There are many legacy control systems that continue to reliably operate and control industrial processes in all industry sectors around the world. The systems manufactured, designed, and installed in the 1970s, 1980s, and 1990s are indicative of just how reliable the technology incorporated into the hardware and software of these systems really are.
These high levels of reliability leave the operators of these facilities to manage a double-edged sword; the legacy control system continues to operate and control the process with a high level of availability, making the justification for upgrading the control system very difficult. The need and benefits for control system upgrades are highly scrutinized by stakeholders that control capital budgets – why upgrade a system that continues to reliably meet its intended function?
The problem is, compared to other projects the return on investment (ROI) of a control system upgrade is less tangible and typically low on the list of projects to be funded. It is easier to justify and fund projects that can demonstrate clear ROI in dollars; for example, increased production resulting from equipment debottlenecking is easily calculated to establish project ROI.
So, how can ROI be established for control system upgrades? There are two sides to the equation when determining ROI; the potential risks attached to legacy systems, and the benefits that can be gained with modern systems.
Risks Associated with Not Upgrading a Legacy Control System
RISK #1 - INCREASED RISK OF SYSTEM FAILURE
The increased risk of control system failure results in decreased reliability and increased downtime. Lost production and unplanned outages often decrease revenue and increase operational costs.
RISK #2 - OBSOLESCENCE OF HARDWARE/SOFTWARE
Control system vendors publish support lifecycles for their legacy control systems and once they reach the stage of obsolescence, support is typically discontinued or offered on a “best effort” basis. This includes:
- Availability of parts - even if there are spare parts stocked in the facility warehouse, those parts have likely already reached end of life. It would be risky to use them to continue operating a legacy system, as their failure rates will be relatively high.
- Availability of technical support
- Flexibility to interface and communicate with other control systems
- Potential software updates to fix bugs and maintain compatibility with modern computer operating systems and hardware
This increases operational risk with extended unplanned outages (or the inability to recover from one) and reduced functionality, while adding costs associated with increased maintenance, lost production, and decreased product quality.
RISK #3 - REDUCED SUPPORT AVAILABILITY
Supporting legacy control systems is difficult; as systems age and technology evolves, so do technical resources. Personnel familiar and competent with obsolete technologies and software are nearing the end of their careers and many are no longer in the workforce. Those who are still around often command premium rates.
Increased difficulty in troubleshooting complex system issues and sourcing technical expertise for projects that require engineering leads to higher maintenance and engineering costs, and delays the realization of project benefits. Simply put, reduced support availability magnifies the risks associated with retaining legacy control systems.
Risk #4 - Limited System Expandability
Operations requirements can change in order to increase plant production or meet process safety requirements. Expanding legacy control sytems to accommodate these changes is difficult, and performing adequate design and procuring the additional hardware and software required for the system expansion could be very hard or even impossible in some cases.
Benefits of Upgrading to a Modern Control System
BENEFIT #1 – NEW AND IMPROVED FUNCTIONALITY
New technologies are continually being developed that introduce operational and maintenance efficiencies as well as advanced data management functionality. Cutting edge data analytics, process performance optimization, enhanced operational decision-making ability, and the reduction in risk (cost) of executing projects are all aspects contributing to operational excellence that modern control systems help make possible.
BENEFIT # 2 - OPERATIONAL EFFICIENCY IMPROVEMENTS
There have been many gains in operational efficiencies with the advancement of new technologies in control systems, and legacy control systems limit the ability to take advantage of these opportunities. Reduced operational risk and cost; reduced downtime, increased product quality, decreased energy usage and increased operator effectiveness are all low hanging fruit that can pay dividends to the operation once the control system has been modernized.
Putting it All Together to Determine the ROI of Control System Upgrades
In reading the factors described above there is a common theme we can derive – calculating the negative impact to the bottom line with defined and quantified risk events combined with the positive impact of operational excellence opportunities that are available by upgrading to modern technologies is a credible basis for calculating ROI.
The question isn't “what will an upgrade to your legacy control system cost?” The question is “what are the costs of not upgrading your legacy control system and how much operational risk are you willing to accept?” This question deserves serious consideration and, if framed correctly, will make decision-makers sit up and take notice.