Rusting in Turbine Oil Systems

Abstract

Rust-inhibited petroleum lubricating oils, now widely used, prevent rusting in turbine oil systems except under certain adverse operating conditions. This paper reviews the mechanism of rusting occurring in the liquid and vapor regions of a turbine oil system. Current accelerated rusting tests are discussed as related to rusting in service. Often, the bench-scale rusting tests used do not predict accurately the protection afforded in service. This can be the result of failure to recognize the important rusting variables and poor choice of bench test. Factors relating to rust-promoting conditions are reviewed. The importance of removal of water from the oil and avoidance of contamination with salt are stressed. A method is presented for monitoring rusting in turbine oil systems. Examples are given of its successful use in the field. The method permits continual surveillance of the existent rust protection afforded by the oil.