The great migration
Before deciding, always look for risk versus return
By John Bryant and Mike Vernak
The plant is running for now, but it just keeps taking longer and longer to find replacement parts.
You often look for them on eBay because the parts houses you typically use no longer have what you need, and the in stock parts are getting more expensive.
Finding service is getting tougher, too. Your legacy system might be 20 or more years old, and the engineers and technicians who originally installed it are retiring. Even the incumbent vendors are not supporting these old systems anymore.
It is a double-edge sword because while you managed to keep the plant running, upper management does not feel the pressure of a system working on borrowed time. In fact, as long as the plant is running and there is no downtime, dollars go elsewhere.
Things will not last, but what can you do? It is difficult to justify a system migration based only on what might happen. However, if you are able to demonstrate the improvements that new technology can provide, your argument for migration strengthens.
Arkema, an Axis, Ala.-based industrial chemical producer, used a phased DCS legacy migration program to migrate their existing platform to an updated control scalable for future upgrades.
When it all comes down to it, return on investment (ROI) on risk mitigation is not enough, you also have to show how you can gain a competitive advantage in the marketplace.
All hands on deck
Migration decisions can break down into risk mitigation and performance improvements. Risk mitigation is about what keeps you up at night, and performance improvements are what provide a sustainable, competitive advantage.
Productivity gains if it means crippling current production. Do I have to update my system all at once? How long do we have to stop production? How can I budget a project of this type? These are just some of the typical questions asked.
Companies today view migration decisions as a key part of a business strategy, offering a competitive advantage. Migrating to newer equipment can offer many benefits such as increased information flow through improved system integration, more production with greater throughput, less training and spares, and reduced energy costs through sustainable manufacturing systems.
The design of most legacy systems was for a specific use. A distributed control system (DCS) once connected only to the process itself, whether for a chemical plant, steel mill, or utility plant. But not any more. Now, companies can replace DCS systems with a single, plant-wide, integrated system, connecting conveyor lines, discrete manufacturing, drive, batch and safety control systems, and the shipping department.
Using a single platform also helps reduce maintenance and training costs, which is a huge fixed cost for most companies. The entire plant can see additional performance growth due to the increased availability of data and the corresponding improvement in information flow.
A single, plant-wide system allows for an unlimited number of end-user enabled reports, which are easy enough for the company to create based on the increased informational data available. This means better control over quality, tighter process management, and greater potential for a satisfied customer. That all adds up to a competitive advantage.
In addition, expert data-sharing helps produce higher quality products, increased operator knowledge, and provides corporate entities with improved production capabilities. When a single, information-enabled system is in play, plant managers have much more data available to make faster and smarter decisions.
Right migration strategy
To execute a rip-and-replace migration, customers must be willing to shut down the process for a period of time, which can get expensive. Today’s 24/7 market often makes downtime not an option. When a plant is not running 100% of the time, it may not make its projected profit.
Although there is a proper time and place for a rip-and-replace strategy, companies often look for ways to reduce the short-term complexity and expense, even when total system replacement is the goal. Phased migration approaches offer many advantages. By looking at one section of the system at a time, the customer reduces the risk of unseen complications halting the migration midstream. A migration in one area often provides you with more spares for another area, allowing more time to evaluate the next move.
A phased migration approach demands a high level of system, industry, and project management knowledge. The installation company must have a solid knowledge of the new and legacy systems as well as a full understanding of the specific industry’s requirements. Project management experience is also essential, since execution timing and budgeting only allows for a very small margin of error. Nonetheless, the person doing the project needs to have the right skill level to get the job done.
The key stage in the migration strategy order is when the customer replaces the least supported systems first—typically the human-machine interface (HMI) consoles. Twenty years ago, before the influx of standardized protocols, these consoles were proprietary. Today, however, those older HMI systems just do not get support. Customers find it easier to spend money to replace operator consoles and engineering workstations with modern PC-based platforms. An additional benefit of this migration is that console replacements do not require downtime. HMIs are a plug-and-replace item and can interoperate with the existing operator stations. You can also customize new consoles to have the same look and feel as the old system.
When it comes to deciding to implement a migration, it can become an emotional decision. The old system may have its quirks, but the operators know it inside and out. Even though a migration is often justified, risk can still be a factor. However, deploying new operator consoles side by side with the old ones—even before removing the legacy system consoles—helps ease the pain and the fear associated with migration.
Emotion at the door
Another central element to any retrofit is making sure everyone is a part of the decision-making process. When dealing with an existing system, emotional decisions do play a role. The operators and the maintenance and production teams should meet with the entire migration team so there is a common understanding of the processes, maintenance, and the type of production information that will be available.
For example, if the operator feels the new HMI screens look too different than the version operators trained on, they will need additional training. Plus, it may cause operators to misinterpret data and therefore not run the process correctly. You need to mitigate this risk upfront. Ultimately, a migration project is not successful until the operators agree it is successful.
