Subsea Spool Tie-In Incident

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

What Happened?

• Divers were working on the seabed in poor visibility during subsea spool tie-in operations
• After the pipe handling frame (PHF) landed, the Diving Supervisor instructed the crane operator to lower the crane hook to allow the diver to disconnect rigging
• The crane operator reported 'no weight' on the crane wire
• The Diving Supervisor assumed the hook had reached the seabed and instructed the diver to proceed with disconnecting the PHF
• While positioned beneath the PHF, the crane hook unexpectedly struck the diver's helmet as the diver moved to disconnect the rigging
• The diver reported being unharmed and returned to the dive bell
• The dive was aborted
• Inspection revealed the diver's reclaim helmet had damage beyond repair, including the side block
• The helmet's integrity was maintained, this shows the durability of diving helmets
• The diver was unharmed

What Went Right?

• Diver 2 promptly assisted Diver 1, with no injuries sustained
• Both divers immediately returned to the bell safely
• Locating beacons fixed to both divers and the crane block enabled accurate tracking
• All procedures, lifting plans, and Job Hazard Analysis (JHA's) were followed throughout the operation
• The diver was uninjured because the protective equipment absorbed the impact

What Went Wrong?

• The crane hook came to rest on the top beam of the PHF when lowered for rigging disconnection
• This caused a 'no weight' reading, leading the crane operator to think 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

What Was the Cause?

• Inadequate length of crane pennant, which did not provide enough distance between the divers and the crane hook
• Poor visibility, hindering the ability to accurately observe the crane hook's position

Lessons and Actions

• Maintain adequate distance between divers and crane hook
• The length of the crane pennant should be sufficient to maintain a safe distance between divers and the crane hook during subsea operations to reduce the risk of accidental contact, especially in limited visibility
• Enhanced visibility aids and monitoring is essential
• Use alternative methods such as additional locating beacons, underwater cameras, or sonar in low visibility to track the position of critical equipment like the crane hook
• Improved monitoring can prevent misjudgments about the location of the crane hook
• Reinforce communications and challenge assumptions
• Assumptions about equipment position should be minimised
• Clear communication and confirmation procedures between the dive supervisor, crane operator, and divers should be reinforced
• All parties should be fully aware of the equipment's 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
• Updated the Job Hazard Analysis (JHA) to incorporate lessons learned from this incident, regarding safe distances, visibility, and communication requirements for subsea lifting operations