Lap Joint Flange

Lap joint pipe flanges slide directly over the pipe and are most commonly used with stub end fittings. A pipe is usually welded to the Stub End and the Lap Joint pipe flange is free to rotate around the stub end. Lap Joint pipe flanges are often used for applications that require frequent dismantling.

Lap joint flanges feature a flat face and are always used in conjunction with a stub end.  A stub end is inserted in the bore of the flange and welded with the pipe.

Lap joint flanges resemble, in shape, slip-on flanges except for the radius at the crossing of the flange face and the bore to accommodate the flanged portion of the stub end.

A lap joint flange slips over the pipe and seats on the back of the stub end and the two are kept together by the pressure of the bolts.

The use of lap joint flanges in combination with stub ends is a cost-effective solution for stainless steel or nickel alloy pipelines, as the material of the lap joint flange can be of a lower grade (generally carbon steel) than the material of the stub end (which has to match the pipe grade, as in contact with the conveyed fluid).

This arrangement, therefore, has these two advantages:

reduces the overall cost of the pipeline’s flanged joints, as the use of higher-grade materials is minimized;

bolting operations are simplified, as the lap joint flange can be rotated around the pipe to help with bolts alignment.