Method of repairing buried sewage pipes

Abstract

A method of repairing a damaged (e.g., cracked) portion of a buried sewage pipe by permeating one or more layers of fibrous material with a hardenable plastic compound (such as epoxy resin), convoluting the thus obtained mat around a radially expandible length of hose to permit frictional engagement between the internal surface of the mat and the external surface of the hose, introducing the hose into a selected defective portion of the pipe, expanding the hose and the convoluted mat so that the mat engages the internal surface of the pipe, deflating the hose, and withdrawing the hose from the pipe, preferably after the plastic compound has set wherein a film of polyethylene is inserted between the external surface of the hose and the internal surface of the convoluted mat to enhance friction and to thus compel the hose to turn in the course of the expanding step. Expansion of the hose results in expulsion of some plastic compound beyond the peripheral surface of the convoluted mat; such compound bonds the expanded convoluted mat to the pipe and at least partially fills the crack or cracks in the adjacent portion of the pipe. Some plastic compound is also expelled at the axial ends of the convoluted mat to form a smooth transition between the internal surface of the pipe and the internal surface of the expanded convoluted mat.