ELEVEN FIREFIGHTERS KILLED IN EXPLOSION OF PROPANE RAIL CAR – DOXOL GAS DISTRIBUTION PLANT – KINGMAN, ARIZONA – JULY 5, 1973

Eleven Firefighters Killed in Explosion of Propane Rail Car – Doxol Gas Distribution Plant – Kingman, Arizona – July 5, 1973

 On July 5, 1973, 11 Kingman Arizona firefighters and one civilian were killed in a catastrophic BLEVE (Boiling Liquid Expanding Vapor Explosion) at the Doxol Gas Distribution Plant. The explosion occurred following a fire that broke out as liquid propane was being transferred from a railroad car to a storage tank. The Kingman Fire Department received a call that a Santa Fe propane car was on fire. Firefighters from the Kingman and Hualapai Fire Departments worked to extinguish the fire when the BLEVE occurred. The explosion immediately killed three firefighters and fatally burned eight other firefighters as burning debris and shrapnel from the shattered tank car rained down on the area igniting brush and several structures. One civilian employee of the gas plant was also fatally injured in the incident and more than 95 other persons including firefighters, police officers, and civilians suffered burns from the radiant heat. More than $1 million in property damage was reported. The explosion has become a classic incident studied in hazardous materials training programs worldwide.

Kingman is a city in, and the county seat of, Mohave County, Arizona. It is located 105 miles southeast of Las Vegas, Nevada, and 180 miles northwest of Arizona’s state capital, Phoenix. The population was 32,689 at the U.S. 2020 census. At the time of the incident, the city was protected by the Kingman Fire Department, a combination force of six career firefighters and 36 volunteers operating out of two stations. One career member was on duty in each station at all times. The equipment in service at the time of the explosion included four engines and a rescue vehicle. Station 2 was just a half-mile west of the Doxol Gas Western Energy bulk plant, where the explosion took place. Fire protection features of the Doxol facility consisted of portable dry chemical extinguishers near the storage tanks and in the office. The nearest public-water-supply fire hydrant was 1,200 feet north of the site on Hoover Street.

Thursday, July 5, 1973, was a typical summer day in Arizona. The temperature topped 100 degrees F and a light westerly wind was blowing in at 12 mph. Workers at the Doxol plant, located on the east side of Kingman two miles from the downtown area, were preparing to off-load a 33,500-gallon water-capacity rail car containing liquefied propane gas (LPG).

The Doxol Gas Western Energy bulk plant was located at 2512 East Highway 66 in the Hilltop business district on the southeast side of Kingman, Arizona. consisted of an office and two above-ground LPG storage tanks – one 30,000 gallons and the other 18,000 gallons. Located on the southwest side of Route 66, the office was approximately 70 feet from the highway. The two storage tanks were located at the rear of the office about 200 feet from the highway. Note: Stationary propane tanks are generally not insulated, and flame impingement on the vapor space can cause metal failure in much the same way as the rail car did in the Kingman incident. Usually, four employees were present at the small facility – a clerk, the manager and two delivery personnel. At the time of the explosion, there were just three employees on duty at the plant. Just east of the Doxol plant were the Double G Tire Company, 600 feet away; the Country Kitchen restaurant; 800 feet away; and the Phillips Truck Stop, 900 feet away.

Racks to off-load rail cars were located on the south side of the rail siding with underground piping running to the storage tanks. Kingman was serviced by the Santa Fe Railroad, which had delivered the tank car to the Doxol plant exactly a month earlier. The delay in off-loading the rail car is believed to have occurred because the fuel demand during the summer is low and the bulk storage tanks were full. The loading rack where the tank car was resting was 30 feet across the Santa Fe’s main line southeast of the main Doxol facility, 450 feet from the highway. LPG tank cars at that time were not insulated and all of the valves were located within the dome cover at the top of the tank. This tank was constructed of 11/16-inch carbon steel with a hydrostatic test pressure of 340 psi and a rupture pressure of 500 psi. The pressure relief valve was set to expel excess pressure from the tank at 280 psi.

At 1:30 p.m., workers began to connect the hoses to the rail car to start the off-loading process. During such an off-loading procedure, liquid lines are attached to the two liquid valves in the dome cover housing at the top of the rail car. Vapors are collected and routed into the vapor space of the tank. After all connections are made, the valves are opened slowly at first so as not to trip the excess flow valves. Connections are routinely checked for leakage and the valves fully opened when no leaks are present.

