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Marine Casualty Report. Tankship Puerto Rican O.N. 535000, Explosion and Fire in the Pacific Ocean, on 31 October 1984 with Loss of Life.

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At approximately 0324, October 31, 1984, the tankship PUERTO RICAN suffered explosions and fire in number 6 center void space and the adjacent wing cargo tanks. The explosions and fire damaged the hull of the vessel to the extent that it broke in two and the stern section sank three days later. The pilot and one crew member were thrown overboard by the explosions and is missing and presumed dead. The Commandant has concurred with the board that the actual cause of casualty cannot be established with certainty but the most probable cause was the failure to repair a gouge, later to become an opening, in the stainless steel cladding in the bulkhead separating 5 center port cargo tank and 6 center void space allowing caustic soda cargo to enter the void. The caustic soda reacted with the zinc coatings in the 6 center void space producing hydrogen gas which ignited. This led to a sequence of explosions and fire which led to the loss of the vessel. Contributing to the casualty was the failure of the master to locate the missing caustic soda cargo which leaked from 5 center port tank into 6 center void space. This report contains the U.S. Coast Guard Marine Board of Investigation Report and the Action taken by the Commandant to determine the proximate cause of the casualty and provide a response to the recommendations to prevent recurrence. Author

Subject Categories:

  • Weapons Effects (Biological)
  • Explosions

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