SIS Migration Opens Door to Integrated Safety

Repsol Embarks on Seven-year Migration to Unify its Control and Safety Systems

By Keith Larson

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Repsol, Spain's largest integrated oil and gas company, was at a safety crossroads. The fleet of safety instrumented systems (SISs) at its five domestic refineries consisted of some 150 programmable logic controllers (PLCs) from a variety of suppliers. The one thing they had in common?  Impending obsolescence, according to Mario Macias Montano, advanced process control engineer, Repsol.

Montano shared Repsol's ongoing journey toward an integrated safety and control environment with fellow delegates from the Europe, Middle East and Africa (EMEA) region at the Honeywell User Group (HUG) meeting, November 4-7, in Nice, France.

The Repsol refineries faced problems with availability of spare parts for older systems, and had to keep on hand older PCs with obsolete Windows operating systems just to communicate with the PLCs for maintenance and configuration tasks. Further motivating action, the company had adopted new internal safety rules based on the IEC 61508 and 61511 international safety standards, and safety-integrity level (SIL) analysis revealed that some existing SIS implementations were not in line with desired protection.

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An SIS overhaul was clearly in order, and in 2007 Repsol began evaluating its options for a global substitution project. "Obsolescence and safety system availability were driving forces," Montano said. "But we also were looking for better HMI [human-machine interface] performance and benefits to be gained through integration with other plant systems," Montano said. "We saw an opportunity to build an integrated system for both control and safety functions," Montano said.

In part because the company already was using control systems from Honeywell Process Solutions, Honeywell was assigned the contract to replace the older safety systems in its five Spanish refineries. The two companies currently are well into a long-term engagement that began in 2011 and runs through 2018, phasing SIS upgrades and integration activities into planned shutdowns. The project scope encompasses the migration of all older PLCs and accompanying logic to the Honeywell Safety Manager platform, with the option to upgrade existing logic in line with latest SIL analyses. An initial estimate for the project's hardware, software and services requirements was based on the I/O count of the PLCs to be replaced, with material services discounts based on the number of PLCs actually migrated, Montano said.

Maintenance costs for the new systems are now predictable, Montano said, and the systems swapped out thus far provide an in-house source of spare parts for safety systems not yet transitioned to the new platform. The integration of alarms and equipment status notifications within the new HMI environment also is helping to reduce downtime and boost overall reliability. "The new systems also provide easier integration with other systems as well as improved cyber security and alarm management," Montano said.

In addition to granting safer operations, the newly integrated control and safety environment has prepared Repsol for the future, Montano said. "We have flexibility for future upgrades and with remote access can respond quickly to any problems that arise."

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