The ASTM A182 specification covers both forged and rolled alloy and stainless steel forged fittings, pipe flanges and valves. These pipe fittings and other components are parts that can be used in high temperature applications. F5 is an Alloy Steel Gradeade specifically developed for the primary forming of forged products. https://www.shasanpiping.com/alloy-steel-f5-flanges-manufacturers-exporters-suppliers-stockists.html