For welding procedure qualification, ASME IX does not regard pipe diameter as an essential variable and, thus, procedure qualification testing using a particular pipe diameter will qualify pipe of any other diameter. Also, QW 211 states that qualification in plate also qualifies for pipe welding and vice versa.
However, in its Forward, ASME IX states that 'the code is not a handbook and cannot replace education, experience and the use of engineering judgement'. Thus, if a wide range of pipe sizes is to be welded in production, depending on fabricator experience with the material and welding processes to be used, it may be appropriate to consider whether test welds should be made on pipes at the minimum and maximum diameter or at other representative diameters.
Performance qualification (welder/welding operator)
For performance qualification testing, pipe diameter is an essential variable for the arc welding processes that are listed. The qualifying ranges for pipe groove welds (QW-403.16 & QW-452.3) are:
|Outside Diameter of Test Coupon||Outside Diameter Qualified|
|Less than 25mm
|25 to 73mm