Acid Peril: No Clear Answer in Mobil Study

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Times Staff Writer

Safety officials say the most troubling issue at Mobil’s Torrance refinery is the use of hydrofluoric acid.

It’s a chemical so toxic that the federal government labels it “acutely hazardous.” It is so dangerous that exposure to concentrations as low as 50 parts per million for 30 minutes can be fatal.

A safety study on the refinery by Gage-Babcock & Associates and the Mittelhauser Corp., released last weekend, raised a host of issues about the plant, including a charge--hotly contested by Mobil--that management is lax in enforcing safety regulations.


In the ensuing dispute about safety and discipline, the issue of hydrofluoric acid, which is discussed in a section on acutely hazardous chemicals, faded into the background.

But for those who had hoped to find a clear-cut answer about hydrofluoric acid in the report, there was none.

More studies--by Mobil, by the South Coast Air Quality Management District and by an industry group--are pending. The report and Mobil say these studies will provide better clues into how, and whether, you can handle hydrofluoric acid in an urban setting.

The consultants said their study was hampered because Mobil chose to unveil a key safety system too late for them to assess whether it would work. The system is designed to rapidly transfer hydrofluoric acid to underground tanks in a disaster.

Careful Wording

Refinery Manager Wyman Robb, who had mentioned in public meetings in the fall that Mobil intended to install such a system, said in an interview that he is uncertain why Mobil told Gage-Babcock & Associates about the system only four days before the report was released.

With that system pending, the consultants were careful in their wording of the main conclusion it drew about Mobil’s use of hydrofluoric acid.


The refinery, the study said, “has the design elements required for normal safe operation and basic prevention of an accidental release.” But the report goes on to warn that, “considering the extremely hazardous nature of hydrofluoric acid, additional measures should be considered to provide extra protection.”

Torrance Councilman Dan Walker, Mobil’s most vociferous critic on the council, declared after reading the report that his concern remains “one single catastrophic incident encompassing hydrofluoric acid that may occur 30 years from now. One incident,” he said, “could be devastating to this community and to possibly tens of thousands of people.”

What makes hydrofluoric acid so dangerous is not only that a minute concentration will severely affect the eyes, lungs and other tissues, but that a major release could create a dense ground-hugging cloud with lethal concentrations of the acid up to 5 miles away. That conclusion was the result of industry-sponsored testing involving a series of spills in 1986 in Nevada.

In the largest known accidental release, a cloud of hydrogen fluoride--the acid’s gaseous formforced the evacuation of 4,000 people in Texas City, Tex., on Oct. 30, 1987, after a crane at the Marathon Petroleum Co. refinery dropped a piece of heavy equipment on a pipe leading to a tank containing hydrofluoric acid. An estimated 6,000 gallons were released over several hours. Several hundred people had to be hospitalized and the gas defoliated trees in its path.

In addition to not being able to analyze the new rapid transfer storage system for hydrofluoric acid, the consultants say several other factors kept them from making a complete analysis:

- They do not have an in-depth risk assessment study under way that, among other things, will examine the likelihood of scenarios--such as an earthquake or plane crash--that could cause a major release of hydrofluoric acid. The refinery typically has 250,000 pounds of the substance on site.


Mobil is preparing that study under orders from the Torrance Fire Department in accord with a state law that is intended to provide the public with better information about and protection against chemical disasters. The law was passed in the wake of the deaths of 3,000 people who died in 1984 when a Union Carbide plant released methyl isocyanate gas in Bhopal, India.

- Gage-Babcock noted it also lacked the results of industry-sponsored wind-tunnel hydrofluoric acid releases in Nevada last summer. Analysis of those tests is expected to lead to specific design recommendations on how to build safety systems--chiefly, fine-droplet water sprays--to limit the effects of a major release. Up to 90% of the acid fumes have been knocked down by sprays in some of the tests.

- Also pending is a report from the South Coast Air Quality Management District task force assessing the wisdom of using the acid in urban areas. The report will include a section on the risk of transporting the acid, as well as the trade-offs obtained by using less dangerous sulfuric acid as an alternative to hydrofluoric acid in boosting the octane of unleaded gasoline. Most refineries in Los Angeles County use sulfuric acid.

