Soil Sockets, Couplers & Reducers
The joining and size-changing fittings. Sockets and couplers connect pipe to pipe; reducers step the system down from one diameter to the next; expansion sockets absorb thermal movement along long straight runs.
Also searched as: double socket, slip coupler, repair coupler, expansion socket, reducer, reducing socket
Double socket and slip coupler
A double socket joins two plain-ended pipes with a seal or solvent socket at each end. A slip coupler (repair coupler) has no internal register, so it can be slid fully onto one pipe and then back over the joint — the fitting to specify when cutting into an existing run or making a closure joint where neither pipe can be moved.
Expansion socket
On long straight solvent-welded runs, thermal movement has to go somewhere. An expansion socket has a deep, unglued spigot entry that lets the pipe slide. Fit them at the intervals given in the Technical Manual, and make sure the pipe is genuinely free to move in its brackets either side — a clamped bracket next to an expansion socket defeats the fitting.
Reducers
Level-invert and concentric reducers are available for the standard size steps: 200×160, 160×110, 110×82 and 110×50mm. On a horizontal run always use a level-invert pattern so the pipe soffit steps rather than the invert, otherwise solids are lifted at the size change.