ASME B16.1 pdf download Gray Iron Pipe Flanges and Flanged Fittings Classes 25, 125, and 250 6.2 Bolting ASTM A307 Grade B bolting material is recommended forgrayiron flange assembly. Where grayiron flanges are bolted to steel flanges, see ASME B16.5 for bolting limita- tions. 7 FITTING DIMENSIONS AND TOLERANCES 7.1 Wall Thickness It is recognized that some variations are absolutely...