Knowing your facility, its equipment and the associated assets within is crucial to operating in a safe, risk-free, and cost effective manner. But as we well know, nothing is guaranteed to be completely risk-free. 

So how do you own or operate a facility and its asset equipment while also ensuring best practices for safe operations? How do you determine what the potential threats or emergencies could be at any given time? 

Consider a risk-based inspection. Risk-based inspections cover the best practices for preventing potential threats or emergencies while also giving you a solid foundation for what could happen, how it could happen, and when. This is calculated by researching both the probability of failure and the consequence of failure. 

Both modern and traditional industries have implemented risk-based inspections to their respective needs. Let’s take a look at how using a risk-based inspection works and why you should be using this method in your facilities. 

What is a Risk-Based Inspection?

Knowing what could happen is better than waiting to see what happens when it actually does. This is where a risk-based inspection comes into play. 

A risk-based inspection uses the methodology of risk, threat, or emergency to determine how to maintain safe operations for plant equipment. Focusing on the risk factors behind equipment or facility malfunction, risk-based inspections (or RBIs) follow a preventative approach based on predictions, data, and analysis rather than a reaction to an emergency when it actually occurs. 

Prioritizing potential emergencies, malfunctions, and other high-risk situations is not only cost-effective but also ensures the safety of anyone in the facility or using the respective equipment in question. 

RBI follows three basic things ━ previous experiences, predictions, and the possibility of failure. RBIs follow a more rigid approach than routine-based and maintenance inspections to assessing risks and conducting inspections, as equipment standards grow and change over time. 

Critical Factors

In conducting a risk analysis, there are two critical risk factors to consider ━ the probability of failure and the consequence of failure. 

Weighing these critical factors together, the RBI model stands as an equation. 

Risk = the probability of failure X the consequence of failure 

This equation is associated with each piece of equipment (and their respective parts) within a facility. By focusing on this prioritized list, a risk-based inspection can reduce the chances of failure in the long run. Let’s take a look at the pieces to the risk-based equation and how it is implemented in manufacturing plants. 

Probability of Failure

The probability of failure involves a company evaluating the likelihood (probability) of failure due to damage, deterioration, or degradation of the equipment being inspected. This is calculated based on the types of damage or degradation of equipment (or parts) that can occur. 

Consequence of Failure

The consequence of failure represents the fiscal responsibility of the company if a part (or whole) of a machine or piece of equipment breaks down. This includes every responsibility from safety and economic concerns to environmental and public health. 

Prioritizing Risk

In calculating risk based on probability and consequence, companies can form a prioritized list. This list will give high priority to items or equipment that have high priority and high consequence (i.e. high risk). Items inspected and calculated as having high probability but low consequence will receive lower probability. 

This priority ranking allows inspectors and companies to determine the most efficient inspection cycle for their facilities and equipment. Risk levels and operating limits as well as the priority list are all compiled to optimize how often inspections are necessary. If there is an item of high priority on the list, inspections may be more frequent to mitigate any potential consequences of damage or emergency. 

In using the risk-based assessment to calculate probability and consequence of failure, companies can focus their resources on specific assets or circumstances that would be considered most high-risk to the plant/facility and the employees working in it. 

The RBI Focus on Data Collection

Inspections are based on predictions, data, and analysis, meaning that inspectors need to collect relevant information about a company and its equipment/machinery history. Have previous damages or malfunctions occurred? What is the existing frequency of these malfunctions? 

Three data collection measures are used in the RBI model. 


Qualitative data is collected based on the knowledge and experience of the inspectors for the risk-based assessment. 


Quantitative data is collected based on predictions and the probability of damages, malfunctions, or emergencies occurring. 


Following a dual approach, the semi-quantitative measure combines both qualitative and quantitative data collection to perform the risk-based assessment. 

By combining these data collection models with the Risk = probability X consequence equation, companies can easily see which pieces of equipment or machinery may cause the highest financial and safety risks to the company. This will then allow the company to plan, adjust, and schedule regular maintenance and inspection routines that will ensure operational fluidity and safety. 

But Why Use the RBI Model Over Individual Routine Inspections? 

While normal routine inspections should still be conducted for overall maintenance structures within a company, considering using the RBI model could provide a facility with more benefits than simple cost efficiency. 

  • Improves risk management policies through routine assessment and data collection
  • Prevents severe malfunctions and damages, therefore reducing operational downtime (from equipment or machinery)
  • Saving money and minimizing fiscal responsibility from unplanned outages, injury, and other negative outcomes
  • Eliminates unnecessary inspections for equipment maintenance (since the equipment risk prevention plans are already in place), therefore optimizing work turnaround times and other resources 

There are two RBI inspection codes that are used in facility and equipment management. 

API RB 580 is a risk-based inspection document that details RBI standards from development to implementation and maintenance of a risk-based inspection program. API RB 581, supplementing API RB 580, details a quantitative approach to risk-based inspections, focusing heavily on the assessment of probability of failure and consequence of failure. 

What Industries Could Most Benefit From the RBI Model?

Think about the various industries that use heavy-duty machinery or equipment for day-to-day operations. Could the RBI model be beneficial if carried out regularly in these companies? 

Several industries are known for using the RBI model successfully to fix, maintain, and prevent damage to equipment. Refineries, petrochemical plants, chemical processing plants (especially those involving tanks), and oil or gas production facilities (where increased fire hazards also exist) frequently use the RBI model to protect equipment and operations related to above ground storage tanks, process piping, pressure vessels, heat exchanges, and more. 

Hire a Certified STI & API Tank Inspection Professional

We are only as good as the service we provide, and we go the extra mile to ensure all of our personnel are trained to industry standards. 

At NDT Tanknicians, we embrace the tough challenge set in place to be certified by entities such as the Environmental Protection Agency (EPA,) American Petroleum Institute (API,) Steel Tank Institute (STI,) American Society for Nondestructive Testing (ASNT,) and the National Association of Corrosion Engineers (NACE,) to name a few. 

We’re capable of providing top-to-bottom coverage for all of your Storage Tank requirements; servicing a broad spectrum of clientele, both small and large. Our ability to streamline an entire project gives us an edge over the competition by providing our clients with the peace of mind and convenience of trusting one service provider to become familiar with all of their current and future needs, rather than half a dozen. This keeps costs to a minimum, quality control consistent and communication among crews seamless. 

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