The corrosion mitigation of cable sheaths and other underground metallic structures in a metropolitan area involves many problems not encountered in the protection of cross-country cables and pipe lines. It is difficult for any one operator to apply protection to small section of his system or the entire system without increasing corrosion on other systems in the same area.
A description is given of how Miami utility companies participated jointly in the designing and installation of a cathodic protection system. Purpose of the project was to provide protection to all metallic structures in a certain downtown area. Eleven 50-ampere rectifiers were installed at selected locations throughout the area.
The selecting of reference electrode locations is discussed in detail. Other topics considered include cathodic protection design factors, tests made to determine need for resistance bonds, changes in construction practice, use of magnesium anodes and cost of installing cathodic protection.
After eight years time the Miami cooperative corrosion control program was found to have provided good protection to electric and gas and communication systems. Corrosion failures on protected communication system cables were found to be almost nonexistent. Corrosion failures on electric cable sheaths were found to have dropped to one per year.
