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ABSTRACT
Gas turbines are designed in such a way as to work continuously from year to year, and to achieve this, proper routine maintenances must be accommodated. The cost of corrective maintenances is very high when catastrophic failure is allowed to occur. Adequate predictive and preventive maintenances are needed in any power station to avert catastrophic damages and in doing that, maintenance cost are reduced, other businesses will improve. For these reason and to ensure effective performances, research on reliability, availability and maintainability (RAM) are carried out using OMOTOSHO power station as a case study. The research was based on six years data, from 2012 to 2017 taken from operations daily record log books of the 8 gas turbine units. Weibull distribution probability method was used and Weibull scale and shape parameters were evaluated using least square method. Weibull Mean time between failures (WMTBF) predictions was also calculated. The cumulative distribution function was used to evaluate the unreliability path and maintainability. The probability density function and hazard rate were used to ascertain the extent of risks in all the turbine units. Also exponential method was used to estimate the availability of all the gas turbine units and finally, Weibull probability plot and Pearson’s correlation were used to ensure that the data collected obey Weibull and how accurate the variables correlate to each other in terms of linear best fit. From the result obtained, the station attained the highest average availability and reliability of 82.05% and 79.98% respectively in 2014, and average least reliability of 55.6% in 2017. Hence, the predicted WMTBF, reliability, and availability will assist the maintenance team of the station to plan ahead in future to avert catastrophic failure by early application of predictive and preventive maintenance. Again, the values of MTBF and MTTR established the fact that increase in MTBF and decrease in MTTR result in corresponding increase in reliability and availability, therefore adequate maintenance practices are required to increase the MTBF and reduce MTTR.
