Slip on Flange Is fundamentally a ring placed over the end of the pipe, with a flange face extending from the end of the pipe by sufficient distance to apply a welded bead to the inner diameter. As the name suggests these flanges slip over a pipe and hence known as Slip On Flanges. A slip-on flange is also known as SO flange. It’s a kind of flange that are slightly bigger than the pipe and slides over the pipe, with internal design. Since the inner dimension of the flange is slightly bigger than the external dimension of the pipe, the top and bottom of the flange can be connected directly to equipment or pipe by fillet welding the SO flange. It is used to insert the pipe into the flange’s inner hole. Slip-on pipe flanges are used with a raised or flat face. Slip-On Flanges are a suitable choice for low-pressure applications. Slip on flange is excessively utilized in many fluid pipelines.