Subsea Spool Tie-in Incident

• During subsea spool tie-in operations, a crane hook unexpectedly struck a diver's helmet.

What Happened

• During subsea spool tie-in operations in poor visibility, divers were working on the seabed.
• After landing the pipe handling frame (PHF), the Diving Supervisor ordered the crane operator to lower the crane hook to allow the diver to disconnect rigging.
• When the crane operator reported 'no weight', the Diving Supervisor assumed the hook reached the seabed and instructed the diver to disconnect the PHF.
• As the diver moved to disconnect the rigging, the crane hook unexpectedly struck the diver's helmet.
• The diver was unharmed and returned to the dive bell, and the dive was aborted.
• Inspection revealed the diver's reclaim helmet was damaged beyond repair, including the side block.
• The helmet's integrity was maintained, demonstrating the high quality and durability of the diving helmets.
• The diver was unharmed.

What Went Right

• Diver 2 helped Diver 1, ensuring no injuries.
• Both divers returned to the bell safely.
• Both divers and the crane block had locating beacons for accurate tracking.
• Procedures, lifting plans, and Job Hazard Analysis (JHA's) were followed.
• The protective equipment protected the diver from injury.

What Went Wrong

• The crane hook landed on the PHF's top beam during disconnection, resulting in a 'no weight' reading.
• The crane operator incorrectly assumed the hook was on the seabed.
• As the diver approached the disconnection point, the hook slipped and hit the diver's helmet.

What Was the Cause

• The crane pennant/stinger's length was inadequate, not providing enough distance between the divers and the crane hook.
• Visibility was poor, hindering the ability to see the crane hook.

Lessons and Actions

• Maintain adequate distance between divers and crane hook by using a sufficiently long crane pennant/stinger to reduce contact risk in low visibility.
• Use enhanced visibility aids and monitoring:
  • Use alternative methods like additional locating beacons, underwater cameras, or sonar to better track the position of crane hook and critical equipment in poor visibility.
• Reinforce communications, challenge assumptions by:
  • Minimising assumptions regarding equipment position.
• Reinforce clear communication and confirmation between the dive supervisor, crane operator, and divers to ensure awareness of equipment location.
• Updated project procedures now specify minimum pennant lengths for different operations.
• Pre-operation inspections of rigging and lifting equipment, including crane hooks and pennants, are conducted to ensure safety standards.
• The Job Hazard Analysis (JHA) was updated to include lessons learned about safe distances, visibility, and communication for subsea lifting operations.