JIS B 1181 Hexagon Nuts

Table 5 — Proof loads for bolts and screws (see Column 2 of Table 4)

Nominal size of bolt or screw Stress area Grade P Grade S Grade T Grade V Grade X
Proof stress 20 tonf/in² Proof stress 38 tonf/in² Proof stress 41 tonf/in² Proof stress 49.5 tonf/in² Proof stress 60 tonf/in²
Proof load
UNC UNF UNC UNF UNC UNF UNC UNF UNC UNF UNC UNF
in in² in² ton ton ton ton ton ton ton ton ton ton
1/4 0.0324 0.0368 0.648 0.736 1.231 1.398 1.328 1.509 1.603 1.822 1.944 2.208
5/16 0.0532 0.0587 1.064 1.174 2.021 2.230 2.181 2.406 2.633 2.905 3.192 3.522
3/8 0.0786 0.0886 1.572 1.772 2.986 3.367 3.222 3.633 3.890 4.385 4.716 5.316
7/16 0.1078 0.1198 2.156 2.396 4.097 4.552 4.420 4.911 5.335 5.929 6.468 7.188
1/2 0.1438 0.1612 2.876 3.224 5.466 6.127 5.896 6.610 7.119 7.980 8.628 9.672
9/16 0.184 0.205 3.68 4.10 6.992 7.791 7.544 8.407 9.107 10.15 11.04 12.30
5/8 0.229 0.258 4.58 5.16 8.702 9.804 9.389 10.58 11.33 12.77 13.74 15.48
3/4 0.338 0.375 6.76 7.50 12.84 14.25 13.86 15.38 16.73 18.57 20.28 22.50
7/8 0.467 0.513 9.34 10.26 17.74 19.49 19.14 21.03 23.12 25.39 28.02 30.78
1 0.612 0.667 12.24 13.34 23.26 25.34 25.09 27.35 30.30 33.01 36.72 40.02
1 1/8 0.771 — 15.42 — 29.30 — 31.61 — 38.17 — 46.26 —
1 1/4 0.978 — 19.56 — 37.16 — 40.10 — 48.41 — 58.68 —
1 3/8 1.166 — 23.32 — 44.31 — 47.80 — 57.72 — 69.96 —
1 1/2 1.418 — 28.36 — 53.89 — 58.15 — 70.20 — 85.08 —
1 3/4 1.92 — 38.4 — 72.97 — 78.72 — 95.04 — 115.2 —
2 2.52 — 50.4 — 95.76 — 103.3 — 124.7 — 151.2 —

Stress area x proof stress = proof load