Evaluation of a utility`s critical piping systems -- A comparison between stations and re-evaluation after 5 years

At the request of the Nevada Power Company, Bechtel Power Corporation (Bechtel) performed an initial evaluation of the main steam and hot reheat piping systems for the utility generating units during the 1987--1988 period. The purpose of the evaluation was to assess the present and theoretical (design) condition of the piping systems for continued base load operation at full design conditions. Follow-up evaluations were performed for many of the units beginning in 1994. Units included in the evaluation were Reid Gardner Units 1 through 4, Sunrise Unit 1, and Clark Unit 2. This paper provides a comparison of the piping conditions between the units within each station and a station-by-station comparison within the utility`s system. To determine the present condition of the piping systems, physical walkdown, piping stress analysis, metallography, and nondestructive examination (NDE) were performed. The result of the assessment, recommendations, and subsequent evaluations are discussed.