What is P-Numbers?

You might be asking, what is P-Numbers? P-Number is often used in WPS and Welder’s Qualification.

 

In accordance to QW-420.1 of ASME IX, to reduce the numbers of welding and brazing procedure qualification required, base metals have been assigned P-Numbers, and for ferrous base metals which have specified impact test requirements, Group Numbers within P-Numbers. 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 metal maybe indiscriminately substituted for a base metal which was used in the qualification test without consideration of compatability from the stand point of metallurgical properties, and service requirements. Where notch-toughness is a consideration, it is presupposed that the base metals meet the specific requirements.

 

P-NUMBERS OF BASE METALS

Base Metal	Welding	Brazing
Steel and Steel Alloys	P-No. 1 through P-No. 11 incl. P-No. 5A, 5B and 5C	P-No. 101 through P-No. 103
Aluminum and Aluminum-base Alloys	P-No.21 through P-No. 25	P-No. 104 and P-No. 105
Copper and Copper-Base Alloys	P-No. 31 through P-No. 35	P-No. 107 and P-No. 108
Nickel and Nickel base Alloys	P-No. 41 through P-No. 47	P-No. 110 through P-No. 112
Titanium and Titanium base Alloys	P-No. 51 through P-No. 53	P-No. 115
Zirconium and zirconium base Alloys	P-No. 61 through P-No. 62	P-No. 117

 

 

The P-Numbers of each specific materials are listed in QW/QB-422 of ASME IX.