BS 7751-1:1994

This standard BS 7751-1:1994 Prevailing torque type wire thread inserts is classified in these ICS categories:

• 21.040.10 Metric screw threads

This Part of BS 7751 specifies requirements for prevailing torque wire thread inserts which, when fitted into an appropriately prepared hole, will:

1. provide ISO metric coarse pitch female threads of tolerance class 5H or 6H in the free running coils with sizes from M2.2 to M39 inclusive;
2. accept ISO metric male threads conforming to BS 3643-1:1981 and BS 3643-2:1981;
3. give a frictional resistance to rotation of a male threaded component assembled with it, of such a value that the insert assembly is considered self locking;
4. operate successfully in the temperature range − 50 °C to + 300 °C.

NOTE ISO metric MJ threads conforming to BS 6293-1 and BS 6293-2 may be used with these inserts.