Accelerated Corrosion of Copper-Nickel Piping
NATIONAL MATERIALS ADVISORY BOARD (NAS-NAE) WASHINGTON DC
Pagination or Media Count:
Unexpectedly severe corrosion occurred in cupro-nickel piping in seawater cooling systems aboard ships built in one location. A workshop, convened to discuss the problem, identified turbulence as a major contributing factor, and the practice of running the seawater loop wide open while throttling the fresh-water loop as contributory to the turbulence. Recommendations of the committee were 1 reduce the velocity of flow in the pipes 2 use long radius elbows whenever possible and 3 conduct research of development to evaluate the following remedial measures--a suitability of alternate materials b determination of the significance of the iron content in alloy 706 90Cu-10Ni c investigation of the relative corrosion rate when a negative potential is applied to the system, using the cupro-nickel piping as a cathode d control of seawater pH to a value of about 9.0 and e use of electrochemical probes to detect changes in corrosion rates. The committee, in commenting on the Navys research program, felt that the turbulence aspect had been given inadequate attention, that the role of ammonia had not been given adequate consideration, that the design of the shore-based simulation test did not sufficiently resemble the installed conditions, and that more should be done on characterizing reaction product films.
- Properties of Metals and Alloys
- Pumps, Filters, Pipes, Tubing, Fittings and Valves