What [may] went wrong at LG Chemicals plant in Visakhapatnam, India

While I was collecting the facts to write this blog post, there were concerns going on second leak on the accident site. However, it was just a control measure to get the styrene container under required status. The Ministry of Home Affairs , India issued a clarification report that second leak at the LG Polymers factory in Vizag was a small technical leak which was necessary to bring the container in control. Anyway, the first leak itself made a worst nightmare for people in the vicinity. 11 innocent civilians were dead and hundreds hospitalized after styrene gas leak at LG polymer plant in Andhra Pradesh on Thursday (May 7).

LG Polymers Manager Mohan Rao responded to the gas leakage where he said that the lockdown was responsible for the accident the plant was closed over a month.’We could not maintain the refrigeration of chemicals due to lockdown leading to leakage of styrene gas’#LGPolymers #Vizag pic.twitter.com/NvSSosivs8

— manasa chennapragada (@mansachenaprgda) May 7, 2020

According Ms. Chennapragada, an Indian journalist, LG Polymers Manager Mohan Rao has told that the gas leakage was due to the failure of refrigeration system of chemicals. He can be seen passing the blame to the government and its lockdown, however, those allegations are not subjective to the focus of this blog post. Anyway, as Mr. Mohan said, it is clear that the store styrene was not under proper refrigeration system when the start up happen after a shutdown due to the recent Covid19 related lock-down.

Since Styrene has low flash-point (31 Celsius) and also susceptible for rapid self-polymerization, the tanks should always needed to keep refrigerated and also with added inhibitors. Refrigeration keep the styrene at a point much lower than its flash-point while inhibitor avoid self polymerization. The prevention of self polymerization is critical since this reaction is highly exothermic. And after sometime of the reported accident  there was news that they are bringing in PTBC (para-tertiary butyl catechol) as a polymerization inhibitor to stop self-polymerization in the Styrene tank @ LG Chemicals, Visakhapatnam. So we can confidently believe that exothermic self-polymerization has happened. Once this started, the only solution which is known to them and us [perhaps someone knows better] is addition inhibitor [which they have already done] and keep spraying water to reduce temperature [which they are doing]. Sometime they may need to release some pressure inside the tanks also. Perhaps what was mistaken to the second leak 8 May morning. And also it is vital to agitate PTBC well in the tank. 

So initiation of the disaster is quite clear. However, the spread of syrene to a considerable radius is leaving us to think further. Styrene is a liquid with high boiling point. So technically it can not stay at gaseous phase for a long time. This is my hypothesis to the matter. When initial self polymerization happens Perhaps it stayed in vapor form (a mixture of gas and liquid) where liquid form involves in self-polymerization giving away enough heat to keep the gaseous phase alive. Another hypothesis is perhaps gas explosion happens as leaked styrene capture a ignition source. Perhaps both hypothesizes occurred.        

India under Covid19 related lock-down. Foreign experts may not quickly able to visit the site and study the case. However, gradually we may get the full technical report. Let us stay alert and learn from this failure, so we can improve chemical engineering to avoid this happens again in somewhere in world!