A668 Mechanical Requirements
Class |
Size, inches |
Tensile, min ksi |
Yield, min ksi |
Elong, % min in 2” |
RA, % min |
Hardness, HBN |
A |
Up to 20 |
47 |
- |
- |
- |
183 max |
B |
Up to 20 |
60 |
30 |
24 |
36 |
120-174 |
C |
Up to 12 |
66 |
33 |
23 |
36 |
137-183 |
12 to 20 |
66 |
33 |
22 |
34 |
137-183 |
D |
Up to 8 |
75 |
37.5 |
24 |
40 |
149-207 |
8 to 12 |
75 |
37.5 |
22 |
35 |
149-207 |
12 to 20 |
75 |
37.5 |
20 |
19 |
149-207 |
Over 20 |
75 |
37.5 |
19 |
30 |
149-207 |
E |
Up to 8 |
85 |
44 |
25 |
40 |
174-217 |
8 to 12 |
85 |
44 |
23 |
37 |
174-217 |
12 to 20 |
83 |
43 |
22 |
35 |
174-217 |
F |
Up to 4 |
90 |
55 |
20 |
39 |
187-235 |
4 to 7 |
85 |
50 |
20 |
39 |
174-217 |
7 to 10 |
85 |
50 |
19 |
37 |
174-217 |
10 to 20 |
82 |
48 |
19 |
36 |
174-217 |
G |
Up to 12 |
80 |
50 |
24 |
40 |
163-207 |
12 to 20 |
80 |
50 |
22 |
38 |
163-207 |
H |
Up to 7 |
90 |
60 |
22 |
44 |
187-235 |
7 to 10 |
90 |
58 |
21 |
42 |
187-235 |
10 to 20 |
90 |
58 |
18 |
40 |
187-235 |
J |
Up to 7 |
95 |
70 |
20 |
50 |
197-255 |
7 to 10 |
90 |
65 |
20 |
50 |
187-235 |
10 to 20 |
90 |
65 |
18 |
48 |
207-255 |
K |
Up to 7 |
105 |
80 |
20 |
50 |
212-269 |
7 to 10 |
100 |
75 |
19 |
50 |
207-269 |
10 to 20 |
100 |
75 |
18 |
48 |
207-269 |
L |
Up to 4 |
125 |
105 |
16 |
50 |
255-321 |
4 to 7 |
115 |
95 |
16 |
45 |
235-302 |
7 to 10 |
110 |
85 |
16 |
45 |
223-293 |
10 to 20 |
110 |
85 |
14 |
40 |
223-293 |
M |
Up to 4 |
145 |
120 |
15 |
45 |
293-352 |
4 to 7 |
140 |
115 |
14 |
40 |
285-341 |
7 to 10 |
135 |
110 |
13 |
40 |
269-331 |
10 to 20 |
135 |
110 |
12 |
38 |
269-341 |
N |
Up to 4 |
170 |
140 |
13 |
40 |
331-401 |
4 to 7 |
165 |
135 |
12 |
35 |
331-401 |
7 to 10 |
160 |
130 |
11 |
35 |
321-388 |
10 to 20 |
160 |
130 |
11 |
35 |
321-402 |
Classes with an added ‘H’ are supplied on the basis of hardness values only. For example, AH.
Classes A-F are carbon steel, classes G-N are alloy steel |