BS EN 1759-1 :2004 Standard for a single system of flanges specifies requirements for circular steel flanges in Class designations Class 150 to Class 2 500 and nominal sizes from NPS ½ to NPS 24.

This standard specifies the flange types and their facings,dimensions,tolerances,threading,bolt sizes,flange jointing face surface finish,marking,materials and pressure/temperature ratings.BS EN 1759-1:2004 Standard for a single system of flanges specifies requirements for circular steel flanges in Class designations Class 150 to Class 2 500 and nominal sizes from NPS ½ to NPS 24.

This standard does not apply to flanges made from bar stock by turning, or to flanges of types 11, 12, 13, 14 and 15 made from plate material.