EXPLOSION OF TANK TRUCK AT AMBALA ON 14.04.09
The truck which I had loaded on 11.04.09 was reported to have met with an accident at Ambala(a city on National Highway -1). The truck is said to have rammed into a wall and then it caught fire. In the meawhile it had rammed on one Railway Security Gaurd. That gaurd was found to be dead on the spot.
The driver found that he is in a heavily populated area and if the truck explodes there he will take life of a lot of people along with him. Realising this, he picked up speed and jump away from the vehicle after 1.5 kms.
Later, the Tank Truck has exploded and it has huge volume of LPG in it(16235 Kgs). Just imagine the extend of loss of life and property had it exploded in the residential area 1.5 kms before.
Initially, I thought it is a case of PUVCE ( Vapor Cloud Explosion) as I tried to connect the tits and bits from my analysis. But when the wall and other factors came in to picture, I was clear it is an BLEVE.
The driver found that he is in a heavily populated area and if the truck explodes there he will take life of a lot of people along with him. Realising this, he picked up speed and jump away from the vehicle after 1.5 kms.
Later, the Tank Truck has exploded and it has huge volume of LPG in it(16235 Kgs). Just imagine the extend of loss of life and property had it exploded in the residential area 1.5 kms before.
Initially, I thought it is a case of PUVCE ( Vapor Cloud Explosion) as I tried to connect the tits and bits from my analysis. But when the wall and other factors came in to picture, I was clear it is an BLEVE.
Tanker undergoing BLEVE
BLEEVE is initiated by a small rupture in body
for example, due to corrosion, or failure under pressure
Vapour portion may rapidly leak, lowering the pressure inside the container
Sudden drop in pressure -> violent boiling of the liquid->large amounts of vapour
Vapour portion may rapidly leak, lowering the pressure inside the container
Sudden drop in pressure -> violent boiling of the liquid->large amounts of vapour
This fault line results in further rupture and hence Explosion.
Vapor pressure > Design Pressure -> ruptures the vessel -> torn along the fault line
So, the necessary condition for the explosion is
(over pressure Wave) VAP. PRSSURE> DESIGN PRESSURE.
forming a fireball ->fuel-air explosion->vapour cloud explosion (VCE)
Holocaust sort of effect. (Just imagine the pictures from movies depicting the WWII nuclear explosion in Nagasaki, Japan).
Well, VCE can be more dangerous as it can move to areas, where it can burn without any prior fire prevention arrangements
A relevant Question - What the hell was the safety valves or Pressure release Valve doing
The relief valve on the top is designed to vent off excess pressure in order to prevent the rupture of the tank itself. Given a fire of sufficient duration and intensity, the pressure being generated by the boiling and expanding gas can exceed the ability of the valve to vent the excess. Hence, the PRV was rendered useless.
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