Abstract: On November 2, 2009, Employee #1 entered the Number 1 starboard fuel tank on the tank barge Custom Fuel Number 1. The last cargo in the cargo tanks was diesel fuel. The barge came from the facility gas-free plant where a Marine Chemist Certificate was placed on the barge. Daily checks of the cargo tanks were conducted by the shipyard competent person and forced air ventilation was being used as per instructions on the Marine Chemist Certificate. Employee #1 entered the cargo tank to conduct welding operations. Within 15 minutes after entering the cargo tank, Employee #1 exited the cargo tank complaining of breathing difficulties. Shipyard personnel attended to Employee #1. Employee #1 lost consciousness and CPR was started. Local rescue responders were summoned and upon arrival continued CPR on Employee #1. Shortly thereafter the paramedics arrived and pronounced Employee #1 dead.