Assessing risk in risky times

Risk assessment has been part of the chemical engineering scope for years. The possibilities of an attack might have changed, but the consequences — a runaway reaction, a spill, etc. — are the same.

By Nick Basta

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Later this month in Scottsdale, Ariz., the Center for Chemical Process Safety (CCPS), an industry alliance organized by the American Institute of Chemical Engineers, will hold its annual International Conference. The world's experts will gather to discuss a specialized topic: analyzing the risks of, and protective measures against, runaway reactions, process upsets, spills and vapor cloud emissions that are unique to the process industries.

It could hardly be more timely to address some of the issues of a worried nation. "Risk" has taken on a new dimension in these terror-tinged times. Billions of dollars have been spent since 9/11 to harden the perimeters around high-risk buildings, including chemical plants. To chemical process safety professionals, the possibilities of a hostile attack might have changed, but the consequences,"a runaway reaction, a spill or a vapor cloud,"are the same.

"We ask ourselves, what is the likelihood of a particular release scenario," notes Irv Rosenthal, outgoing board member of the Chemical Safety and Hazard Investigation Board, a federally chartered agency that conducts investigations of major plant accidents. "Once a release occurs, we have the tools to analyze those consequences."

The point is an important one, because the concerns over catastrophic releases ," accidental or not,"have generated several efforts in Congress to mandate, in some fashion, so-called "inherently safer" technologies. For the most part, industry resisted this push.

Risk assessment has been part of the chemical engineering scope for years. The Environmental Protection Agency has been responsible for the regulatory review of risk management plans (RMPs) since 1996, and the Occupational Safety and Health Administration has mandated the development of process safety management (PSM) plans since 1992.

"A concept like inherent safety requires a proper understanding of risk, hazards, and the consequences of losing containment or control of hazardous materials and energies," says Robert Johnson, a principal with Unwin Co.,Columbus, Ohio, and a speaker at the upcoming CCPS meeting. In essence, the risk of an event must be weighed both in terms of its severity of consequences and its likelihood of occurrence. "Under such programs as PSM, many companies have successfully made their facilities inherently safer by reducing inventories of hazardous chemicals," he notes.

However, he cautions that hazard reduction is not synonymous with risk reduction. A company could have one large chlorine storage vessel (high-consequence), or could use many smaller cylinders (lower-consequence). However, the likelihood of an accidental release is usually greatest when storage containers are being hooked up or disconnected from processes; these connections are more frequent when smaller containers are being used. "Inherent safety does not automatically translate into lower risk," Johnson concludes.

Both the PSM and RMP regulatory programs, which deal with risk assessment and safety improvements, borrow from the Responsible Care program of the American Chemistry Council (ACC), which originated in the post-Bhopal years of the late 1980s. ACC was at work on an expansion of Responsible Care around 9/11, and was able to publish its Site Security Guidelines for the U.S. Chemical Industry in October 2001. By the beginning of 2003, all 120 "highest priority" chemical plants among the ACC membership completed security assessments; approximately 500 ACC-member facilities had done so through July, 2003.

Meanwhile, ACC has supported Senate bill S.994, the Chemical Facilities Security Act under current consideration, mindful that it may bring the new Department of Homeland Security into the risk-assessment mix.

Are the process industries safer today? The answer is not clear-cut. While workplace accidents and illnesses have declined in recent years, there is not a one-to-one correspondence between plant safety and worker safety, say industry experts. Databases of actual industrial spills or explosions are complicated by transportation data, natural disasters and other incompatible results.

"Major companies have had to come to terms with reactivity hazards and risk assesment," says CCPS director Scott Berger. "Smaller companies sometimes don't know what they don't know when it comes to hazards." says Scott Berger, director of CCPS. "The tools are out there; it's a matter of applying them."

Nick Basta is editor at large for Chemical Processing magazine. E-mail him at nbasta@putman.net.

 

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