Issue Date: July 23, 2012
Chemical Safety Board Video Urges Chemical Companies To Use Inherently Safer Design
To prevent or limit death and damage from plant accidents, chemical companies should weave inherently safer process design into corporate planning, says the Chemical Safety & Hazard Investigation Board (CSB) in a new video.
The 11-minute safety video underscores the importance of using basic safer processes and shifting to less hazardous materials in chemical manufacturing, rather than adding more complex process controls to improve safety.
CSB released the video on July 11. It was triggered by recommendations of a National Academy of Sciences report that Congress ordered and CSB commissioned in 2009. NAS just completed the report in May. NAS finds great benefits in using inherently safer design processes, but companies do not always use them (C&EN, May 21, page 5).
CSB identifies four principles to guide manufacturing managers and engineers: replacing one hazardous material with another that’s less hazardous; minimizing amounts of hazardous material used in a manufacturing process; moderating process conditions, such as by lowering pressures or temperatures, to make processes safer; and simplifying processes so they are less prone to failure.
“The first choice after an accident is to say how we can improve the design so this can’t happen,” Trevor Kletz points out in the video. Kletz is an author, a retired chemical engineer with 35 years of experience, and the developer of the concept of inherently safer design processes. “Very often you can change the design, often very cheaply and very easily, but people don’t do it,” Kletz adds.
A failure to make changes proactively is what led to several accidents discussed in the video. One was the focus of the NAS report: a 2008 explosion at the Bayer CropScience pesticide plant near Charleston, W.Va., that killed two workers and injured eight others. Debris came close to striking a storage tank holding 13,000 lb of methyl isocyanate (MIC), a highly toxic intermediate that caused thousands of deaths in 1984 when it leaked from a chemical plant in Bhopal, India.
Since 1984, Bayer and previous owners of the West Virginia plant had been considering eliminating use and storage of MIC at the facility but did not do so, the CSB video notes. At the time of the 2008 accident, the facility was the only one in the U.S. that produced and stored large quantities of MIC. After the incident and because of the CSB investigation and community pressure, Bayer began reexamining its use of MIC, the video points out. But the company opted to keep using the hazardous chemical and planned to reopen the damaged unit.
A lawsuit filed by community members led to a court order blocking Bayer from restarting the unit, according to the video. Meanwhile, the U.S. Environmental Protection Agency and Bayer reached an agreement for the company to phase out production of carbamate pesticides made from MIC. And in March 2011, Bayer announced it would end MIC use at the West Virginia plant.
NAS, however, broadened its investigation to include the application of inherently safer design to the chemical industry.
CSB believes strongly in inherently safer design and in expanding industry’s use of the approach, board Chairman Rafael Moure-Eraso has repeatedly said. That view is reflected in the board’s work. For example, the video points to a study by NAS panel member Paul Amyotte, a chemical engineering professor at Dalhousie University in Halifax, Nova Scotia, that found more than 90 references to the application of inherently safer technologies in CSB reports.
Inherently safer design is a “philosophy for design and operation of any technology, including chemical processing,” NAS panel member and longtime chemical engineering consultant Dennis Hendershot stresses in the video. “It is not a specific technology or a set of tools and activities, but it’s really an approach to design and it is a way of thinking.”
Both Hendershot and Amyotte emphasize that the approach should be built into manufacturing processes, not added on.
The approach has recently been applied successfully to a common industrial construction practice that uses natural gas to clean pipes, the video says.
In February 2010, during construction of the Kleen Energy natural gas power plant in Connecticut, six workers died when natural gas they were using to clean pipes accumulated and exploded. “We were surprised to learn that such an unsafe procedure was commonly used throughout the electric power industry,” says Dan Tillema, a CSB investigator, in the video.
After an investigation, CSB recommended an industry-wide shift to the use of compressed air to clean pipes. In this case, the inherently safer design-based recommendation met with success. It was incorporated into Connecticut construction laws and is now included in industrial fire codes.
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