High potential near miss: Person found unconscious in confined space

  • Safety Flash
  • Published on 18 June 2019
  • Generated on 9 April 2026
  • IMCA SF 14/19
  • 2 minute read

During commissioning activities, a commissioning engineer was found unconscious inside a gas valve unit (GVU).

What happened?

The engineer received CPR and regained consciousness before being transported to the hospital for further diagnosis. Luckily, he has made full recovery.

During commissioning, a commissioning engineer was found unconscious inside a gas valve unit (GVU)

Pressure holding tests were being conducted, controlled from an interface cabinet. Nitrogen gas was used as the test medium. The pressure build-up was taking longer than usual so the vendor performing the test suspected that there was a leak somewhere. He heard a hissing sound coming from inside one of the GVUs (where the piping runs through) and suspected that the leak was coming from the piping inside the GVU. 

The vendor informed the commissioning engineer about the leakage and returned to the interface cabinet.

Shortly afterwards the vendor noticed the commissioning engineer entering the GVU through the manhole opening. The vendor rushed to the GVU, but the commissioning engineer was already overcome by the nitrogen and had collapsed inside the unit.

The commissioning engineer was rescued, CPR was administered, and he regained consciousness before being transported to the hospital supported by additional oxygen. The engineer has since made a full recovery and is back on duty.

What went wrong?

  • The gas valve unit (GVU) is clearly a confined space; however, the experienced engineer decided to enter alone via the manhole opening.

  • There were no confined space entry controls in place at that particular GVU, i.e.:

    • no confined space entry permit in place

    • no atmospheric test results at the location

    • no safety watch in place.

What lessons were learned?

Never enter a confined space unless a permit is active, and all controls are in place to ensure your safety, such as; the atmosphere has been successfully tested; a safety watch is at the entrance; you know what the rescue plan is; and you have discussed your entry with your supervisor.

Members may wish to refer to: 

  • IMCA video: Be prepared to work safely: Confined space: the dangers
  • IMCA video: Working in confined spaces

Latest Safety Flashes:

MAIB: Sinking of tug Biter with loss of two lives

MAIB has published Accident Investigation 17/2024 relating to the girting and capsize of tug Biter with the loss of two lives.

Read more
Dropped object – strop parted over sharp edge

A cylinder was lifted to a height of approximately 6 metres over deck of the vessel, the sharp steel edges of the cylinder cut through the firehose protection and caused the strop to part.

Read more
Person injured when pry bar slipped

A crew member who was applying downward pressure to their pry bar to lift a track, fell towards the deck when the pry bar slipped.

Read more
MSF: High potential near miss during FRC maintenance

The Marine Safety Forum has published Safety Alert 26-01 relating to an incident where there was an unplanned lowering of an FRC to the sea

Read more
BSEE: Crane incident leads to serious facial injuries

BSEE has published Safety Alert 512 relating to a crane incident during well abandonment which led to a worker being struck and suffering serious facial injuries.

Read more

IMCA Safety Flashes summarise key safety matters and incidents, allowing lessons to be more easily learnt for the benefit of the entire offshore industry.

The effectiveness of the IMCA Safety Flash system depends on the industry sharing information and so avoiding repeat incidents. Incidents are classified according to IOGP's Life Saving Rules.

All information is anonymised or sanitised, as appropriate, and warnings for graphic content included where possible.

IMCA makes every effort to ensure both the accuracy and reliability of the information shared, but is not be liable for any guidance and/or recommendation and/or statement herein contained.

The information contained in this document does not fulfil or replace any individual's or Member's legal, regulatory or other duties or obligations in respect of their operations. Individuals and Members remain solely responsible for the safe, lawful and proper conduct of their operations.

Share your safety incidents with IMCA online. Sign-up to receive Safety Flashes straight to your email.