Weld Neck Flange

As one of the most prevalent flange types in the global piping industry, RFWN Flanges (Raised Face Weld Neck Flanges) are easily distinguishable by their long, tapered hub—this hub is precisely matched to the wall thickness (bore) of the connected pipe, ensuring optimal compatibility and structural integrity.

Both standard weld neck flanges and long weld neck flanges offer exceptional reinforcement capabilities, making them ideal for applications that involve high pressure, as well as extreme low-pressure and high-pressure operating conditions. Additionally, they effectively mitigate low-cycle fatigue, which is often caused by pipeline expansion or other variable forces acting on the piping system.

The bore of a weld neck flange is precision-machined to align perfectly with the inner diameter (ID) of the pipe or fitting it connects to. This precise alignment creates a seamless transition between the pipe and the flange, eliminating turbulence at the weld neck—a critical feature for maintaining stable fluid flow. For this reason, specifying the pipe schedule when purchasing a weld neck flange is essential to ensure proper fit and performance.

Weld neck flanges are attached to pipes via full penetration welding, which delivers superior stress distribution through their tapered neck design. In critical applications, these welds are also regularly inspeced using radiography or ultrasonic testing (UT) to ensure weld quality and structural reliability, minimizing the risk of leaks or failures.

Raised face and flat face configurations are both available for weld neck flanges, with raised face being the most commonly used option. Most standard weld neck flanges come with either a standard bore or an extra heavy bore. For heavier pressure classes—typically 600# to 1500#—weld neck flanges with Sch 120 or Sch 160 bores are also widely utilized in industrial settings.

We offer a comprehensive range of weld neck flanges, crafted from a variety of high-quality materials including ASTM A105, 20#, Q235, 16Mn, ASTM A350 LF1, LF2 CL1/CL2, LF3 CL1/CL2, stainless steel, duplex and super duplex steels, as well as nickel alloys. Whether you prefer to shop online or request a custom quote, feel free to contact us—we are ready to meet your specific flange requirements!