The Risk Associated with Starting Up of Process Units after Lockdown: Case Study on Vizag Gas Leak

World Health Organization (WHO) has reported the death of about 65000 people due to industrial accidents between 2009 and 2018. International Labor Organization (ILO) estimates that every year 2.3 million people around the world succumb to work related accidents or diseases; and the reports suggested that it is about 6000 deaths per single day. Presently COVID -19 pandemic have taken the lives of many people around the world. Besides, it also caused the shutdown of many process units. Restarting of those, especially chemical plants which deals with hazardous chemicals is of great concern and if proper care is not taken it would further worsen the situation. One such incident was Vizag gas leak which occurred on 7th May 2020. Vizag accident, one of the major styrene gas leaks occurred in the world, is the first styrene monomer leak in India. On 7th may 2020, a vapor cloud was spread around the LG Polymers plant Vishakhapatnam, which took away 12 lives and 585 being hospitalized. The storage of styrene in the M6 tank for a long period during the COVID lockdown, and the startup of the plant without proper safety guidelines paved way to the Vizag accident. The resultant uncontrolled release of styrene gas which spread around a radius of 3 km was the prime reason for the catastrophe. Styrene monomer should be kept in a temperature of 10-18⸰C otherwise will self-polymerizes to polystyrene without any external initiators. Substandard maintenance of M6 tank and poor refrigeration contributed to the increase in the temperature and further release of styrene to the atmosphere. A detailed case study of the accident and a quantitative risk assessment (QRA) of the facility is carried out and presented in this paper. The accident investigation is carried out and presented with the help of Event Tree Analysis (ETA). Quantitative Risk Assessment using aloha software was done to analyze how the area was affected due to the leakage of styrene. The analysis showed that the gas spreads in a semi elliptical shape with 1.3 miles radius. The obtained area was categorized on the basis of Acute Exposure Guideline Levels (AEGL) of 20 ppm, 130 ppm, 1100 ppm for AEGL-1, AEGL-2 and AEGL-3 respectively