From an RBI matrix to an executable inspection program

01

Define scope and decision

State equipment types, system boundaries, operating period and the decisions the assessment supports. Fixed equipment, piping and rotating equipment do not share a damage model merely because they fit on one risk matrix. Keep an explicit list of items with inadequate data.

02

Damage mechanisms before risk scores

For each equipment item, review material, service, temperature, pressure, operating history and plausible degradation mechanisms. Link each assumption to evidence: inspection findings, process excursions, corrosion loops and specialist judgment. A risk score is hard to defend when its damage mechanism is missing.

03

Separate screening from quantification

Screening ranks items for further review with limited data. Detailed analysis requires inputs, method, assumptions and quality checks appropriate to its purpose. Do not present a custom 3×3 or 5×5 matrix as an API RP 581 calculation. Where evidence is weak, record uncertainty and the actions needed to reduce it.

04

Turn results into an inspection plan

An action should name the area, suitable NDT method, coverage, timing, access constraints, acceptance route and owner. Judge inspection effectiveness against the target damage mechanism, rather than simply counting inspections.

05

Close the learning loop

After each inspection, update thickness data, findings, repairs, process conditions and risk assumptions. Record why an interval or scope changed. RBI is an iterative decision process, not a calculation report archived after one issue.

06

Build a data dossier and expose uncertainty

Each equipment item needs a minimum dossier: design and materials, actual operating conditions, service fluid, corrosion allowance, thickness readings with dates, repair history, incidents, insulation, and inspection results. Record provenance for every value: design document, field measurement, estimate, or specialist judgment. Some gaps may be temporarily acceptable for screening, but they should not be silently replaced with defaults in detailed assessment.

Classify uncertainty by its effect on the decision. Missing recent thickness, unverified material, or changed operating conditions may change the priority order. When two inspection options have similar risk scores, sensitivity analysis shows which assumptions dominate. A data-acquisition action needs an owner, due date, and a clear decision to revisit when evidence arrives.

07

Connect damage mechanisms to inspection methods

Build a damage-mechanism register by corrosion loop or operating-condition group. For each mechanism, identify vulnerable locations, observable signs, expected degradation, supporting evidence, and an inspection technique capable of detection. CUI, localized corrosion, erosion, and cracking cannot all be addressed by the same fixed-point thickness program. Inspection effectiveness depends on coverage, detectability, access, and execution quality.

An inspection plan must say more than “inspect periodically.” Name the component or circuit, NDT technique, coverage, schedule, shutdown or access needs, evaluation route, finding management, and the trigger for engineering assessment. If the claimed risk reduction relies on a method that cannot be executed in the field, revise the plan or record the limitation before approving the interval.

08

Control change and approval

Version the assessment and record its author, reviewer, approver, and effective date. A change in material, fluid, operating envelope, repair status, or NDT results should identify affected items for reassessment. A material change should not wait for the next site-wide review cycle. Any extension of inspection interval needs a documented argument based on evidence, uncertainty, and controls that remain valid.

At pilot close, hand over the equipment register, damage-mechanism log, risk ranking, inspection plan, data-gap register, and update procedure. Judge quality by the share of actions with owners and dates, closure of findings, and traceability from evidence to decisions. An attractive risk chart does not replace a program that can be scheduled, executed, and updated.

09

Illustrative example: one corrosion loop

Suppose one corrosion loop contains 25 piping circuits. Screening prioritizes them using service, materials, inspection history, and loss-of-containment consequence. The RBI team finds five circuits without recent thickness data and two with changed operating conditions. Instead of applying one interval to the entire loop, it commissions data collection, reviews damage mechanisms, and locates inspection points that can detect the expected degradation. The inspection plan names circuits, CMLs or areas, NDT methods, coverage, access, timing, and owners. Findings then update corrosion-rate assumptions and risk ranking, with a recorded reason for any interval change. This illustrates the decision flow; the actual method and intervals require approval by the competent team under applicable requirements.