Two men were involved in the off-loading operation that day. As the off-loading proceeded, one of the men detected a small leak in one of the connections. Connections were typically tightened by striking them with a non-sparking brass-alloy wrench. These workers, however, used an aluminum-alloy wrench. Despite their efforts to tighten the connection, the leak continued. The liquid connection was once again struck with the wrench. That’s when a fire erupted. It is thought that a spark was created as the wrench struck the steel fitting, because of magnesium being present in the alloy of the wrench.

Both men fell from the top of the tank car, their clothing on fire, resulting in severe burns from the fire and extreme heat. One of them later died of his burn injuries. The other man ran back to the office building where he was driven to an Arizona Department of Public Safety Officer a quarter mile away to report the fire. It is believed that an ambulance was called for the injured man before a call was made to the fire department.

Kingman firefighters received the first call for help at 1:57 p.m. and arrived on scene three minutes later. Initially, a call went out to the Truxton Canyon and Hualapai fire districts for mutual aid assistance. The fire spread quickly and was impinging on the top of the rail car where the vapor space is located. Police officers from Kingman, the state Highway Patrol, and deputies from the Sheriff’s Office began blocking the roads in an effort to control the gathering crowd.

Every liquefied gas container has an approximate 20% vapor space above the liquid in the tank to allow for expansion of the liquid to vapor within the tank during shipping and storage. This is the most dangerous place for flame impingement to occur because there is nothing to absorb the heat but the metal itself. Steel does not absorb heat well so when temperatures reach above 400 degrees F, the integrity of the tank is quickly in jeopardy.

National Fire Protection Association (NFPA) statistics show that pressure tanks can fail from flame impingement within the first 15 to 20 minutes of the first flame exposure. It is estimated that the Kingman fire burned for eight minutes before firefighters arrived and an additional two minutes before the first water was applied from the engine booster tank to cool the propane rail car. The BLEVE occurred at 2:10 p.m., just 19 minutes after the first flame impingement on the top of the tank. Note: Flame impingement on the liquid level is a somewhat less dangerous situation because the liquid will absorb the heat and protect the integrity of the tank. However, the increased heat will cause the already boiling liquid to boil faster, causing the pressure inside the tank to increase.

Firefighters’ tactical objectives at Kingman were to provide water to cool the tank and prevent an explosion. An engine with a 1,000-gallon booster tank was positioned 75 feet from the rail car and two one-inch booster lines were put into service to cool the tank shell. Note: The water flow from a one-inch booster line is about 30 gpm. If water is applied effectively to the point of flame impingement, the temperature of the shell cannot go above 212 degrees F, well below the failure temperature of the steel. This operation requires large quantities of water. The NFPA recommends that an uninterrupted water supply of 500 gpm be applied to the surface of the tank for cooling.

While the first firefighters attempted to cool the rail car from the booster tank of the engine, others began laying two 2 ½-inch hoselines to the hydrant 1,200 feet away to supply a deluge gun located 50 feet from the burning tank car. The first 2 ½-inch hose lay was completed but the firefighters ran out of hose for the second supply line. The first line was being charged when the explosion occurred. Thirteen firefighters were within 150 feet of the burning rail car when the blast occurred. Eleven of them died from severe thermal burns – one career member and 10 volunteers. A 12th firefighter was taken to the hospital in critical condition but survived.

Protective equipment typical for firefighters at the time were cotton duck turnout coats with wool linings and helmets made of polycarbonate plastic. This was the type of protection worn by the Kingman firefighters. It is reported that at the time of the explosion some firefighters had full protective gear, while others wore only coats and helmets or just coats. Those firefighters killed had the coats and their street clothes burned off of their bodies by the fire and radiant heat created from the explosion.

The tank broke into pieces from the force of the blast and one half of the tank bounced end over end westward down the tracks, landing 1,200 feet from its original location on the siding. The other portion of the tank tore along the welds and flattened out on the ground. A ground-level fireball ensued and extended 150 to 200 feet in all directions from the center of the blast. This was followed by a large mushroom cloud of flame extending several hundred feet into the air, measuring 800 to 1,000 feet in diameter.

Fireball flame temperatures can reach well over 3,500 degrees F. The fireball and radiant heat set five buildings on fire, including the tire company, restaurant, truck stop and gas company office building, and started several brushfires. Radiant heat was so intense that it caused the relief valve on the 30,000-gallon storage tank to activate. The released vapors, however, did not ignite; once the pressure was relieved, the valve closed and remained closed from that point on.

