Diving Bell Bailout Manifold Failure

Bailout Manifold Failure

• A diving bell bailout manifold failed due to pressure, luckily no divers were in the bell
• The bell was being prepped for diving with the DSV waiting, bell checks okayed
• The bell trunk was isolated at 31 msw, while the system was at 32 msw
• A rush of gas was heard an hour after bell checks
• A bell internal camera showed visible misting, indicating a gas leak
• Investigation revealed four pieces of a failed nut from the bailout manifold assembly
• Diving operations were stopped so both bells could surface and all bailouts could undergo inspection
• Uneven rubber boots on each cylinder likely caused stress when moved
• The securing strap holding the bottles was found to be loose
• The bailout manifold design was less robust compared to others used by the company
• Forensic testing showed lateral force was likely introduced via improper securing, causing stress corrosion cracking and internal corrosion over time
• The bailout manifold assemblies have been replaced with a more robust version
• Ensure familiarity with maintenance tasks for bailout alignment, integrity, and boots
• Nuts used are made from copper alloy CW614N, which is prone to stress corrosion cracking and dezincification, a common alloy used in manifold assemblies

Master Links and Lifeboat Release

• A vessel used the opportunity to perform annual checks, including a lifeboat launch and davit inspections
• The lifeboat launch was unmanned, following company procedure
• The fore and aft master links connecting the lifeboat to its falls became disconnected in an uncontrolled manner
• There were no injuries but there was slight damage to the lifeboat
• The lifeboat was lowered, the weight transferred, and the falls slacked as expected
• The forward master link disconnected, prompting crew in the rescue boat to monitor the lifeboat
• As the rescue boat approached, the aft master link also disconnected
• At this point, the lifeboat was only tethered by the forward and aft painters
• The forward painter was attached to the painter release mechanism, and the aft painter to the bitt used for stowage
• The forward painter then disconnected and the forward master link hit the painter release system
• The lifeboat swung 180 degrees, and the aft painter connected to the bitt became loose
• The lifeboat was then free to drift away and the rescue boat recovered it
• The master link handles were incorrectly facing inboard impacting the hook safety latch and releasing the hooks
• Master links should be replaced with ones that have handles orientated to the sides

Sheared Bolts on Lifting Trunnion

• After installing an offshore renewables Transition Piece (TP), crews found the lifting trunnion cover plate on the hatch cover with its three securing screws
• The securing screws had sheared
• The cover plate weighed 44 kg and fell about 0.5 m
• A survey beam and GNSS positioning equipment antenna were damaged, the antenna was fixed and the survey lifting beam was replaced with a spare
• The process for verifying if the screws attaching the cover plate to the lifting trunnions was incorrect
• The side forces on the cover plate were greater than the screws could withstand; this was a human error

Hose Management and Chemicals

• Someone was affected while non-potable water was being flushed through a hose
• The person started coughing as the hose contents filled the bucket bottom, they were asked to wash their hands and get fresh air, which improved their condition
• The engineers noticed a yellow/brown liquid in the water, indicating an issue
• The affected person came into contact with the fluid, and did not wear gloves, assuming it was only water
• The hose contained stagnant water and some cooling medium liquid because it had sat coiled in a cupboard for two years without dripping dry
• The hose had been used to fill the system with Antifrogen (a cooling agent) in July 2019, but wasn’t properly flushed afterward
• The hose has now been disposed, and two new hoses were prepared; one for cooling agent and one for non-potable water
• Hoses should be cleaned after use and dried before storage

Grouting Operations Chemical Reaction

• A sub-contract grouting team cleaned equipment with high-pressure water jets after a grouting operation on an offshore wind farm transition piece
• A team member received first-degree burns on their knees and left calf as well as minor irritation spots elsewhere
• Injuries were treated on board and healed after three weeks
• The affected person had grout dust on their overalls
• Contact with the water jet caused them to get soaked in the skin
• The water mixed with the grouting dust, which created a corrosive solution that burned their skin
• The Safety Data Sheet for the grout lacked information about the hazard of grout dust mixing with water and becoming corrosive
• This lack of hazard identification meant no risk mitigation measures were introduced during the risk assessment