1. The steam under pressure is suddenly exposed to much lower pressure i.e. Atmospheric Pressure resulting it to expand to almost 10–15 times expansion of its volume.
2. The tremendous amount of energy stored in the pressurized boiler water is suddenly released prompting sudden evaporation of 15 to 20% of the water to get converted into Flash steam. This steam also expands to more than 1700 times its original volume causing catastrophic damages.