Mechanical Joint Saddle Fittings
Mechanical joint saddle fittings are made from PE, metals, and other materials. For mechanical joint outlets, the service or branch pipe is either supported with a tubular stiffener in the pipe ID, or the pipe end is fitted over a spigot (insert) end of the fitting. The outlet joint is completed using mechanical compression around the service or branch pipe OD. Depending upon design, gaskets may or may not be used. The connection between the saddle base and the main may be by hot plate saddle fusion, electrofusion, or by mechanical connection. Some mechanical joint saddle fittings can have an internal cutter to pierce the main pipe wall. Tapping tees or tapping saddles are generally suitable for installation on a "live" or pressurized main (hot tapping). Branch saddles or service saddles that do not have internal cutters may also be hot tapped using special tapping equipment.
Additional information and details on mechanical couplings are provided in Chapter 9 of the Plastic Pipe Institute (PPI) Handbook of Polyethylene Pipe, which is available at www.plasticpipe.org/pdf/chapter09.pdf.