This paper applies to individuals charged with maintaining the reliability of shell and tube heat exchangers. These persons typically specify and/or retain the services of others to examine heat exchangers with nondestructive test methods, such as eddy current and are responsible for submitting run-repair-replace recommendations to management.
Electromagnetic Testing (ET) uses the electromagnetic characteristics of components made of conductive materials to determine their condition. Eddy Current Testing (ECT), an electromagnetic method that utilizes induced electrical currents, is usually used to examine non-ferromagnetic materials.
ECT’s high rate of examination, relatively good accuracy with thin wall components, repeatability and volumetric measurement make it an ideal method for examining nonmagnetic heat exchanger tubes. This paper will provide a brief description of the method, concentrating on ECT because most power generation industry heat exchanger tubing is non-ferromagnetic in nature. This paper will also address the following:
• Training and Certification of Technicians.
• ET signal analysis, an exacting science?
• ASME Section V, Appendix II vs. Appendix VIII for in-situ ECT of all heat exchanger tubing.
• Signal analysis variables and limitations.
• A need to know the potential degradation mechanisms.
• Condition assessment vs. eddy current testing.