Life Expectancy for Fossil Steam Turbine Casings after 1000 000 Hours

Abstract

Today with the rapid development of nuclear electricity generation on a large scale, there arises the problem of maintaining fossil fuel generating stations that have been in operation for some 100 000 h or more. Operators usually hope to prolong the service life of units where safety margins permit, with objectives attaining beyond 150 000 h. This is an extremely ambitious program that is thwarted by the very nature of the work demanded from this type of thermal generating station: namely fulfillment of the needs of daily and seasonal peak periods, which increase the number of severe thermal operating transients. This paper examines the question of metallurgical studies carried out by Alsthom-Atlantique on stator steel castings with a view to estimating their expectation of life potential. This work constitutes the second part of a study entitled “Quenching, Tempering, and Aging of Chromium-Molybdenum-Vanadium Cast Steels” in the Journal of Evaluation and Testing, Vol. 9, No. 2, March 1981.