Isolation
Any rehabilitation or replacement works on pressure mains require the sections of main being rehabilitated or replaced to be isolated from the system. Procedures for isolation when using any of the trenchless methods are the same as normal mains isolation procedures. No special measures are necessary when the trenchless techniques are used.
Industry standard methods such as Iris stop, line stop, bag stop and squeeze-off may be employed in accordance with applicable national safety regulations in the same way as for all other works on mains that require isolation.
Slip-lining is perhaps the oldest of all trenchless techniques . It involves the insertion of a new PE100 or PE100-RC liner pipe of standard diameter and SDR into an existing pipe. Under the right conditions, slip lining is also the simplest trenchless technique. A new pipe with an outside dimension smaller than the inside dimension of the host pipe is either pulled or pushed into the host pipe. The ideal host pipes for slip lining are straight with no deformities, no or modest bends, no severe protrusions into the pipe, and only modest offset joints.
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