A Long Weld Neck (LWN) flange is a type of flange with an extended neck that resembles a pipe, allowing it to connect seamlessly with pipelines. Unlike regular weld neck flanges, the elongated neck is designed for applications involving high pressure, extreme temperatures, and critical stress conditions. The extended neck provides additional structural support, making it ideal for connecting vessels, valves, or equipment in industries like oil and gas, petrochemicals, and power generation.

The primary difference lies in the neck length. Long Weld Neck flanges have a longer neck, which provides additional support and enables a seamless transition with the connected pipe, especially in high-stress situations. This unique design reduces stress concentration at the weld area, enhancing the flange’s resistance to bending, temperature fluctuations, and mechanical loads. Standard weld neck flanges are generally used for lower-stress applications.

Long Weld Neck flanges are made from various materials depending on the service conditions. Common materials include carbon steel, stainless steel, alloy steel, duplex, and super duplex stainless steels, and even nickel-based alloys for highly corrosive environments. Material selection depends on factors like operating temperature, pressure, and corrosion resistance requirements of the application, with higher-grade materials chosen for extreme conditions.