Bolt Grades & Strength

Proof strength (Sp) and ultimate tensile strength (Su) for common bolt property classes and SAE grades. Preload is typically set at 65–90% of the proof load (Sp × tensile stress area).

Class / grade	System	Proof Sp	Ultimate Su
4.8	Metric	310 MPa	420 MPa
8.8	Metric	580 MPa	800 MPa
10.9	Metric	830 MPa	1040 MPa
12.9	Metric	970 MPa	1220 MPa
SAE2	Inch	55000 psi	74000 psi
SAE5	Inch	85000 psi	120000 psi
SAE8	Inch	120000 psi	150000 psi

Torque from these with the Bolt Torque tool.

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