Design, Technical and Operating Integrity

Asset integrity is the ability of an asset to perform its required function effectively and efficiently while protecting health, safety and the environment. It is usefully divided into three phases.

• Design integrity — the asset was designed correctly for its duty, with appropriate codes, materials, protective systems and margins. Failures here are built in and expensive to correct.
• Technical integrity — the asset was built and installed as designed, and is maintained and inspected so that it remains capable. Failures here accumulate through deferral and inadequate inspection.
• Operating integrity — the asset is operated within its design envelope by competent people. Failures here are rapid: operating outside limits can damage equipment in minutes.

Safety-critical equipment

Not everything can be maintained to the same standard, so equipment is classified by the consequence of its failure. Safety-critical elements — those whose failure could cause or fail to prevent a major accident — receive defined performance standards, protected maintenance and inspection, and are excluded from deferral without high-level authorisation. Identifying them is a risk assessment task, typically derived from the bow-ties or hazard studies.