Case Studies of Pulsed Eddy Current to Measure Wall Loss in Feedwater Piping and Heater Shells

Abstract

There have been several feedwater piping and heater shell failures in power plants caused by flow-accelerated corrosion (FAC). This failure mechanism may be one of the most important types of damage to find proactively because FAC damage has occasionally resulted in catastrophic failures and human fatalities. Predicting, detecting, and resolving significant FAC damage can significantly reduce future forced outages and increase personnel safety. This paper describes the implementation of recent developments to perform cost-effective FAC examinations. These advances include the use of specialized pulsed eddy current (PEC) hardware and software to scan for wall thinning without removing insulation. Recent results are based on the current version, MK II, of this equipment. The authors have performed more than 200 power plant projects with this PEC equipment, examining numerous pipes and shells. This work consists of more than 70 projects of wall loss examinations for the nuclear industry, including examinations of feedwater heater shells inside the condenser. Results of wall loss measurements regarding PEC average wall thickness (AWT) measurements, ultrasonic thickness examinations (UTTH), and the PEC evaluated Defect Algorithm are compared in this study.