A gas leak followed by explosion occurred during an inspection process due to the loose of valve bolt.

Proximate causes:
• Inadequate training/knowledge transfer (Lack of understanding the process);
• Lack of work rules/policies/ standards/procedures (wrong procedures for inspections);
• Inadequate work rules plan (lack of the pre-start safety review before inspection).

Source: A web-based collection and analysis of process safety incidents (https://www.sciencedirect.com/science/article/abs/pii/S0950423016302285)
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