The industry has known about the dangers of ‘runaway’ chemicals for years. Then disaster struck in OC

The chemical industry is well aware of the dangers of the kind of thermal reaction that forced 50,000 people from their homes in Orange County last weekend, renewing years of warnings from researchers about the potential dangers.

About 15% of incidents in the US involving uncontrolled chemical reactions between 1980 and 2001 were heat-related incidents involving rapid chemical decomposition, according to a study published in the journal ACS Omega, citing information from the US Chemical Safety and Hazard Investigation Board.

Such incidents have led to deaths around the world, but some experts say the industry has struggled to improve safety.

In Orange County, the problem was caused by thousands of gallons of a highly toxic chemical in a failing pressurized chemical tank that was burning at a Garden Grove airline. There was a fire or flames burning over several blocks of the city, and there were businesses, dozens of houses and an elementary school in the area of ​​the explosion that could cause damage.

A worst-case scenario was avoided over the Memorial Day weekend. But serious questions remain about how such a disaster could happen.

Authorities suspect a cooling system responsible for maintaining the temperature of a tank full of a hazardous chemical at GKN Aerospace failed, leading to a crisis in the area that led to the evacuation, Orange County Fire Authority interim chief TJ McGovern said Tuesday.

This may have led to a build-up of heat in a pressurized tank filled with 7,000 liters of a highly reactive liquid chemical called methyl methacrylate, or MMA, which is used to make things like Plexiglass and furniture.

“We don’t know why, but it stopped cooling,” McGovern said Tuesday. “That’s what started this event, where the product got hot and was released through the relief valve, and that’s how this whole response started. Now we can get to the tanks, so there’s a lot more to come as to what caused that.”

Fire officials and experts were faced with a seemingly impossible scenario: a “boiling liquid expandable vapor explosion,” or BLEVE, which could cause widespread damage and release toxic substances into the air, or a chemical spill that could contaminate waterways and oceans. Inhaling MMA can irritate the lungs and, at high exposure levels, can cause severe respiratory distress and hospitalization; Long-term exposure has been linked to severe organ damage.

Although the fire department talked about the burning of the gas “smoky” and on Friday said that the tank “no longer cleans any kind of product,” the health officer of the region, Dr. Regina Chinsio-Kwong, on Monday said that no smoke or fog was released during the incident. The US Environmental Protection Agency said its air monitors found no toxic chemicals in the air, but environmentalists were skeptical that no toxic substances were released.

The suspected failure of the cooling system, along with the introduction of heat into the MMA pressurized tank, planted the seeds of potential disaster.

When liquid MMA is exposed to heat or light, it will begin to react, said Elaine Villanueva Bernal, a lecturer in Cal State Long Beach’s department of chemistry and biochemistry.

As the MMA solidifies, “it generates heat, and in generating that heat, it drives the chain reaction, so it keeps going and going,” Bernal said.

When it gets out of control, this leads to a process called thermal runaway.

MMA is a highly reactive chemical, a monomer that can be used to make strong, durable, lightweight and transparent plastic polymers. But introducing heat to MMA in a pressurized tank caused the chemical to react, starting its transition from a liquid to a solid state, producing more heat.

Ultimately, it can result in BLEVE.

That refers to when a liquid is “pressurized rapidly, causing a rapid transition from liquid to vapor with the release of associated energy,” and is “usually accompanied by a large aerosol fireball,” according to the American Institute of Chemical Engineers’ Center for Chemical Process Safety.

GKN Aerospace, based in Britain, makes landing gears, jet engines and other components for commercial and military aircraft at its Garden Grove facility. The company did not respond to questions Tuesday, but previously said “we apologize for the ongoing inconvenience caused by this incident and our priority remains a safe solution.”

Orange County ended up in much better shape than events elsewhere. In India, 12 people died and more than 580 were injured after a hot styrene escape and styrene vapor release occurred at the LG Polymers plant in the port city of Visakhapatnam in 2020. A committee appointed by India’s highest environmental court blamed “gross human failure” and a lack of basic safety standards for the disaster, the Associated Press reported.

“Lessons have not been learned,” the ACS Omega study said, referring specifically to styrene-related escape events.

Also in 2012, one person died and 36 were injured in a chemical fire at a chemical plant in Himeji, Japan. The disaster occurred after excessive “polymerization of acrylic acid” in a central storage tank, a study published in the journal Process Safety and Environmental Protection, citing information from the factory’s operator, Nippon Shokubai Co.

A study published in 2023 called for more attention to be paid to MMA.

“The right choice of operating conditions is often the first line of defense against thermal events,” says the study, published in the journal Thermochimica Acta. Without assessing potential thermal hazards, implementing safe process designs and strengthening thermal safety, “a worst-case reaction may pose a serious threat to safety processing and industrial-scale equipment and human lives.”

A report by the US Chemical Safety and Hazard Investigation Board, issued in 2002, called for the need to “improve existing hazard management” after two accidents in the 1990s in New Jersey, one of which killed five workers.

“Accidents are a major chemical safety concern,” the report concluded.

In the case of the Orange County chemical tank, officials watched as the temperature in the crippled tank rose from 77 degrees Fahrenheit on Friday, to 90 degrees on Saturday, to at least 100 degrees on Sunday — the high reading on the scale. At one point, the tank started to explode.

The simplest solution – pumping a neutralizing agent to stop the reaction – failed because, it is possible that the MMA in the valve reacted and changed from a liquid to a solid and closed the valve, which means that the neutralizing agent could not be pumped in, and the toxic liquid could not be removed, according to Elias Picazo, assistant professor of chemistry at USC.

Crews were unable to “find anything in the compromised tank because, the theory is, the product was starting to solidify and close the dump valves,” McGovern said.

All the officials could do was to spray cool water into the tank, hoping that by cooling it, the disaster would be averted. On Monday, Craig Covey, chief of the Orange County Fire Authority, said firefighters wanted the MMA chemical to be more stable and gel-like — rather than the flammable liquid they were dealing with. “You have to control the temperature to get that egg done right, and not crack the shell,” Covey said.

However, in the end there was no explosion or large spill of liquid that could contaminate waterways and the sea. The cooling strategy seems to have worked.

On Monday, “we really turned a corner,” McGovern said. Officials confirmed there was a crack in the tank and it was no longer pressurized, taking BLEVE concerns “off the table,” he said.

Officials then narrowed down the exit.

The crack “allowed us to get more of our crew into the tank,” he said. “They were able to start to peel back the outer wall of the tank and remove the insert.”

They can then push their unheated pipe lines higher into the inner tank to initiate better cooling mechanisms and reduce the internal temperature of the object. As of Tuesday morning, the thing was hovering between 90 and 92 degrees Fahrenheit and water was still flowing through it.

Later on Tuesday, workers began shutting off the cooling water in the tank. The crew would start with one of the two water systems and see how the temperature responded.

“We are looking for any fluctuation, we don’t want the internal temperature to rise because we are shutting off the water, we would really like it to decrease, but as long as it does not move we are looking for the stability of the internal temperature.”

If the temperature remains unchanged, they will consider shutting off the secondary water supply. Then, if the temperature doesn’t change, “it will tell us that the fire problem, or the small explosion, is reduced,” McGovern said.

By Tuesday night, all evacuation orders had been lifted, with authorities saying there was no remaining risk of an explosion, chemical leak or fire.

Times staff writers Tony Briscoe, Clara Harter and Meg James contributed to this report.