Nominal Dia of Products and Threads per
in. |
Stress Area. sq. in |
Grade 2 |
Grade 5 |
Grade 8 |
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Proof Load, lb. |
Tensile Strength Min, lb. |
Proof Load, lb. |
Tensile Strength Min, lb. |
Proof Load, lb. |
Tensile Strength Min, lb. |
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COARSE Thread Series - UNRC |
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1/4 - 20 |
0.0318 |
1750 |
2350 |
2700 |
3800 |
3800 |
4750 |
5/16 - 18 |
0.0524 |
2900 |
3900 |
4450 |
6300 |
6300 |
7850 |
3/8 - 16 |
0.0775 |
4250 |
5750 |
6600 |
9300 |
9300 |
11600 |
7/16 - 14 |
0.1063 |
5850 |
7850 |
9050 |
12800 |
12800 |
15900 |
1/2 - 13 |
0.1419 |
7800 |
10500 |
12100 |
17000 |
17000 |
21300 |
9/16 - 12 |
0.1820 |
10000 |
13500 |
15500 |
21800 |
21800 |
27300 |
5/8 - 11 |
0.2260 |
12400 |
16700 |
19200 |
27100 |
27100 |
33900 |
3/4 - 10 |
0.3340 |
18400 |
24700 |
28400 |
40100 |
40100 |
50100 |
7/8 - 9 |
0.4620 |
15200 |
27700 |
39300 |
55400 |
55400 |
69300 |
1-8 |
0.6060 |
20000 |
36400 |
51500 |
72700 |
72700 |
90900 |
1 1/8 |
0.7630 |
25200 |
45800 |
56500 |
80100 |
91600 |
114400 |
1 1/4-7 |
0.9690 |
32000 |
58100 |
71700 |
101700 |
116300 |
145400 |
1 3/8-6 |
1.1550 |
38100 |
69300 |
85500 |
121300 |
138600 |
173200 |
1 1/2-6 |
1.4050 |
46400 |
84300 |
104000 |
147500 |
168600 |
210800 |
FINE Thread Series - UNRC |
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1/4 - 28 |
0.0364 |
2000 |
2700 |
3100 |
4350 |
4350 |
5450 |
5/16 - 24 |
0.0580 |
3200 |
4300 |
4900 |
6950 |
6950 |
8700 |
3/8 - 24 |
0.0878 |
4800 |
6500 |
7450 |
10500 |
10500 |
13200 |
7/16 - 20 |
0.1187 |
6550 |
8800 |
10100 |
14200 |
14200 |
17800 |
1/2 - 20 |
0.1599 |
8800 |
11800 |
13600 |
19200 |
19200 |
24000 |
9/16 - 18 |
0.2030 |
11200 |
15000 |
17300 |
24400 |
24400 |
30400 |
5/8 - 18 |
0.2560 |
14100 |
18900 |
21800 |
30700 |
30700 |
38400 |
3/4 - 16 |
0.3730 |
20500 |
27600 |
31700 |
44800 |
44800 |
56000 |
7/8 - 14 |
0.5090 |
16800 |
30500 |
43300 |
61100 |
61100 |
76400 |
1-12 |
0.6630 |
21900 |
39800 |
56400 |
79600 |
79600 |
99400 |
1-14 uns |
0.6790 |
22400 |
40700 |
57700 |
81500 |
81500 |
101900 |
1 1/8-12 |
0.8560 |
28200 |
51400 |
63300 |
89900 |
102700 |
128400 |
1 1/4-12 |
1.0730 |
35400 |
64400 |
79400 |
112700 |
128800 |
161000 |
1 3/8-12 |
1.3150 |
43400 |
78900 |
97300 |
138100 |
157800 |
197200 |
1 1/2-12 |
1.5810 |
52200 |
94900 |
117000 |
166000 |
189700 |
237200 |
Proof Loads and tensile strengths
are computed by multiplying the proof load stresses and tensile strengths
stresses by the stress area of the thread. |
As = 0.7854 [D-0.9743/n] squared |
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where D equals nominal diameter in in.
and n equals thread per inch. |
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Proof Load Tensile Strength for Grade 2, 5, & 8
