Lap Joint type Flanges are used with their associated stub end that is welded to the pipe and the lap joint then works as a backing ring. These Flanges have a larger radius at the intersections of the bore and flange face. These Flanges are designed with bolt holes that can be aligned with the matching flange after the weld is completed. Lap Joint type Flanges have a larger radius at the intersections of the bore and flange face.