The slip on flange has a low hub and slips onto the pipe prior to welding. Welding is carried out on the inside and outside to provide sufficient strength and prevent leakage. Slip on flanges are all bored slightly larger than the OD of the matching pipe to allow for the welds to hold.
Slip-On Flanges are probably the most common type of flanges in the industry and are ideal for lower pressure applications. You do not have to specify the pipe schedule when using slip-on flanges due to the fact that its inside diameter is determined by the outside diameter of the pipe. This outside diameter of the pipe does not change for the different schedules. This often makes these easier to stock for vendors. Fabricators also like the fact that these flanges are slightly easier to align than weld neck flanges.
They also are slightly easier to cut pipe to the proper length for. They can be used for high temperature and pressure applications but are not generally recommended as compared to other types of flanges. ASME B16.5 Code limits their usage in the 1500#-2500# (lbs.) weight classes. The three most common types of facings that We carries for slip-on flanges are raised face (most common), flat face, and ring type joint (RTJ). We offers these flanges in stainless and alloy material.
Slip-on flanges, abbreviated as SOF, are designed to slip over the outside of pipe, long-tangent elbows, reducers, and swages. The flange has poor resistance to shock and vibration. It is easier to align than a weld neck flange. This flange is ideal for low pressure applications since the strength when under internal pressure is about one third that of a weld neck flange. This flange has a raised face.