Lap joint pipe flange is a flange type popular in piping system, especially for the corrosive piping system on the purpose of saving the cost.  Lap joint flange also named loose ring flange or back up flange, they are a two part flange consisting of a lap joint stub end which is welded to the pipes and a backing lap joint flange which is slide onto the pipe before welding the stub end, the Lap Joint is free to rotate around the stub end.

Lap Joint flanges are very similar to Slip On flanges, but lap Joint flanges include a radius or chamfer at the back side for the Stub End making it only fit to Lap Joint Stub Ends and not like slip on flange has a 1.6 or 2mm raised face at the back side, the lap joint flange is totally flat at the back side of flange.  Material for lap joint flange and stub end is different to achieve a greater cost flexibility. Material used for lap joint flange include carbon steel, alloy steel or stainless steel, lap joint stub end maybe with a material in higher steel grade.

The lap joint flanges are available in common dimensions like other flange types making it easy to integrate them into existing piping systems or use alongside other piping components. 

Stub Ends also match both pipe material and wall schedule to maintain both inside and outside diameters of your piping process. This style is typically used in engineered piping systems with critical wall thickness requirements.

PENGTONG sells all kinds of lap joint flange in steel grade ST37 or A105. Please email or call us for your flange quote!