Evaluation of Petroleum Product Storage Tank Inspection and Maintenance Practices at a Depot in Warri, South South Nigeria

Storage tank integrity is a critical safety and environmental concern at petroleum depots in the Niger Delta, where aging infrastructure, aggressive saline-humid environments, and operational pressures combine to elevate the risk of catastrophic tank failures and hydrocarbon releases. This study evaluates petroleum product storage tank inspection and maintenance practices at a depot in Warri, Delta State, South South Nigeria. A comprehensive inspection audit reviews tank inspection frequencies, non-destructive testing records including ultrasonic thickness measurement, magnetic flux leakage, and radiographic inspection reports, cathodic protection system effectiveness, floating roof seal condition, and maintenance work order completion rates. The audit framework is aligned with American Petroleum Institute Standard 653 for in-service tank inspection and relevant Nigerian Department of Petroleum Resources guidelines. Maintenance personnel interviews and document reviews reveal gaps in preventive maintenance scheduling, corrosion allowance calculations, and spare parts management for critical components. Risk-based inspection principles are applied to develop a tank-specific inspection prioritisation matrix based on consequence of failure and current condition rating. An optimised inspection and maintenance schedule is designed for five selected tanks across different size categories. The study also evaluates the adequacy of emergency shutdown systems and secondary containment infrastructure. A professional gap analysis and remediation action plan are presented as the key deliverable for depot management and regulatory compliance reporting. Keywords: storage tank inspection, petroleum depot, Warri, American Petroleum Institute 653, risk-based inspection