This part of the Def Stan comprises:

a) NATO stock numbers

b) Management Codes

c) Dimensions of Ministry of Defence preferred sizes of existing and replacements are:

- Imperial sized anti-extrusion thin back-up rings that are compatible with the Imperial-sized Oring grooves to BS ISO 3601-2 and O-ring to BS ISO 3601-1

- Metric sized anti-extrusion spiral back-up rings to BS 5106

- Metric sized anti-extrusion spiral back-up rings not included within BS 5106 but are compatible with Metric sized O-ring grooves to BS 4518

This Def Stan is applicable to HM surface ships, submarines, ship and submarine systems including weapon systems, equipment, and dockyard support equipment within the temperature ranges stated within Def Stan 02-337 Part 1.

Exemptions: examples of the applications which will not be satisfied by the materials specified within this Def Stan are:

a) explosives

b) special electrical properties

c) those where there are environmental temperature requirements below -30°C