This standard specifies a torsional test for the determination of the breaking torque of bolts and screws with nominal diameters 1mm to 10mm with property classes 8.8 to 12.9 in accordance with GB 3098.1.
The test applies to bolts and screws with thread less than M3 for which no breaking and proof loads are indicated in GB 3098.1, as well as to short bolts and screws with nominal diameters 3mm to 10mm which cannot be subjected to a tensile test.
The minimum breaking torques are not valid for hexagon socket set screws.
2 Normative Reference
The following standard contains provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below.
GB 3098.1-82 Mechanical Properties of Fasteners - Bolts, Screws and Studs
3 Torsional Test
3.1 Principle
Determination of the breaking torque by clamping the bolt or screw to be tested into a test device.
3.2 Apparatus
3.2.1 Test device for torsional test, such as is shown in Figure 1.
3.2.2 Torquemeter, with a scale which shall not exceed the quintuple of the respective minimum breaking torque. The maximum inaccuracy of the torquemeter shall be ±7% of the minimum breaking torque to be tested.
GB/T 3098.13-1996 The following standards are cited：
