1 Answers
Risk Based Inspection is an Optimal maintenance business process used to examine equipment such as pressure vessels, quick opening closure - doors, heat exchangers, and piping in industrial plants. RBI is a decision-making methodology for optimizing inspection plans. The RBI concept lies in that the risk of failure can be assessed in relation to a level that is acceptable, and inspection and repair used to ensure that the level of risk is below that acceptance limit. It examines the Health, Safety and Environment and business risk of ‘active’ and ‘potential’ Damage Mechanisms to assess and rank failure probability and consequence. This ranking is used to optimize inspection intervals based on site-acceptable risk levels and operating limits, while mitigating risks as appropriate. RBI analysis can be qualitative, quantitative or semi-quantitative in nature.
Probability of Failure is estimated on the basis of the types of degradation mechanisms operating in the component. It is calculated as the area of overlap between the distributions of the degradation rate for each degradation mechanism with the distribution of the resistance of the component to failure.
Consequence of Failure is defined for all consequences that are of importance , such as safety, economy and environment. Consequence of failure is evaluated as the outcome of a failure based on the assumption that such a failure will occur.
Accuracy is a function of analysis methodology, data quality and consistency of execution. Precision is a function of the selected metrics and computational methods. Risk presented as a single numeric value does not guarantee greater accuracy compared to a risk matrix , because of uncertainty that is inherent with probabilities and consequences.