1-1/2" Grade 2 Bolt Torque: 869.4 ft·lbs

Torque Values by Surface Condition

UNC — Coarse Thread — 6 TPI

Stress area: 1.405 in² · Proof load: 46,365 lbs · Clamp load (75%): 34,774 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	869.4	1178.7	10432.1	12019.1
Oiled	0.15	652.0	884.0	7824.1	9014.3
Zinc Plated	0.18	782.4	1060.8	9388.9	10817.2
Waxed	0.1	434.7	589.4	5216.1	6009.6
MoS₂	0.12	521.6	707.2	6259.3	7211.5
Galvanized	0.25	1086.7	1473.4	13040.2	15023.9

UNF — Fine Thread — 12 TPI

Stress area: 1.581 in² · Proof load: 52,173 lbs · Clamp load (75%): 39,130 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	978.3	1326.4	11738.9	13524.7
Oiled	0.15	733.7	994.8	8804.2	10143.5
Zinc Plated	0.18	880.4	1193.7	10565.0	12172.2
Waxed	0.1	489.1	663.1	5869.5	6762.4
MoS₂	0.12	586.9	795.7	7043.4	8114.8
Galvanized	0.25	1222.8	1657.9	14673.7	16905.9

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 434.7 ft·lbs (waxed) to 1086.7 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 × 33,000 psi × 1.405 in² = 34,774 lbs

Step 2 — Torque (dry): T = 0.20 × 1.5 in × 34,774 lbs ÷ 12 = 869.3 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

Large general-purpose bolts, same grade but 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

Size1-1/2"

Grade2

Diameter1.5" (38.10 mm)

TPI (UNC)6

Tensile60,000 psi

Yield36,000 psi

Proof33,000 psi

1-1/2" Grade 2 Torque Spec