Erosion/Corrosion Wear Detection for Fossil Power Plants at Pacific Gas and Electric Company

Eight years ago PG&E began a program for its fossil plants for early detection, repair and prevention of Erosion/Corrosion (E/C) failure mechanisms. Since its inception, hundreds of worn piping components have been detected and repaired before failure. E/C failures have become very rare. A number of recurring patterns have become evident allowing a certain degree of location predictability using practical methods. Prediction methods include wear calculations combined with PG&E and industry experience. In general, 50 to 75 components are evaluated for E/C wear at each outage, mostly with through insulation Radiographic Testing (RT) while the plant is in operation. Inspection locations are chosen based on a practical approach to Risk-Based Analysis (RBA). Wear rate, failure mode, and potential personnel exposure are considered in the selection process.

Judging by the number of E/C induced failures that have happened in the past several years in both fossil and nuclear plants, many utilities do not have similar programs or have not considered some of the most basic forms of potential E/C failure. Some utilities approach the issue far too analytically and create a false sense of security by checking only a very limited number of locations based on calculated predictions of worst locations.