How Much Risk are you Willing to Accept? The Right Maintenance Strategy Saves Time and Money

Risk-based maintenance has a lot of supporters. However, few companies actually succeed in fully implementing this strategy. The experts at Bayer Technology Service have come up with a feasible approach and show how much can be achieved with minimal effort.

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Any plant manager would like nothing better than best-in-class performance and one hundred percent system availability. However in real life, planned maintenance activities work and unplanned downtime make these goals difficult to achieve. Maintenance teams often find themselves having to react after the fact. Very few plant operators are able to keep a continuous process plant running without any unplanned downtime. The experts at Bayer Technology Services (BTS) believe that uncompromising Risk Based Asset Management (RBAM) may be the best solution to the problem. Practical experience so far indicates that this approach offers significant savings potential.

With the aid of an RBI (Risked Based Inspection) study, BTS experts were able to delay turn around work at a continuous processing plant for two years, with respectable results. Yields increased by three percent, and savings in maintenance and service costs amounted to around € 2 million.

There are a number of maintenance strategies to choose from, and each has its own rationale. With the classical run-to-failure approach, equipment is replaced when it is defective. Preventive maintenance and condition-based maintenance are two other alternatives. “The decision on which approach to take for a certain production equipment depends on the individual circumstances,” explained Jürgen Potthoff who is a member of the BTS sales team. Condition based maintenance enables operators to fully exploit asset reserves. This strategy has a lot of supporters, but anyone who goes down this road should be aware of the fact that they will have to invest up front in condition monitoring systems and that the approach is labor intensive. People often fail to realize that data acquisition is only half of the story. The data still has to be analyzed to produce meaningful results. In some cases, there is no reasonable relationship between the amount of effort invested in monitoring and the losses which are caused when the equipment fails. Potthoff is convinced that resources are often not utilized in the most effective manner.

BTS extended its horizon to include external customers in 2002. According to Potthoff, the number of projects has now passed the 100 mark. “As part of the Bayer community, we have the expertise of a service provider as well as the experience base of a plant operator,” claimed Potthoff. The RBAM process, which is favored by BTS, is a practical approach which is developed from the industry for the industry. It is important to keep in mind that identification of cheapest maintenance strategy is not the only issue. The solution also has to be sustainable over the long term. Latest since the new work equipment directive sanctions the use of RBI and extended inspection intervals, this approach conforms to current regulatory requirements. A project carried out by BTS shows how moving from time-based to risk-based maintenance can save money. Production asset yields increased by 20 percent, and the user saved € 1 million in inspection costs over a period of five years.

Something for check list fans

But what exactly does the term risk-based mean? Risk-based maintenance is centered on two key issues. The first is whether the failure of a subsystem jeopardizes achievement of the overall business objectives. The second consideration is the extent of the failure risk, which in turn determines what effect the subsystem has on goal achievement. According to Potthoff, the BTS approach is holistic, integrated and risk-based. That may sound abstract, but what it means is simply this: if you want to put the optimal solution in place, you are going to need standardized, clearly defined parameters which provide a basis for your repair, maintenance and long-term investment decisions.

Every decision is derived from the plant strategy, in other words definition of the cost and availability goals. The most important RBAM and RBI planning tool is the risk matrix which is tailored to company needs and defines the acceptable level of risk. At BTS, RBI is based on a quantitative methodology for determining the consequences and probabilities of potential faults.

The first step is a detailed assessment of all production equipment for which BTS applies the Reliability Centered Maintenance (RCM) approach which breaks the assets down into the individual parts and assesses the cause of failure (Fault Tree Analysis combined with Root Cause Failure Analysis). If you want to introduce RBAM, you have some hard work ahead of you. There are a number of questions to answer for every asset. What is the expected availability? What costs arise if the asset develops a fault? What is the MTBF? Do you have redundancy? Because the strategy is always derived from corporate goals, the second step is to prioritize the effects which equipment failure will have on goal achievement. The third step is to define a technical action plan including investments and maintenance activities which reduces the risks which were identified in step 2 to a level which supports achievement of the costs and availability goals. During the fourth step, sustainable computer-based methodologies provide integration of the risk management process into day-to-day operations. BTS BayKBI-S software supports integration of RBI into routine operations. Ease of operation and effective modeling of the core processes in the maintenance business such as inspection planning are the key features of the software.

Corrosion in piping and reactors is a frequent cause of failure if the damage is not detected early enough. According to a recent study published by the National Association of Corrosion Engineers (NACE International), corrosion causes $ 17.6 billion worth of damage each year in the US process industry alone. As a result, corrosion monitoring plays a major role in process risk management. BTS Baycorroxxion is an online corrosion monitoring solution which can be integrated into existing process control systems.

This solution provides real time information which can be used to detect changes in process parameters and evaluate the effect of these changes on system corrosiveness. Operators have a tool which helps them to determine at exactly what point in the process corrosion is occurring, to take corrective action and to directly monitor the success level. This approach was taken for equipment which is part of a batch production system, and it is equally suitable for continuous process systems. Operators have access to reliable information about the actual condition of their equipment, and they can use the data to estimate remaining service life. The advantages from the operator standpoint are obvious. Inspection or retrofit work can be planned well in advance for periods when production asset utilization is low.

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