5/16" Grade 2 Torque Specification

Torque Values by Surface Condition

Stress area: 0.0524 in² · Proof load: 2,882 lbs · Clamp load (75%): 2,162 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	11.3	15.3	135.6	156.0
Oiled	0.15	8.4	11.4	100.8	116.2
Zinc Plated	0.18	10.1	13.7	121.2	139.7
Waxed	0.1	5.6	7.6	67.2	77.5
MoS₂	0.12	6.8	9.2	81.6	93.8
Galvanized	0.25	14.1	19.1	169.2	194.8

Stress area: 0.058 in² · Proof load: 3,190 lbs · Clamp load (75%): 2,392 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	12.5	16.9	150.0	172.3
Oiled	0.15	9.3	12.6	111.6	128.5
Zinc Plated	0.18	11.2	15.2	134.4	155.0
Waxed	0.1	6.2	8.4	74.4	85.7
MoS₂	0.12	7.5	10.2	90.0	104.0
Galvanized	0.25	15.6	21.2	187.2	216.2

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 55,000 psi × 0.0524 in² = 2,162 lbs

Step 2 — Torque (dry): T = 0.20 × 0.3125 in × 2,162 lbs ÷ 12 = 11.3 ft·lbs

Proof stress per SAE J429 Table 3. Stress area per ASME B1.1. K-factor per VDI 2230.

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

• 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.

Size5/16"

Grade2

Diameter0.3125" (7.94 mm)

TPI (UNC)18

Tensile74,000 psi

Yield57,000 psi

Proof55,000 psi