This standard BS EN 12560-3:2001 Flanges and their joints. Gaskets for Class-designated flanges is classified in these ICS categories:
23.040.80 Seals for pipe and hose assemblies
This standard specifies the dimensions, types, design, materials and marking requirements of IBC (inside bolt circle) non-metallic PTFE envelope gaskets for use with flanges complying with EN 1759-1, EN 1759-3, EN 1759-4 for Class designation 150 and 300 for sizes up to and including NPS 24 (DN600).