“Quality is never an accident; it is always the result of high intention, sincere effort, intelligent direction, and skillful execution; it represents the wise choice of many alternatives.” -William A. Foster
Asset Integrity Management (AIM) aims to effectively manage assets to gain maximum value, profitability, and returns while safeguarding personnel, the community, and the environment. In the race to achieve excellence in AIM, Risk Based Inspection (RBI) has emerged as a winner in recent times.
RBI is being adopted in the petroleum & Petrochemical, Chemical, and Process Industries around the globe as it has been proven to bring huge business benefits and profitability to the operating plants and their Inspecting organizations.
In RBI approach, a risk assessment is conducted to identify risk drivers, and based on the identified risks and damage mechanisms that contribute to the risk, inspection methods that should be used are determined, the extent of inspection to be conducted is specified and the frequency of inspection is recommended. This approach brings out comparatively less risky assets, which are proposed to be kept out of immediate inspection needs. This optimizes the inspection program and takes AIM to a greater level.
RBI approach and management tool addresses areas of risk management that are not covered in other risk management tools such as process hazards analysis and reliability-centered maintenance. RBI is generally an integral part of a management system that defines and maintains IOWs, and MOC processes and uses these as a basis to manage and control damage mechanisms in static equipment items.

RBI should not be viewed as a substitute for process hazard analysis or HAZOP studies. RBI supplements other safety management systems by focusing on the mechanical integrity of pressure equipment items and minimizes the risk of loss of containment due to deterioration. RBI is a data-intensive and data-driven methodology and requires reliable collection and validation of plant and equipment information and data.
Some modern software such as GE’s APM-Meridian, Bentley APM, CENOSCO IMS, and RiskWise have built-in capabilities to drive the analysis outcomes. The advancements in data collection, transmission, telecommunication, and big data management using machine learning and AI have taken the capabilities of RBI to a higher level of excellence. In-process plant operations monitoring programs are established to detect and evaluate deterioration that affects plant and equipment, caused by corrosion and corrosive elements in the process fluid handled and also due to interactions between the operating environment, the material of construction, and operating parameters such as temperature, pressure, and flow conditions.
Setting the inspection interval schedules and shutdown planning has evolved. From traditional time-bound schedules to condition-based inspection planning. In-service inspection standards such as API 570, 510, 653, and OISD recommend condition-based inspection planning and mandate inspection to be planned based on half the remaining life. On-stream inspection instead of internal inspection based on low deterioration rates, internal inspection requirements for damage mechanisms related to process environment-induced cracking, and consequence-based inspection intervals / due dates. RBI emerges as a next-generation inspection approach and interval date setting based on the actual risk that is present in the asset and components.
There is a wide variety of approaches and types of RBI assessments that range from qualitative to fully quantitative and all the in-between combinations, which are termed as semi-quantitative approaches, can be adopted to provide an optimized analysis. The choice of approach depends on the objectives of the study, number of equipment items to be studied, available resources, assessment framework, time frame, and nature and quality of data available. The approach chosen initially can be varied as the analysis progresses, and this flexibility in adopting different approaches adds a lot of value in understanding the risks that are present in the plant systems by the users. One of the objectives of undertaking an RBI study is to understand risks that are existing in the plant systems currently. The efficiency of the analysis depends on the quality of data that goes into the study and the adopted approach for the analysis.
The data forms an important and integral part of an RBI approach. Data is usually collected from design, construction records, design basis documents, operating and process records, and stream information; RBI also borrows data from other safety initiatives. The focus should be on the precision of the data collected and the validation of the data. Any errors in data collection and handling can change the risk picture and project a safe asset as a risky one. An experienced and dedicated team will help in the collection of data concerning current Industry standards and regulations.
Probability of failure and the Consequence of failure are two terminologies that shape the framework of the risk matrix that determines the risk to an asset. To determine the assets that qualify for RBI, the Probability of failure and the Consequence of failure of every asset is estimated, a calculated risk number is assigned to every asset and all the assets are ranked based on the risk numbers

From this list, only the assets that fall beyond the acceptable risk limits are chosen for inspection planning, and assets that fall within the acceptable limits, that are considered less/not risky, are kept out of the inspection planning. The chosen riskier assets are taken up for inspection in the current schedules or scheduled for the next turnaround.
This ranking and identifying riskier assets drive inspection planning and bring out the business benefits of optimized inspection planning.
The provided image represents a risk plot pictorially depicting the risk scenario of an asset. A risk plot or risk matrix is a plot between the probability of failure shown in the y-axis and the consequence of failure shown in the x-axis. In this plot, all assets are plotted based on their POF and COF, and this helps turnaround planners and plant management teams to plan inspections, and repairs, and check turnaround schedules to avoid unwanted shutdowns, which are expensive. Assets that are in the green zone are considered low-risk assets and have not been inspected for some time or run length, and assets that are in red/yellow are considered for immediate inspection plans or scheduled for the next turnaround that may be around the corner.
API 580 is the referenced publication that acts as a guide for implementing RBI programs. This standard is supplemented with API 581, a guidance document that provides detailed methodologies, to calculate the Probability of failure of assets and the consequence of failure of assets both qualitatively and quantitatively using simple tables and more advanced quantitative methods using statistical tools and detailed calculations.
It should be kept in mind that we are always governed by regulations and regulatory standards, national standards, and guidance documents. Any regulatory requirement takes precedence over the analysis results. Regulatory bodies such as OISD and PESO are recognizing RBI efforts and are encouraging inspection planning based on RBI approaches. Although RBI is not an initiative that focuses on budgets, it brings budgetary benefits in terms of cost savings by producing optimized inspection efforts and plans.
Finally, this approach is getting organizations to drive towards achieving “nil loss of containment” and meet the target net zero to achieve our national goal to become KYOTO protocol compliant by 2030.
RBI terms & definitions:
Absolute risk: An ideal and accurate description and quantification of risk.
Acceptable risk: a level of risk that is acceptable to the owner–user.
Risk-based inspection:
Risk: the combination of the probability of an event and its consequence. In some situations, risk is a deviation from the expected. When probability and consequence are expressed numerically, the risk is the product
- Damage mechanism: The physical manifestation of damage.
- Qualitative approach: A risk analysis using primarily subject matter expertise and experience to assign broad categorization for POF and COF.
- Quantitative approach: A risk analysis that is used primarily model-based approaches where numerical values are calculated and more discreet input data is used.
- Unmitigated risk: risk before mitigation activities.
- ALARP: As low as reasonably possible, a concept of minimization that postulates that attributes such as risk can only be reduced to a certain minimum under current technology and with reasonable costs.
