Risk-based inspection of pressure components in power and process plants

An important application of reliability and risk assessment in pressure vessels and piping engineering is risk-based ranking of pressure components for inservice inspection. The higher-ranked components may then be inspected more often or by more rigorous nondestructive examination procedures than the lower-ranked components in the plants. The development of risk-based ranking of components has its origin in the nuclear power industry. More recently, it has been employed in fossil power and process plants. One major differences between nuclear power plant risk assessment and fossil-power/process plant risk assessment is that the former has only one dominant risk (undesired event), namely, core melt accident, whereas the latter may have more than one dominant risk, for example, explosion, catastrophic rupture, leakage of toxic chemicals, etc. This paper presents a ranking procedure that can be used in cases of possible multiple undesired events, and thus applicable to fossil power and process plants.