Screw connections can be "normal" and "secured". In the normal case, the prestressing is created by the nut. Secured connections posess different elements:

1. Additional prestressing created by a spring lock washer or a domed washer

2. Double nut

3. Safety plate

4. Tack welding (nut to bolt)

Material groupMaterialsComment
A11.4300 1.4305
A21.4301 1.4303 1.4306Standard
A31.4306 1.4550 1.4590
A41.4401 1.4404Standard
A51.4436 1.4571 1.4580
Spring lock washers