One method of repairing the junction between main and lateral sewer pipelines is shown in U.S. Pat. No. 6,039,079, which is hereby incorporated in its entirety. A liner assembly, as shown in FIG. 3 of the '079 patent, includes a lateral liner 26 connected to a flat sheet liner 28. Both liners 26, 28 are formed of felt or other resin absorbent material. The resin is absorbed into both liners in an uncured state and the liners are held in place in the host pipelines as the resin is cured and hardened to form a hardened liner.
However, it is the general case that the main pipe extends between two service pipes or access shafts, which may be manholes. The main pipe extending between two manholes may include multiple lateral pipes extending therefrom. Furthermore, the lateral pipes may extend at different angles, both in relation to the radial configuration of the main pipe and to the angle between the axis of the main pipe and the axis of the lateral pipe. The plurality of lateral pipes extending from the same circumferential ring on the main pipe can make it more difficult to repair both the main and lateral pipes.
For example, as disclosed in U.S. Pat. No. 6,337,114, it has been the case where each lateral pipe is lined from the main pipe, and then the main pipe is lined. In order to do this, a portion of the main pipe is repaired at the junction between the main and lateral pipes. Therefore, the portion of the pipe is essentially double lined, first, by the repair of the lateral pipe, and then by the main pipe repair. The additional layers of pipe repairing liner can create obstructions in the main pipe. Obstructions are unwanted in pipes such as these, as they can reduce cross section of the pipe and may inhibit the flow.
In addition, the time and expense associated with lining the lateral pipes separately, and then lining the main pipe, is great. It takes a rather long time for resin impregnated into the repair liners to cure. A repair crew has to wait until the previous repairs have cured and hardened prior to moving on to the next repair. This can cause days' worth of delays when repairing the pipes. The delays and the amount of repair material needed to repair the main and lateral pipes increases the cost of the repairs as well, for both the repair crew and the municipality or organization paying for the repair.
Therefore, there is a need in the art for a method and apparatus for repairing main and lateral pipes that allows a repair crew to repair one or more lateral pipes extending from a main pipe at the same time of repairing the main pipe.
USPTO Backgrounds
USPTO Backgrounds