scope:

This Standard specifies the functional properties for prevailing torque steel nuts when tested at an ambient temperature range of +10 °C to +35 °C.

It includes a combined test method to determine the prevailing torque properties and the coefficient of total friction as the torque/clamp force properties at the same time.

It applies to prevailing torque all metal type nuts and prevailing torque non-metallic insert type nuts (hereafter referred to as nuts):

- with triangular ISO thread in accordance with JIS B 0205-1;

- with diameter/pitch combination in accordance with JIS B 0205-3;

- with coarse pitch thread M5 to M39 or with fine pitch thread M8 ×1 to M39 ×3;

- with thread tolerances in accordance with JIS B 0209-2;

- with mechanical properties in accordance with JIS B 1052-2.

Prevailing torque values specified in this Standard are based on laboratory test conditions.

NOTE 1 Actual prevailing torques in practical application can vary.

NOTE 2 Prevailing torque all metal type nuts conforming to the requirements of this Standard are used in applications ranging from −50 °C to +150 °C.

NOTE 3 Prevailing torque non-metallic insert type nuts conforming to the requirements of this Standard are used in applications ranging from −50 °C to +120 °C. At the temperature outside this range, the capability of functional properties (torque and clamp force, and prevailing torque properties) may be reduced (see Annex A).

NOTE 4 The International Standard corresponding to this Standard and the symbol of degree of correspondence are as follows.

ISO 2320:2015 Fasteners-Prevailing torque steel nuts-Functional properties (MOD)

In addition, symbols which denote the degree of correspondence in the contents between the relevant International Standard and JIS are IDT (identical), MOD (modified), and NEQ (not equivalent) according to ISO/IEC Guide 21-1.