The Hazard and Operability (Hazop) technique has been well developed and applied in process flowsystems for identifying potential deviations from design intent and developing both hardware and procedural solutions to counter such deviations. Hazop studies are now routinely carried out on topside designs.

An examination of incidents on offshore oil and gas platforms indicates that a breakdown in operating or maintenance procedures caused by human error, inadequate procedures, or changed conditionson deck has been a significant contributor in several incidents. Preventive actions have traditionally focused on tightening up procedures and reinforcement of training.

If the philosophy of Hazop were applied to maintenance procedures, it would be possible to anticipate specific potential deviations, procedural failures and human errors that could result in serious incidents. New procedures could be developed, existing procedures modified, and where necessary,work practices could be changed, or hardware modifications could be effected to eliminate certain work practices. Such an approach becomes all the more important with the spate of new technologies introduced in each new platform design.

This paper provides a framework for applying Hazop techniques to maintenance procedures on offshore oil and gas platforms. A combination of human error analysis and Hazop prompt words would assist in the identification of non-recoverable errors in implementing the work permit system, preparation for maintenance, maintenance activities themselves, handover and restart The elimination or mitigation against non-recoverable errors would significantly help in improving maintenance safety.

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