Subsea Spool Tie-in Incident

Study Notes

During subsea spool tie-in operations, a crane hook struck a diver's helmet unexpectedly.
The incident occurred on March 6, 2025.

During subsea spool tie-ins, divers worked on the seabed with poor visibility.
The Diving Supervisor told the crane operator to lower the crane hook to the seabed, to allow the diver to disconnect rigging from the crane after landing the pipe handling frame (PHF).
The crane operator reported 'no weight' on the crane wire, so the Diving Supervisor assumed the hook touched the seabed and told the diver to proceed with disconnecting the PHF from the crane.
The crane hook struck the diver's helmet while the diver was positioned beneath the PHF and moving to disconnect the rigging.
The diver was unharmed and returned immediately to the dive bell; the dive was aborted.
The diver's reclaim helmet was damaged beyond repair, including the side block, but its integrity was maintained.

Diver 2 assisted Diver 1 promptly, to ensure no injuries were sustained
Both divers immediately returned to bell safely.
Both divers and the crane block had locating beacons fixed to them enabling accurate tracking.
Procedures, lifting plans, and Job Hazard Analysis (JHA's) were followed throughout the operation.
The diver remained uninjured because the helmet absorbed the impact.

The crane hook came to rest on the top beam of the PHF when lowered for PHF rigging disconnection, gave a 'no weight' reading.
The crane operator assumed the hook had reached the seabed.
The hook slipped off the beam and struck the side of the diver's helmet as the diver approached the disconnection point.

The crane pennant/stinger was of inadequate length, providing little distance between the divers and the crane hook.
Poor visibility.

Ensure adequate distance between divers and crane hook.
The crane pennant/stinger should be long enough to keep divers and the crane hook safely separated during subsea operations, to reduce accidental contact in limited visibility.
Use enhanced visibility aids and monitoring.
Alternative methods should be considered in poor visibility, such as additional locating beacons, underwater cameras, or sonar.
Improved monitoring can help prevent misjudgements about the location of the crane hook.
Assumptions regarding equipment position should be minimised.
Reinforce communications and challenge assumptions.
Reinforce clear communication and confirmation procedures between the dive supervisor, crane operator, and divers, to ensure all parties know of the equipment's location at all times.
Update project procedures to specify minimum pennant lengths for different operations.
Conduct pre-operation inspections of all rigging and lifting equipment, including crane hooks and pennants, to ensure they meet safety standards and are appropriate for the operation.
Update the Job Hazard Analysis (JHA) to incorporate lessons learned regarding safe distances, visibility, and communication for subsea lifting operations.