a chemical factory producing o-chloro para nitro aniline,
3:4 dichloro aniline, 2:3 dichloro aniline, 3:5 dichloro
aniline, meta-toludine etc. 3 explosions occurred
at intervals of a few seconds and there was a fire.on
4-7-2002 at about 8.30 A.M. during distillation
of 3:4 Dichloro aniline.
Incident: Charging of 3:4 dichloro aniline
crude (about 12 ton) was completed on 3-7-2002 in
the second shift. Then vacuum were applied. Heating
was there started. Within half an hour. Temperature
of the column reached the desired level. In the second
shift of 3-7-2002, vacuum, re-boiler and column were
working satisfactorily. On 4-7-2002, about 1.5 Ton
material collected in the low boiler inter cut receiver
whereas 10 Ton material (3:4 DCA) was in process in
the re-boiler and column. At about 8.00 A.M. on
4-7-2002 vacuum were found low and mercury in the
meno-meter was thrown off. Thus due to vacuum failure,
system was pressurized. Vent valve of the vacuum trap
was opened. At that time, 3 explosions occurred at
intervals of a few seconds and there was a fire.
Cause of the incident: During distillation
of 3:4 Dichloro aniline, vacuum failed and heating
in the re-boiler was going on there was a rise in
the temperature of the distillation column. Because
of the rise in the temperature, partial decomposition
of 3:4 dichloro aniline took place and hydrogen chloride
and tar were produced. 3:4 dichloro aniline reacted
vigorously with hydrogen chloride in presence of catalyst.
Temperature and pressure of the column could not be
controlled resulted in an explosion, followed by fire.
Area & persons affected: 4 workers died,
4 were seriously injured, 3 workers received ......
injuries. Fire brigade personnel were injured during
the rescue operation. Entire plant (3:4 DCA) collapsed.
Some of the parts of the structure and condenser flew
off and fell in the nearby shed about 70 to 80 feet
Action to be taken for non repetition of such incident:
¨ Instead of oil heating system in the re-boiler
for heating 3:4 DCA, steam heating system shall be
provided and it shall be interconnected to vacuum
system in such a way that if the vacuum drops beyond
safe limits, steam supply shall be cut off immediately.
¨ Appliances provided on the distillation column
and healing system shall be examined and tested by
competent person and records shall be kept.
¨ Processes carried out in the factory shall be
isolated from each other.