Lap joint flange facing

[KunAbdel]

In weld neck flanges we specify the facing of the flange for example raised face (RF) and based on that we use a specific gasket to match the facing of the flange

What about lap joint? In autocad plant 3d I can only find Flat face (FF) in the catalogue is it true?

 

[EngrPaper]

The hub of the lap joint forms a raised face. The backing ring sits behind the hub.