Assessing the safety integrity level of liquefied petroleum gas refilling plants in Nigeria: A review and case study

Safety is a fundamental pillar of every process, protecting the plant, personnel, community, and environment. Breaching safety protocols can lead to catastrophic events, resulting in the destruction of lives and property while polluting the natural environment. This study reviews the current knowledge on the safety integrity level (SIL) assessment of Nigerian Liquefied Petroleum Gas (LPG) refilling plants, highlighting techniques, regulatory frameworks, best practices, technological advancements, and the associated challenges. It also assesses the SIL of a case study plant to examine the level of risk reduction achieved by adhering to regulatory standards and safety guidelines from the Nigerian Midstream and Downstream Petroleum Regulatory Authority. The plant's data was analyzed using major hazard techniques, determining SIL for two credible scenarios: truck/car ignition during delivery/discharge leading to tank explosion or relief valve release. Consequence modelling was carried out for the most probable scenario, the relief valve release. Risk factors of 1.776 x 10-7 and 3.534 x 10-4/year were identified for tank explosion and relief valve release, respectively. Consequence modelling of the relief valve release indicated a toxic effect range of 62.2 m downwind, with a flammable vapor cloud spreading 45.7 m at 60 % of the lower explosive limit. The overpressure effect ranged up to 33.8 m with a peak of 0.7 psi. After compounding the numerous LPG plants in the country, the findings show a tolerable risk for tank explosion but an alarming risk for relief valve release, emphasizing the potential for severe damage within 50 m downwind of the incident point