How to scope a major instrument upgrade

Shell brought a 10,000-instrument olefins plant from pneumatics to fieldbus with zero unplanned outages.

By Paul Studebaker

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When engineers began a three-year project 15 years ago to convert the 10,000 instruments at Shell Norco Chemicals olefins plant from pneumatics to Foundation fieldbus, the first casualty was their preconceived notion that the project would be easy to justify. “Outages were few and small, in large part because the plant was so good at keeping the old system working. It had been obsolete for 20 years, and they were scavenging parts off Craig’s List. But they had a first-quartile olefins plant,” said Hyonsook Kang, consultant and retired Shell project and engineering manager. “How do you get the money? Management was gung ho about it being the right thing to do, but they had no desire to fund it.”

Speaking to her session attendees at the 2016 Yokogawa Users Group conference this week in Orlando, Kang said, “It’s hard to show return on investment (ROI), to prove the risk of leaving the old system in place.” The first step is to involve the right people—make sure the business, the project and the plant are represented—and that “everyone buys into it,” she said. Consider the cost of maintaining the old system, whether or not it is safe, and the impact of future regulations. How much longer could it last?

Then, what will be the actual cost of the migration? “When we really started looking, the economics were much different than we thought,” Kang said. “The downtime for the migration was also much different—it was mostly done on existing planned outages.”

Top three drivers

In the case of the olefins plant, Kang’s team found the top three drivers were obsolescence, safety and operational excellence. Look for obsolescence in the DCS, SIS, operation stations, field instruments and wiring, Kang recommended. “Also look at third-party devices—we found lots of little devices nobody knew how to maintain.”

Safety and environmental monitoring systems may not meet pending standards and regulations. “SIS standards are becoming more stringent. Parts of the world are not allowing any grandfathering, and I think that will come to the United States,” Kang said. Look at modular automation for operational safety, considering how a possible accident could affect the owners’ company in terms of workforce safety, equipment damage and loss of reputation. “Loss of reputation is serious,” Kang said. “One time we had a process burp a little oil, just enough to create a sheen and make the news. The company stock dropped 10%.”

Operational excellence can be improved by taking the opportunity to implement advanced process control (APC), improve cybersecurity, deal with an aging workforce and increase operator effectiveness. “APC doesn’t cost much to implement and you get a big bang for it,” Kang said. In an offshore emergency, companies increasingly want to be able to move people to the shore and continue to operate. Consolidating control rooms can materially improve operator effectiveness, she said: “You want it to take a squad, not a village, to operate and maintain a system.”

Step by step

Calculating an accurate scope and cost depends on a comprehensive system survey. Kang recommends:

1. Owner to conduct preliminary field survey.

2. Owner to complete preliminary system architecture drawings including field instruments, wiring, analyzers, etc.

3. Owner to engage the main automation contractor (MAC) with preliminary scope.

4. MAC to conduct extensive field survey.

5. MAC to develop extensive system and product architecture drawing. Review piece by piece, by physical location, whether the re-instrumentation will address key project drivers.

6. MAC to produce the final project scope and execute the project with no trips or incidents.

During the surveys, look at field wiring, third-party components and backplanes. “After a thorough survey, our scope turned out to be quite different,” Kang said. Look at the existing process equipment. “Do you need manifolds? Are they tight? Do they block and bleed?” she asked. “Look at the process I/O and how it’s organized. Can it be improved? Is the cabling old and crispy from UV exposure? It changes a lot of what you need to do. Get the entire scope.”

To support drawings and specifications, “We bought a lot of donuts and awarded baseball caps to get all the old documents out of people’s drawers,” Kang said. “Be sure to include skid equipment, racks and UPSs.”

The olefins project followed a typical pattern for re-use of existing infrastructure in a plant from the 1950s or 1960s, including: 35% reuse of wiring, 20% of I/O panels, 20% of controllers, 7% of workstations, and 5% of monitors.

Finally, before the scope is finalized, “Make a premise document with a definition of success, and review it with all the stakeholders to be sure everyone will be satisfied,” Kang said. “And build in a technology refresh cycle, perhaps every four to five years, to recognize the fact that technology changes and wears out.”

More information on how owner organizations can better understand, plan and scope reinstrumentation projects is available in a comprehensive new Yokogawa e-book entitled “Update, Upgrade, Migrate or Replace: The Road to Successful Plant Reinstrumentation and Control Improvement Projects.” Get your free copy.