BS 3293

Foreword.. BS 3293:1960 is a dimensional British Standard only and applies to forged carbon steel slip-on and welding neck flanges of nominal sizes 26 in and larger, for use in the petroleum industry. Drilling, bolting, facing and thickness dimensions are applicable also to integral end flanges of valve and fittings. Four classes of flanges are provided for, namely Classes 150, 300, 400 and 600. BS 3293:1960 does not include pressure/temperature ratings; the flange designations quoted are for identification purposes only.

British Standards