Dimensions and marking of IBC gaskets for flanges to BS 1560 having Class designations 150 and 300 and for sizes up to and including 24.Cross References:BS 1560:Section 3.1BS 1560:Section 3.2BS 1560:Section 3.3BS 3381BS 4504:Section 3.1BS 4504:Section 3.2BS 4504:Section 3.3BS 4865:Part 3Asbestos Regulations 1969