In addition to these reports:

- A ballot initiative sponsored by Walker would have the effect of eliminating the use of hydrofluoric acid at Mobil’s refinery. Its introduction last month drew fire from some of Walker’s council colleagues, who criticized it as premature. If the signature campaign gathers impetus, the issue will remain before the public for months.

- The city of Torrance is about to complete a study to determine the limits of its authority to regulate safety and operations at the refinery, including the use of hydrofluoric acid.

Despite the limitations of the Gage-Babcock study, it did contain some useful suggestions and perceptions, according to refinery and city officials.


The most disturbing, according to Walker, is the recognition--in the section of the report dealing with fire protection--that water spray systems are vulnerable to an explosion that might destroy them. Water sprays have been identified in the Nevada testing as the most promising method of controlling hydrofluoric acid spills.

“Fixed water-spray protection has questionable reliability in operations that have an explosion potential,” the report said. “An explosion can readily disable the system as a result of broken piping, for instance.”

“I noted that with great interest,” Walker said.

The report found that major improvements in the refinery’s firefighting system, scheduled for 1989, would enable employees to pour 15,000 gallons of water a minute on a major hydrofluoric acid release.

That sort of capability could compensate for the destruction of a fixed fine-water spray system, the report said. But the consultants cautioned that this sort of firefighting tactic “takes time and such a delay might be too late. . . . “

Refinery manager Robb said that one recommendation pertaining to the safe use of hydrofluoric acid--providing two safety valves in a line to prevent leakage--usually is considered unnecessary duplication.

Leakage of hydrofluoric acid into a tank where it reacted violently with a potassium caustic is the probable cause of the thunderous explosion and 2-day fire at the refinery in November, 1987, during which an estimated 100 pounds of hydrofluoric acid was released.


Robb conceded in an interview that the danger of hydrofluoric acid might justify the use of two valves in the alkylation unit, where the acid is used.

Some of the recommendations regarding hydrofluoric acid in the Gage-Babcock report are highly technical in nature. They advocate, for example, that specific tanks be fitted with an extra relief valve and fluid level gauges, or that bypass systems for certain tanks be installed to limit any release of the substance.

Some of the recommendations and observations appear to be obvious, however.

For example, the report urges Mobil to check the foundations of storage tanks to make sure they meet earthquake standards.

And the consultants noted on an inspection trip that they could smell acid fumes 30 feet away from a neutralization pit in the alkylation unit, although the area was being continuously hosed with water. The report declared the pit “inadequate,” and reported that Mobil said it is “planning to upgrade this system.”

A LOOK AT HYDROFLUORIC ACID Hydrofluoric acid is a clear colorless liquid with a boiling point of 67 degrees; it forms hydrogen fluoride gas at that temperature. In a refinery, it is used as a catalyst to boost the octane of unleaded gasoline.

A series of industry-sponsored tests in 1986 showed that a major release of the acid could produce a ground-hugging cloud of hydrogen fluoride gas that could be lethal as far away as 5 miles.


About 100 gallons were released in a 2-day fire in November, 1987, at the Mobil refinery.

In December, Councilman Dan Walker wrote an initiative measure to sharply restrict storage of the chemical in Torrance. The measure would limit storage of it to 250 gallons; Mobil had 29,762 gallons on hand last month.


Concentration in parts per million0.5 to 3 p.p.m. Effects Threshold at which it can be smelled. Concentration in parts per million2 p.p.m. EffectsA worker exposed repeatedly for 6-hour periods may feel stinging in the eyes, nose and face. Concentration in parts per million3 p.p.m. Effects A single exposure over 8 hours at this average concentration will not harm the average worker,according to OSHA. Concentration in parts per million More than 10 p.p.m. Effects Possible lung injury. Concentration in parts per million 20 p.p.m. Effects Poses an immediate danger to life and health; may cause unconsciousness after a 30-minute exposure. Concentration in parts per million More than 50 p.p.m. Effects Vapor is intolerably irritating, damages lungs and may cause serious injury. This concentration is lowest level known to be lethal for someone exposed for 30 minutes. Concentration in parts per million 110 p.p.m. Effects Lowest level known to cause harmful effects after a 1-minute exposure.