Mattress beam landed very close to divers

What happened?

During subsea lifting operations with divers in the water, a large mattress lifting beam was lowered inappropriately close to the divers.  The two saturation divers were deployed on the seabed at 156 msw, assisting with concrete mattress recovery using a mattress lifting beam attached to the vessel main crane.  The beam weighed 696kg in seawater.

What went wrong?

Investigation showed:

• Dive Team lost sight of the beam during descent, due to:
  • lack of due care and attention to load coming down
  • ROV was on seabed, and did not provide eyes on load from established short mark
  • poor visibility;
• Failure to stop the job:
  • acceptance of risk and failure to reassess the situation post-incident
  • failure to properly record and report events to management onboard at the time of the incident.

What actions were taken?

Our member undertook to check that company procedures were being properly followed with regard to ensuring that:

• Divers are clear of moving loads and maintain a safe distance at all times – not under the load nor in the ‘DROPS cone of exposure’;
• The divers can see the mattress beam and are in a position to control the lowering of the load by relaying instructions to the crane operator via the dive supervisor;
• There is an ROV to determine water depth and height of subsea assets, locate the mattress beam and confirm its status;
• The crane wire/lifting beam is fitted with mini beacon, light sticks, strobes etc as appropriate and is lowered to the ‘short mark’ above the assets or the seabed;
• The beam deployment is conducted at a minimum distance offset from client assets;
• The crane line out meter is zeroed when loads pass through waterline.
• Reaffirm requirements of company incident reporting process.

Members may wish to refer to the following IMCA guidance documents:

• Guidelines for lifting operations (IMCA SEL 019, IMCA D 060, IMCA LR 006, IMCA M 187)
• Guidance on operational communications (IMCA D 046, IMCA M 205)
• IMCA international code of practice for offshore diving (IMCA D 014)

The following incidents may be of interest:

• Diver injured during subsea lifting operations
• Near-miss: Dropped taut wire clump weight
• Diver struck by lifting frame while installing concrete mattresses (2004)