A “Toolbox” for Forensic Engineers

242 Forensic Materials Engineering: Case Studies
Partition
Wall
Bund Wall
Overflow
W 3
Outside Wall
Pipework
Sight
Tube
Short
Panel
Compressor
Equipment
Caustic
Jet
Figure 7.27 Plan of caustic soda tank welded together from polypropylene
panels to form a 2.7-m-diameter tank. The jet of caustic soda emerged from the
weld line of the lowest unreinforced panel and crossed the bund wall intended
to inhibit escape of fluid from the tank.
small business manufacturing “dairy detergent.” 5,6 This detergent is a dilute
solution of caustic soda to which various other chemicals are added to aid
the cleansing effect when flushing out dairy equipment on farms, for example.
Concentrated (40%) caustic soda is the basic raw material for the final
product, and just four deliveries had been made to the factory when the
failure occurred in late 1994. Each delivery involved complete filling of the
tank by a full load.
The failure fortunately occurred after the work shift had left for the day,
and it was spotted by the production director, who was alone in the office
above the factory floor. He heard a “bang” followed by the sound of “rain”
and, looking out onto the factory floor, saw a jet of fluid shooting across the
open space (Figure 7.27). The protective wall around the tank completely
failed to constrict the fluid, which ran along the floor and into an adjacent
unit that printed tachograph discs. Here the damage was extensive as specialist
printing equipment was attacked and wrecked. The local fire deparment
was called on to contain the fluid and prevent escape into the outer
environment. Eventually a specialist recovery team company was hired to
remove the fluid.
W 4
W 2
W 1