Investigation of Corrosion on Inland Petroleum Distribution System Aluminum Pipe Grooved Ends Caused by Rubber Gaskets.

Because of fuel leaks at a number of mechanically connected joints, the Inland Petroleum Distribution System IPDS unit at Fort Lee, VA, was disassembled. Corrosion had occurred on the bare surfaces of the aluminum pipe single-grooved ends in the connection joints. These corroded surfaces were in contact with the rubber gaskets inside the IPDS joint couplings. An investigation was performed to determine the cause of the corrosion. The joint gasket was made of epichlorohydrin rubber material, which contains a high chlorine content. Some chlorine, in the form of ions, combined with water or moisture trapped in the joint gaps to form hydrochloric acid to corrode the aluminum. Therefore, the primary cause of corrosion on the bare aluminum surfaces was the improper use of epichlorohydrin rubber material for the gaskets inside the joint couplings. A simple accelerated corrosion test procedure was established to verify the mode of corrosion on the bare aluminum surfaces. Samples of the original IPDS rubber gaskets were taken, and new sample gaskets made of two different rubber materials i.e., reformulated epichlorohydrin and nitrile were evaluated on bare aluminum surfaces.