Alloy Steel Grade F9 flange is thinner compared to other flanges. Therefore, ASTM A182 F9 blind flanges typically fit well into compact work areas. Additionally, the A182 F9 material contains a certain amount of chromium and molybdenum, both of which help maintain durability and therefore a long lifespan. Additionally, the addition of chromium and molybdenum to grade A182 F9 improves ... https://www.shasanpiping.com/alloy-steel-f9-flanges-manufacturers-exporters-suppliers-stockists.html