1973 — July 5, LP gas railroad tank car fire & explosion, Doxel Gas Co., Kingman, AZ– 13

— 13 Khan & Abbasi. “Major Accidents in Process Industries…,” LPPI Journal, Vol. 12, 1999.
— 13 NFPA. “Multiple-Death Fires, 1973,” Fire Journal. Vol. 68, No. 3, May 1974, p. 76.
— 13 National Fire Protection Association. The 1984 Fire Almanac. 1983, p. 140.
— 13 Sharry and Walls. “LP-Gas Distribution Plant Fire.” Fire Journal, 68/1, Jan 1974, p. 52.
— 12 National Fire Protection Association. Key Dates in Fire History. 1996.

Narrative Information

NFPA: “LP-Gas tank car, Kingman, Arizona. Twelve fire fighters and one gas company employee were killed and 95 other people were injured when an LP-Gas railroad tank car burned and ruptured in Kingman, Arizona. The fire occurred on July 5 during unloading operations at the Doxol Gas Distribution Plant.” (National Fire Protection Association. “Multiple-Death Fires, 1973,” Fire Journal. Vol. 68, No. 3, May 1974, p. 76).

Shabby and Walls: “On Thursday, July 5, 1973, a fire occurred at the Doxol Gas Distribution Plant in Kingman, Arizona. Early in the fire a railroad tank car of LP-Gas ruptured. The re¬sulting fireball killed 13 people and injured 95 others. Twelve of the victims were fire fighters

“The distribution plant was located in the eastern part of Kingman, about two miles from the downtown area. It consisted of a railroad siding, a tank car-unloading rack, two aboveground horizontal storage tanks, three truck and cylinder-loading tracks, a storage yard, and a small office… Normally four employees were on duty a manager, two delivery men, and a clerk. At the time of the fire there were three employees at the plant.

“The plant office was 70 feet south of Highway 66. The two storage tanks were located behind the office, about 200 feet south of the highway, in a 110-foot-by¬110-foot storage yard which was enclosed with a chain- link fence. The yard also contained three loading racks, where delivery trucks and customers’ cylinders were filled. Located about 450 feet south of the highway and behind the storage tanks was the main line of the Santa Fe Railroad. Tank cars were unloaded at a rail siding about 30 feet south of the main rail line. An unloading rack was located on the south side of the siding; from there piping passed underground beneath the siding and the main railroad tracks to the storage tanks.

“The unloading rack at the rail siding consisted of two standpipes, one three inches in diameter, for transfer of liquefied gas, and the other 1½ inches in diameter, through which LP-Gas vapor was pumped into and nut of the vapor space of the railroad tank car. Each stand¬pipe had a control valve at its base, and each was pro¬vided with a swiveled counterbalanced loading boom, which extended the piping over the tank car for ease in making connections. The liquid standpipe (the larger one) was connected to a T from which two 2-inch pipes extended. This U-shaped arrangement straddled the tank car dome so that 2-inch hoses about four to five feet long from the two ends of the U could be con¬nected to unloading adapters which, in turn. were con¬nected to the two liquid valves in the dome. The vapor hose was l½ inches in diameter.

“The unloading adapters were assembled from steel pipe nipples and elbows, and had half of a steel Acme is hose coupling on one end. There were no shut¬off or excess flow check valves in the adapters)
Fire Protection

“The fire protection at the distribution plant consisted of portable dry chemical extinguishers located in the storage yard and in the office. There was no private water supply and the nearest public fire hydrant was located about 1,200 feet north of the site of the fire…

“The Kingman Fire Department consisted of 30 vol¬unteers, six paid men, and two stations (one of the fire stations was located approximately half a mile west of the distribution plant). Work schedules were arranged so that one paid fire fighter was on duty at all times at each station. The officers of the Department were elected from among the volunteers….

Transfer Operations

“On June 5, 1973 the tank car was delivered to the rail siding at the Doxol Plant, where it remained with its cargo until July 5, the day of the fire. It is reasonable to assume that with gas consumption low during the hot months, the storage tanks were too full to be able to accept the tank car contents. This would account for the delay in unloading.

