Systems Obsolescence Mitigation Strategy

Systems Obsolescence Mitigation Strategy

The majority of industrial plants around the world have long since deployed microprocessor-based systems to automate the monitoring, control and protection of their equipment and production processes.  These systems include programmable logic controllers (PLC), distributed control systems (DCS), safety instrument systems (SIS) and other digital systems ranging from tank gauging systems to motor operated valve networks to electrical substation automation.  Technically, systems could also include field instrumentation and control valves.  Owner/Operators have been enjoying the benefits of the digital revolution since the mid-1970s – longer equipment life, extended run length between turnarounds, increased plant throughput, higher profit margins, reduced manpower, improved operations and personnel safety and easier compliance with government regulations.  By and large these systems have delivered reliable operation over the years and become an almost forgotten part of a plant’s critical infrastructure.

Unfortunately, many of these microprocessor-based systems are beginning to show signs of age and failing to meet the expectations of plant management and engineering staff alike.  Decades of exposure to multiple types of stresses coupled with limited preventative maintenance are leading to increasing failure rates with adverse consequences on operations, profitability and safety.  In parallel, support for these systems by the vendor and plant personnel is becoming increasingly difficult as vendors phase out obsolete product lines and knowledgeable specialists retire or move on to other areas.  As a result, the net mean time to repair a critical failure is increasing.  In some cases failures become unrepairable, requiring an extended downtime to design and commission a replacement system.  Finally, these obsolete systems are often capacity-limited and cannot meet the ever-increasing demands for automation and compliance.

Plant management across industry are now facing the prospect of spending enormous amounts of precious capital over the next 10-15 years for replacing these obsolete systems just to maintain capacity.  As careful stewards of their company’s assets, they are asking a number of tough questions.  How much longer can we safely operate with the legacy equipment?  Can’t we find another way to maintain these systems?  Isn’t there a root cause for observed failures that we can fix?  Can’t we find a way to extend the life of the systems without major investment?  What are the hard benefits of a newer systems platform?  What is the value of the new system’s increased functionality?  What is the expected life of a replacement system and how will we support it?  If we need to replace the system, what is the business justification?  How long will it take to implement the replacement and can we do it without loss of production?

To assist clients making decisions about mitigating systems obsolescence, Becht Engineering recommends applying a risk-based economic assessment methodology to determine the best strategy going forward.  The Becht Engineering approach incorporates systems criticality, actual failure rates, root causes of failures, obsolescence assessments, risk analysis, legacy system capacity constraints, gap and opportunity analysis, systems life extension assessment, support capability assessment, planning and execution metrics for replacement and upgrade projects, and migration strategies and metrics for moving to the new system.  The outcome of the assessment yields a set of recommendations for ongoing maintenance, life extension and/or optimal timing for system replacement.  

The context of the Becht Engineering assessment is shown conceptually in Figure 1.  This figure shows the industry-accepted “bathtub” curve for component reliability.  The curve assumes a combination of initial quality-related “infant mortality” failures, followed by stress-related failures during the device’s useful life culminating with a period of escalating failures when degradation mechanisms dominate.  The challenge is to estimate when the inflection point for escalating failures will occur, how rapidly it will rise to an unacceptable level and whether a replacement project can be completed before the unacceptable threshold is reached.  Superimposed on this curve are time frames where there is a loss of spare parts availability, loss of engineering and maintenance support capability, inability to remanufacture replacement parts, operating system obsolescence even when the hardware is not obsolete and where the opportunity value of the new system exceeds the support cost and loss of opportunity by the old system.  Frequently, these events can occur long before the end of the useful life of the equipment is reached.

Becht Engineering has conducted a number of such assessments over the years.  In one instance, the client was able to improve the performance of the legacy systems through identified life extension activities and defer capital deployment by 15 years.  In another case, an alternate support strategy for the legacy systems was identified, allowing the client to defer significant capital investment for over a decade while planning for a paced replacement that was manageable with existing resources.  In other cases, system replacements were able to be justified either solely on a risk-based analysis or a combination of reduce risk and economic value offered by the new system.  

In conclusion, a risk-based business-driven plan to proactively address systems obsolescence is vital for continued plant operability, profitability and safety.  Becht Engineering is able to assist Owner/Operators analyze their plant or system-specific situations, supply recommendations for cost-effective solutions and provide assistance with detailed planning and execution of replacement and upgrade projects.


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About The Author

Torney Van Acker has over 35 years of domestic and international experience with ExxonMobil planning and developing large complex control system replacement projects in the petroleum refining and chemical industry as well as developing the instrumentation, control and safety systems scope for large Upstream production projects at a number of onshore and offshore locations.

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