Class 900 Flanges

Kalp Alloys is a leading manufacturer and supplier of Class 900 Flanges (also known as 900 lb flanges or 900# flanges) conforming to ASME B16.5 standard. We supply Class 900 pipe flanges in all standard types — Slip-On (SOF), Welding Neck (WNF), Socket Welding (SWF), Threaded (THDF), Lap Joint (LJF), and Blind (BLF) — in sizes ranging from NPS 1/2″ to NPS 24″. Our flanges are manufactured in a wide range of materials including Stainless Steel (SS 304, 316L, 321), Carbon Steel, Alloy Steel, Duplex, and Nickel Alloys to meet the most demanding industrial requirements.

A Class 900 flange is a pressure-class designation under the ASME B16.5 standard (Steel Pipe Flanges and Flanged Fittings). The “900” refers to the pressure class — engineered for severe-duty, high-pressure, and high-temperature piping systems. Class 900 flanges are rated at approximately 2220 psi (153 bar) at ambient temperature (38°C) for carbon steel.

They are widely used in oil & gas exploration, high-pressure steam lines, power generation, refinery process piping, and offshore platforms where extreme pressures and temperatures are encountered. Because of their heavy-duty construction and exceptional pressure capacity, ASME B16.5 Class 900 flanges are the preferred choice for critical service applications requiring performance well beyond Class 600.