1-1/2" Grade 5 Bolt Torque: 1949.5 ft·lbs

Torque Values by Surface Condition

UNC — Coarse Thread — 6 TPI

Stress area: 1.405 in² · Proof load: 103,970 lbs · Clamp load (75%): 77,978 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	1949.5	2643.2	23393.2	26951.9
Oiled	0.15	1462.1	1982.3	17544.9	20214.0
Zinc Plated	0.18	1754.5	2378.8	21053.9	24256.7
Waxed	0.1	974.7	1321.5	11696.6	13476.0
MoS₂	0.12	1169.7	1585.9	14035.9	16171.2
Galvanized	0.25	2436.8	3303.9	29241.6	33689.9

UNF — Fine Thread — 12 TPI

Stress area: 1.581 in² · Proof load: 116,994 lbs · Clamp load (75%): 87,746 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	2193.7	2974.3	26323.7	30328.1
Oiled	0.15	1645.2	2230.6	19742.7	22746.1
Zinc Plated	0.18	1974.3	2676.8	23691.3	27295.3
Waxed	0.1	1096.8	1487.1	13161.8	15164.1
MoS₂	0.12	1316.2	1784.5	15794.2	18196.9
Galvanized	0.25	2742.1	3717.8	32904.6	37910.2

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 974.7 ft·lbs (waxed) to 2436.8 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 × 1.405 in² = 77,978 lbs

Step 2 — Torque (dry): T = 0.20 × 1.5 in × 77,978 lbs ÷ 12 = 1949.4 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

Size1-1/2"

Grade5

Diameter1.5" (38.10 mm)

TPI (UNC)6

Tensile105,000 psi

Yield81,000 psi

Proof74,000 psi

1-1/2" Grade 5 Torque Spec