This incident, reported in the UK MAIB Safety Digest 1/2025 and reviewed by IMCA, highlights two separate safety issues related to energy isolation procedures and temporary electrical modifications onboard vessels. Both cases underscore significant risks due to deviations from standard practices.
What Happened
During a routine engine room audit, it was observed that LOTO procedures were not fully implemented. Specifically, Electrical equipment on the main switchboard was turned off during hydraulic pipeline repairs, but no LOTO device was applied. A valve involved in the mechanical isolation of a hydraulic system was closed and tagged, but the required locking device was missing.
Separately, undocumented disconnections and unauthorized bypassing of critical electrical systems were found onboard. These alterations were presumed to have occurred during Dynamic Positioning (DP) trials. However, no records existed, and no reinstatement procedures had been followed after the modifications.
Why It Happened
The incident revealed inadequate application of standard isolation procedures by responsible personnel, including failures in both mechanical and electrical isolation. Despite prior fleet-wide instructions to maintain sufficient stock, appropriate Lock Out/Tag Out (LOTO) devices were not available for critical electrical points. There was a general lack of control-of-work discipline, further compounded by unauthorized system modifications likely made during Dynamic Positioning (DP) trials without any supporting documentation. These temporary changes were not reinstated due to miscommunication during shift changes, and there was no verification process in place to ensure full system restoration after trials or troubleshooting.
Actions Taken
While specific corrective actions were not detailed, the incidents prompted a review of LOTO practices. They emphasized the need for improved inventory of LOTO equipment and tighter control of temporary system modifications.
Lessons Learned
- Simply switching off equipment or closing a valve does not ensure isolation. LOTO must be applied to all energy sources during maintenance or repair.
- Vessels must carry suitable LOTO devices for all critical isolation points. Gaps in equipment availability directly compromise safety.
- Any temporary modification to critical systems must be logged, approved, and traced through proper channels.
- After trials or testing, all altered systems must be formally returned to their original state and verified by a responsible party.
- Team transitions should always include comprehensive updates on any system changes or outstanding restoration tasks.
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Source: IMCA Trading Ltd
