Reliability Engineering and System Safety 29 (1990) 5-14

Tools for Analysis and Tools for Action: A History of the Projects and Publications of the Center for Chemical

Process Safety

T h o m a s W. C a r m o d y

Center for Chemical Process Safety, American Institute of Chemical Engineers, 345 East 47th Street, New York, New York 10017, USA

A BS TRA CT

The American Institute of Chemical Engineers created the Center for Chemical Process Safety in 1985 to help prevent catastrophic chemical accidents. To fuifill its charter of improving safety in the manufacture and handling of chemicals, the Center has devoted itself to establishing and publishing the latest scientific and engineering practices (not standards)for prevention and mitigation of incidents involving toxic and/or reactive materials. The Center encourages the use of this information not only through these publications, but also through seminars, symposia and continuing education programs for practicing engineers, and through the development of materials for undergraduate engineering education curricula. To advance the state-of-the-art in engineering practices, the Center also sponsors research in the prevention and mitigation of catastrophic events. This article surveys the history of projects the Center has undertaken and the publications it has issued since its inception.

I N T R O D U C T I O N

The accident in Bhopal, India, on 3 December 1984, focused public concern around the world on the safety of the chemical industry. In late December of that year, leaders of the American Institute of Chemical Engineers (AIChE) discussed the public's concerns and how the Institute might address them. It was in these discussions that the idea of the Center for Chemical Process Safety evolved.

Since chemical engineers design, build and operate chemical plants, the officials decided that AIChE was the logical sponsor for such a center.

5 Reliability Engineering and System Safety 0951-8320/90/$03"50 © 1990 Elsevier Science Publishers Ltd, England. Printed in Great Britain

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AIChE leaders proposed the Center for Chemical Process Safety concept to officials of government agencies involved in the regulation of environmental and safety matters. They greeted the idea with interest, so AIChE next approached industry leaders to gauge their response.

On 26 February 1985, 13 representatives of leading chemical and petroleum companies met with AIChE officers to discuss the proposed center. The participants agreed to form a task force to study the safety center concept and the issues of chemical process safety more fully.

Dr Harold S. Kemp, a retired DuPont executive and then AIChE vice- president, was chosen to chair the task force. Joining him were eight senior health and safety managers from the companies represented at the meeting. In subsequent sessions, the task force defined the Center's goals. In a 'Mission Statement', the task force said: 'The immediate application of the knowledge and talent of chemical engineers and related scientific disciplines can develop the information urgently required to provide the basis for needed regulation, improved industrial practices, and other measures directed at minimizing public risk resulting from accidents that occur in the manufacture and handling of toxic and/or reactive materials'.

The task force recommended that a Center for Chemical Process Safety be established and operated by AIChE and financially supported by grants from industry, foundations and the US government. The group also suggested that AIChE establish an advisory board of prominent individuals from various public and private sector constituencies.

At a meeting in Houston, Texas, on 25 March 1985, AIChE's governing Council approved the plan to establish the process safety center.

HAZARD EVALUATION BECOMES INITIAL FOCUS

The Center's original mandate dealt with four issues considered 'crucially important to minimizing risks to chemical industry employees and the general public', according to Dr John P. Sachs, 1985 president of AIChE. At a meeting in April of that year, Sachs listed those four issues as: hazard evaluation procedures, bulk storage and handling of toxic or reactive materials, plant operating procedures and safety training. 'These issues explore the areas which have concerned both the chemical industry and the general public since the accident in Bhopal', Sachs observed.

In an informal canvas of chemical engineers and chemical industry executives, 'everyone agreed that acceptable practices for hazard evaluation procedures should get top priority', Sachs said. He added that action on other items would logically flow from this initial area of inquiry.

In October 1985, the Center issued Guidelines for Hazard Evaluation

Tools for analysis and tools for action 7

Procedures. The recommendations in the book were based upon the belief that 'actions to . . . improve safety are no better than the extent to which hazards are recognized'.

The guidelines concentrated on hazards involving the release of flammable, combustible, highly reactive or toxic materials in amounts sufficient to endanger the health and safety of chemical plant employees and neighboring communities. The culmination of the 6-month-old Safety Center's first project, the guidelines reviewed procedures being used by many chemical and petrochemical companies in the United States, Canada and Europe. Researchers at Battelle Columbus Laboratories studied and edited these procedures to develop the guidelines.

While labeling adherence to good practices of the past an important approach to hazard evaluation and control, the book's editors devoted much of their attention to 'predictive hazard evaluation'. Where materials or methods which differ from established practice are employed, the volume offered procedures for predicting potential hazards through systematic, element-by-element examination of the process or plant.

