At many facilities, pressure vessel inspections are treated as a routine task, something we do simply because regulations require it. While that mindset keeps us compliant, it often overlooks a greater opportunity: using inspections to actively improve asset integrity, reliability, resource management, and downtime reduction. That’s where Risk-Based Inspection (RBI) comes in.
Instead of inspecting everything on a fixed schedule, RBI allows you to focus your efforts where it matters most: on the equipment that poses the greatest risk.
What is Risk-based inspection (RBI)?
RBI, as defined in API 580 – Risk Based Inspection, is a structured method that helps prioritize inspections based on a combination of risks:
- Probability of Failure (PoF): how likely something is to fail.
- Consequence of Failure (CoF): what happens if it fails.
This risk-based approach is based on understanding actual operating conditions, material properties, degradation mechanisms, and historical performance, not just a calendar date.
What is TBI (Time-based inspection)?
In a TBI scheme, all equipment and piping are inspected under a fixed routine, using an arbitrary set of techniques. This is resource-intensive and results in unnecessary downtime intervals and durations.
Optimized Inspections
In addition to reducing risks and improving safety, RBI plans can also lead to cost savings.
RBI allows you to identify equipment that:
- Does not require mitigation.
- Requires less inspection coverage.
- Requires greater mitigation or alternative measures.
Inspection plans resulting from an RBI program use fewer resources because they focus on the areas that need it most. The program effectively measures risk and defines appropriate mitigation.
According to API 510 – Pressure Vessel Inspection Code, unless there is an RBI plan, intrusive inspections on pressure vessels must be performed every 10 years or halfway through their remaining service life (whichever comes first). With RBI, the user can adjust that frequency:
- High-risk assets → more frequent inspections.
- Low-risk assets → less frequent inspections.
An effective RBI plan also allows resources to be optimized by inspecting vessels under similar service conditions. In these cases, it is not necessary to perform internal inspections of all vessels; RBI allows similar assets to be grouped together and data from one of them to be used to reduce the scope of the others.
Through a systematic review of damage mechanisms, failure modes, and mitigation strategies, RBI makes it possible to perform in-service inspections instead of internal inspections.
Deferral management
Sometimes, despite the best planning, inspections cannot be performed exactly on the scheduled date. This is part of the reality of complex operations.
API 510 allows for some flexibility: it permits deferrals, but under a rigorous process. The following is required:
- Proper risk assessment
- Alignment with the inspection and operations teams
- Clear documentation.
This is where RBI can be leveraged. When a vessel’s inspection interval is set using RBI, the risk model can be revisited to understand what changes if the date is delayed. If necessary, the decision can be supported by additional NDT (Non-Destructive Testing) methods or other monitoring techniques.
- For short postponements (less than 10% of the original interval or up to 6 months), the inspector can decide.
- For longer deferrals, a more in-depth assessment and formal approval process is required.
An effective RBI program ensures that deferrals are based on actual risks and not assumptions, allowing timelines to be adjusted without compromising safety or regulatory compliance.
The AsInt platform
At AsInt, we offer a versatile RBI framework that supports multiple standards on a single platform. We provide configurable assessment templates that can be customized to meet specific customer requirements.
Among the standards supported are:
- API 580
- API 581
- European PED
- NR13
- EN16991
Conclusion
RBI is not just about meeting inspection requirements, but about making inspections smarter.
By focusing on risk rather than fixed intervals, RBI helps operators to:
- Avoid unnecessary downtime.
- Allocate resources more effectively.
- Direct attention where it is truly needed.
It also offers flexibility to handle deferrals and similar in-service equipment without compromising safety or compliance.
For companies managing complex operations and tight schedules, RBI represents a practical way to move beyond simple compliance to a more thoughtful, risk-aware inspection strategy.
This article was developed by AsInt and published as part of the sixth edition of Inspenet Brief September 2025, dedicated to technical content from the energy and industrial sectors.
