Lap Joint Flanges have all the same common dimensions as any other flange named on this website however it does not have a raised face. Lap Joint Flanges are used in conjunction with "Lap Joint Stub Ends". These flanges are nearly identical to Slip On flanges with the exception of the radius at the intersection of the flange face and the bore in order to accommodate the flanged portion of the Stub End. Their pressure-holding ability is little, if any, better than that of Slip On flanges and the fatigue life for the assembly is only one tenth that of Welding Neck flanges. Lap Joint Flanges may be used at all pressures and are available in a full size range. These flanges slip over the pipe, and are not welded or otherwise fastened to it. Bolting pressure is transmitted to the gasket by the pressure of the flange against the back of the pipe lap (Stub End).
Lap Joint flanges have certain special advantages including:
- Freedom to swivel around the pipe facilitates the lining up of opposing flange bolt holes.
- Lack of contact with the fluid in the pipe often permits the use of inexpensive carbon steel flanges with corrosion resistant pipe.
- In systems which erode or corrode quickly, the flanges may be salvaged for re-use.
A105 - The standard forged carbon steel piping components for ambient and high temperature / pressure systems
SS304 - A common standard for stainless steel due to its malleability, high corrosive resistance weld-ability
SS316 - A molybdenum stainless steel that provides excellent tensile, creep and stress-rupture strengths at elevated temperatures