NEW DIRECTOR AND NEW DIRECTIONS

While its first project was underway, the Center also took steps to establish liaison relationships with other professional societies and trade associations to keep up to date on activities and needs in the process safety area. In this way, the Center wanted to avoid duplication of effort and obtain current input for its own work. But, unlike the trade associations with which it has interacted, the Center has involved itself in technical issues only, not in public policy.

The Center also began the search for a permanent director. In late 1985, I was fortunate to be appointed to that post. I was at that time a former corporate director of product safety for Union Carbide.

My first major task was organizing a crucial fundraising drive. I also began to focus the Center's activities on scientific and engineering practices that could prevent or mitigate episodic events involving the release of toxic and reactive materials.

My experience in industry had taught me that most chemical process safety issues were already being adequately addressed. Loss prevention, personal safety and occuoational safety were all well-established areas of safety expertise. But, there was not a well-established, widely used body of engineering knowledge relative to the prevention of episodic events. So, for the past several years, the Center has emphasized new, 'high-tech' engineering practices--such as vapor cloud modeling and quantitative risk

8 Thomas W. Carmody

assessment--work our advisory board believes to be distinctive and essential.

Since 1985, the Center's list of research projects, publications, meetings and educational activities has grown. More than fifty companies and foundations have signed on as sponsors or associates of the Center. They come from all aspects of the process industries and from many firms not normally considered part of this industrial group.

PUBLICATIONS

Since the publication of Guidelines .]or Hazard Evaluation Procedures in 1985, the Center has added six more volumes to its continuing series of safety guidelines.

Guidelines for Use of Vapor Cloud Dispersion Models was the second CCPS publication to make an appearance. It represents an effort to provide engineers with the information they need to model emissions of hazardous materials both at the source and downwind. The book offers an overview of problems and modeling procedures, followed by sections which examine input data, source emission models, transport and dispersion models, and model evaluation and uncertainty. Appendices listing and describing operational models based on questionnaires sent to model developers, and hypothetical hazardous chemical release scenarios suggested by industry representatives, are also included. The guidelines point out that gaps exist in current technology and that further research, into models for two-phase jets, for example, is needed. The project which resulted in the development of the dispersion model guidelines was originally chaired by Gary Page of American Cyanamid and more recently headed by Rudolf Diener of Exxon Research and Engineering. The text was prepared by Sigma Research Corporation.

Early last year, we published a Workbook of Test Cases jor Vapor Cloud Dispersion Models, which offers release scenarios, overviews of equations and models, and the application of models to the sample scenarios. Those scenarios include an elevated continuous release of dense normal butane gas, a release of liquid ammonia from a pressurized tank, and a release of liquid acetone into a diked area. Steven Hanna and David Strimaitis put the workbook together.

'The safe storage and handling of high toxic hazard materials (HTHMs) require a sound and responsible management philosophy, together with a combination of superior siting, design, fabrication, erection, inspection, monitoring, maintenance, operation and management of such facilities.' These words appear in the preface of Guidelines for Safe Storage and

Tools for analysis and tools for action 9

Handling of High Toxic Hazard Materials. The editors go on to say: 'These elements are necessary parts of a reliable system to prevent equipment or human failures that might lead to the release of, and possible acute exposure of the public or on-site personnel to, HTHMs. These guidelines deal with all these elements including references for mitigating the impact of such releases should they occur'. Overseen by the Center's Storage and Handling Subcommittee, under the leadership of Robert Smith of Dow Chemical, the guidelines were prepared by Arthur D. Little, Inc.

Guidelines for Vapor Release Mitigation describes methods of detecting, containing and isolating accidental releases with stacks, scrubbers, flares, incinerators and other devices and countermeasures. The volume also examines procedures for developing emergency plans. The product of work by the Mitigation Subcommittee, chaired by Stanley J. Schechter of Rohm and Haas, much of the volume focuses on the role of engineering design in accident mitigation. While designers of chemical processes consider minimal inventory of hazardous materials a desirable goal, even a minimum of material can create a dangerous environment. These guidelines should help engineers build equipment that minimizes the chance of an accident or the rate or duration of a leak, should one occur.

Guidelines for Chemical Process Quantitative Risk Analysis is one of our recent additions. This new volume builds on Guidelines for Hazard Evaluation Procedures and is designed to provide the engineer with the information he or she needs to determine the quantitative risk from a hazard. After an introduction to the fundamentals of quantitative risk assessment (a good overview for management), these guidelines detail event- probability and failure frequency analysis, including fault trees, event trees, common-cause failures, human errors and external events. Tutorials and case studies that teach the user how to handle simple assessments and how to identify those more complex assessments that require outside consultation round out the text.

Another risk assessment entry in the series is Guidelines for Process Equipment Reliability Data, with Data Tables, which supplements Guidelines for Chemical Process Quantitative Risk Analysis with failure rate data. It contains data in our Generic Failure Rate Data Base, information on several generic data resources, and procedures to develop failure rate data using information from the plant and process studied. A CCPS Taxonomy was developed for this volume as a step toward collecting and collating equipment reliability data for the entire CPI.

