Torque technology

Torque wrenches from HAZET are designed solely for tightening screw joints. The wrench is not intended to be used as a lever tool, clamping tool or impact tool under any circumstances!

Torque wrenches are calibrated hand tools and must be handled accordingly with due care. Avoid any mechanical, chemical and thermal exposure that goes beyond the the stresses of normal use. The torque wrench must never be immersed in liquids or used as an impact tool as this can pose a risk of accidents and damage.


Extreme climatic conditions (cold, heat, air humidity) can have an effect on release accuracy. Before using the device, check that the insert and/or the insert tool holder used are seated firmly. Position the tool so that it cannot slip from the screw joint. This poses a hazard to persons and/or a risk of material damage.

When using inserts or insert tool holders, ensure their design conforms to standards and that their shape and size are correct for the screw joint to be tightened.

Also adhere to the maximum permitted load for the insert or insert tool holder used. This can be lower than the achievable release torque for the torque wrench. Custom-made tools can be dangerous and may not be used. Failure to comply can result in injury and/or material damage.

DIN EN ISO 6789:2017 for torque tools allows a maximum permissible relative deviation of ±4 % or ±6 % in direction of actuation. HAZET undercuts this standard specification with ±3 % with System 5000, ±2 % with SYSTEM 6000 and ± 3% with System 6000 US standard as well as HAZET no. 6150-1 CT and 6160-1 CT. The direction of actuation with which this release accuracy tolerance is achieved is identified by an arrow mark on the pipes of all torque wrenches and as an indication in the certificate.

All HAZET torque wrenches up to System 6300 have both a setting scale and an automatic close-gap release - audible and palpable when torque setting is reached. At low values the perceptible signal gets weaker. The products of SYSTEM 6300 have a small setting scale. These can either be purchased pre-set or set to the desired value with the aid of a torque tester.

Every HAZET torque wrench comes with a certificate in compliance with DIN EN ISO 6789:2017-2. This contains all necessary information such as the values recorded during calibration, the relative expanded uncertainty of measurement and the interval of the relative uncertainty of measurement W′ at each calibration point. In addition to the details in compliance with DIN EN ISO 6789:2017-2, each HAZET certificate even contains the indication of the maximum permissible relative deviation.
The certificates from torque wrenches with plug connection for holding insert tools contain additional information about the effective length of the insert tool to be used for calibration. Insert tools with the specified effective length of the certificate must be used for the recalibration of torque wrenches with plug connection.
When using insert tools with a deviating effective length, the torque to be set must be calculated (you can find the corresponding formula in our tool catalogue). In addition to our extensive range of torque wrenches, we also offer the necessary service. Here we offer adjustment, calibration and repair for all torque wrenches / torque testers. Maintenance service boxes are also available for our mechanical torque wrenches.

You can find associated documents, such as operating instructions, on our torque technology in the online catalogue or in our spare parts shop.