1-1/8" Grade 5 Bolt Torque: 794.0 ft·lbs

Torque Values by Surface Condition

UNC — Coarse Thread — 7 TPI

Stress area: 0.763 in² · Proof load: 56,462 lbs · Clamp load (75%): 42,346 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	794.0	1076.5	9528.0	10977.4
Oiled	0.15	595.5	807.4	7146.0	8233.1
Zinc Plated	0.18	714.6	968.9	8575.2	9879.7
Waxed	0.1	397.0	538.3	4764.0	5488.7
MoS₂	0.12	476.4	645.9	5716.8	6586.4
Galvanized	0.25	992.5	1345.7	11910.0	13721.8

UNF — Fine Thread — 12 TPI

Stress area: 0.856 in² · Proof load: 63,344 lbs · Clamp load (75%): 47,508 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	890.8	1207.8	10689.3	12315.4
Oiled	0.15	668.1	905.8	8017.0	9236.6
Zinc Plated	0.18	801.7	1087.0	9620.4	11083.9
Waxed	0.1	445.4	603.9	5344.7	6157.7
MoS₂	0.12	534.5	724.7	6413.6	7389.2
Galvanized	0.25	1113.5	1509.7	13361.6	15394.3

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 397.0 ft·lbs (waxed) to 992.5 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 × 0.763 in² = 42,346 lbs

Step 2 — Torque (dry): T = 0.20 × 1.125 in × 42,346 lbs ÷ 12 = 794.0 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

Size1-1/8"

Grade5

Diameter1.125" (28.57 mm)

TPI (UNC)7

Tensile105,000 psi

Yield81,000 psi

Proof74,000 psi

1-1/8" Grade 5 Torque Spec