Description of the incident:
The foreman instructed the victim from the stringer deck (3 levels above accident location) to remove the covers of 6 different tanks located on three different decks (levels) in the FPSO hull aft Machinery Space, in preparation of such “cleaning inspections”.
The victim & his coworker removed two tanks covers on the stringer deck. They then went down to the 3rd deck and removed three additional covers on three other tanks. They then went down to the 4th deck.
The victim and his coworker then discovered that the last “tank” they had to work on (“tank” is the word inappropriately used on the instruction list given by the foreman to the victim) was not a tank, but a box containing solenoid valves. According to his coworker, the victim assumed that the “tank” he had to work on was the one next to this box (the hydrophore skid is located just 2 â€“ 3 m from the solenoid valve deck box) and started to remove the cover.
The victim removed all but 2 bolts with a hand tool / spanner, standing on the hydrophore skid control panel (i.e., he was not standing or kneeling on top of the tank cover at that time).
As the two last bolts were too tight, he went up to the 3rd deck to look for and take back a pneumatic tool / impact wrench. He came back and this time climbed onto the top cover of the hydrophore tank. At that time his co-worker was holding the air hose on the floor.
The victim removed the first remaining bolt and when he started to remove the last bolt the cover blew off and violently hit his belly.
After the dust went away, the coworker found the victim laying on top of the then-opened top hole of the hydrophore tank.
The victim was quickly evacuated to Ulsan University Hospital but died in life support about 2 hours later.
Summary of causes of the accident:
- Direct causes:
- Tank was under pressure
- The victim & his co-worker opened the wrong tank
- Contributive causes:
- The workers did not install a proper working platform
- Root causes:
- The foreman did not directly show all the equipment to be opened to the workers.
- Written details given to the victim were confusing: they referred to a “tank” not a “box”.
- Tank was pre-charged by vendor at 5 bars.
- There was no safety warning sign on the pressurized tank (other than the name plate which mentioned the preset pressure & a pressure gauge).
- The pressurized tank final documentation did not include obvious warning signs / notices.
- Co-worker did not read the pressure gauge installed on the tank and is unsure whether the victim himself read the gauge.
- The inspection check-list issued by Quality Management Department does not mention that the tank is pressurized.
- Corrective actions:
- All tanks on the FPSO were checked to verify if proper safety warning was in place.
- The site team checked the technical reason why this tank had to be delivered pre-charged at 5 bars by the vendor: It is not a mandatory requirement but vendor’s standard practice (to facilitate start-up by clients).
- Develop procedures to ensure that shipping of vessels under pressure is avoided if possible and if applied is explicitly notified by unmistakable warning signs on the equipment itself and by appropriate documentation separate for vendor final documentation.
- Organize a specific toolbox with Supervisors and foremen to reinforce the need of walkthrough when giving tasks to their employees (as well as working at height precautions, precautions when working with a tank).
- Include additional HSE criteria in the Procurement “Inspection & expediting procedureâ€