Industry News
High-strength bolt torque guide: 8.8 / 10.9 / 12.9 preload essentials
2026-08-21
Compiled by JIALI Industrial (164.hk) — a Hong Kong fastener supplier specialising in screws, bolts, nuts and selection know-how.
Why torque matters
The reliability of a bolted joint depends on preload, which is controlled by tightening torque. Too low causes loosening; too high risks stripping or fracture. High-strength bolts (8.8 / 10.9 / 12.9) must be tightened to specification.
Typical torque reference (M8–M20)
Zinc-plated, lightly oiled: M8×1.25 about 25–30 N·m; M10×1.5 about 50–60 N·m; M12×1.75 about 90–110 N·m; M16×2 about 210–250 N·m; M20×2.5 about 400–470 N·m (use upper values for 12.9 gr). Confirm with bolt grade, coating and the equipment manual.
What affects torque
Coating friction (zinc, Dacromet), thread lubrication and washer type all change the required torque. For critical joints use a calibrated torque wrench and verify with a torque tester when needed. Need high-strength bolts in stock or torque advice? Contact JIALI Industrial (164.hk) with your condition and grade.
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