Municipal Pipe Material Joints: Design and Sealing

Joints in buried municipal pipes are arguably one of the most critical components of the overall system, the weak link that determines the integrity of water and wastewater systems against leaks and inflow/infiltration (I/I). Elastomeric or rubber gasketed “push-on” or “bell-and-spigot” joints are one of the most common ways by which pipe sections are joined. The American Water Works Association’s (AWWA’s) Manual of Water Supply Practice M75 Elastomers for Waterworks: Pipes, Valves, and Fittings is the first manual of its kind and focuses exclusively on the elastomeric gaskets that seal the various types of joints. While pipe joints are discussed in AWWA M75, an understanding of the unique joint types of each pipe material is not covered in depth. This paper focuses on the state-of-the-art of joints found in two of the most widely specified pipe materials in water and wastewater systems: polyvinyl chloride (PVC) and ductile iron pipe. Discussions will also include joints of other pipe materials including thermoplastics such as corrugated HDPE and thermosets such as fiberglass pipe; vitrified clay pipe (VCP); spiral welded steel pipe; and both pressure and gravity concrete cylinder and non-cylinder pipes. Properties of elastomers for each joint type as outlined in pertinent standards will also be discussed and summarized.