Floating production platform evacuated amid power outage

What happened?

The United States’ Bureau of Safety and Environmental Enforcement (BSEE) has published Safety Alert 333, relating to the evacuation of a floating production platform in the U.S Gulf of Mexico, which occurred as a consequence of a power outage.

What went wrong? What were the causes?

• At the time of the incident, the floating production facility was operating on a single uninterruptible power supply (UPS), which failed. This failure cut automatic battery back-up to emergency power users, including the vessel management system (VMS) and operational critical telecoms;
• When the emergency generator was started, in the process of syncing the emergency generator with main power, the UPS’s static bypass switch opened due to the emergency generator’s frequency falling slightly out of range with normal power. When the static bypass switch opened, all loads on the emergency bus lost power as a result of these loads being dropped and an abandon platform sequence was initiated;
• Several attempts to re-establish power were unsuccessful due to the logic sequence in the VMS, which continued to send shutdown trip signals to the emergency generator circuit breaker whenever the control system rebooted. This logic sequence was hidden from the workers because the VMS ordinarily rebooted from battery power, which was unavailable. The backup script in the application did not inhibit the abandon platform shutdown signal during reboot.

What actions were taken? What lessons were learned?

The solution that resulted in power restoration was to physically inhibit (disconnect wires) to the emergency generator breaker.

BSEE recommends that operators consider the following options:

• Review ‘black start’ procedures to include, as a minimum consideration, the complete loss of power to the VMS;
• Consult with the original equipment manufacturer (OEM) to evaluate and make appropriate recommendations for UPS protective features and their impact on availability of sub-distribution systems;
• Review the performance of critical ventilation systems relative to their basis of design and develop a strategy to address maintenance requirements;
• Review the project engineering handover process for critical electrical systems to ensure personnel are properly trained to operate new equipment. Particularly, electrical technicians should be knowledgeable of what is necessary to power up emergency loads after failures;
• Create or review a platform evacuation procedure specifically prompted by a facility blackout. This evacuation procedure is unique because it is:
  • more urgent than an evacuation due to, for example, a hurricane
  • the procedure should consider a possibility of limited communications and reduced availability of resources due to the blackout;
• Verify that all necessary safety and environmental management system (SEMS) documentation (emergency response plans, as-built electrical drawings, piping & instrumentation diagrams, operating procedures, etc.) are up-to-date and accessible in hardcopy format.

If you have further questions not addressed in the recommendations above, contact BSEE at the number listed on the Safety Alert.

Members may wish to refer to the following incident:

• Power loss within dive control