Barrier Health Review

This is a periodic verification against an existing bow tie's barrier set, not the analysis that identifies barriers in the first place and not a one-off check on a single control.

ISO 31000 cl.6.6 covers monitoring and review of the risk management process — this record's sections walk from confirming verification actually happened, through rating each barrier type's current health, to how degradation gets responded to.

Barrier health review isn't itself a statutory form, but the regimes that expect a bow tie behind a major hazard also expect ongoing evidence its barriers still function.

The scoring is mechanical once the answers are in. The judgement sits in deciding whether those answers are honest, which is harder for a review that's asking barrier owners to mark their own work.

Reviews completed by the barrier owners themselves tend to repeat a small set of self-marking gaps.

A site's quarterly barrier health reviews for an ammonia release bow tie marked Detection Systems Calibrated Yes for six consecutive quarters, based on the barrier owner confirming the detector was 'still there and showing normal readings'. No calibration certificate was ever attached, and Verification Evidence Reviewed was answered Yes regardless.

An external audit asked for the calibration records and found the detector hadn't been formally calibrated in over two years — readings looked normal because the detector had drifted to reading everything as normal. The fix was procedural: Verification Evidence Reviewed now requires an attached calibration certificate before it can be marked Yes, closing the gap between 'looks fine' and 'verified fine'.

The review form is quick to complete. Making sure the verification behind it is real, and that a degrading pattern gets escalated rather than repeated quietly, is where the effort actually lives.

KnowComply

Holds the barrier health review library against its linked bow ties and critical control verifications, and flags any hazard whose review is overdue or whose critical barrier was marked absent.

KnowMaintain

Tracks calibration and maintenance schedules for hardware and detection barriers, so a missed maintenance task surfaces directly against the barrier it puts at risk before the next review cycle.

KnowTrain

Confirms competence barriers are genuinely current by checking training and certification records against the barrier, rather than accepting a self-reported Yes on Competence Barriers Current.

Ella

Rolls barrier health results across sites into one view for Management Review, and holds every write for your approval before it touches a record.

Barrier degradation

The gradual, often invisible loss of a barrier's effectiveness — through drift, wear, procedural shortcut, or neglect — as distinct from a sudden, obvious failure.

Verification evidence

A documented test, inspection, calibration record or equivalent proof that a barrier was actually checked, rather than assumed to still be working.

Critical barrier

A barrier identified in the source bow tie as one that alone stands between a threat and the top event, warranting more frequent and more rigorous verification than the general barrier set.

Interim control

A temporary measure applied to compensate for a barrier known to be degraded or absent, kept in place until the original barrier is restored.

Common cause failure

When multiple barriers that appear independent share an underlying weakness, so a single failure removes protection at more than one point simultaneously.