 Flanges used in piping (orifice, threaded, slip-on, blind, weld neck, socket, lap-joint, and reducing) are available with a variety of facings, such as raised, flat, and ring-joint.Slip-on flanges are slipped over the pipe and welded to provide strength and prevent leakage.This flange is less expensive than a weld neck and requires less accuracy when cutting pipe to length.