Safety Considerations in the Chemical Process Industries

Abstract

The chemical industry is one of the safest industries, but its safety record in the eyes of the public has suffered. Perhaps this is because sometimes when there is an accident in a chemical plant it is spectacular and receives a great deal of attention. The public often associates the chemical industry with environmental and safety problems, which results in a negative image of the industry.

Process safety is important because good process safety performance, the lack of major process safety incidents, allows a company the freedom to manage its business without the interference of government regulators, litigation, and adverse public opinion. By avoiding injuries to people, major property loss, and business interruption loss, process safety results in the creation of positive business value for a company. The actions that are required to manage process safety well are the same actions required to manage business well.

Occupational Safety Versus Process Safety

It is important to differentiate between occupational safety which involves accident prevention through work systems which are aimed at minimizing the risk of injury to workers and process safety which involves the prevention and mitigation of fires, explosions, and accidental chemical releases that can have far-reaching impacts. Occupational safety focuses on the prevention of worker injuries and occupational illness, primarily relating to trips, slips, falls, cuts, burns etc. These injuries result from the failures in the control of traditional work procedures. Process safety focuses on the prevention of leaks, spills, process upsets, toxic releases, and equipment failures which may or may not injure or result in fatalities to workers or others at or near the site. This chapter deals primarily with process safety.

Process Safety Technology Issues

The Internet provides considerable information on incidents, good industry practice, and design guidelines. The best practices in industry are briefly discussed in this chapter. Details are readily available from resources listed in the references section at the end of the chapter. Hazards from combustion and runaway reactions play a leading role in many chemical process accidents. Knowledge of these reactions is essential for the control of process hazards. Much of the damage and loss of life in chemical accidents are caused by a loss of containment that results in a sudden release of hazardous material at high pressures, which may or may not result in fire; so it is important to understand how loss of containment and sudden pressure releases can occur. Loss of containment can be due, for example, to ruptured high pressure tanks, runaway reactions, flammable vapor clouds, or pressure developed from external fire. Fires can cause severe damage to people and property from thermal radiation. Chemical releases from fires and pressure releases can form toxic clouds that can be dangerous to people over large areas. Static electricity often is a hidden cause of accidents. It is very important to understand the reactive nature of the chemicals involved in a chemical facility.

Process Safety Management Issues

Chemical process safety involves both the technical and the management aspects of the chemical industry, and this chapter addresses both. It is not enough to be aware of how to predict the effect of process hazards and how to design systems to reduce the risks of these hazards. It also is important to consider how chemical process safety can be managed. Technical and management people at all levels in an organization have process safety management responsibility and can contribute to the overall management of safer chemical processing plants.

Loss of containment due to mechanical failure or misoperation is a major cause of chemical process accidents. The publication One hundred largest losses: a thirty year review of property damage losses in the hydrocarbon-chemical industry (M&M Protection Consultants, 12th edn, Riverside Plaza, Chicago, 1998) cites loss of containment as the leading cause of property loss in the chemical process industries.

It has become clear that process safety can be and must be managed as any other part of the business. A process safety management system is focused on preparedness for the prevention and mitigation of catastrophic releases of chemicals or energy from a process associated with a facility. It also includes the response to and restoration from these events. The term process safety management was first recognized on a broad scale in the late 1980s after Bhopal (see case histories). It formed the basis for many of the American Institute of Chemical Engineers’ Center for Chemical Process Safety’s guideline books and eventually led to US regulations (OSHA PSM) in 1992.