Vizag tragedy: ‘Low-lying area may still have concentration of styrene gas’

The inhabitants of five villages around the LG plant, from which styrene gas leaked on Thursday leading to the death of 11 people, should avoid low-lying areas as the gas — which is three times denser than air — may still be lingering, an expert has said.

The authorities are planning to allow 1,500 people to return to their homes in the vicinity of the plant in RR Venkatapuram, Visakhapatnam, after a forensic expert team declared the surroundings safe.

“Once such a mishap happens, it is entirely up to the mother nature to take care of it. Weather conditions would play a major role in diluting the gas. So there is a need to check whether the toxic gas is present in the air,” said Rahul Raman, a Principal Engineer with Chennai-based Kaypear Consulting, who specialises in Process Safety Management of Hazardous Chemicals.

The authorities have still not pin-pointed what led to the leakage of the styrene gas, which is used for making polymer, polysterene.

Raman, who is a member of Design Institute of Emergency Relief Systems, a sub-organisation of the American Institute of Chemical Engineers, noted several possible scenarios.

Possible scenarios

He claims such a runaway reaction must have been triggered in at least 24-36 hours before the gas leak. Since styrene is a highly reactive chemical, its reaction is controlled using an an inhibitor. But when the concentration of the inhibitor falls, it could lead to the runaway reaction.

The second reason could be that there was that the re-circulation system, that keeps styrene refrigerated below a certain temperature, was not working. The fluid is generally taken out of the vessel and cooled and put back into the container in the normal process. The preliminary report submitted by the LG Polymers India Limited to the district authorities pointed to a malfunctioning of the refrigeration system.

It is possible that there was a build-up temperature that has happened inside the tank. “But the reaction leading to the leak might have commenced quite some time back and the plant operators may have overlooked it,” he said.

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