Lap Joint Flanges

Lap Joint Flanges (LJ Flanges) are used on piping fitted with lapped pipe or with lap joint stub ends the combined initial cost of the two items being approximately one-third higher than that of comparable Welding Neck Flanges. 

Lap Joint Flange is having two components, a stub end, and a loose backing flange. Stub end is butt welded to the pipe and Backing flange freely move over the pipe. The backing flange can be of different material than stub material and normally of the carbon steel to save the cost. Lap flange is used where frequent dismantling is required, and space is constrained.

Furthermore, a standard lap Joint Flange will typically have a longer hub length in comparison to a Slip On Flange, but this is often considered unnecessary for many applications.

The lap joint flange is practically identical to a slip-on flange except it has a radius at the intersection of the bore and flange face.