Abstract: A system and method for repairing the damaged portion of a flow-line of a Corrugated Metal Pipe is disclosed. A containment mold is created on the interior surface of the CMP using a series of overlapping rigid sheets that are attached to the CMP along the damaged flow-line. This mold is provided with injection ports through which a hydro-insensitive expanding polymer may be injected. External pressure is applied to the rigid sheet during injection and hardening of the polymer. The result is a single monolithic structure forming a patch over the damaged CMP flow-line.