This International Standard specifies the mechanical and performance properties for prevailing torque type steel hexagon nuts (including those with flange) when tested over an ambient temperature range of 10 ℃ to 35 ℃. Properties will vary at higher and lower temperature.
It applies to prevailing torque type nuts
- with nominal thread diameters up to and including 39 mm;
- of triangular ISO thread according to ISO 68;
- with diameter/pitch combinations according to ISO 261;
- with thread tolerances 6H according to ISO 965-2;
- with specific mechanical requirements;
- with dimensions as specified in product standards provided they make reference to this International Standard;
- within the temperature range -50 ℃ to +300 ℃ for all metal type nuts;
- within the temperature range -50 ℃ to +120 ℃ for non-metallic insert type nuts.
It does not apply to nuts requiring special properties which may require special materials or coatings to improve
- weldability;
- corrosion resistance;
- performance outside the above specified temperature ranges.
Prevailing torque performance decreases with increasing re-use. The nut user should consider the implications of decreased performance prior to re-use.
NOTE—Information on torque/clamping force performance requirements and testing are given in the annex C. These functional requirements and the acompanying test procedure are still under discussion and cannot be specified mandatorily for the time being.
note:1) By careful choice of non-metallic materials higher service temperature properties can be attained by agree-ment between user and manufacturer.
BS EN ISO 2320:1998 history
2016BS EN ISO 2320:2015 Fasteners. Prevailing torque steel nuts. Functional properties
2008BS EN ISO 2320:2008 Prevailing torque type steel nuts - Mechanical and performance properties
1998BS EN ISO 2320:1998 Prevailing torque type steel hexagon nuts - Mechanical and performance properties
1973BS 4929-1:1973 Specification for steel hexagon prevailing-torque type nuts. Metric series