ASME P-Numbers
To reduce the number of welding and brazing procedure qualifications required base metals have been assigned P-Numbers by the ASME BPVC. Ferrous metals which have specified impact test requirements have been assigned Group Numbers within P-Numbers.
These assignments have been based on comparable base metal characteristics, such as:
-
Composition
-
Weldability
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Brazeability
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Mechanical Properties
Indiscriminant substitution of materials in a set of P-Numbers or Group Numbers may lead to problems or potentially failures. Engineering assessment is necessary prior to a change in materials.
When a base metal with a UNS number Designation is assigned a P-Number, then a base metal listed in a different ASME material specification with the same UNS number shall be considered that P-Number.
The table below is a guide and is for instructive purposes only. Anyone specifying materials or requirements should refer directly to the ASME Boiler and Pressure Vessel Code to specify materials, P-Numbers, procedures, or other requirements and not rely on the table below. The table below is only a rather incomplete and approximate summary of ASME data.
|
P-Numbers |
Base Metal (Typical or Example) |
|
1 |
Carbon Manganese Steels (four Group Numbers) |
|
2 |
Not Used |
|
3 |
Half Molybdenum or half Chromium, half Molybdenum (three Group Numbers) |
|
4 |
One and a quarter Chromium, half Molybdenum (two Group Numbers) |
|
5A |
Two and a quarter Chromium, one Molybdenum |
|
5B |
Five Chromium, half Molybdenum or nine Chromium, one Molybdenum (two Group Numbers) |
|
5C |
Chromium, Molybdenum, Vanadium (five Group Numbers) |
|
6 |
Martensitic Stainless Steels (Grade 410, 415, 429) (six Group Numbers) |
|
7 |
Ferritic Stainless Steels (Grade 409, 430) |
|
8 |
Austenitic Stainless Steels
|
|
9A, B, C |
Two to four Nickel Steels |
|
10A, B, C, F |
Various low alloy steels |
|
10H |
Duplex and Super Duplex Stainless Steel (Grades 31803, 32750) |
|
10I |
High Chromium Stainless Steel |
|
10J |
High Chromium, Molybdenum Stainless Steel |
|
10K |
High Chromium, Molybdenum, Nickel Stainless Steel |
|
11A |
Various high strength low alloy steels (six Group Numbers) |
|
11B |
Various high strength low alloy steels (ten Group Numbers) |
|
12 to 20 |
Not Used |
|
21 |
High Aluminum content (1000 and 3000 series) |
|
22 |
Aluminum (5000 series - 5052, 5454) |
|
23 |
Aluminum (6000 series – 6061, 6063) |
|
24 |
Not Used |
|
25 |
Aluminum (5000 series - 5083, 5086, 5456) |
|
26 to 30 |
Not used |
|
31 |
High Copper content |
|
32 |
Brass |
|
33 |
Copper Silicone |
|
34 |
Copper Nickel |
|
35 |
Copper Aluminum |
|
36 to 40 |
Not Used |
|
41 |
High Nickel content |
|
42 |
Nickel, Copper - (Monel 500) |
|
43 |
Nickel, Chromium, Iron - (Inconel) |
|
44 |
Nickel, Molybdenum – (Hastelloy B2, C22, C276, X) |
|
45 |
Nickel, Chromium |
|
46 |
Nickel, Chromium, Silicone |
|
47 |
Nickel, Chromium, Tungsten |
|
47 to 50 |
Not Used |
|
51, 52, 53 |
Titanium Alloys |
|
61, 62 |
Zirconium Alloys |