Industrial accidents are, thankfully, not a commonplace event. EMDAT lists only 32 such disasters in 2011, the worst of these being the explosion of an oil pipeline in Nairobi, Kenya in which 120 people lost their lives.
In past however there have been a number of extremely devastating accidents:-
1984 Bhopal India - A faulty tank containing poisonous methyl isocyanate leaked at a Union Carbide plant and left 2,500 people dead initially, and 300,000 people affected ni some way.
1986 Chernobyl - A reactor at the Chernobyl nuclear plant, near Pripyat in the Ukraine (then Russia), exploded. Further explosions and the resulting fire sent a plume of highly radioactive fallout into the atmosphere and over an extensive geographical area. 31 claimed direct deaths plus as many as 4,000 deaths from cancer in those exposed
1988 Piper Alpha - An explosion and resulting fire on a North Sea oil production platform killed 167 men. To date it is rated as the world's worst offshore oil disaster in terms both of lives lost and impact to industry.
To date in 2012 the worst industrial accident has been in Hebei province in China which resulted in 25 deaths in an accident in a coal mine.