Risk based inspection
A knowledge-based approach helps maximize maintenance efficiency and system availability

Is there a silver bullet which will help you lower your maintenance costs and increase the availability of your chemical systems at the same time? This article describes some interesting strategies which use a knowledge-based approach.

There has been an ongoing effort since the 1940’s to increase the efficiency of maintenance operations. Methods include the traditional reactive approach and condition monitoring, which is a more recent development. Risk Based Inspection (RBI) is a logical extension of traditional maintenance strategies, which cuts down on maintenance effort while reducing leaks and equipment down time. This seemingly paradoxical result is achieved by shifting the emphasis from “overinspection” of uncritical apparatus/pressure vessels to increased maintenance activity on components which are more likely to fail and cause more serious problems when they do fail. Maintenance teams can use criticality analysis to identify high-risk equipment, enabling them to reduce risk to the overall system and increase system safety and reliability.

RBI and RCM (Reliability Centered Maintenance) are systematic, knowledge-based strategies which give users a tool for making structured business decisions relating to maintenance and system availability. Using RBI, users can:
-assess previous maintenance activity to define inspection priorities
-identify critical failure mechanisms which would otherwise be overlooked
-identify the weakest points in the system
-concentrate inspection capacity on the problem areas in the system
-carry out informed maintenance to reduce downtime
-assess the consequences which changes in method are likely to have on equipment integrity
-optimize maintenance, inspection and repair activity as part of the risk minimization strategy
-assess future inspection and maintenance plans
-improve inspection effectiveness by focusing on failure mechanisms
-reduce technical uncertainty
-minimize system downtime due to unexpected failure
-improve system availability and optimize inspection effort and cost
-reduce system risk and enhance safety
-increase system reliability
Multi-national companies now realize that this approach has a positive effect on human health and the environment, and they recognize the contribution which RBI can make to improved system safety and availability in their European plants. As a result, this methodology is becoming increasing popular in Europe. The RIMAP project, which was subsidized by the EU, has already laid the foundation for development of CEN standards and the creation of a legal framework for widespread use of the RBI approach in Europe.
RBI in the chemical and
petrochemical industries
Unlike plants in the petroleum processing industry where comprehensive catalogues of failure mechanisms have been developed, similar compendiums do not exist in the chemical and petrochemical industries. The existence of complex corrosion systems makes it absolutely necessary to call on the expertise of corrosion specialists. Bayer began working with materials specialists at its Bayer Technology Services affiliate years ago to develop RBI inspection and maintenance planning at its plants worldwide. After carrying out assessments, the company was for example able to completely defer maintenance and inspection downtime for two years, which translated to a three percent increase in output for the year. By using the RBI approach for pipes, safety valves and around 2,500 pieces of equipment, the company was able to enhance plant safety while significantly reducing the risk factor. The company was also able to save around two million dollars.