An energy recovery system for a pipe manufacturing process is shown. A compression or injection molding operation is used to form a sealing gasket which is used in the subsequent pipe manufacturing operation. A Stirling engine cycle is used to recover heat during the gasket manufacture. The Stirling engine is driven by waste heat from the mold members or other associated parts of the injection or compression molding apparatus. The recovered waste heat is used to subsequently heat the female pipe end which is being belled in the pipe manufacturing process.