This standard specifies requirements, dimensions and tolerances for five types of anti-extrusion rings for static application, which are also known as back-up rings:
a) spiral type (T1);
b) angle cut type (T2);
c) solid type (T3);
d) angle cut concave type (T4);
e) solid concave type (T5).
These anti-extrusion rings are intended to be used with selected O-ring sizes specified in SS 1586 and the relevant housing dimensions specified in SS 1588.