ISO 2320:2015 pdf free

ISO 2320:2015 pdf free.Fasteners一Prevailing torque steel nuts一Functional properties.
The proof load test shall be carried out in accordance with ISO 898-2. Additionally, the following applies.
The nut to be tested shall be assembled on a test bolt (see 9.3) or on a hardened steel mandrel. The maximum prevailing torque to assemble the nut through 360° rotation shall be recorded after the first full thread has passed through the prevailing torque feature and assembly continues until three full threads protrude through the nut. For referee test purposes, a hardened steel mandrel shall be used for prevailing torque non-metallic insert type nuts and a test bolt shall be used for prevailing torque all metal type nuts. The maximum prevailing torque occurring during the assembly of the nut on the test bolt or mandrel shall be recorded after the first full form thread has passed through the prevailing torque feature.
A load equal to the specified proof load for the nut, as specified in ISO 898-2, shall be applied through thetest  bolt or mandrel against the nut-bearing surface in an axial direction and shall be held for 15 s. The nut shall resist this load without thread stripping or rupture. The proof load test is decisive for acceptance.
The maximum prevailing torque occurring during disassembly of the nut after a half-turn to full disengagement measured with the nut in motion shall not exceed the recorded maximum prevailing torque during assembly.
NOTE Any nut used in the prevailing torque test (see 9.3) may be used for the proof load test, as long as the nut threads are not damaged.
The test bolt/screw is placed in the testing device such that the protrusion through the prevailing torque feature of the nut after seating is in accordance with Figure 1.
The nut to be tested is engaged by hand on the bolt/screw thread until the prevailing torque feature is in contact with the bolt/screw. The end of the test bolt/screw shall not protrude through the nut before testing. The threaded length for tightening shall be three to five pitches in accordance with Figure 1.
The starting point of the installation phase corresponds to the start-up of the tightening device (see point 1 in Figure 2).ISO 2320 pdf free.