9/16" Grade 2 Bolt Torque: 70.4 ft·lbs / 95.4 N·m

Torque Values by Surface Condition

UNC — Coarse Thread — 12 TPI

Stress area: 0.182 in² · Proof load: 10,010 lbs · Clamp load (75%): 7,508 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	70.4	95.4	844.6	973.1
Oiled	0.15	52.8	71.6	633.4	729.8
Zinc Plated	0.18	63.3	85.8	760.1	875.8
Waxed	0.1	35.2	47.7	422.3	486.5
MoS₂	0.12	42.2	57.2	506.8	583.8
Galvanized	0.25	88.0	119.3	1055.7	1216.3

UNF — Fine Thread — 18 TPI

Stress area: 0.203 in² · Proof load: 11,165 lbs · Clamp load (75%): 8,374 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	78.5	106.4	942.0	1085.4
Oiled	0.15	58.9	79.9	706.5	814.0
Zinc Plated	0.18	70.7	95.9	847.8	976.8
Waxed	0.1	39.3	53.3	471.0	542.7
MoS₂	0.12	47.1	63.9	565.2	651.2
Galvanized	0.25	98.1	133.0	1177.6	1356.7

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 35.2 ft·lbs (waxed) to 88.0 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 × 55,000 psi × 0.182 in² = 7,508 lbs

Step 2 — Torque (dry): T = 0.20 × 0.5625 in × 7,508 lbs ÷ 12 = 70.4 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 2

General-purpose, non-critical bolting. Most common ungraded hardware-store bolts.

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

Size9/16"

Grade2

Diameter0.5625" (14.29 mm)

TPI (UNC)12

Tensile74,000 psi

Yield57,000 psi

Proof55,000 psi

9/16" Grade 2 Torque Spec