Carbon steel flanges, also an important type of carbon steel pipe fittings, provide an easy access for cleaning, inspection or modification of a piping system. Carbon steel flanges are joined to each other by bolting and joined to the piping system by welding or threading and are designed to the specific pressure ratings; 150lb, 300lb, 400lb, 600lb, 900lb, 1500lb and 2500lb. Steel pipe flanges are classified as per ASME B16.5 standard. There are various types of flanges forged and machined from steel rods and billets. Among the most commonly used flanges include slip on flange, weld neck flange, threaded flange and blind flanges.