scope:

This Part of the NES specifies the requirements for the manufacture, testing and quality assurance documentation for unplated steel bolts, screws, studs, studbolts, nuts and washers. The following classes of Metric and Unified threaded fasteners are specified:

Class I-Metric or Unified externally threaded fasteners from 6mm to 48mm (¼" to 2") thread diameter for use where the temperature is between 0º C and 300º C.

Class A-Metric or Unified nuts from 6mm to 48mm (¼" to 2") thread diameter for use where the temperature is between 0º C and 300º C.

Class III-Metric or Unified externally threaded fasteners from 6mm to 27mm (¼" to 1") thread diameter for use where the temperature is between 0º C and 520º C.

Class B-Metric or Unified nuts from 6mm to 27mm (¼" to 1") thread diameter for use where the temperature is between 0º C and 520º C.

Notes:

Class II is not used.

Zinc plated fasteners are unsuitable for applications where the temperature may rise above 60º C.

Washers specified in this NES may be used with Class I, A, III and B threaded fasteners.