This part of EN 1092 specifies requirements for circular flanges made from ductile, grey and malleable cast iron for DN 10 to DN 4000 and PN 63. (See 4.1 and 4.2). This standard specifies the types of flanges and their facings, dimension and tolerances, bolt sizes, surface finish of jointing faces, marking testing, quality assurance and materials together with associated pressure/ temperature (p/T) ratings.