- Context of the incident
- The tragedy
- Infrastructure involved
- Learned lessons
- Industrial Security
- Safe distance
- Disaster assistance
- References
The San Juanico explosions was an accident that occurred in the early morning of November 19, 1984 that killed 503 people and injured more than 7,000 people, according to official figures. Also called the San Juan Ixhuatepec accident, it is considered one of the most impressive industrial tragedies in Mexican history.
The chain of explosions was registered in several of the gas containers, some 20 kilometers north of Mexico City where Petróleos Mexicanos (PEMEX) had a storage and distribution center for liquefied petroleum gas (LPG).
More than 500 deaths left the industrial accident. Source: El Universal
More explosions were recorded after the BLEVE (Explosion of vapors that expand when boiling the liquid, for its acronym in English), when the vapor penetrated the surrounding houses and had contact with the domestic gas tanks of 30 kilograms.
Context of the incident
San Juan Ixhuatepec is a Mexican town, in the municipality of Tlalnepantla de Baz, which borders the municipality of Ecatepec de Morelos. Towards the 1950s, with the accelerated urbanization of the Metropolitan Area of the Valley of Mexico, the popularly known San Juanico also presented this rapid growth.
In 1959 land was assigned to PEMEX for the establishment of a plant to process liquefied petroleum gas (LPG), which would come from different refineries in the country. This would have both a domestic and industrial use that would serve the new developing areas. Two years later, in 1961, the first plant of this company was inaugurated with a capacity for 16 million cubic meters of LP gas.
In parallel, a group of private companies established around the inaugurated plant, with the purpose of distributing domestic gas in the form of cylinders.
The tragedy
Model of the LPG containers that exploded during the tragedy. Source: Igelball - first upload: July 27, 2003 - from: Wikipedia, CC BY-SA 3.0, In San Juan Ixhuatepec, within the Metropolitan Area of Mexico City, on November 19, 1984 at 5:44 am an explosion occurred in one of the PEMEX storage and distribution plants. Additionally, another 8 explosions were registered, whose intensity reached the magnitude of 0.5 degrees on the Richter scale. The flames reached up to 500 meters high and could be completely extinguished 40 hours later.
There is no clear information that explains the beginning of the accident. However, it is believed that minutes before a 20 cm diameter pipe carrying LPG broke due to the overfilling of one of the containers, causing a gas leak for almost 10 minutes. This generated the formation of a large, slowly moving, flammable vapor cloud about 2 meters high that covered an area of 200x150m 2.
When the cloud exploded and ignited, in addition to the plant, the neighboring houses-rooms that surrounded it were affected and a domino effect of explosions was generated. The last explosion occurred at 10 a.m. the next day. Rescue work began at 8 a.m. and the fire was extinguished at almost midnight on November 20.
Officially 503 people died, 7,000 were injured and about 60,000 people had to evacuate the area. The explosion left a 200-meter-radius crater, some 150 houses destroyed, and damage to an area of up to a kilometer from the plant.
Infrastructure involved
Only four of the original deposits remained standing. All of the affected tanks contained essentially pressurized propane and butane.
The most important units were 2 spheres of 2,400m3, 4 spheres of 1,600 m3, 4 cylinders of 270m3, 14 cylinders of 180m3, 21 cylinders of 36m3, 6 cylinders of 54m3, 3 cylinders of 45m3, the control room, the house pumps and fire pumps
Learned lessons
Much has been studied and discussed this case by experts, authorities and the community. All have tried to deduce the lessons learned, so that an accident of this magnitude does not repeat itself. Among them are:
Industrial Security
Maintenance and daily inspection of a LPG distribution plant are vital. The necessary safety equipment must be in place, such as gas alarms in sufficient quantities to detect any leak at its earliest stage, without reaching the limit of the explosion.
But this involves not only allocating resources and equipping the venue, but also advanced training of staff.
The team must have an emergency plan, in which preventive protection is implemented and drills are carried out at least once a year with both the personnel and the fire department and technicians who would be involved in an emergency. These preventive measures must be constantly reviewed and updated.
Safe distance
The free area around the PEMEX plant had been considerably reduced, reaching irregular settlements of the local population, just 130 meters away from some tanks.
The security measures indicate that they must be at least 400 meters apart. However, in the case of the San Juanico tragedy a new record was recorded, when a 30-ton tank landed 1,200 meters from the plant. In other industrial incidents, the maximum distance had been 800 meters, so this was considered the area of total safety.
Disaster assistance
Rescue efforts, as well as the joint work of organizations, volunteers, doctors and security forces played a key role. The work of the first hours is usually the one with the highest risk, but the most important when caring for the injured. In this case, the chaos of traffic, difficult topography and other obstacles prevented maximum effectiveness in those first moments.
Analysts, however, consider that despite the dimensions of the disaster and those first inconveniences, the subsequent management was satisfactory. An army-operated plan was put in place, which is usually implemented in cases of earthquake. The number of rescuers was about the same as the number of injured.
All the rescue actions were evidence that the trained personnel, the equipment, the amount of transport and the number of special units and everything that translates into sufficient resources are essential for this type of industrial accident.
References
- Arturson, G. The tragedy of San Juanico-the most severe LPG disaster in history, Burns, Volume 13, Issue 2, 1987, Pages 87-102, ISSN 0305-4179, doi.org/10.1016/0305-4179(87) 90096-9.
- López-Molina, Antioco & Vázquez-Román, Richart & Díaz-Ovalle, Christian. (2011). Learning from the Accident of San Juan Ixhuatepec-México. Technological information. 121-128. 10.4067 / S0718-07642012000600013.
- Explosions in San Juan Ixhuatepec of 1984. (2019, September 17). Wikipedia, The Encyclopedia. Recovered from es.wikipedia.org
- Monsiváis, C. Chronicle of San Juanico: the facts, the interpretations, the mythologies. Cuadernos Políticos, number 42, Mexico DF, ed. It was, January-March, 1985, pp. 87-101
- Wikipedia contributors. (2019, October 26). San Juanico disaster. In Wikipedia, The Free Encyclopedia. Recovered from wikipedia.org
- Zaragoza's University. (sf). Accident in San Juan de Ixhuatepec. Recovered from unizar.es/