Overview

ASTM D 4378, Practice for In-Service Monitoring of Mineral Turbine Oils for Steam and Gas Turbines, was developed by Subcommittee D02.C on Turbine Oils in response to the needs of the electrical power generation community. The organizations for which this document is intended are the utilities and industries which generate their own electrical power. The purpose of D 4378 is to recommend: 1. Which tests to run. 2. The frequency of testing. 3. The interpretation of the results. 4. Corrective actions. 5. Limiting values. This symposium brought together suppliers and consumers to present their views on turbine fluid monitoring. An overview was presented by Roberton giving the user needs that generated D 4378. The history of the document was discussed with the reasons for having the tests which are included, the basis for interpreting the results, and the appropriateness of the limits. The necessity for a monitoring program was brought forth by Bonett, who presented the experiences of an American utility. These show that a program can identify problems so that corrective action can be taken in time to prevent a major shutdown. The views of an American lubricant supplier were given by Trabert and Schreuders, who stressed the need for close cooperation between the turbine operator, the turbine manufacturer, and the lubricant supplier to ensure the successful operation and effective monitoring of a turbine circulating system. Ohgake and his associates reported on the technological revolution in Japan since 1955. Maximum unit capacity has increased from 66 MW in 1955 to 1000 MW in 1987. At the same time, steam pressure of 60 kg/cm 2 in 1955 has risen to 246 kg/cm 2 with a corresponding rise in steam temperature from 480~ to 566~ Turbine oil operating temperatures increased by 10 to 15~ thereby potentially more than doubling the oxidative degradation rate of the lubricant. Ohgake confirmed the use of ASTM D 2272 in their monitoring programs and for the calculation of turbine severity, and also indicated that the concept of regular makeup (replacing part of the oil charge) to compensate for oil degradation was still considered a useful practice to ensure long oil service life. In Japan and in the United States, increased demands have been placed on turbine lubricating oils by changes in the design of the turbine generators. The increased use of combined cycle stations has added the requirement that the same lubricant be used in both gas and steam turbines. (In a combined cycle installation,