Interesting conversation.

If you have a copy of Section IX in front of you, look at QW/QB-422 for a listing of all the P numbers (no more S-numbers) and the group numbers.

As already mentioned, group numbers only come into play when notch toughness requirements are imposed by the applicable construction code, i.e., Section I, Section, VIII, B31.1, B31.3, etc. Already, you can see that you cannot work with Section IX alone. You need to review the requirements of the construction code to determine if the basic requirements of Section IX have been modified or expanded by the applicable construction code. Preheat, interpass temperature, and post weld heat treatment requirements are among the variables addressed by the construction code. Any additional requirements for welder qualification would also be addressed by the construction code. For example; when welding piping systems that are required to meet B31.3, High Pressure, the welders must be qualified by guided bend testing. Radiography is not a permitted alternative for performance qualification in that instance.

Listing the P-number, group number, A-number, or F-number is useless to most welders. There is no way for the welder to correlate the P-number or the group number listed in the WPS to the markings typically found on raw material. For example; pipe is typically line marked along its length with the ASTM/ASME specification, grade or alloy, diameter, and schedule (wall thickness). The P-number is nowhere to be found on the raw material as identified by the manufacturer. Likewise, the bill of materials or the drawing is most likely to list the ASTM/ASME material specification and the grade or alloy, but not the P-number or the group. This leaves the welder scratching his head. Is this material covered by this WPS or isn't it?

Before someone say, "All the welder has to do is follow the engineer's or the supervisor's instructions." Let's agree that most job shops where the vast majority of the welding and manufacturing is accomplished usually have little in the way of infrastructure to support their manufacturing operations. And the staff that is available is stretched thin (we call it lean manufacturing) and rarely have the where with all to truly understand the intricacies of welding codes.

One solution to the problem is to list the appropriate P-numbers, etc. in the WPS, but also include a reference to an annex. The annex can be a listing of all the base metal specifications, grades, alloys, etc. that is used by the contractor and that are covered by the WPS. The annex is a reference the welder can easily keep with the WPSs and is available when there is a question regarding which base metals can be welded.

When I write an annex for base metals, I include the base metal specification grade, alloy, thickness range, preheat, and the product form. I include preheat requirements in the annex because it is a convenient location to place a detailed preheat table that correlates the preheat requirements to the thickness of the base metals listed. This reduces the physical size of the WPS and provides an easy to use reference for the welders. The annex does not have to list every base metal specifications, only the one's typically used by the shop.

One word of advice, make sure you have all the applicable code sections available to review when you are working to ASME B&PV code or any of the piping codes. Section IX lists the basic requirements, but it is not a standalone document. It must be used in conjunction with the applicable construction codes for additional requirements such as preheat, whether post weld heat treatment is required or whether notch toughness testing is required. Without that information, your WPS and supporting PQR may not weather a complete review.

A second word of advice, the material groupings of AWS B2.1 include many materials not included in Section IX. Do not fall into the trap of thinking an AISI or AMS material can be substituted for an ASME approved base metal simply because it is listed as a M-number in AWS B2.1 that is the same as the P-number found in ASME Section IX. The chemical composition of the AISI listed material may be the same as that of an ASME base metal specification, but things like the mechanical processing and thermal heat treatment also can influence the mechanical properties of the metals being used. AISI does not typically publish the mechanical properties, only the chemistry.

Best regards - Al