One person has died and five others have been hospitalised after an intoxication incident on board a Boskalis semi-submersible heavy lift vessel that was transporting a floating production, storage and offloading vessel from China to Brazil.

The incident occurred earlier this week as the Boskalis semisub heavy-lift vessel Vanguard was transporting the FPSO due to be delivered to operator Petrobras in Brazil later this month.

During the journey, preservation works were taking place on board of the FPSO, part of the pre-delivery activities.

While travelling, six workers — all Brazilian nationals — illegally consumed a cleaning liquid found on board the FPSO, Boskalis said.

According to Boskalis, the liquid consumed was a substance customarily used for degreasing purposes. It is thought to have contained a mixture of ethanol and the severely toxic methanol.

“The affected persons reported this to our crew approximately 36 hours after consumption at which point serious signs of illness were becoming apparent. Swift and immediate action was taken by our crew,” Boskalis said.

The Vanguard changed course towards the coast of South Africa and a medical evacuation by helicopter was organised, however, one of the affected workers died before medical assistance arrived on site.

“The remaining five persons were successfully evacuated, hospitalised in Durban, South Africa and are recovering from the intoxication,” Boskalis said.

While no details were given on the reasons behind the intoxication, Boskalis stressed its strict zero alcohol tolerance policy on its offshore vessels.

The P-70 FPSO, built at China’s Offshore Oil Engineering Company (COOEC), and Vanguard have recently resumed their journey to Brazil.

The FPSO is expected to arrive in Brazilian waters to begin operations for state-controlled Petrobras at the Atapu pre-salt field in the Santos basin.