Risk Management with Inspection Activities
Inspection is the primary risk-management lever
Once risk is ranked, the inspection plan decides what to inspect, where on the component, how (method and coverage), and when (interval or due date). The plan should target the damage mechanism that dominates the risk, at the locations where that mechanism acts, using methods capable of detecting it.
Effectiveness, not quantity
Inspection effectiveness is a judgment of how likely a given inspection activity is to find the expected damage at the expected locations, graded in categories such as highly effective, usually effective, fairly effective, poorly effective, and ineffective. Ten poorly targeted visual checks may be less effective than one properly scoped, full-coverage, mechanism-specific examination. Effective inspection reduces POF by shortening the period in which damage exists undetected; timely detection can also reduce COF where it permits isolation or shutdown before a large release.
Interval logic
Higher-risk items and faster-acting mechanisms warrant shorter intervals and more effective methods; low-risk items can be extended, provided the basis is documented and the damage mechanism is well understood. Confidence in the mechanism and in past inspection results justifies longer intervals; uncertainty argues for shorter ones.
Traps
- Adding inspection frequency to already low-risk items, which yields little risk reduction.
- Specifying a method that cannot detect the mechanism (e.g., external visual for internal pitting).
- Assuming inspection reduces risk without a follow-up repair or response process.
- Ignoring coverage: a spot check of one location is not full-coverage examination.
Rule of thumb
Match the method to the mechanism, and let the risk ranking set the interval. If inspection cannot detect the credible mechanism in time, redesign the inspection rather than simply repeating it.