One of the VLCC was converted into an FPSO (Floating, Production, Storage and Offloading) vessel. This vessel was secured in turret mooring in Atlantic off North West Africa. Normal oil processing was going on.On this incident day, around midnight, vessel’s abandon ship alarm sounded. Every body mustered in the muster station, and it was announced that everything alright, and that it was a false alarm.
This alarm stops all activities through an abandon vessel shut down. All the running machinery to be restored. Emergency generator did not start and the FPSO had the emergency supply from the emergency battery.
Once it was made known that alarm was false, engineers were busy in restoring the equipments. Within a few minutes, there was fire alarm coming from the emergency fire pump room located in forward. The diesel driven pump started automatically as it was kept on ‘auto’ mode and as soon as the power supply went off, it started automatically.Again all people mustered in the muster station and head count was taken.
The reinstating operations were suspended. One of the fire teams was ordered to proceed to forward to assess the condition. They found the entire compartment, full of steam. 2/E stopped the fire pump engine by closing the remote shut off for fuel.Since no valves were opened in the fire main, the impeller started churning, and hence the pump became overheated and the trapped water became steam.
Due to the temperature rise, the pressure increased, and in the line one of joints burst and the compartment got filled up with steam. There was no relief valve fitted onto the fire main.It was totally forgotten that the fire pump in the forward would start when the power supply fails.
The fire main had a relief valve earlier, and while converting, this was removed and was overlooked to fit it back.The AVSD unit was replaced with new one and also a new relief valve was fitted onto the fire main to lift in such cases of exigencies.