In the newsletter of few months ago, we talked about the Risk Base Inspection. After many requests for more information on this topic, we’ll see below, in particular, what it is and what are the benefits of its application in terms of safety and costs.

The Risk Based Inspection method (RBI) is used to optimize the frequency of inspections of facilities and equipment. This method was developed from the API-580 and API-581 issued by the American Petroleum Institute and it’s now being used for the management of inspections and maintenance in the chemical and petrochemical plants.

The goal of this control method is to fill the gaps of inspections, checks and maintenance scheduling based on fixed timings, which normally does not take into account previous experiences, not allowing to vary the frequencies of the checks carried out on the equipment and, in general, on the plants. 

The advantages

The inspect of a plant using the RBI method may offer significant advantages; in fact, a greater focus on critical equipment giving priority to those with a higher degree of risk, should increase the safety and productivity of inspections, decreasing the time of controls and, consequently, also the costs. 

A RBI study must begin with a careful collection of information, both on the equipment and on the possible mechanisms of damage, especially by using data previously collected, information on the status of the equipment in time, levels of degradation etc ...

In this sense, you should take into strong consideration what reported in the equipment booklets of use and maintenance, even if normally, in these documents, inspection dates are given based on fixed frequencies over time. Once defined the level of risk, you can go by the inspection planning based on the considerations drawn from the analysis carried out. The goal of this planning is to minimize the possible risk identifying the damage mechanisms for each device. 

The RBI study will take into consideration several factors:

• the most appropriate inspection intervals;
• the purpose of the inspection;
• the methods and data of previous evaluations;
• inspection and maintenance.

So, all the necessary changes will be done to avoid the risk of breakage of the equipment, compatibly with the time and cost of implementation. It’s essential, in fact, the balance benefits/costs of a work. A great tool to use is a matrix probability/impact, which provides the level of risk and shows whether to reduce or increase the frequency of inspections and maintenance services. 

The output of the planning will be:

• matrix probability/impact;
• the time schedule (Gantt chart) of the interventions;
• check list;
• inspection reports.

Through these tools will be able to plan interventions and, based on the results of inspections, remodel continuously monitoring frequencies in order to optimize costs, ensuring, at the same, time the safety.