Panzer VIII Maus
Panzerkampfwagen VIII Maus ("Mouse") was a German World War II super-heavy tank completed in late 1944. It is the heaviest fully enclosed armoured fighting vehicle ever built. Five were ordered, but only two hulls and one turret were completed before the testing grounds were captured by advancing Soviet military forces.
History of the oil tanker
The increase in scale brought a new problem. Until then, the washing of tanks after cargo discharge was done by water. In December 1969 three tankers exploded during tank washing. The Dutch Shell tanker "Marpessa" sank off Dakar and became the largest merchant vessel ever lost. The other two, the British Shell tanker "Mactra" and the Norwegian "Kong Haakon VII" were damaged heavily, but remained afloat. Shell investigated the matter and came to the conclusion that water drops that impact steel with high velocity generates static electricity that can cause explosions in combination with cargo vapors. This only became apparent with the large sizes of the tanks of VLCC's.