Accident investigators in China have published a report on their probe into a vessel refitting mishap that left four people dead in the central province of Hunan earlier this year.
The incident occurred at around 14:08 local time on March 8 as a refit was being performed on a 40-year-old, 28-metre-long vessel that officials claim had no name, no certificates, and no port of registry.
The report said that four people boarded the vessel in Hunan's Yueyang City on the morning of March 8 to test whether its lube oil pump was operating normally and to undertake welding activities.
The two explosions occurred within seconds of each other, causing significant damage and generating enough force that three of the four people who were present at the time were thrown overboard. These three individuals were already deceased when they were pulled out of the water in the late evening of the same date.
The fourth victim was also found deceased. However, the exact cause of this individual's death and details on where he was discovered have not been disclosed.
The investigation revealed that there was a high concentration of combustible gas on board the vessel as the welding works were being undertaken. Officials said this gas was the result of the transfer of 400 litres of fuel oil into the onboard tanks from another vessel earlier that same day for the purpose of testing the lube pump.
It was also determined that the hot works were being carried out without proper ventilation, detection systems, and other safety measures in place. The sparks caused by the welding therefore ignited the accumulated gas to trigger the first explosion, and the flames from this explosion ignited the same gas, resulting in the second explosion.
Two people have since been arrested in connection with the incident.
The probe also revealed that the owner of the vessel had regularly purchased ageing ships to be modified illegally using unqualified personnel. However, as the owner was also among the four individuals who perished in the incident, local authorities had decided not to investigate him further to determine the extent of his criminal responsibility.