Risk-Based Inspection (RBI): A Complete Guide for Asset Owners

What is Risk-Based Inspection?

Risk-Based Inspection (RBI) is a systematic methodology for prioritizing and planning inspections based on risk rather than fixed time intervals. It focuses inspection resources on equipment with the highest risk of failure.

The fundamental principle: Risk = Probability of Failure × Consequence of Failure

Why Move from Time-Based to Risk-Based?

Problems with Time-Based Inspection

• Inspects low-risk equipment too frequently, wasting resources
• May miss high-risk equipment that needs more attention
• Doesn't account for actual operating conditions
• Results in unnecessary shutdowns

Benefits of RBI

The RBI Methodology: Step by Step

Step 1: Define Scope and Objectives

Identify which equipment and systems will be included. Typically includes pressure vessels, piping, tankage, and rotating equipment.

Step 2: Collect Data

Gather essential information:

• Design specifications and materials of construction
• Operating conditions (temperature, pressure, flow)
• Historical inspection data and findings
• Maintenance and repair history

Step 3: Identify Damage Mechanisms

Determine what degradation mechanisms can affect each piece of equipment. The Corrosion Engineering Guide covers the underlying chemistry and rate models for each mechanism, and the Pressure Vessel Inspection reference walks through the API 510 / API 579-1 fitness-for-service workflow that consumes the RBI output.

• Internal corrosion: Uniform, pitting, erosion-corrosion
• External corrosion: Under insulation, atmospheric — see our CUI complete guide for detection and prevention specifics
• Stress corrosion cracking: Chloride SCC, caustic SCC
• High-temperature mechanisms: Creep, oxidation

Step 4: Assess Probability and Consequence

Calculate likelihood of failure and evaluate impact across safety, environmental, and production dimensions.

Step 5: Develop Inspection Plans

Create tailored inspection plans specifying techniques, coverage, intervals, and acceptance criteria. To staff the resulting scopes, post each work order on NDT Connect for parallel quotes from API 510/570/653-experienced contractors; the API 510 standards page covers the inspection-interval rules RBI is meant to optimise against.