Following the explosion, calls for mutual aid went out to the Lake Havasu City, Mohave Valley and Bullhead City fire departments. There was a catastrophic-disaster clause in the county’s mutual aid agreements and when the explosion occurred an all-hands call went out to the fire departments in the county. Chiefs of the Lake Havasu City and Bull Head City departments set up a command post at Kingman Fire Station 2. Responding mutual aid companies were assigned to extinguish the numerous fires, the last of which was brought under control at 5:30 p.m. Residents were evacuated within a four to six block radius around the blast and gas and power was turned off in the area.

Many of the photos of the fire and explosion were taken by Hank Graham, a Santa Fe Railroad conductor. He was working on a short train servicing the industries along the railroad in Kingman when the incident occurred. Graham had been notified of the fire at the Doxol plant and was advised not to proceed into the area. While maneuvering several rail cars, he saw the smoke from the fire. Graham pulled out his camera and started taking photos of the incident. When the train stopped, he proceeded to a point on Route 66 where a police officer was blocking traffic access from the incident. He wanted to know how long the rail line would be blocked. Graham then began photographing the burning tank car’s relief valve and awaited the fireball that would be created when it opened. While he was preparing to take another photo of the flaming relief valve, the BLEVE occurred, burning the hair off of his arms.

Three Kingman firefighters were killed instantly, former Fire Chief William F. Casson, Assistant Chief Myron B. “Jimmy” Cox, and Firefighter Roger Hubka. Injured Kingman firefighters were transferred to the burn center but eight would later die from their severe burns including John Campbell, Joe Chambers, Chris Sanders, Art Stringer, Frank “Butch” Henry, Don Webb, Alan Hanson, and Lee Williams. Other firefighters were transported to the burn center but survived including Scott McCoy and Huey Stringer of the Kingman Fire Department and Steven Mitchell of the Hualapai Fire Department.

No other hazmat incident has occurred in the United States that has had more of a positive impact on the fire service than the Kingman incident. Many changes in procedures, regulations, and hazardous materials training occurred across the fire service as a result of this explosion. In the years since the Kingman explosion, rail cars have been manufactured with an outer layer of insulation and tank skin surrounding the inner tank to provide time before a fire can reach the inner tank. This insulation adds about one hour to the 15-to-20-minute time of flame impingement before a BLEVE is likely to occur.

Members of the Kingman Arizona Fire Department killed in the line of duty at the Doxol Gas Distribution Plant Explosion on July 5, 1973:

• Assistant Chief Myron B. “Jimmy” Cox, age 55, was a 22-year veteran member of the Kingman Fire Department. He worked as a driver for the Kingman Bake Shop. He was a member of the city planning and zoning commission, a piano player and a long-time member of the Elks.
• Captain William Llewellyn Casson, age 52, was a 27-year veteran member of the Kingman Fire Department and a former Fire Chief. He worked as a regional manager for Citizen’s Utilities Company. He served as a director of the Kingman Chamber of Commerce, and a 31-year member of the Elks.
• Lieutenant Joseph Mintor Chambers III, age 37, was a 16-year volunteer member of the Kingman Fire Department. He was a member of the Elks, and one of the organizers of Kingman’s original Jaycees chapter.
• Fireman Richard Lee Williams, age 47, was a volunteer member of the Kingman Fire Department. He had been the principal of Kingman High School since 1959, a coach there between 1949-1955, and a member of the Elks, the American Legion and a Rotarian.
• Fireman John Otis Campbell, age 41, was a volunteer member of the Kingman Fire Department. He was the head of the Kingman Water Department and the assistant city works director. He was also a Little League manager who died on the eve of the opening of a Little League tournament.
• Fireman Christopher Grey Sanders, age 38, was a volunteer member of the Kingman Fire Department. He was a certified first aid instructor and the director of the Mohave Big Brothers. Sanders loaded others into an ambulance before evacuating himself from the scene and helped a newspaper reporter drive the vehicle to the hospital with victims burnt less severely than himself.
• Fireman Donald Gene Webb, age 38, was a volunteer member of the Kingman Fire Department. He was a gas station owner, an Elks official and a Rotarian.
• Fireman Alan H. Hansen, age 34, was a volunteer member of the Kingman Fire Department and an Arizona highway patrolman. He suffered burns over 50% of his body trying to help an unconscious fireman.
• Fireman Frank Stewart “Butch” Henry, age 28, was a seven-year volunteer member of the Kingman Fire Department. He worked as a manager of the ICX Truck Lines.
• Fireman Roger Allen Hubka, age 27, was a volunteer member of the Kingman Fire Department. He worked as a service manager for Double G Tire Company (one of the companies that was totally destroyed), and a Pop Warner football coach.
• Fireman Arthur Celeland Stringer, age 25, was a one-month volunteer member of the Kingman Fire Department. He was a Vietnam veteran and member of the Arizona National Guard. His father, also a volunteer fireman, was seriously burned in the incident.

