Sliplining is a process by which continuous or discreet pipes are inserted within existing (host) pipes. Examples include the pulling in of long lengths of PE pipes within water mains or the insertion of individual pipes within sewers.
This is generally a low cost technique, which has the disadvantage of reducing the original bore of the pipe. However, reduced friction usually associated with the liner pipes may negate this and may even ultimately improve the flow properties. The host pipe is first cleaned and any intrusions removed before the sliplining process begins.
Pipe types that can be used for slip lining include plastic (PE usually butt fusion welded to the full length of the lining required or PVC in discreet lengths with pressure joints); concrete, composite, GRP jacking or clayware pipes (using a jacking frame and discreet pipe lengths to achieve the insertion). The latter option whilst available is currently experiencing limited use.
Once sliplining is completed in some cases the annulus between liner pipe and host pipe may be grouted to create a composite of host and lined pipe.