Clogged cooling system likely cause of gas leak in Andhra Pradesh, three investigators say

They said workers at LG Polymers, a unit of South Korea’s LG Chem (051910.KS) near the southern city of Visakhapatnam, did not use a warning system to alert local residents but informed company management after the leak in the early hours of May 7.

The three investigators asked not to be named as they are not authorised to publicly discuss the investigation, launched by the government of Andhra Pradesh state.

LG Polymers said the situation at the plant was now under control but it, and LG Chem, did not respond to detailed questions from Reuters for this article.

About 800 people taken to hospital after the leak, and some were asleep when gas drifted over their homes. Police have filed a culpable homicide complaint against LG Polymers.

When a Reuters witness visited the Venkatapuram village adjoining the plant on Tuesday, leaves on trees exposed to the gas looked shrivelled and had turned brown.

The Andhra Pradesh state government declined to give any details of its investigation.

The three investigators said the temperature inside the oldest of the three storage tanks holding styrene monomer, a raw material used in polystyrene products, rose to over 150 degrees Celsius (302°F), more than six times the permitted level.

“The chiller unit was clogged because of a polymerization process, which occurs when temperature exceeds certain levels,” one of the officials said.

To slow the polymerization process, a chemical reaction that generates heat, styrene monomer must be stored at 20-30 degrees Celsius with a cooling system and chemical compounds, or inhibitors, typically used to keep temperatures under control.

If unchecked, the heat generated from the polymerization process causes the chemical to vaporize.

But the cooling system was clogged and the likely cause of the blockage was a chemical reaction inside the tank holding the styrene monomer, the three investigators said.

The skeletal workforce at the facility overnight was unable to bring the situation under control, they said.

“When temperatures started rising, the staff at the plant were not able to use the cooling system,” one said.

LG Polymers said in a statement on Thursday that it planned to ship remaining styrene monomer inventories to South Korea.

“The team of production, environment, and safety experts are currently investigating the cause of the incident,” it said.