BS 3293:1960 is a material and dimensionalstandard only and applies to forged carbon steelslip-on and welding neck flanges of nominalsizes 26 in and larger, for use in the petroleumindustry. Drilling, bolting, facing and thicknessdimensions are applicable also to integral endflanges of valve and fittings.
Four classes of flanges are provided for, namelyClasses 150, 300, 400 and 600.
BS 3293:1960 does not includepressure/temperature ratings; the flangedesignations quoted are for identification purposesonly.