“Transfer of the tank car contents to the storage tanks was accomplished by the pressure differential method. A compressor was placed in the vapor piping between the storage tanks and the tank car. The compressor took suction from the vapor space of the storage tank being filled and discharged into the vapor space of the tank car. thereby forcing the liquefied gas from the tank car to the storage tank.
The Fire
“On July 5 it was clear in Kingman. The temperature was 105⁰F and the wind was from the west at 12 mph. Sometime before 1:30 pm two employees of the Doxol Company began to connect the tank car to the unloading rack. The unloading adapters were screwed in place and the unloading rack hoses connected. All the valves were ‘cracked’ open and the connections were checked for leaks. As each connection was checked, the valve was opened fully. This was done to the east liquid valve and to the vapor valve and prob¬ably to the west valve. One of the two employees thought he detected a slight leak. Attempts were made to tighten the connections by hitting them with a large aluminum alloy wrench. This was done several times to each connection. The leak apparently continued, and the tightening process was attempted again. This time, when the westerly liquid connection was hit, fire en¬sued, Both men fell from the top of the tank car. One of them fell backward to the south side of the tank car and was seen crawling north across the track under the tank car. He later died of severe burns. The other man fell to the north side of the tank car and ran into the office building with his clothing on fire. He was driven to the Arizona Department of Public Safety Office, about a quarter of a mile away, where he reported the fire, and then was taken to the hospital.
“The Kingman Fire Department received the first call at 1:57 pm. The dispatcher sounded the alarm and fire fighters arrived at the scene at approximately 2 pm.

“Meanwhile the fire had gained intensity and seemed to be directed in a southeast direction, directly exposing the unloading rack. Soon additional flames were seen on the south side of the tank, running eastward along the top of the tank shell, and at the bottom of the east portion of the tank car. The fire continued to intensify as a large volume of fire shot upward from the dome. This pulsating fire was accompanied by the loud screaming and whooshing sound characteristic of an operating safety relief valve.
“The initial tactical objective was to cool the tank. A pumper with a 1.000-gallon water tank was brought near the railroad tracks about 75 feet north of the tank car; from there fire fighters approached the tank car with two one-inch booster lines and directed water on the tank shell in an effort to provide some cooling while they waited for the second engine to arrive with a deluge gun…

“When the second engine arrived, three men set up the deluge gun about 50 feet north of the burning tank car. The engine was positioned next to the storage yard about 200 feet north of the tank car. Two 2½-inch hose lines from this engine were connected to the gun. The crew of the first engine reeled in their two booster lines and started to lay a 2.2-inch hose line from the second engine to the nearest hydrant, which was about 1,200 feet away. They had finished laying one line and had laid about half of the second when they ran out of hose. The completed line was being charged with water at 2:10 pm when the tank car ruptured.

“The force of the explosion sent the westerly half of the tank car bouncing end over end in a westerly direc¬tion along the track for 1,200 feet. The easterly portion of the car split open on the top and flattened out. A ground-level fireball extended about 150 to 200 feet on all sides of the initial explosion site. This first fireball was immediately followed by a flaming mushroom cloud several hundred feet high and 800 to 1,000 feet in diameter…

“The mushroom cloud quickly dissipated, leaving five small buildings on fire and several brush fires. The storage tanks had been exposed to brief but intense heat, which activated the safety relief valve on the 30,000-gallon tank. However, the vapors coming from that valve did not ignite and after the tank pressure had been relieved, the valve closed….

“The initial ground-level fireball had severely ex¬posed the storage yard, the two storage tanks, and the 20-foot-bv-60-foot corrugated metal office building. The office building was destroyed, as were most of the vehicles in the immediate area of the fireball. Several small LP-Gas cylinders in the storage yard had burned at their relief valves, and one had ruptured.

“Flaming debris and radiant heat from the mushroom cloud had ignited the Double G Tire Company, 600 feet east of the explosion site; the Kountry Kitchen Restaurant, 800 feet east; and the Phillips Truck Shop, 900 feet east. Total damages are estimated at $1 mil¬lion.

Casualties
“Thirteen fire fighters were within 150 feet of the tank car at the time of the rupture; of those 13, 12 died of extensive burns. The remaining fire fighter was in serious condition at the time of this writing. The thir¬teenth victim was one of the two employees who had been knocked from the top of the tank car. Most of the 95 injured were spectators clustered along Highway 66, approximately 1,000 feet from the explosion site…..
“Analysis of the Origin and Development of the Fire
“From the observations of witnesses and the surviving employee, it appears that small vapor leaks existed at connections in or near the dome prior to ignition. When the easterly tank car liquid valve was opened, liquid flowed into the unloading manifold, charging it and the riser above the closed riser valve to about 170 psig pressure. Whether or not the west tank car valve was completely open ( all three valves later were found open ), this adapter and hose were charged because there were no check valves or shutoff valves in the manifold.

