PROBABILISTIC SAFETY AND RELIABILITY ASSESSMENT OF STEAM BOILER INSTRUMENTATION AND CONTROL SYSTEMS IN A UNIVERSITY HOSPITAL: A CASE STUDY FROM PATHUM THANI, THAILAND
DOI:
https://doi.org/10.55766/sujst8134Keywords:
Failure Probability, Hazard And Operability Study (HAZOP), Mean Time Before Failure (MTBF), Steam BoilerAbstract
Fires and explosions caused by steam boiler malfunctions can lead to severe injuries, fatalities, and extensive property damage, particularly in hospital environments where uninterrupted and safe operation is essential for patient care. This study evaluated the reliability of a steam boiler at a university hospital by quantifying the overall process failure probability, annual probability of failure, and mean time before failure (MTBF) of its instrumentation and control system components. A Hazard and Operability (HAZOP) study was conducted to identify potential fire and explosion hazards and operability deviations. The qualitative HAZOP findings were integrated with quantitative reliability analysis using a Reliability-Centered Maintenance (RCM) framework. Data was obtained from piping and instrumentation diagrams and classified into four system nodes: feed water tank, fuel oil tank, critical alarm, and steam node. The results revealed substantial variability in reliability across subsystems. The feed water tank subsystem (Loop 1) exhibited a high failure probability of 0.926 and a short MTBF of 0.385 years, indicating the need for frequent preventive maintenance. In contrast, the steam boiler loop control subsystem (Loop 6) showed a lower failure probability of 0.287, an annual failure probability of 33.8%, and a longer MTBF of 2.956 years. These findings confirm an inverse relationship between failure probability and MTBF and provide practical guidance for hospital safety managers to prioritize high-risk components, optimize maintenance strategies, and strengthen operational controls to enhance boiler safety and operational continuity.
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