ASME B16-1 pdf download Gray Iron Pipe Flanges and Flanged Fittings Classes 25, 125, and 250 Equipment shall be designed to produce wall thick- nesses given in the tables. Wall thickness at no point shall be less than 87.5% of the thickness given in the tables. 7.2 Facing (a) Classes 25 and 125 gray iron flanges and flanged fittings shall...