance with QW 193?
The answer to this is no. The Committee’s reply in the Interpretation affirms this.
The performance qualifications and procedure qualifications are mutually exclusive, and have to be treated separately. When the applicable Code Section does not call for the use of QW 193, then for both procedure qualification and performance qualification, Section IX gives a choice in method of qualification.
The procedure qualification can be done either on a groove weld in accordance with QW 202, or a demonstration mockup in accordance with QW 193.
Likewise, the performance qualification can be done either on a groove weld (or fillet weld, if applicable) in accordance with QW 303.1 (or QW 303.2), or a demonstration mockup in accordance with QW 193.
The choices for procedure qualification and performance qualification are standalone.
Therefore, the welder qualified on a groove weld is eligible to weld with a WPS qualified in accordance with QW 193.
The above discussion also means that the vice-versa is permitted too. A welder qualified with demonstration mock-ups of QW 193 is eligible to weld tube-to-tubesheet joints with a WPS qualified with a groove weld, when the applicable Code Section specifies welder qualification in accordance with QW 193.
So this was about the welder qualification and procedure qualification for tube-to-tube sheet welding. Please do let me know your thoughts in the comments section below.
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