A petroleum product, propylene gas is highly flammable. Static electricity, when using a mobile phone, a stray spark from a car exhaust, would have the potential to ignite a cloud of gas vapor, causing an explosion. However, propylene is not toxic to breathe and first responders only needed a PPE kit to venture near the leak.
What is the first step taken in such situations?
Standard practice around the world dictates that the area around the leak be isolated. Although the extent of this zone depends on the amount of gas escaping into the air, a minimum radius of 50 meters is recommended. At some times after the incident, the lower explosive limit (LEL) was also in the dangerous zone at a distance of 500 meters.
When asked, officials of the Maharashtra State Road Development Corporation (MSRDC) said that “incident management” of varying range is the responsibility of the contractor responsible for the road, in this case, IRB Mp Expressway Pvt Ltd.
A company spokesperson said, “The company has a robust Emergency Response Protocol (ERP) and a well-trained and qualified team already in place, well equipped with the necessary machinery and systems to handle such situations. In fact, the IRB team, after analyzing the situation and understanding the severity of the problem, took immediate action of stopping traffic at a safe distance from the accident site with the help of law enforcement authorities as the first and foremost safety response.”
As a result, traffic was initially cut off on both sections of the road.
What is the next step?
Once the severity of the leak and the presence of the gas in the air is determined, the next step is to attempt to contain this sphere of influence, for example with water sprinklers. In the case of propylene, a water spray may help contain the leak.
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While the IRB arranged the necessary mechanical resources such as heavy cranes, ambulances and quick response vehicles (QRVs) loaded with equipment such as gas cutters, compressors, pumps, etc., fire tenders reached the spot. However, in order to use all of the above safely, the team of chemical experts had to arrive. He arrived at the scene at 8:30 p.m. The QRV, which would normally be useful in an LPG tanker incident, was not up to the task of dealing with propylene. Coordination continued by telephone.
What should happen next according to global protocols?
Once preliminary safety measures have been implemented, the next step is to stop the source of the leak. This can be done by fixing leak points, emptying the gas tank, or even burning the gas in a controlled manner if possible. Moving the tanker out of the way, ensuring safe passage and allowing traffic to move again are the final steps.
In it Bombay–Pune In the highway incident, experts and the National Disaster Management Force (NDRF), who reached the spot on Tuesday at 11.30 pm, soon realized that the damage to all the valves could not be stopped at the spot.
At the same time, authorities targeted several companies manufacturing and handling chemicals, from BPCL, which had supplied the propylene to the tanker in question, to HPCL, Reliance Industries, Deepak Chemicals and Fertilizers, etc. This chain reached Mec Elec Industrial Services, 10 kilometers away, a company specialized in testing and certifying tank trucks that transport dangerous chemicals, which came to the rescue at 8:30 p.m.
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“The team was able to repair two of the three leaks on Tuesday night, but the third proved difficult as liquid gas continued to leak out,” said Madhav Divekar, managing director of Mec Elec Industrial Services. “Attempts continued on Wednesday, but it was then decided to transfer the gas to another tanker, until the amount on the truck was reduced so we could try to fix the valve again.”
Decanting operations continued until the damaged valve was emitting only steam, indicating gas levels were at 50 percent. With caution and cranes, the tanker was lifted and placed upright, where the damage to the third valve was attended to.
For safe transportation, another decanting operation was carried out to empty the contents of the truck at some distance, after which the truck was taken to Mec Elec’s tanker testing facility in Thane.
Was traffic allowed immediately?
Traffic was only allowed on the Mumbai coach after a gap of 30 minutes, allowing the gas to disperse sufficiently due to the proximity of a tunnel. Propylene is heavier than air and, therefore, dispersion is not immediate.