A tank receives, after a negative reactivity test with the bottom supernatant of the tank, 20 m of methyl hydro-dichloro-silane, then 24 m of a mixture of oil and tar (negative reactivity test) and 10 m of a Tar mixture (no reactivity test). Simultaneously, the operator feeds an oven by pumping into the tank. A reaction appears 24 hours after these discharges, filters clog up, the tank overflows, then the reaction stops. The management states that there is no danger; 15 days later a sudden release of hydrogen occurs with a projection of solid polymer within a radius of 25 m. The tank is found inflated and disengaged from its base, broken anchors.