Optimization of Maintenance Strategy for Large Rotating Equipment

Abstract

Listen

Translate article

Abstract Present PM philosophy of CB CRU is scheduled maintenance based on running hours of the engine. This time based maintenance is fixed at every 7500 running hours, referred to as Mini-check, others as Intermediate and Major Overhaul that are fixed at 15000 and 30000 running hours respectively. The current operational practice is also such that it is only functional when the primary CRU i.e. ManTurbo is under maintenance, making CB-CRU function as interim or during summer when electrical power consumption is to be reduced. Even though the CB-CRU is operated less frequently for the last 4 years, the number of failures has increased. Hence, a review of the maintenance philosophy was required due to change in operating scenario. Scientific/statistical (RCM) approach was undertaken to evaluate the effectiveness of the existing maintenance philosophy. Reliability analysis tools were used to analyze failure data collected from site logbook and PM records from year 2009 to date. The data were segregated and following methods were used:Weibull Analysis, Recurrent Data Analysis for analysis of failure frequency and pattern.FMEA & RCM to review Mini-check scope and formulate the proactive maintenance task. One of the major outcome of the study was that while performing Mini-check there is always a possibility of introducing inherent failures. This would negatively affect the purpose of doing Mini-check in terms of unscheduled maintenance.Hence based on the study it is recommend to stop the PM @7500 hours to monitor and observe the impact on CB CRU availability, for a period of three years. While the scheduled maintenance at 7500 hours is stop, the following additional activities/recommendations are to be implement based on the study:Increase Recip-Trap frequency to twice a month.Compressor Gland Leakage Inspection once in a month.Lubrication System, start at least once a month and operate for 24 hours when CB-CRU is in standby mode for prolonged period.Engine to be started at least quarterly and operated for 4 hours with no-load.Intermediate Overhaul to be conducted in every 4 years or 15000 running hours.Awareness Sessions to be conducted once a year for all relevant teams.Auto Ignition and Pressure balancing system to be implemented in one CB CRU as pilot.