Lap Joint Flanges must be used with their associated stub end. The stub is welded to the pipe and the Lap Joint then works as a backing ring. The main advantage of this type of flange is that the bolt holes can be aligned with the matching flange after the welds have been completed. A Lap Joint Flange is not suitable for areas with high external or dynamic loads. A Swivel Ring Flange should be used for this type of application.