OH CR4P!

Chemical plants have been the sites for some of the worst industrial disasters. Although rare, the potential for major catastrophes is much higher when dealing with dangerous and volatile chemicals. Accidents usually happen when people lack or lose respect for the power of the substances they handle. Flixborough, Bhopal, Oppau, and Toulouse are some of the names that may come to mind.

(Image Credit: Seastar Chemicals, Inc.) -->

But chemical accidents are not just a thing of the past. Recently, there are signs that oil company Citgo may not be properly handling its hydrofluoric acid (HF). A series of acid leaks at a refinery in Corpus Christi, Texas, is being investigated by the Chemical Safety & Hazard Investigation Board (CSB). While nobody was injured from the leaks, there is concern since the company has a history of issues with HF.

Hydrofluoric Acid - Don't Mess With It

Refineries like the one in question use hydrofluoric acid as an alkylation catalyst for making high-octane fuels. About one-third of all U.S. refineries (around 50) use the acid. Hydrofluoric acid is also an etchant and cleaner used in pickling processes and rust removal applications to remove oxides.

While many acids can be hazardous in their concentrated forms, hydrofluoric acid is among the most dangerous. Although by chemical definition it is considered a weak acid (due to its lower tendency to dissociate), it is incredibly corrosive and toxic. In concentrations near or above 50%, it can cause severe chemical burns, blindness (if exposed to the eyes), systemic poisoning (which can cause death), and tissue damage. In lower concentrations, pain from skin contact may not even occur until hours after exposure, making it potentially even more dangerous.

Not your typical chemistry class acid burn… These were not evident until a day after the incident. (Image Credit: Wikipedia - Dr. Charles Eaton, www.eatonhand.com)

Treating HF surface burns requires rinsing with calcium gluconate or a similar source of calcium ions which will sequester the fluoride ions released from the acid. Further medical treatment is typically needed because the substance absorbs through the skin, and (in high doses) can lead to severe calcium depletion which causes cardiac arrest.

A History of HF Problems

The refinery's problems with HF started in July 2009, when an accident and intense fire injured two workers and resulted in the release of 4,000 lb. of HF from the alkylation unit. Since then, the site has had four smaller leaks of HF, one in September of 2011 and the others in March of this year. The company noted to officials that no fires occurred as a result of these leaks and that its safety improvements since 2009 "helped our refinery team and the local fire department respond quickly and ensure the safety of our workers and our neighbors."

(Image Credit: CSB.gov) -->

The Corpus Christi refinery is not the only one under scrutiny for hydrofluoric acid accidents. CSB data shows that several refinery accidents it is currently or has investigated have involved HF. The potential dangers of HF have put other refinery accidents under the microscope of labor unions looking to replace HF with less dangerous alternatives. The March 6, 2011 explosion at Valero Energy refinery in Memphis is the leading case. While HF was not the cause of the blast (which killed one worker and badly burned two others), it could have affected more than 700,000 people living near the city if its stores had been released.

Slow Resolutions

The CSB is currently overwhelmed with investigations because of the ever-growing workload amidst an annual budget that has been stagnant for years. Because of its lack of resources, CSB has declined to review the Valero accident. It will continue its work on 14 ongoing accident investigations, many of which are several years old and seven of which involved refineries.

Labor unions and community groups are also seeking to replace both hydrofluoric acid and sulfuric acid (another alkylation catalyst), pushing for refineries to explore the effectiveness of solid state catalysts and other alternatives.

But like with most alternatives, my guess is it will be some time before any of them become viable enough to predominantly replace HF and sulfuric acid. The best fix, for now at least, is to ensure that refineries are taking the steps to improve safety practices and prevent future problems with these dangerous chemicals.

References

C&EN Magazine (April 2, 2012) - Hydrofluoric Acid Safety

CSB.gov