US Patent 7942167 Expandable pipe for restoring a conduit

An expandable pipe (20) for restoring a damaged conduit (22) includes a liner (24) formed of polypropylene material. The liner (24) presents exterior surface (26) defining a plurality of grooves (28) and surrounding a center opening (32). The grooves (28) contain a grout material (30) and provide for controlled placement of the grout material (30). The grooves (28) maintain the placement of the grout material (30) when sliding the expandable pipe (20) into the conduit (22). The grout material (30) includes urethane and recycled fibers (36), and expands in volume upon contact with moisture. The grout material (30) expands to fill cracks in the conduit (22). The grooves (28) also render the expandable pipe (20) bendable in width (W) at the groves for folding and transporting the expandable pipe (20) and for maneuvering around bends of the conduit (22).