How often should torque wrenches be calibrated?

Production uses ~40 click-type torque wrenches daily. ISO 6789 talks about 5000 cycles or 12 months — is that mandatory? How do people set intervals defensibly?

2 Answers

Metrology Atlas Editorial ✓ Verified expert answer 3 days ago

ISO 6789-1:2017 recommends a maximum of 12 months or ~5000 load cycles as a starting interval, whichever comes first — it is not law, but deviating needs justification.

A defensible program per ILAC-G24: start at 12 months (or shorter for heavy use), record as-found data every cycle, then adjust per tool family: if >95 % of wrenches come back in tolerance two cycles running, you may extend; any out-of-tolerance triggers shortening and a reverse-traceability review of joints torqued since the last good calibration.

Also add a quick in-service check: a torque checker at the crib catches gross drift between calibrations and is cheap insurance.

Metrology Atlas Editorial 3 days ago

Data point from our plant: click wrenches used at >80 % of capacity drifted out roughly 3× as often as those used mid-range. We now spec tools so working torque sits at 40–60 % of capacity and interval extensions became sustainable.

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