As we all know, a company can no longer continue practices and operations that present unacceptable levels of risk to the public, customers or in-plant personnel. Putting a quality chemical process safety management program in place reduces risks, protects people, offers economic rewards,

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and helps preserve our natural environment. Another of our new books, Guidelines for the Technical Management of Chemical Process Safety describes the elements that must be considered in the development of a management system in the context of plant design, construction and operation. We're also offering a special course to complement these guidelines, specifically geared to the manufacturing, engineering and research directors and managers who are charged with safely manufactur- ing, using and handling hazardous materials.

Of course, a number of other titles are in the works, including ones which will deal with handling emergency release effluents and the control of hazardous chemical processes.

RESEARCH PROJECTS

In developing its 'Guidelines', the Center has come to believe that it should expand its research. For example, development of the Guidelines for Use of Vapor Cloud Dispersion Models revealed an important need for additional study.

In the area of vapor cloud research, there are a number of gaps in our understanding of the behavior of highly toxic and flammable gas clouds that can form during process accidents. The Center will develop information that will allow engineers to predict that behavior more accurately. Such knowledge will help mitigate, dilute or disperse these clouds should a release occur. In this way, safety and health hazards to the community beyond the fence and to the environment will be reduced.

The subject of vapor cloud research is so broad, and the needs are so great, that the Center is coordinating its efforts with other organizations, including the US Environmental Protection Agency, the Chemical Manufacturers Association, the American Petroleum Institute, the Chlorine Institute, the Fertilizer Institute and a variety of groups abroad.

The Center is conducting its multi-year vapor cloud research program in two stages. The first stage consists of model development; the second, data acquisition and model validation. A generic model that describes aerosol formation and behavior has been developed. The model will predict when an accidental release can result in an aerosol, characterize the resulting aerosol by amount and particle size and distribution, and detail the disposition of the aerosol through evaporation, fall-out, or other means. This generic model will be the basis for more specific source-term models for dealing with such two-phase flow phenomena. The validation of the models will be experimental--a series of small-scale releases of specific materials. Studying the behavior of the materials, determining conditions at which aerosols form

Tools for analysis and tools for action 11

and the amount and particle size of the aerosol will allow verification of the computer models.

In other areas, the Technical Process Safety Management Subcommittee has identified two projects to help executives better manage for safety. The first deals with the cost-effectiveness of technical management programs. The Center will work to develop ways to relate technical management programs, including preventive maintenance, employee training and hazard evaluations, to profitability and return on investment. In a similar manner, the second research project will examine ways to measure the effectiveness of safety audits. Because on-going audits can be so expensive, some method for measuring their economic benefits is called for. Proving the effectiveness of measures aimed at preventing major chemical accidents will build management support for such programs.

In the past, AIChE's Design Institute for Emergency Relief Systems has conducted research on the effects of specific temperatures and pressures on the flow of materials through safety devices, like valves and rupture disks. This research has demonstrated that, in emergencies, two-phase flashing flow may occur and these safety devices, sometimes designed for single-phase flow, may not be adequately sized. Emergency releases of toxic materials to the atmosphere are no longer acceptable. They must be treated with equipment such as scrubbers, flares and knock-out drums. The Center believes that parameters for the design of devices which treat materials in emergencies should be more clearly defined, particularly for two-phase flow, and is developing a specific research program in this area.

MEETINGS

Since its founding, the Center has sponsored a number of international safety conferences.

In February 1987, 500 engineers and other professionals from government, industry and academia met in Washington, DC to discuss ways of improving the safety of chemical plants and processes. Sponsored by the Center, the US Environmental Protection Agency and the World Bank, the International Symposium on Preventing Major Chemical Accidents featured a keynote address by Lee Thomas, EPA administrator. Among other speakers were: John Moore, assistant EPA administrator for pesticides and toxiesubstances; Geraldine Cox, vice-president and technical director of the Chemical Manufacturers Association; Fred Millar, director, toxic chemical safety and health project, Environmental Policy Institute; and G. Thyagarajan, director of the Council of Scientific and Industrial Research in India. The program examined hazard identification, the safe

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storage and handling of chemicals, and human factors in accident prevention, among other topics.

An International Conference on Vapor Cloud Modeling, sponsored by the Center, the (British) Institution of Chemical Engineers and the US Environmental Protection Agency, was held in Cambridge, Massachusetts, in November 1987. Three hundred and fifty engineers focused on field-scale testing, vapor cloud dispersion models, recent developments in vapor cloud modeling, and fire and explosion modeling.

