705.8.1 Slip Joints.
In fixture drains and traps, slip joints of approved materials shall be permitted to be used in accordance with their approvals.
A drainage slip joint is made of three pieces: a friction ring, a gasket and a slip joint nut. The gasket is made of a compressible pliable fiber, rubber or plastic material. The nut is tightened on the fitting and the gasket is compressed around the pipe being joined by the slip joint (see Figure 705.8.1). The use of slip joints is restricted to accessible or exposed locations (see Section 402.10). In waste piping, their use is permissible on the inlet side of the fixture trap. One slip joint on the outlet side of the fixture trap is permitted (see Section 1003.2). Ground joints and ferrule type connections are not considered slip joints (Section 705.8.3).