Fixed-Roof Hydrocarbon Oil Storage Tank: An Approach to Reliability Engineering Tools

Hydrocarbon bulk oil storage tanks are critical assets in an oil terminal and pumping station. These tanks are used for receiving, storage and pumping operations around the year. American Petroleum Institute (API) provides legislation (API-653) for their maintenance. In this study, a system of bulk storage tanks is considered along with associated instrumentation for a terminal station of one of the leading oil companies based in Karachi, Pakistan. An approach of reliability-centered maintenance (RCM) for the system and associated instrumentation is applied. A failure mode and effects analysis (FMEA) is also performed using failure data. The risk priority number (RPN) for each failure has been calculated for the existing maintenance plan and the additional recommended controls. Existing maintenance strategies are analyzed. The shortcomings are identified, and an RCM framework is proposed. The reliability of the system with and without RCM is considered. The results revealed that if the RCM approach is utilized, its reliability as of today would have been the same as it was exhibited nine years ago, that is, 99.72% which is a 0.52% increase from the case if RCM is not implemented. Furthermore, RPN decreases up to nearly 67% after implementing the proposed controls, for the storage tank foundation. This implies that the risk of damage to the tank foundation can be decreased by a staggering 67%.