A Long Weld Neck Flange is an integral self-reinforcing Flange connection primarily for ASME Pressure Vessel applications. The Long Weld Neck (LWN) Flange was designed to be used in place of a Weld Neck Flange and piece of pipe for a bolt up connection to the vessel. This design reduced the stress on the neck and transferred it to the base where it connected to the vessel.

The Long Weld Neck Flange is the most common of the self-reinforced nozzle designs. The heavy barrel type nozzles offer a thicker neck for higher pressure and temperature applications. The Flange end and sealing face are designed to ASME B16.5 for pipe size ½” to 24” and ASME B16.47 for pipe size 26” to 60”. Typically the longer the nominal size and pressure, the longer the length of the neck. The standard bore for the LWN Flange is the same as the pipe size but can be ordered to any bore, the standard barrel lengths are 9”, 12” and 16”, but they will be made to meet the customer’s requirements.