ASME P-Numbers

P-Number Groupings per ASME Section IX

WHAT IS A P-NUMBER?

A P-Number is an alphanumeric designation assigned to a group of base metals. These materials are grouped based on their similar weldability, mechanical characteristics, and alloy types such as Carbon Steel, Low Alloy Steel or Chrome Steel, Stainless Steel, Aluminum, and Nickel for example.

P-Numbers are assigned to base metals to reduce the number of welding and brazing procedure qualifications required to perform work.

With a fundamental understanding this system can be very useful in simplifying the determination of who is qualified to perform joining work within the ASME codes.

P-Numbers are made of numbers and sometimes include letters. It is important to note that each P-Number is considered a separate and unique number. For example, base metals assigned P-No. 5A are an entirely different group than P-No. 5B.

P-NUMBER and F-NUMBER and A-NUMBER

  • P-Number : Base Metal

  • F-Number : Filler Metal

  • A-Number : Weld metal in the “as-welded” state

P Number F Number A Number

BASE METAL GROUPINGS

Code bodies have different jurisdictions and applications that exist in response to industry, product application, and geographies. A general example of this would be that ASME primarily covers pressure boundary welding, and AWS covers structural applications. 

As a result of these differences a variety of material groupings, and naming conventions have been created.

Base Metal Grouping Names

Table demonstrating the different Base Material Grouping Names


Some base materials (Specification & Type) may be common between the different code standards, and others will not be. Some carbon steels like structural I-Beam listed in D1.1 will not be listed in ASME. It is also the case that common carbon steel pipe listed in ASME will not be listed in AWS standards. This can be confusing at times as both material shapes are considered to be carbon steel, but understanding the jurisdictional application helps to resolve the confusion.

BASE METAL ALLOY GROUPINGS

P-Numbers have been laid out as chronological numeric segments which are assigned to different alloy groups as detailed in the following ASME P-Number Alloy Groupings from Section IX QW-420.

 P-Number Range  Alloy Group 
 P-1 thru P-15F Steel Alloys
 P-21 thru P-26 Aluminum Alloys
 P-31 thru P-35 Copper Alloys
 P-41 thru P-49 Nickel Alloys
 P-51 thru P-53 Titanium Alloys
 P-61 thru P-62 Zirconium Alloys

P-NUMBER LIST

The following is a comprehensive list of P-Numbers, their general material description, and some typical material specification examples.

