The Story

In September of 1980, in the middle of a hot day, a tank barge carrying methanol (methyl alcohol) exploded violently while underway on the Ohio River. In a 14-barge tow, the methanol barge and one other barge were at the rear of the tow and being pushed backwards. This placed the bow of the methanol barge right next to the towboat. The investigation revealed a number of factors that more than likely caused the explosion.

When the barge was being cleaned prior to loading, a quantity of methanol apparently was drained into the bow rake compartment which housed the cargo pump and associated underdeck cargo piping. This is disputed, but five days later a liquid visually identified as "water" was observed in that compartment during checkoff just before loading. The amount of "water" was not large enough to cause alarm. Methanol is a colorless liquid resembling water (as are several other hazardous liquids), and its vapors are described in the CHRIS manual as being irritating. Depending on prevailing conditions, it would be possible to observe the liquid without smelling the vapors, in which case it could be mistaken for water.

There were three paths of escape for vapors in the bow rake. There were two vents, a high vent and a low vent (though the low vent was probably blocked by the liquid in the bottom of the compartment), and a three-foot by three foot spring-assisted hatch which provided access into the compartment. When this hatch was not dogged down and it was not dogged at the time of the explosion, a gap remained through which vapor could exit. There were also fractures in the starboard bow corner.

Immediately after the explosion, flames and smoke were observed on the bow of the towboat where synthetic lines and diesel fuel were stored for operating small pumps. However, the area of this fire was shielded from the explosion fireball by the four tow knees. Furthermore, synthetic lines are not readily combustible (when exposed to intense heat they melt and puddle), and samples of the diesel fuel found in that area were tested by the Kentucky State Police Crime Lab and found to have a flash point between 110 F and 190°F. The ambient air temperature was 91°F, and the diesel fuel was stored in the shade. Both the synthetic line and the diesel fuel would have had to have been heated for some time before they burned. Consequently, these combustibles may have been the source of ignition for the explosion.

After the explosion, investigators found cigarette butts in the general bow area where the lines and diesel fuel were stored. The captain, the pilot, and all three deckhands on board were smokers. The source of the cigarette butts in the fire area was unclear, but one possibility was identified. The center window in the pilothouse was open at the time of the explosion, and the area of the fire was within range of a "flicked" cigarette butt. This area was not within view from the pilot's normal operating station.

Lesson Learned

There are several points worth noting in this case. It appears that proper care was not taken in the cleaning of the barge. Subsequently, the failure to determine whether the liquid in the rake was water or methanol set the stage for disaster. The location of the tank barge with a volatile cargo next to the towboat may not have been necessary and does not appear to have been considered by the crew. Even if there had been no fractures and the hatch had not been left undogged, venting of vapor could have been expected on a hot day, and the possibility of vapor streams from a barge a few feet away (or even farther up in the tow) would have been a good reason to prohibit smoking on deck. The cigarette butts observed in various places on deck during the investigation are indications of misuse of smoking materials. The debris from the fire on the towboat and the fire itself suggest sloppy housekeeping, possibly including spillage of flammable liquids.