Building on the experience of these two 1987 meetings, the (British) Institution of Chemical Engineers, in association with the Center and the World Bank, sponsored 'Preventing Major Chemical and Related Process Accidents' in May 1988. The symposium concentrated on managerial control, regulatory control, Third World needs, and the assessment and control of major hazards. Plenary addresses were delivered by representa- tives of the European Economic Community, the International Labor Organization, a wide variety of national governments' agencies, including the US EPA and the United Kingdom Atomic Energy Authority, and major universities and companies.

In Cambridge, Massachusetts, in March of last year, the Center and the (British) Institution of Chemical Engineers cooperated in presenting the 'International Symposium on Runaway Reactions'. The program focused on the prevention of uncontrolled chemical reactions and state-of-the-art methodology in theory, testing methods and applications.

And, in January, in cooperation with the EPA, we sponsored a 'Chemical Process Safety Management Conference' in Atlanta, Georgia. Sessions expanded on the 12 central technical elements of process safety manage- ment which were identified in 'Chemical Process Safety Management: A Challenge to Commitment', a 1988 CCPS brochure. EPA recommendations to Congress on Section 305(b) of Title III of the Superfund Amendments and Reauthorization Act were also reviewed.

EDUCATION

In 1987, the Center created an Undergraduate Education Committee to encourage the integration of safety and health concepts into existing chemical engineering curricula. At the suggestion of educators who are advising the committee, the Center directed its efforts to the development of homework problems.

The problems, which present practical industrial examples of such concepts as storage and handling of hazardous materials, toxicology and industrial hygiene, fire protection and release mitigation can be used in various undergraduate chemical engineering courses as individual assign-

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ments or class projects. They are designed to be self-standing and include an introduction describing the safety concept and chemical engineering principle demonstrated. Instructors are provided with background information and the problems' solutions.

All available problems are listed on a matrix which identifies the loss prevention principle demonstrated and suggests the engineering course where it may be used. For example, a professor of fluid mechanics can choose a problem of toxic exposure relating to a ventilation system. A professor of kinetics can use a problem illustrating runaway reaction temperature. A professor of thermodynamics can select a problem of unconfined burning of a vapor cloud or a heat transfer class might calculate the required venting rate of a flammable solvent tank in the event of a fire in the immediate area.

Nineteen problems, which, in addition to the topics mentioned above, cover process controls, properties of materials, explosions and inerting and purging, are currently being tested at 20 universities. The committee plans to develop a total of 100 problems teaching 37 safety and health concepts.

In other educational activity, under the Center's sponsorship, AIChE has scheduled 12 courses in its 'CCPS Series' of continuing education programs.

IN CONCLUSION

AIChE has a history of offering corporations and government agencies the opportunity to join together in cooperative sponsorship of needed research. The Center for Chemical Process Safety is the largest example of these endeavors. It has been a privilege to be a part of CCPS and the contributions it's making to the safety of many industries. But, needless to say, these contributions could not be made without the dedication of many people in industry who have volunteered their time and efforts to our Technical Steering Committee and our various project subcommittees. This history has really been a chronicle of their efforts.

BIBLIOGRAPHY

Arthur D. Little, Inc. & LeVine, R., Guidelines for Safe Storage and Handling of High Toxic Hazard Materials. CCPS, American Institute of Chemical Engineers, New York, 1987.

Battelle Columbus Division, Guidelines for Hazard Evaluation Procedures. CCPS, American Institute of Chemical Engineers, New York, 1985.

'Chemical Process Safety Management: A Challenge to Commitment.' CCPS, American Institute of Chemical Engineers, New York, 1988.

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Guidelines for Chemical Process Quantitative Risk Analysis. CCPS, American Institute of Chemical Engineers, New York, 1989.

Guidelines for Process Equipment Reliability Data, with Data Tables. CCPS, American Institute of Chemical Engineers, New York, 1989.

Guidelines for the Technical Management of Chemical Process Safety. CCPS, American Institute of Chemical Engineers, New York, 1989.

Hanna, S. R. & Drivas, P. J., Guidelines for Use of Vapor Cloud Dispersion Models. CCPS, American Institute of Chemical Engineers, New York, 1987.

Hanna, S. R. & Strimaitis, D., Workbook of Test Cases for Vapor Cloud Dispersion Models. CCPS, American Institute of Chemical Engineers, New York, 1989.

International Conference on Vapor-Cloud Modeling (Conference Proceedings), CCPS, American Institute of Chemical Engineers, New York, 1987.

International Symposium on Runaway Reactions (Conference Proceedings). CCPS, American Institute of Chemical Engineers, New York, 1989.

Prugh, R. W., Guidelines for Vapor Release Mitigation. CCPS, American Institute of Chemical Engineers, New York, 1988.

Woodward, J. L. (Ed.), International Symposium on Preventing Major Chemical Accidents (Conference Proceedings). CCPS, American Institute of Chemical Engineers, New York, 1987.