ASME P-Number Chart

P-Number Table

 P-Number  General Description   Typical Material Specification Within This P-Number Group 
1Carbon SteelSA-36, SA-106 Gr. B, SA-350 Gr. LF1, SA-516 Gr. 70
31/2 Cr & 1/2 Mo SteelsSA-209 T1, SA-213 T2, SA-234 WP1, SA-335 P1 & P2
41-1/4 Cr-Mo SteelsSA-182 F11 CL. 1, SA-213 T11, SA-335 P11
5A2-1/4 Cr-Mo Steels up to 75 ksiSA-182 F22 CL. 1, SA-213 T22, SA-335 P22
5B5 to 9 Cr-Mo Steels up to 85 ksiSA-182 F5 & F9, SA-213 T5 & T9, SA-234 WP5 & WP9
5C2-1/4 to 9 Cr-Mo Steels over 85 ksiSA-182 F3V, SA-336 F3V, SA-508 3V, SA-541 3V
6Stainless Steel - MartensiticSA-216 TP410 & TP429, SA-182 F6B, F6NM & F429, A473 410
7Stainless Steel - FerriticSA-240 TYPE 405, 409, & 410S, SA-240 TYPE 430
8Stainless Steel - AusteniticSA-182 F304L, SA-182 F316L, SA-240 TYPE 304L & 316L
9A2% Ni SteelSA-182 FR, SA-234 WPR, SA-333 GR. 9, SA-350 LF9
9B3% Ni SteelSA-333 3, SA-350 LF3, Cl. 2
9C4.5% Ni SteelSA-352 LC4
10ALow Alloy SteelSA-225 C & D, SA-487 GR. 1, Cl. A & B
10BLow Alloy SteelSA-213 T17
10CLow Alloy SteelSA-612 UNS K02900
10HStainless Steel - DuplexSA-240 S31803, S32205 & S32750, SA-789 S32205
10IStainless Steel - High CrSA-182 FXM-27CB, SA-240 S44635, SA-336 FXM-27CB
10JStainless Steel - High Cr & MoSA-240 S44700, SA-268 S44735, SA-479 S44700
10KStainless Steel - High Cr, Mo & NiSA-240 S44700, SA-268 S44735, SA-479 S44700
11AHSLA (High Strength Low Alloy)SA-333 8, SA-420 WPL8, SA-533 TYPE A, Cl. 3
11BHSLA (High Strength Low Alloy)SA-517 A, E, F, & B, SA-592 F
11CAge Hardening Alloy Steel Forgings A859 TYPE A, Cl. 1
15E9% Cr, Creep strength enhancedSA-182 F92, SA-213 T91 & T92, SA-335 P91 & P92
21Aluminum - 1000 & 3000 seriesSB-209 A95050, SB-221 A91100, SB-234 A91060
22Aluminum - 5000 seriesSB-209 A95052, SB-221 A95454, SB-234 A95052
23Aluminum - 6000 seriesSB-209 A96061, SB-221 A96061, SB-221 A96063
25Aluminum - 5000 seriesSB-209 A95456, SB-221 A95456, SB-241 A95086
26Aluminum CastingsSB-26 A24430 & A03560
31CopperSB-111 C10200, SB-152 C10400, SB-187 C10200
32BrassSB-111 C28000, SB-135 C23000, SB-283 C46400
33Cu-Si AlloysSB-198 C65500, SB-283 C65500
34Cu-Ni AlloysSB-111 C70400, SB-359 C70600, SB-466 C71500
35Aluminum Bronze AlloysSB-111 C60800, SB-148 C95500, SB-150 C61400
41Nickel AlloysSB-160 N02200, SB-161 N02200, SB-162 N02200
42Ni-Cu AlloysUNS N04400, N04405 (MONELS)
43Ni-Cr-Fe AlloysUNS N06600, N06625, N10276 (INCONELS & HASTELLOYS)
44Ni-Mo & Ni-Mo-Cr AlloysUNS N06022, N10629, N10665, N10675 (HASTELLOYS]
45Ni-Cr- Fe & Ni-Fe-Cr-Mo-Cu AlloysUNS N08020, N08800, N08810, N08825 (INCOLOYS)
46Ni-Cr-Si AlloysUNS N06045, N08330, N12160
49Ni-Cr-Co-Mo-Fe-W AlloysSB-815 UNS R31233, SB-818 UNS R31233
51Titanium Alloy 35-58 ksiUNS R50250, R50400, R52400, R52404
52Titanium Alloy 65-70 ksiUNS R50550, R53400
53Titanium Alloy 90 ksiUNS R56320, R56323
61Zirconium 55 ksiSB-523 TYPE R60702 - ALL PRODUCT FORMS UNS R60702
62Zirconium 70-80 ksiSB-523 TYPE R60705 - ALL PRODUCT FORMS UNS R60705

S-NUMBER

In 2009, S-Numbers were removed from Section IX. S-Numbers were assigned to materials that were acceptable for use by the ASME B31 Code or had been deemed acceptable by Code Cases within the Boiler and Pressure Vessel Code, but which were not included in ASME Section II. They are no longer used, and base metals previously assigned S-Numbers have now been assigned P-Numbers and Group Numbers. So P-Numbers are now the single system used.

GROUP NUMBER

Ferrous base metals have been assigned Group Numbers, which create subsets of P-Numbers. Group numbers are primarily required when WPS’s are required to be qualified by impact testing or in other words when supplementary essential variables apply to the welding procedure.

SPECIFICATION, TYPE OR GRADE

Both the materials specification and the Type or Grade are essential information in having the correct material. The material specification essentially calls out the product form.  The Type or Grade of that specification is more aligned to the metallurgy of that product form and heavily influences the P-Number as well as the Group Number of the material. 

There are some material specifications that are almost exclusively one P-Number, such as SA-240 & SA-312, where almost all of the materials in those specifications are P-No. 8. This can sometimes lead to the incorrect assumption that the specification alone is a sufficient amount of information to determine a material’s P-Number.

The following table provides examples of materials where Type or Grade can change the P-Number of the material.

ASME P-Number Spec and Grade

ASME P-Number Spec and Grade


The following is an example of how Type or Grade can change the Group Number within a single material specification.

ASME P-Number Spec and Grade

ASME P-Number Spec and Grade



FERROUS & NON-FERROUS MATERIALS

In general, ferrous metals contain iron; non-ferrous metals, on the other hand, do not contain iron. ASTM and ASME have created a prefix convention for identifying ferrous and non-ferrous materials.

A/SA is used to define those materials which are ferrous.

B/SB is used to define those materials which are non-ferrous.

Next
Next

ASME Base Metal Specifications