Until recently, no repair system for the DN100 to DN150 pipe range has been available for sealing the service laterals of downpipes, house sewers and lateral connection pipes, for example pipe sizes from DN50 to DN150.

New lateral connection repair system for house sewers Trelleborg epros GmbH of Duisburg recently introduced a system called ‘eprosLCR-B‘ managing to scale down to lateral and house sewer sizes the method utilised for main sewer rehabilitation in which a packer is used to invert a fibreglass lateral connection repair (LCR) unit into the main/lateral interface. The eprosLCR-B system is designed for applications in DN 100 to DN 150 main pipes, with DN 50 to DN 150 laterals at connecting angles of 45 to 90 degrees, with LCR lengths of 150 to 280 mm.

A field trial was set up in co-operation with the State Building Administration of Würzburg to subject the eprosLCR-B system to a performance test. In short, the results of the test convinced both customers and relining experts of its applicability in the field. The 100 to 150 mm diameter lateral connections in the relined house sewer pipes had been omitted as there had been no appropriate method available at the time. Performance test

The first test phase was to install four LCRs. If these installations proved satisfactory, the repair of the remaining 15 service laterals would follow.

The fibreglass LCR was first impregnated with epros patch liner resin and then inverted over the packer finger, which had been lubricated with a release agent, with the rim of the LCR being in firm contact with the packer body. In contrast with other known packers, the eprosLCR-B packer includes a lateral finger which is extended into the lateral. The packer finger must of course be retracted during packer introduction into the main pipe. For this purpose, a specifically designed reversion technique retracts the finger while inverting the LCR down to its rim. A thin binding wire holds the reversed finger during transport. The wire comes off as soon as pressure is applied to the packer during the installation process.

A camera is put into the pipeline from the building side through the pipe to the connection point. This is used to monitor the exact positioning of the packer. The packer itself is introduced from a manhole or clean out of the house sewer and pushed with air rods to the lateral opening.

In this way, it is possible to mark the push rods to identify the distance to be travelled by the packer and to make a final check to ensure the diameter and angle of the packer are consistent with the geometry of the host pipe. The remaining work is very easy with just a little exercise being required. The camera operator gives directions for the accurate positioning of the packer. At his command, the packer will be slowly inflated. Due to the binding wire, the rim of the LCR is first pressed against the main pipe wall around the lateral opening. Then, as the binder comes off, the LCR on the finger is inverted into the lateral, job done. The cure time is about 90 minutes. After this time, the packer is removed from the line and the result can be inspected with the camera.

Convincing results

The results of the test convinced both customers and relining experts of its applicability in the field.

“The results of the ‘test repairs‘ have convinced me”, said Robert Thoma from the State Building Administration. “Simple handling and short installation time are two key benefits for any method, because they are crucial to the price-performance ratio. But of course, the final result is what actually matters. We were very positively surprised by the smooth operation and the result.“