Abstract
U.S. Navy ships experience scaling/macro-fouling of seawater cooling system components based on homeport location and operational areas. This leads to significant system downtime and manpower expenditure for subsequent system cleanings. Currently approved Navy cleaning methods such as hydro-lancing and hot acid cleaning have significant use drawbacks. Hydro-lancing is costly and labor intensive, requires significant staging, as well as being an invasive method; hot acid cleaning is not “friendly” for personnel use and has environmental safety issues.
In efforts to reduce the cost and effort associated with these cleanings, the Navy has identified several commercial descaling solvent products for removing seawater system scale. The present document represents work conducted by the Naval Research Laboratory in Key West, FL (NRLKW) to determine the effect of descaling solvent on the behavior of 70/30 Cupro-nickel and to validate the Uniform Industrial Process Instruction (UIPI) #5050-93 method of cleaning.
As a result of this research, it has been determined that cleaning of 70/30 Cupro-nickel with a 50%(vol) descaling solvent solution does in fact remove the passive/oxide film which naturally forms in flowing natural seawater on these alloys. These experiments also indicate that cleanings should be followed by a minimum of 3 weeks of operation under flowing natural seawater in order to return to the original passive film protectiveness.
