Maintenance, inspection, and testing error

When performing maintenance, even experienced, highly-trained people can make errors, potentially returning equipment or systems to service in an unsafe state. However, these errors are often predictable and can be identified and managed.

Maintenance failures due to human error include incorrect reassembly, wrong specification of replacement items, omission of a task step, re-commissioning errors, safety features left disconnected, instrument set-points incorrectly set and leaving tools inside plant.

It is essential that factors that increase the likelihood of error during maintenance are considered to design, manage and improve safe maintenance, inspection and testing activities.

Reducing maintenance, inspection and testing error

A human error in maintenance processes can lead directly to an injury or introduce a fault into the plant which can then malfunction at a later date, potentially leading to a catastrophic incident such as a loss of containment of dangerous substances. Such undetected faults are known as ‘unrevealed errors’ and can be reduced by performing adequate inspection and testing. Plant failure can expose people to many hazards as plant is often an integral part of higher order controls such as isolation.

The incident on the Piper Alpha oil platform in 1988 is a well-known example of a catastrophic incident following a maintenance error within the petroleum industry. There are many examples of disasters in other industries where maintenance errors were the root cause. To help avoid such disasters, it is essential that organisations establish a maintenance system of work with clearly defined roles and responsibilities.

Planning

• Provision of adequate resourcing (people, tools, parts etc.) to make tasks achievable.
• Planning and scheduling maintenance activities to ensure tasks can be performed safely.
• Clear task-specific and role-specific competency requirements.
• Clear task, role and work group supervision requirements.
• Provision of role clarity for all people involved in maintenance activities.
• Identification of environmental factors that may impede workers or maintenance operations (e.g. temperature extremes, lighting, atmospheric contaminants or oxygen levels).
• Defined contingency plans; for example, if a job looks like it might run overtime or if emerging problems arise along the way.
• Structured change management (how to deal with changes that arise during maintenance activities, changes to maintenance schedules or changes as a result of plant modifications).

Process

• Clear means to identify plant that is to be isolated/maintained.
• Set methods for how equipment will be maintained to specified requirements.
• Defined processes to identify and assess error potential in safety critical maintenance tasks.
• Provision of clear accept/reject criteria with respect to plant condition prior to being put back into service, or allowed to continue in service.
• Integrated quality assurance into the process to minimise the risk of unrevealed errors.

Communication and consultation

• Provision of all necessary information, including written instructions, permits, diagrams and other paperwork, as well as ensuring labels are clear and up-to-date.
• Provision of reliable and transparent means and opportunities for information to be communicated; particularly so that so that maintenance crews (and others who might be affected by maintenance) know what and where work has been done (this is especially important at shift handover).
• Involvement of all relevant maintenance personnel in plant & equipment design, job design, task analysis, writing procedures etc.