Investigation into the efficiency and effectiveness of Risk Based Inspection (RBI)

Abstract

Risk Based Inspection (RBI) is a risk assessment and management tool that addresses an area not completely addressed in other organisational risk management efforts such as Process Hazards Analyses (PHA) or Reliability-Centred Maintenance (RCM) [11]. It complements these efforts to provide a more comprehensive risks assessment associated with equipment operations. RBI yields Inspection and Maintenance Plan for equipment which identifies the actions that should be implemented to provide reliable and safe operation. RBI is a preventive maintenance strategy that combines predicting the expected failure time and condition monitoring as an effort for preventing potential equipment failures. A literature review was conducted to obtain a wide understanding of the RBI field and to capture some of the improvement methods which may have been highlighted by other researchers for baseline purposes. An RBI implementation case study was performed, focusing on the largest power producing utility in Africa, to investigate the efficiency and effectiveness of RBI implementation, thus the results obtained from this case study could have a significant impact in the RBI and Asset Management environment. Efficiency in this study refers to achieving financial benefits, while effectiveness means serving the technical and risk mitigation purpose of a RBI implementation. To evaluate the efficiency of RBI implementation, costs for executing scopes of work prior to RBI implementation were compared to RBI scopes Pre-Outage and Post-Outage scopes execution costs on two power stations that were identified as the most advanced in RBI implementation roll-out plans. Effectiveness was evaluated by assessing the RBI implementation against typical organisation’s objectives through audit findings, interviews, and lessons learnt. Data Analysis was performed as described below: - Cost analysis was performed, comparing the RBI versus Prior RBI maintenance scopes execution costs on the two identified power stations through an excel Model. - Most recurring audit findings were identified through reviewing the audit reports. - A bow-tie risk assessment was performed for the identified eight most recurring audit findings, and probabilities and consequences mitigations were recommended. - Lessons learnt were compiled from the audit findings, bow-tie risk analysis mitigations, interviews results, and RBI sharing sessions.

A proposed framework was developed for RBI implementation improvement methods. The results showed that RBI is generally a cost effective process when the prior RBI scope execution cost was compared to RBI scope execution cost. RBI could reduce the maintenance costs through scope optimisation and downtime reduction. The RBI implementation process was found deficient for the specific instances, based on the audit findings and bow-tie risk assessment conducted in the case study. The most significant improvement areas identified included, ensuring that RBI scopes have are uploaded into the Computerised Maintenance Management System and there is only one consolidated final inspection scope submitted to Outage Department and tracked for tasks completion during the outage. This study revealed that the case studied organisation is currently not efficient in implementing RBI, and could benefit significantly if they improve through executing the RBI maintenance inspection scopes as planned. The conducted interviews, recurring audit findings, and lessons learnt analysis demonstrated that the organisation is not effective, as it was successful in meeting only one from a total of six RBI implementation objectives. Extending the inspection frequencies to 72 months and beyond for some low risk components through RBI implementation was the only RBI objective in which the organisation was met successfully.