The 3 1/2 Inch Weld Neck Flange (NPS 3 1/2″ | DN90) is a forged, heavy-duty flange designed for high-pressure and high-temperature piping systems. Featuring a long tapered hub, it is butt-welded directly to the pipe to ensure superior strength, smooth stress transition, and enhanced structural integrity. This design minimizes turbulence and erosion while providing excellent resistance to mechanical stress and thermal expansion.

Manufactured in accordance with ASME B16.5, the 3 1/2″ Weld Neck Flange is available in pressure ratings ranging from Class 150 to Class 2500, depending on operational requirements. It is produced in a variety of material grades including Stainless Steel (ASTM A182 F304, F316, F321, F347), Carbon Steel (ASTM A105, A350 LF2), Alloy Steel (F11, F22, F5, F9), Duplex & Super Duplex grades, and Nickel Alloys to meet demanding industrial environments.

The flange is typically supplied with a Raised Face (RF), with optional Flat Face (FF) and Ring Type Joint (RTJ) configurations for higher-pressure sealing applications. Each flange undergoes strict quality inspection and is available with Mill Test Certification (EN 10204 3.1).

It is widely used in oil & gas, petrochemical, power generation, marine, and chemical processing industries.