Did you look through the specification, e.g., ASTM A252-88? Just after the scope should be listed reference specifications and standards. If it isn't found in ASTM A252, one of the reference standards should reference a welding standard. If I were to guess, I would expect to find a reference to ASME Section IX for the qualification of the WPS and welders/welding operators. I would expect to find some reference that would include terms and definition for sprial welded pipe. The manner in which the welding operator and the procedure is qualified iaw Section IX should be independent of the type of weld, i.e., seam or girt.

Grant you that I an not intimately involved with sprial welded pipe, but the ASTM standards and the extensive reference documents listed will usually yield the type of information you are looking for. It is usually a matter of digging through all the standards to mine the information you are looking for. That is no easy task considering the number of references that also reference other standards that reference other standards. The costs involved to purchase all the standards can be substantial.

Best regards - Al