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June 19, 2012

Pigging accidents

An oil pipelines was being cleaned by "pigging", which involves pushing a cylindrical plug through a pipeline for cleaning it. In this incident the pig was pushed by compressed natural gas. The pig got stuck in the pipeline and natural gas blow through occurred past the pig. The natural gas found its way to pumps and storage tanks and was vented through the tanks safety valves. Luckily it did not catch fire. The investigation determined that the blow through of gas due to a stuck pig was not considered in the job safety analysis. There are many other incidents when a pig receiver cover was opened without proper depressurizing and the pig blasting out, killing the operator. Pigs have known to be blown 100 meters away. Do a proper JSA while pigging.
Read a safety advisory bu the National Energy Board in this link.

Contribute to the surviving victims of Bhopal by buying my book "Practical Process Safety Management"

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