BS 3293 is a material and dimensional 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, namely Classes 150, 300, 400, and 600.
Note: BS 3293 does not include pressure/temperature ratings; the flange designations quoted are for identification purposes only.
BS 3293 on carbon steel pipe flanges (over 24 inches nominal size) for the petroleum industry is useful for:
Flanges in BS 3293 are designated as Classes 150, 300, 400, and 600 to facilitate ordering and to ensure interchangeability.
BS 3293 provides guidance on the designation and pressure-temperature ratings, materials for flanges, dimensions, and tolerances, flange facings and gaskets, Spot-facing and back-facing of flanges, inspection, preparation, and despatch. This enables manufacturers to achieve a quality product.