“At this point two possibilities appear. The most likely is that the west liquid hose either failed partially disengaged from their end fitting at the adapter – resulting in a small, but visible liquid leak. If this leak was close to the Acme coupling, it could appear to be coming from the coupling itself. At any rate, an employee did strike the steel unloading connection somewhere, with the apparent intention of hitting the lugs on the Acme coupling to tighten it. Impact of the aluminum alloy wrench upon steel (it is likely that magnesium was another alloying constituent) probably created a spark with sufficient energy to ignite a flammable LP-Gas vapor-air mixture near the point of impact, and flame propagated into and out of the dome area. Within a few seconds, the hose either failed completely or disengaged completely, and liquid escaping from its end and the now fully open end of the adapter was ignited by the still burning flash fire or by a fire persisting at the leaks….
“A tank rupture such as the one in Kingman is known as a BLEVE (Boiling Liquid Expanding Vapor Explosion; pronounced blevey). A BLEVE is brought on when an exposing fire impinges on a tank shell above the liquid level, causing loss of strength of the metal and consequently a rupture from internal pressure. In addition to the rocketing effect on the tank when the gas is first released, ignition of the escaping gas is a virtual certainty because of the exposure fire….” (Sharry, John S, and Wilbur L. Walls. “LP-Gas Distribution Plant Fire.” National Fire Protection Association Fire Journal, Vol. 68. No. 1, Jan 1974, pp 52-57.)

Newspaper

July 6: “Kingman, Ariz. (AP) – “‘Suddenly the tank exploded and the air was filled 200 feet high with burning material,’ said Fire Chief Charles Potter after a railroad tank car filled with propane gas caught fire and exploded here. The explosion, and fire Thursday killed three fireman instantly and injured 70 other persons. A fourth critically burned person died shortly before 11 a.m. EDT at a Phoenix hospital….

“The fire blocked east-west highway and railroad traffic, destroyed two buildings and damaged three others in this northwest Arizona town. The propane gas exploded minutes after firemen began fighting a small blaze in the tank car. Flames and metal shreds were showered over adjoining buildings, lawns and fields. The blast shoved the tank car a quarter of a mile and dug a crater 10 feet deep….

“The accident occurred on a siding of the Santa Fe Railroad, which parallels U.S. 66 through the town. Authorities said the propane apparently was being unloaded at the time…The flames set numerous brush fires in addition to burning the office of Doxel Suburban Gas Co., destination of the gas, two service stations, a beer warehouse and a small supermarket.

“The victims jammed the Mohave County General Hospital. Planes and helicopters flew the most seriously burned victims to hospitals at Phoenix, 175 miles to the southeast, and Las Vegas, Nev., 100 miles to the northwest.

“Slurry bombers, stationed here by the Bureau of Land Management to fight range fires, dumped fire retardant mixtures on the flames which spread across the highway. Helicopters were sent by the highway patrol and two Air Force bases.” (Arizona Daily Sun (Flagstaff). “4 Die, 70 Hurt in Kingman Gas Blast,” July 6, 1973.)

Sources

Khan, Faisal I. and S.A. Abbasi. “Major Accidents in Process Industries and an Analysis of Causes and Consequences.” Journal of Loss Prevention in the Process Industries, Vol. 12, 1999, pp. 361-378. At: http://74.125.47.132/search?q=cache:http://202.38.89.99/Loss_prevention/99503.pdf

National Fire Protection Association. Key Dates in Fire History. 1996. Accessed 2010 at:
http://www.nfpa.org/itemDetail.asp?categoryID=1352&itemID=30955&URL=Research%20&%20Reports/Fire%20statistics/Key%20dates%20in%20fire%20history&cookie%5Ftest=1

National Fire Protection Association. “Multiple-Death Fires, 1973,” Fire Journal. Vol. 68, No. 3, May 1974, pp. 69-71 & 76.

National Fire Protection Association. The 1984 Fire Almanac. Quincy, MA: NFPA, 1983.

Sharry, John S, and Wilbur L. Walls. “LP-Gas Distribution Plant Fire.” National Fire Protection Association Fire Journal, Vol. 68. No. 1, Jan 1974, pp 52-57.