Typically, a slip-on pipe flange is placed over the pipe. The internal diameter of a slip-on pipe flange is normally constructed to be somewhat larger than the pipe’s exterior diameter. As a result, the pipe can be covered by the slip-on flange. To give strength and stop leaks, slip-on pipe flanges are welded, typically from the inside as well as the outside. Slip-on pipe flanges can be constructed with a bore to fit either pipe or tube, and they can occasionally also feature a boss, ring, or hub. Because they both slip over the pipe, ring and hub pipe flanges are referred to as slip-on pipe flanges.

Because they are less expensive and need less precision when cutting pipe to length, slip-on flanges are typically chosen by users over weld neck flanges. Slip-on flanges come in orifice designs and with faces that are raised, flat, or RTJ.