At approximately 05:35 hours on 19 November 1984 a major fire and a series of catastrophic explosions occurred at the government owned and operated PEMEX LPG Terminal at San Juan Ixhuatepec, Mexico City. As a consequence of these events,  at least 650 people were killed and the terminal destroyed. The PEMEX accident is among the most well-known examples of a BLEVE, pronounced "blevvy", an acronym for "boiling liquid expanding vapor explosion." This is a type of explosion that can occur when a vessel containing a pressurized liquid is ruptured. This disaster is one of the largest in industrial history.

The PEMEX LPG terminal in San Juan Ixhuatepec, 20 kilometers north of Mexico City, was a large installation which received supplies from three gas refineries every day. The facilities, owned by the Pemex State Oil Company, consisted of six spherical storage tanks (four with a volume of 1600 m³ and two with a volume of 2400 m³) and 48 horizontal cylindrical bullet tanks of different sizes. At the time of the disaster the storage tanks contained 11,000 m³ of a mixture of propane and butane.

The inhabitants of San Juan Ixhuatepec numbered about 40,000, and a further 60,000 lived in the hills surrounding the village. The majority were poor country people living in one-story houses constructed of concrete pillars filled in with bricks and with roofs of iron sheets

On the morning of 19 November 1984, when the vessels at the PEMEX terminal were being filled with LPG arriving in a pipeline from a refinery 400 kiolmeter away, a drop in the pipeline pressure was noticed by the control room and a pumping station. It occurred because an 8 inch pipe connecting one of the spheres to a series of cylinders had ruptured, but the operators did not think of such a possibility and the release of the LPG from the leaking pipeline continued for 5–10 minutes. The escaping gas formed a 2 meter high cloud covering an area of about 200 meters by 150 meters. The cloud then drifted towards a flare tower, caught fire and precipitated the first BLEVE. The explosion hurled vessel fragments wrapped in burning LPG in all directions. Some of the projectiles hit other vessels, damaging them, or caused local fires which engulfed other vessels. This led to the failure of one vessel after another; most exploding vessels caused nearby vessels to fail.

Four LPG spheres, each containing 1500 m³ of LPG, and several other smaller cylinders holding between 45 m³ and 270 m³ of the liquid suffered BLEVEs. Each BLEVE generated a fireball; such fireballs raged through the streets of Ixhuatepec for about 90 minutes.  A block of perhaps 200 houses built mostly of wood, cardboard, and metal sheets was demolished by these fireballs. Masses of fragments of tanks and pipes, some of them weighing 40 tons, were blown into air and landed as far as 1200 meters away. The PEMEX terminal was nealry completely destroyed. Two of the explosions had an intensity of 0.5 on the Richter scale and were recorded on a seismograph at the University of Mexico.

The accident was responsible for at last 650 deaths and over 6400 injuries. Damages due to the explosion and the resulting fire were estimated at approximately $31 million.

Sources

• Abbasi, Tasneem and S.A. Abbasi, The boiling liquid expanding vapour explosion (BLEVE): Mechanism, consequence assessment, management, Journal of Hazardous MaterialsVolume 141, Issue 3, , 22 March 2007, Pages 489-519.
• Burns, Arthur, The tragedy of San Juanico--the most severe LPG disaster in history, Burns Incl Therm Inj., 1987, Apr;13(2):87-102, Accessed 30 August 2008.
• Marshall, Victor Christopher and Steve Ruhemann, Fundamentals of Process Safety (Institution of Chemical Engineers (IChemE), 2000), ISBN 085295431X, 9780852954317.
• Wells, Geoff, Major Hazards and Their Management, (Institution of Chemical Engineers (IChemE), 1997).