Case study: A West Coast oil refinery undergoes PLC modernization

In 2012, a major energy company’s West Coast oil refinery was producing more than 290,000 barrels of crude oil per day. However, aging equipment made maintaining this production capacity more challenging.

With operations running night and day, the oil and gas industry requires equipment that is not only reliable but also helps enhance worker safety and minimizes security risks. Diminishing the downtime associated with these risks becomes increasingly difficult as equipment approaches obsolescence.

"The oil and gas industry in general is very safety-focused," said Larry Kostamaba the account manager supporting the refinery for Rockwell Automation. "There’s a lot of pressure to be reliable and safe, while minimizing unscheduled downtime as much as possible to remain profitable. The industry is always looking at solutions to address these issues."

With a facility footprint of over 1 square mile and more than 1,100 miles of pipelines, the refinery had an expansive control architecture, operating a distributed control system on top of more than 185 aging programmable logic controllers (PLCs). Nearly half of those PLCs in operation were legacy controllers and had been in operation for more than 25 years. This equipment was rapidly becoming obsolete or had already been discontinued, making replacements and repairs problematic for operators.

The aging PLCs offered limited diagnostic information, making it nearly impossible to tell where network issues were occurring. Troubleshooting often led to hours of unplanned downtime, as well as safety and security risks.

"There have been a lot of new developments with automation technology since the original control system had been put into place — including the ability to access, view and analyze production information captured by the equipment itself. Without diagnostic information, it was difficult to determine the causes of any outages," Kostamaba said. "It could have been anything from a malfunctioning controller or I/O card to an unplugged Ethernet cable."

When operators were alerted of a lost signal there was virtually no way to determine where or why the signal had been lost. They would have to call IT to find out the root of the issue, leaving equipment offline for hours while the technical support team worked to revive the network. With limited diagnostic information, there was often no way to determine whether the source of the network outage could pose a threat to worker safety.

The refinery also lacked a formalized process for making changes to controllers in the field. Individual laptops were used to manage programs and update controllers as needed. While these laptops were regularly backed up, without a central repository to store files and document changes there was limited insight into how, when or what changes were made.

Facility operators needed a way to easily manage and control assets and address the obsolescence risks of the legacy hardware across the sprawling facility. However, all this needed to be done without causing additional downtime while the project was in progress.

Making the switch

After careful consideration, the California refinery turned to Rockwell Automation to design and install a future-ready infrastructure and improve configuration control while minimizing operational interruptions.

"The refinery wanted a plan that would address the obsolescence risk associated with the legacy hardware running their operation," said Kostamaba. "They needed a solution that would improve the change-management process and improve reliability and safety with a future-ready infrastructure in mind."

At the heart of the project was a massive PLC migration. With 185 controllers in operation at the expansive refinery, the company needed to develop a strategy to replace aging equipment without adding costly hours of downtime.

The Rockwell Automation team chose to take a phased approach to the project, upgrading the legacy PLCs in stages rather than replacing all the equipment at the same time. This would allow the refinery to continue operations 24/7 throughout the modernization process.

The company opted to replace the legacy controllers with an Allen-Bradley ControlLogix platform. The new control system would offer tight integration between the programming software, controller and I/O modules, improving visibility into refinery operations.

The new system included I/O chassis-based modules. With the installation of the I/O modules, operators would be able to access comprehensive I/O diagnostics to help detect network failures both in the field and system-wide.

"In addition to the PLC migration, operators at the refinery wanted the ability to troubleshoot the network without contacting the IT department while out in the field," said Kostamaba. "They needed the network diagnostics available at the local HMI (human machine interface)."

Along with the new controllers, Rockwell Automation installed modular-managed Ethernet switches. These switches were standardized across the field. This helped facilitate uniform configuration when placed into production and provided support as needed.

The switches offered a networked solution built on an EtherNet/IP network. With remote access to each controller, operators and engineers would be able to easily access diagnostic information from each controller.

To improve the level of configuration control on-site, the team also implemented a plan to install change management software from Rockwell Automation when the PLC migration was complete. With a centralized tool for managing and tracking asset information, operators finally have a central repository for files and more insight into what changes are being made across the facility.

The new software created a formal procedure for change management and replaced the process of checking out individual laptops each time changes were made to controllers in the field. By securing access to the system and limiting network administrative rights, the software also helps mitigate internal security risks.