In this article, we are going to discuss the different classifications and groupings of base metals(P number & group number) and filler metals (F number & A number) according to ASME IX a which is a very important subject when dealing with creating a welding procedure specification (WPS) and a welding procedure qualification (PQR).

In fact, knowing how to navigate this information will ensure that your welding procedure produces sound welds but also saves you time and money when dealing with different welding requirements.

Base metals (to be welded) and filler metals (electrodes)have numbers allocated by the ASME Boiler and Pressure Vessel Code (BPVC).

ASME has given two number systems to base metals:

• P Number
• Group Number

The numbering system for filler metals is as follows:

• A Number
• F Number

These figures can be found in ASME BPVC Section IX (see Table below);