1-1/4" Grade 5 Bolt Torque: 1120.4 ft·lbs

Torque Values by Surface Condition

UNC — Coarse Thread — 7 TPI

Stress area: 0.969 in² · Proof load: 71,706 lbs · Clamp load (75%): 53,780 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	1120.4	1519.1	13444.9	15490.2
Oiled	0.15	840.3	1139.3	10083.7	11617.6
Zinc Plated	0.18	1008.4	1367.2	12100.4	13941.2
Waxed	0.1	560.2	759.5	6722.4	7745.1
MoS₂	0.12	672.3	911.5	8066.9	9294.1
Galvanized	0.25	1400.5	1898.8	16806.1	19362.7

UNF — Fine Thread — 12 TPI

Stress area: 1.073 in² · Proof load: 79,402 lbs · Clamp load (75%): 59,552 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	1240.7	1682.2	14887.9	17152.7
Oiled	0.15	930.5	1261.6	11165.9	12864.5
Zinc Plated	0.18	1116.6	1513.9	13399.1	15437.4
Waxed	0.1	620.3	841.0	7443.9	8576.3
MoS₂	0.12	744.4	1009.3	8932.7	10291.6
Galvanized	0.25	1550.8	2102.6	18609.8	21440.9

Torque by surface condition

UNC thread, ft·lbs. Values from the table above.

Same bolt, same target clamp load: thread friction alone moves the required torque from 560.2 ft·lbs (waxed) to 1400.5 ft·lbs (hot-dip galvanized), 2.5× as much. Match the row to the fastener's actual finish and lubrication.

How This Value Is Calculated

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 74,000 psi × 0.969 in² = 53,780 lbs

Step 2 — Torque (dry): T = 0.20 × 1.25 in × 53,780 lbs ÷ 12 = 1120.4 ft·lbs

Proof stress per SAE J429 Table 3. Stress area per ASME B1.1. Typical K-factor, consistent with VDI 2230 friction values.

When to Use Grade 5

Same as Grade 5 but with reduced strength at larger diameters

Important Notes

• Torque values are for standard hex bolts with unified threads per ASME B1.1. Socket head cap screws may have different requirements.
• Lubrication reduces required torque significantly — using dry torque values on lubricated bolts risks exceeding yield strength.
• For critical or safety-related applications, always consult the manufacturer's specifications or applicable design standard.
• Re-used bolts may have altered friction characteristics. Inspect threads before reuse.

Specifications

Size1-1/4"

Grade5

Diameter1.25" (31.75 mm)

TPI (UNC)7

Tensile105,000 psi

Yield81,000 psi

Proof74,000 psi

1-1/4" Grade 5 Torque Spec