1974 - Yuyo Maru Nº 10

On November 9, 1974, in Tokyo Bay, Japan, the Japanese LPG gas carrier Yuyo Maru No. 10, carrying refrigerated LPG in her cargo tanks and naphtha in her wing tanks and forward reserve cargo oil tank, was struck approximately at a right angle on her starboard bow by the bow of the Liberian cargo vessel Pacific Ares. As a result of the collision, the outer plating of the forward reserve cargo oil tank and the No. 1 starboard wing tank (both containing naphtha) were broken. This allowed a large amount of naphtha to flow out onto the Pacific Ares and onto the water. The naphtha caught fire, killing five of the Yuyo Maru crew members and 28 on the Pacific Ares.

On November 9, 1974, in Tokyo Bay, Japan, the Japanese LPG gas carrier Yuyo Maru No. 10, carrying refrigerated LPG in her cargo tanks and naphtha in her wing tanks and forward reserve cargo oil tank, was struck approximately at a right angle on her starboard bow by the bow of the Liberian cargo vessel Pacific Ares. As a result of the collision, the outer plating of the forward reserve cargo oil tank and the No. 1 starboard wing tank (both containing naphtha) were broken. This allowed a large amount of naphtha to flow out onto the Pacific Ares and onto the water. The naphtha caught fire, killing five of the Yuyo Maru crew members and 28 on the Pacific Ares.

Fire-fighting efforts began about an hour after the collision. About two hours later, all external fires aboard the Pacific Ares were extinguished. The fire aboard the Yuyo Maru was attacked with fire-fighting foam but, in spite of these efforts, the fire continued to spread to more of the naphtha tanks. The heat from the fire caused the LPG tanks to vent and reportedly melted one relief valve and gasket and packing materials at joints in several vent and gauge lines leading to the LPG tanks. Eventually all naphtha fires on the Yuyo Maru were extinguished; only the LPG venting from the relief valves and heat damaged piping continued to burn. For the most part, these were small, localized fires with an occasional larger flare-up.

Five days after the accident, the decision was made to tow the Yuyo Maru out of the bay. During the towing operation, naphtha was spilled and fire again broke out. Towing was suspended at this time; the ship now being about 23 nautical miles from the shoreline. This ship was subsequently towed further out to sea and was then sunk by the Japanese Defence Agency.

Because this is the largest and the most dramatic incident involving fire aboard an LPG ship, it has often been cited as an example of the hazards posed by such ships. Since the collision did not damage any of the LPG cargo tanks, it is very likely that no fire would have occurred if the naphtha tanks had been empty or were filled with ballast water. The fire was essentially a naphtha fire. The only part of the LPG cargo that was involved was the portion that vented and fed the small fires around the cargo tank hatch area. The naphtha fire never breached the integrity of the cargo tanks but only damaged relief valves, packing, gaskets, etc. on the cargo piping system. And, as a final note, the relative integrity and stability of the LPG ship was demonstrated by the fact that the Japanese Defence Agency was able to sink the ship only with great difficulty using shells, bombs and torpedoes.