Subsea Spool Tie-in Incident

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

What Happened

• Divers working on the seabed in poor visibility during subsea spool tie-in operations.
• After landing the pipe handling frame (PHF), the Diving Supervisor told the crane operator to lower the crane hook to disconnect rigging.
• The crane operator said that there was 'no weight' on the crane wire.
• The Diving Supervisor assumed the hook touched the seabed and told the diver to disconnect the PHF from the crane.
• While a diver was under the PHF disconnecting rigging, the crane hook struck the diver's helmet.
• The diver was unharmed and returned to the dive bell, after which the dive was aborted.
• Inspection found the diver's reclaim helmet to be damaged beyond repair, including the side block.
• The helmet's integrity remained intact despite the impact, demonstrating durability

What Went Right

• Diver 2 promptly assisted Diver 1, ensuring no injuries were sustained.
• Both divers returned to bell safely.
• Divers and the crane block had locating beacons fixed to them enabling accurate tracking.
• All procedures, lifting plans, and Job Hazard Analysis (JHA's) were followed.
• Protective equipment absorbed the impact, preventing diver injury

What Went Wrong

• The crane hook rested on the PHF's top beam during lowering for rigging disconnection.
• The crane operator assumed the hook reached the seabed due to a 'no weight' reading.
• As the diver approached the disconnection point, the hook slipped off the beam and struck the side of the helmet

Cause

• Inadequate length of crane pennant/stinger did not provide a wide enough gap between divers and the crane hook
• Poor visibility hindered the ability to accurately assess crane hook position

Lessons and Actions

• Ensure adequate distance between divers and crane hook.
• Crane pennant/stinger length should maintain a safe gap between divers and the crane hook during subsea operations to reduce inadvertent contact in conditions of limited visibility
• Use Enhanced visibility aids and monitoring.
  • Use alternate solutions in low visibility, such as additional locating beacons, underwater cameras, or sonar to better identify the location of critical equipment like the crane hook.
  • Better monitoring procedures can help prevent location miscalculations for the crane hook
• Reinforce communications and challenge assumptions.
  • Reduce assumptions concerning equipment position.
  • Ensure clear communication and confirmation procedures between the dive supervisor, crane operator, and divers to better understand equipment location.

Additional Member Actions

• Updated project procedures to specify minimum pennant lengths for different operations.
• Conducted 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.
• Updated the Job Hazard Analysis (JHA) to incorporate lessons learned from this incident, particularly regarding safe distances, visibility, and communication requirements for subsea lifting operations.