Nick Chumo Addy Hellebusch Matt Kelley Chris Williams

Introduction  November 19, 1984  San Juanico; a suburb of Mexico City  20 km outside of Mexico City  40,000 residents  Low income families  Homes as close as 130m to plant

Plant and “Process”  Pemex State Oil Company  Storage & Distribution facility for liquefied petroleum gas (LPG) LPG comes in from 3 different refineries  54 LPG storage tanks- 16,000m 3 Daily throughput- 5,000m 3 6 large spherical tanks ○ 2 largest holding 2400m 3 48 smaller tanks of various sizes  Built to API Standards

Right Before Explosion  Being filled from a refinery 400km away  11,000m 3 LPG on site  Fall in pressure The cause of the pressure drop was unidentified no one initiated emergency shutdown

Pemex Before

Pemex After

What Happened  One of the deadliest industrial disasters in world history  The initial vapor cloud explosion was the start of a chain reaction of explosions  There were 19 explosions 15 cylindrical tanks The 4 smaller spheres  Many of the explosions were BLEVEs The relative times can be told from seismic readings

What Happened cont.  Most of the damage to the city was from fires not the explosions  Fragments from the tanks reached over 1,200 m away The fragments were hot enough to start fires Pieces trailed raining LPG as they flew  A concentrated rescue effort was put into action with 3000 rescuers on site  200 firefighters risked their lives

Accident Timeline  5:30am Rupture of 8 in. pipe; Pressure drop in control room  5:40am Ignition of gas cloud; Violent combustion and high flame  5:45am First explosion on seismograph, a BLEVE; Fire department called  5:46am Second BLEVE, one of the most violent  6:00am Police alerted and civilian traffic stopped  6:30am Traffic chaos

Accident Timeline cont.  7:01am Last explosion on seismograph, a BLEVE  7:30am Continuing tank explosions  8-10:00amRescue work at its height  11:00am Last tank explosion  12-6:00pm Rescue work continues  11:00pm Flames extinguished on last large sphere  10:00am Last fires put out (next day)

Root Causes  Official cause of rupture is unknown  One report cited  Overfilled tank caused the inlet line to rupture  Failure of relief valve

Results  deaths; 300+ never identified  severe injuries  10,000-60,000 people made homeless  31 million dollars of damages  Destruction of 1/3 of the LPG supply to Mexico City

Results

Future Preventions  Timely inspections  Maintain industrial standards  Better maintenance  Effective operator training  Housing appropriate distance away

Future Preventions cont.  Proper layout of large LPG storages  Gas detection and emergency isolation  Water system failures  Extra water hydrants in the streets  Planned evacuation routes

Summary  This deadly disaster struck the morning of November 19, 1984  Lasted from 5:30am till 10:00am the next day  Left hundreds dead and thousands injured and homeless  Many lessons can be learned from the tragedy