Welding Number Tables – What Is Piping

To ease welding procedure creation and welding procedure management, the ASME Weld Number tables provide a well-defined numbering system methodology. These numbers are assigned to the Weld base metals and filler metals. Grouping materials reduces the number of welding procedures and welder performance qualification tests for a wide range of materials. ASME Boiler and Pressure Vessel Code (ASME BPVC Section IX) has assigned a grouping scheme for base metals that consists of the P numbers and Group Numbers. Earlier there were ASME S Numbers that were removed by the code from the year 2009. Similarly, the filler metal grouping scheme consists of the F-Numbers and A-Numbers. Refer to Fig. 1, which clarifies what these numbers relate to. Fig. 1: P-Number, F-Number, and A-Number in Welding What is the P Number in Welding? Depending on the material characteristics like composition, weldability, brazeability, design consideration, heat treatment, and mechanical properties, ASME BPVC assigned P-Numbers to the base metals. The code assigned the same P-number for the materials with similar material characteristics. These are listed in Table QW/QB-422 of ASME. While changing the base metal from a qualified WPS to a new base metal, requalification or a new PQR is not required if the new base metal falls in the same P-Number. These base metals are grouped by material and the assigned P-Numbers are constant for that specific material group. For example, the base metals of Low Carbon Steel or Carbon Manganese material fall in P-Number 1. The following table (Table-1) provides the P-number ranges for various metals and alloys. Sr. No.Type of Steel, Metal, AlloyP-Number1.Carbon Steel (C-Mn )12.Low Alloy Steel (Cr-Mo Steels)4, 5A, 5B, 5C, 15E3.Stainless Steels (Cr-Ni steels)8, 10H4.Nickel & Ni-base alloys41 to 495.Aluminum & Aluminum alloys21 to 266.Copper & copper alloys31 to 357.Titanium & titanium alloys51 to 538.Zirconium & zirconium alloys61 and 62Table 1: ASME P-Number Table From the ASME Sec IX table, QW/QB-422 can find the P-number of a specific grade of material, i.e. which material falls under which P-number and what is product form i.e. plate, forging, sheets, fittings, etc. P-number is generally mentioned in WPS & PQR for procedure qualification and in WPQ for performance qualification. What is the F-Number in Welding? As the name suggests, F stands for Filler number. Depending on the composition, the microstructure of the material F-number is assigned to welding consumables i.e. filler wires, electrodes to reduce the procedure and performance qualifications. F-number is generally mentioned in WPS & PQR for procedure qualification and in WPQ for performance qualification. The ASME Sec IX (QW-432 assigned the F-number on the basis of type of consumable, usability of consumable, metallurgical compatibility, heat treatment, and other mechanical properties. Same F no is assigned to carbon steel as well as stainless steel filler wires. For example. For ER70S-6 & ER308 have the same F no. i.e. F no. 6. The following table (Table-2) provides the F-number ranges for various consumables as classified in ASME Section. Sr. No.Type of Steel consumablesF-Number1.Carbon Steel1 to 62.Low Alloy Steel (Cr-Mo Steels)1 to 63.Stainless Steels (Cr-Ni steels)5, 64.Nickel & Ni-base alloys41 to 465.Aluminum & Aluminium alloys21 to 266.Copper & copper alloys31 to 377.Titanium & titanium alloys51 to 568.Zirconium & zirconium alloys619.Hard facing weld metal overlays71 and 72Table 2: ASME F-Number Chart From the ASME Sec IX, table QW-432 can find the F-number of specific consumables classified as per ASME Sec IIC. With the F-number there is a reduction of procedure and performance qualification as the same F-number of material does not require requalification. From the ASME Sec IX, table QW-433 can be referred to for the welder performance qualification range. A snapshot is given below: What is the A-Number in Welding? As from the name, A stands for analysis. A-number is designated by ASME to weld metal deposition composition analysis to reduce the number of procedure qualifications in Welding. From the ASME Sec IX table QW-442 can be referred for different A number is given to a different group of metals/alloys. A-number is generally mentioned in WPS & PQR. It is not essential for performance qualification i.e. not mentioned in WPQ. Note that the A-Number gives the chemical composition of the weld metal in the “as-welded” state, not of the filler metal product in its raw form.