All of the fallen members of the Kingman Fire Department were buried at Mountain View Cemetery in Kingman.

Marin Eugene Mast, age 42, who was a manager of the Doxol Gas Company was also killed in the explosion. He was a Korean War veteran and a member of the Moose Lodge in Illinois where he lived until 1972. He was buried in Oceanside, California.

The Firefighters Memorial Park in Kingman is dedicated to the 11 firefighters who died in the explosion. The park features a picnic shelter area and grills, a playground, a frisbee golf area, soccer fields, a skateboard park and restrooms. The centerpiece of the park is the memorial to the 11 Kingman firefighters and one plant employee who were killed in the explosion. The memorial features a covered pavilion with several granite markers and benches inscribed with the names of the fallen firefighters. The memorial is placed around a circle of brick laid out in a Maltese Cross and badge pattern.

Commentary by Robert Burke:

What Is A BLEVE?

A BLEVE is a boiling liquid expanding vapor explosion. Gases are liquefied to allow the shipment of large volumes of product more economically. The process involves pressurization of the gas at its critical temperature and critical pressure.

Every gas has different critical temperatures and pressures. The boiling point of liquid propane is -40 degrees below zero F. It remains a liquid because of the pressure in the tank pressing down on the surface of the liquid. Liquefied gases other than cryogenics (refrigerated liquids) exist at whatever ambient temperature is present around the tank – if it is 70 degrees F outside, then the temperature of the liquid gas is 70 degrees F. Almost any ambient temperature encountered in this country is above -40 degrees F. Therefore, liquid propane exists as a liquid above its boiling point. At 70 degrees F it is existing at 110 degrees above its boiling point!

When radiant heat, changes in ambient temperature or flame impingement increase the rate of boiling within the tank, the pressure also increases. Each tank has a pressure relief valve to remove the excess pressure. If, however, the pressure is being increased at a greater rate than is being removed, or the tank is weakened as a result of flame impingement or mechanical damage to the tank, a BLEVE can occur.

As the tank fails, the liquid within the tank, which is above its boiling point (thus the term boiling liquid), is released and instantaneously converts to a gas all at once (expanding vapor), which results in a violent “explosion.” The blast causes the container to break into pieces with some of them being rocketed over a half mile away. If the gas is flammable and an ignition source is present, a fireball may also develop.

Gases are liquefied because much more volume of the gas can be shipped and stored when the gas is in the liquid state. This is because one gallon of liquid propane can expand to over 250 gallons of propane gas.

Propane is primarily used as a fuel for vehicles and heating of homes and businesses. It is a colorless, odorless gas in its natural state; however, an odorant is added to detect leaks, and it smells similar to natural gas. Propane is non-toxic but can displace the oxygen in the air and cause simple asphyxiation. The vapor density of propane is 1.53, which makes it heavier than air, so during a leak it will seek low areas such as storm sewers, manholes and basements. It is highly flammable with an explosive range of 2.4% to 9.5% in air.

Propane’s boiling point is approximately -40 degrees F, and it has an auto-ignition temperature of 874 degrees F. The National Fire Protection Association (NFPA) 704 Marking System lists the hazards of propane as Health-1, Flammability-4, Reactivity-0 and Special-0. The United Nations and U.S. Department of Transportation (UN/DOT) list propane as a Class 2.1 Flammable Gas. Its UN four-digit identification number is 1075.

We have attached photos from the incident.

We have also attached a short video (no sound) with actual footage of the explosion and the aftermath: https://youtu.be/abQ9ZjgrK0E

We have also attached the link to the training site of the IAFC website that has a number of resource links on handling LPG emergencies: https://www.iafc.org/events/event/2025/01/27/self-paced/propane-emergencies-training-for-awareness-mission-specific-responders

We have also attached the link to the Emergency Traffic Podcast episode produced by group member Paul Prevost about this incident: https://open.spotify.com/episode/4mf49woKuMPemwE7VkyDPK

Thanks to an article on the incident published by Robert Burke in Firehouse magazine for much of the content of this article.

Honor the brave service of the eleven Kingman firefighters and one plant manager lost in this incident by studying the properties of LPG and visiting a flammable gas distribution facility in your local response district to review with plant personnel the various safety systems in place with your crew members today.

Remember Fallen Brothers.

Get Out There And Know Your Local!!!