Pigging incident

"A worker was killed operating on a natural gas pipeline. At a receiver station the man intended to pick up two so called cleaning pigs, each weighing about 150 kg, diameter 0.5 m. For this purpose the gas pressure in the pig trap was let off by a valve, manometer controlled. According to an eyewitness's statement, the receiver pressure was equal to outside air pressure before the accident. The victim stood right in front of the flap of the receiver when he began to unfix the screws of the flap. Whilst working, the flap snapped out driven by the two cleaning pigs. The man and the devices were flung through a wire-netting fence and dropped down on a nearby field at a distance of 27, 29 and 38 m, respectively, from the receiver. The man died on the scene of the accident. 
It was determined that the second pig had got stuck in the receiver and that gas pressure had built up behind the pigs due to a leaky valve. As a consequence the pigs were expelled at a velocity of approximately 220 km/h causing a pattern of injury comparable to that of a fall from a great height."
Courtesy:
Death by a cleaning pig--an unusual accident at work].
[Article in German]
Weber M1, Arnrich S, Wilk E, Lessig R.


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