Oxidation and varnish have been recognized as problems since the Civil War, but only in the last few years has the problem reached epidemic proportions in power generation and other gas-turbine applications. "The new turbines that have come on-line in the last five years are designed to put out more energy from smaller equipment," says Dave Wooton of Wooton Consulting, "and that means more stress on the unit and the lubricant." But increasing stress is not the only contributor to the problem. In the same time frame, turbine users have switched their turbines from base-load to peaking and from Group I base oils to Groups II and III. "A lot of people blame the new base oils for the problems," says Wooton, "but I'm not one of them. I do believe the new formulations were put together improperly when these oils first came out, because lubricant manufacturers weren't accounting for the different chemistry of the base-stocks. But there are many other problems as well." Regardless of source, Wooton notes that a little varnish can cause a big headache: "If a valve sticks just a little, the computer controlling the unit shuts it down, and the trip-out cost can be USD30,000-USD 100,000 or more."
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