BS EN ISO 6789:2003 pdf.Assembly tools for screws and nuts – Hand torque tools – Requirements and test methods for design conformance testing, quality conformance testing and recalibration procedure.
The revision of the previous edition of ISO 6789 became necessary, because the requirements of ISO 9001, concerning the procedure of the control of test devices, as well as the introduction of calibration services, unambiguously need guidelines in ISO 6789 for calibration and recalibration of hand torque tools.
Further, information about recalibration has been included in the present new issue.
This International Standard specifies the requirements for, and describes the test methods and marking of, hand torque tools used for controlled tightening of bolted connections.
It applies to torque tools in accordance with Clause 4, in particular to indicating and setting torque wrenches in accordance with numbers 258 and 259 of ISO 1703:1983.
5.1.3 Specified measuring range
The requirements and test methods in this International Standard cover a specified measuring range from 20 % to 100 % of the maximum torque value of the respective tool.
The scales of torque tools of Type I shall be marked with a zero position.
5.1.4 Scales
The increment between two graduation marks of a scale shall not exceed 5 % of the maximum value.
5.1.5 Tolerances
5.1.5.1 Indicating torque tools (Type I)
Permissible deviation of the torque value indicated by the tool, from the simultaneous indication of the calibration device, shall be as given in Table 2.
5.1.6 Overloading test
After setting at 100 % of the maximum torque value, all torque tools to be tested shall be loaded three times in each direction of operation to a torque value of 125 % of the maximum capacity (or nominal capacity for tools of Type II, Classes B and E). This does not apply to limiting torque tools.
After the overloading test, the torque tool shall still be within the tolerances specified in 5.1.5 and shall show no physical damage that can be detrimental to the torque accuracy and safety.
5.1.7 Endurance test
All torque tools to be tested shall be cycled at maximum capacity (or nominal capacity for tools of Type II, Classes B and E) for 5 000 cycles, in each direction of operation, at a rate between 5 cycles/mm and 10 cycles/mm.
After the endurance test, the torque tool shall still be within the tolerances specified in 5.1.5 and shall show no physical damage that can be detrimental to the torque accuracy and safety.
5.2 Quality conformance testing
All torque tools shall be tested in accordance with 6.3 and shall comply with the requirements in 5.1.5.BS EN ISO 6789:2003 pdf free download.