The second phase of a migration might include replacing the controllers. This step can take three months to three years depending on the customer’s interest, need, and budget. It is important to note new controllers can go in before the HMI swap-out is complete, if the installation timeline is tight. This approach can work, but is not the only approach.
To allow communication from the new controllers, the migration team needs to develop interface solutions to legacy I/O infrastructures that need to undergo replacement. Also, new controllers can go in place in parallel with legacy systems, using the same I/Os. It takes on a monitor mode only until everyone verifies the system is working correctly. Once both systems are up, old systems can stay in use until everything is double-checked. Then, the team can complete the transfer from the legacy control to the new control platform.
This allows manufacturers to build on past equipment investments, and it also gives those integrating the system a more flexible migration strategy where users can revert back to their old system if issues occur or if the process is beyond the customer’s comfort level.
Migration enablers are tools to make upgrades and replacements more efficient and are particularly important with phased migrations. It is also important to note migration enablers are rarely valuable without a high level of system and technical knowledge. In the right hands, these tools will not only help reduce risks associated with migration, but will also allow the manufacturer to benefit from the years of experience to create such tools.
Experience levels of members of the migration team over the years have developed enablers to convert databases, configurations, graphics, and field I/O connections in order to reduce risk, increase speed, and reduce engineering efforts necessary for the migration. These enablers range from simpler, cross-referencing tools to elaborate ones that take extensive training to use and to verify proper outcomes. Enablers can provide tremendous value as long as the person using them truly understands the technology and potential limitations.
A phase three migration might include adding more controllers and I/O off of the new HMI infrastructure. Another example might be users that need to build a new system onto the existing system.
A utilities company that generates power, with a DCS system controlling the whole plant, finds the Environmental Protection Agency requires their coal-fired system to add flue gas scrubbers on all stacks. The company suddenly needs to build off its HMI infrastructure and add new control systems to operate the scrubbers. They can start to deploy new control systems on these scrubbers and be completely interactive with the rest of the system already in place.
Phase three is when the team can replace the legacy I/O infrastructure. There are special cables to help retain the existing field terminations that bring instrumentation signals up to an I/O module. By incorporating the field wires into this termination unit and cabling the signals from that unit up to the I/O module, they eliminated the need to touch the field wiring, a huge cost in any migration, as well as a prominent place for potential errors.
Working the numbers
Oftentimes users seeking to justify equipment migrations are not from the finance department. Instead, they are middle managers who are ultimately concerned with manufacturing a quality product on time and at a cost point that provides a competitive advantage. It is important for managers to realize formal financial tools used to evaluate migration decisions like ROI and net present value (NPV) are critical to force the collection and comparison of numbers and to consider alternatives. However, without applying experience and wisdom to these numerical outcomes, it is hard to imagine consistently achieving good migration project decisions. Both sides must work together in order to justify a migration.
ROI and NPV are just some of the financial tools used in project justification. However, these concepts are relatively simple to apply depending on the number and type of variables used in the evaluation. After a little thought, one can gain a rough idea of some of the investment components appropriate to include in these models: acquiring hardware and software, support, maintenance, training, spare parts, inventory costs, carrying costs, and the list goes on. To make modeling and data collection more manageable, it is often helpful to make projects more specific by looking at HMIs as one aspect of the project, then creating financial evaluations on that portion alone.
You will have to offset these investment costs with performance gains and risk mitigation. Performance gains will depend on the manufacturing and competitive advantages one gains from new technology, such as improved system integration, increased information flow, throughput to increase production, energy reduction, and reduced training and spares.
This evaluation is sometimes more difficult when doing a phased migration over time because you may not realize some of the benefits in the first phase of the project, which means you could amortize them over time. In some cases, you may not reap most of the benefits until phase two or three is complete. NPV models can help you understand what value the project offers today. Risk mitigation comes from reduced breakdown, easier access to parts, and other service and support.
Risk mitigation can also result in executing the migration. Carrying out migrations in phases, using well-developed enablers that build efficiencies, and working with a migration team that has the system, industry, and project management knowledge to help you evaluate, plan, and execute your project successfully are keys to reducing risk.
Additionally, understanding the areas that offer the greatest ROI upfront and working on those areas first can offer greater short-term returns. These short-term benefits may offset having to wait to receive the performance advantages of a completely new system. This way, customers will get the competitive advantage and performance advances right away. Plus, parts of the migration can work through budgets already in place, without any distribution of capital funds.
Instituting a phased migration is a major step for any manufacturing system. Although replacing an old DCS system with a single, plant-wide system poses some risks, it is important to help your production team realize the potential benefits. If executed correctly, a phased migration can offer increased productivity and a sharper competitive advantage.
ABOUT THE AUTHORS
John Bryant is engineering and maintenance manager at Arkema. His e-mail is email@example.com. Mike Vernak is DCS program manager, Rockwell Automation. His e-mail is Mpvernak@ra.rockwell.com.
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