Impact of process safety management performance and human error on off-site risk : a comparative study.

The research described in this thesis provides a comparative study of the impact of Process Safety Management System (PSMS) performance and Human Error rates on off-site risk from two major hazards sites in Malaysia. One of the sites was built and run by a multinational company until a few years ago while the other was built and run by a local company since its inception. The sites handle bulk quantities of ammonia for downstream distribution. The study considers: the assessment of the sites PSMS performance using a structured audit technique the assessment of human error potential from ammonia road-tanker filling operations assessing the impact of site PSMS and human error potential on off-site risk from the sites investigating the possibility of linking the assessment of site PSMS performance with human error potential Results of Quantitative Risk Assessment (QRA) conducted on the two sites showed a significant difference in terms of individual and societal risk when site specific PSMS performance and human error potential are taken into consideration. The use of site specific Management Factor (MF) and site specific Human Error Probabilities (HEPs) produces a significant impact on the results of the off-site risk as compared to estimates of risk based only on generic failure rates. This finding emphasized the need to consider explicitly the contribution of site specific PSMS performance and human error potential in major hazard risk assessment especially in developing countries like Malaysia where there exists significant differences on these factors between locally owned and multinational sites. The approach to link the results of the site specific PSMS performance audit with the assessment of human error potential was found to be inadequate to describe all the influences which will be exerted on the reliability of individual tasks involving human error potential.