Repair 7

Torque Wrench Certification

Under-torqued hardware may loosen during use, while over-torqued hardware may fail or damage the assembly it is attached to. Torque wrenches provide the means to measure safe, exact tightening force on hardware to prevent such occurrences. These precision tools must be routinely calibrated and certified for continued reliable operation.

Purpose

Like any tool, torque wrenches wear over time. Depending on the type, they may contain tiny gears, teeth, springs, gauges and other moving parts. The more the tool is used, the quicker these parts need to be inspected and replaced.

Frequency

The recommended calibration frequency of torque wrenches varies by manufacturer. Six months to one year is the prevalent calibration cycle. The International Organization of Standards (ISO) 6789:2003 does not use calendar time to recommend calibration, instead providing a calibration standard of 5,000 cycles.

Procedure

Torque wrench calibration and certification involves a thorough inspection and test of the tool. Precise pressure is applied to the wrench while its effectiveness is measured. If the tool does not indicate proper torque at the specified pressure, it is cleaned, repaired and retested.