P Number

 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

Group 1 - Grades 304, 316, 317,347

Group 2 Grades 309, 310

Group 3 - High Manganese Grades

Group 4 - High Molybdenum Grades

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)

101

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 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