A weld neck flange is a type of flange that is designed to be welded to a pipe or fitting. It has a long tapered neck that is welded to the pipe, providing strength and stability to the joint. The weld neck flange also has a raised face, which helps to create a seal when the flange is bolted to another flange or fitting. This type of flange is commonly used in high-pressure and high-temperature applications, as the welded connection provides a strong and reliable joint.