Integral flange or Long Weld Neck (LWN) flange is a type of flange that is commonly used in high-pressure applications, such as in oil and gas pipelines, chemical processing plants, and power generation facilities. The LWN flange is a one-piece forged flange with a long, tapered neck and a flat face or raised face. The neck of the flange is welded to the pipe, which provides a strong and reliable connection that is resistant to bending and deformation.

The LWN flange is designed to distribute the stress evenly across the flange and the pipe, which helps to prevent leakage and damage to the system. The long neck of the flange also provides additional support and reduces the risk of thermal expansion or contraction.

The LWN flange is available in various sizes, pressure ratings, and materials, including carbon steel, stainless steel, and alloy steel. It is commonly used in pipelines that require high-pressure and high-temperature capabilities and in applications where frequent disassembly and maintenance are necessary.

Proper installation and torque of the bolts are crucial to ensure a tight and leak-free seal. The LWN flange must be installed with the proper alignment and clearance to prevent damage to the flange and the pipe. The weld must also be done carefully to ensure that it is strong and secure. Regular inspection and maintenance of the LWN flange are important to ensure that it is functioning properly and to prevent any damage or leaks in the system.