Failure is defined as any change in a component that prevents satisfactory performance of its intended function. Understanding why a component failed is important for several reasons. First, a determination of the mode of damage responsible for the failure is an essential component of any root cause analysis, although in most cases it is not sufficient for identifying the root cause of failure. Second, understanding a component failure provides essential information for preventing additional or similar failures, as well as ensuring appropriate repair or replacement decisions are made. Perhaps most importantly, an erroneous or incomplete analysis can be worse than no analysis at all, since this can prompt inappropriate responses that do not address the basic cause of failure or even increase the potential for additional failures.

In general terms relative to power plant and other industrial components, condition assessments are performed to understand the current condition of components that are operating in environments that can degrade material properties and suitability for service. Condition assessment can be performed using either nondestructive or destructive techniques. With regard to laboratory evaluations, condition assessments often rely on destructive testing to understand the components’ metallurgical condition and to ensure that each component (or similar components which remain in service) are in an acceptable condition for continued operation. Laboratory evaluations can be performed as a standalone assessment or as part of a thorough program intended to identify trends in boiler and power plant equipment damage accumulation. Further, condition assessments can be applied to any component that has the potential for degradation in service, including boiler tubes, piping, turbine rotors, and numerous other metallic components.

Nondestructive examinations performed in power plants can range from assessing waterwall tubing for hydrogen damage to measuring steam side tubing oxide thicknesses for condition assessment to examining high energy piping long seam and girth welds for service-related damage. Sometimes, though, NDE results can be challenging to interpret. Removing a metallurgical sample from the area in question for destructive analysis can be beneficial in assessing the NDE results.