ASME Weld Number Tables – P number base & F number filler

How often have you wished somebody would do something to make this easier? We have! Jump directly to the table using the links below, or better yet, download all of theses helpful ASME Weld Number Tables directly to your computer.

Use the links below to jump directly to a section:

The purpose of the ASME Weld Number tables is to support a numbering system methodology that helps to make welding procedure creation and welding procedure management much easier as well as more affordable.

These numbers¹ have been assigned to base metals and filler metals alike, grouping materials to reduce the number of welding procedures and welder performance qualification tests needed to qualify a wide range of materials (base metals and filler metals). The base metal grouping scheme consists of the P numbers and Group Numbers. It also included the S Numbers until they were removed from the ASME code in 2009. The filler metal grouping scheme consists of the F numbers and A Numbers.

Note¹: these number tables and the information contained were accurate at the time of blog post first publish date in September 2015, to ensure compliance with the current code we recommend referring to latest code book edition or the latest version of welding procedure management and code assistance software ProWrite.

Base Metals: The P Number 

This number is used to group similar Base Metals, allowing qualification of an entire selection versus qualification of just one. These base metals are grouped by material and assigned P Numbers based on what material they are. For example, the P Number 1 is assigned to Carbon Manganese or Low Carbon Steel base metals. 

The table below provides an approximate summary of the assignments:  

Because of these assignments, the cost of the continuous procedure and performance qualification testing does not exist. In most cases, qualifying a welder on a specific material will also qualify that welder on a variety of related materials.

“For example, a welder who qualifies on a P1 to the P1 material is also qualified to weld P-1 through P-15F, P-34, and any P-40s.”

The following tables provide more information.

ASME Section IX’s Number Table from QW-423 Welder Qualifications is shown as follows:

In some cases, qualifying a production coupon for procedure specification also qualifies that procedure to a wider range of materials.

ASME Section IX’s Number Table from QW-424 Procedure Qualifications is shown as follows:

The S Number

The S-Number was removed from ASME Section IX in 2009. The S Number’s purpose was identical to the P Number. However, these numbers were assigned to those materials included for pipework to the ASME B31 Code for Pressure Piping. These materials were also covered by the P-Number, but not the converse.

Related: Want easy access to these ASME tables? Download them here!

The Group Number

This number is used only for impact testing requirements of ferrous metals, subgrouping the P-Number materials by the similarity of metallurgical properties (see above P-Number table). However, per ASME Section IX, “These assignments are based essentially on comparable base metal characteristics, such as composition, weldability, brazeability, and mechanical properties, where this can logically be done. These assignments do not imply that base metals may be indiscriminately substituted for a base metal that was used in the qualification test without consideration of compatibility from the standpoint of metallurgical properties, post weld heat treatment, design, mechanical properties, and service requirements“. These groupings can be found in Table QW/QB-422.

The following table is a replica of ASME Section IX’s Number Table QW-420 that shows the assignment groups for various alloy systems:

Filler Metals: The F Number

This number is used to group filler metals used in welding procedures and welder performance qualifications. The definition of F-Numbers is provided in QW-431 of ASME IX:

“The grouping of electrodes and welding rods in Table QW-432 is based essentially on their usability characteristics, which fundamentally determine the ability of welders to make satisfactory welds with a given filler metal. This grouping is made to reduce the number of welding procedure and performance qualifications, where this can logically be done. The grouping does not imply that base metals or filler metals within a group may be indiscriminately substituted for a metal that was used in the qualification test without consideration of the compatibility of the base and filler metals from the standpoint of metallurgical properties, post weld heat treatment design and service requirements, and mechanical properties”.

F-Numbers of filler metals can be found in ASME Section IX’s Number Table QW-432 an extract is shown as following:

ASME Section IX’s Number Table QW-433 Alternate F-Numbers for welding performance qualification

The A Number

The A-Number is a calculated value based on a combination of the chemical composition of the weld filler metal (which may be found in ASME Section II Part C), and ASME Section IX’s A-Number Table QW-442:

The A-Number is an essential variable for welding procedure specifications for multiple welding processes. It identifies related filler metals based on their chemical composition and allows procedure qualifications for the whole host of related materials.

The Numbers System

The purpose of the number system is to help. It alleviates extra time and cost by qualifying welders and procedures to a host of materials by simply qualifying to one.

If you would like to learn more about how ProWrite uses this weld numbering system to assist welding procedure management and welder qualification management watch our recorded webinar 5 software strategies to increase welding process efficiency. It covers specific areas that provide cost-effective increases in welding process efficiency and details how we ensure the uniform application of generally accepted safe welding practices in the manufacture and fabrication of boilers & pressure vessels.