ARCO chemical's HAZOP experience



Of all the analytical tools available to the process safety professional, perhaps the most critical are those used to identify and analyze process hazards. Such tools have been collectively referred to as “Hazard Evaluation Procedures” by the Center for Chemical Process Safety (CCPS) and as techniques for “Process Hazard Analysis” (PHA) by the Occupational, Safety and Health Administration (OSHA).

One of the best known PHA tools, the Hazard and Operability or HAZOP study, emerged over two decades ago in ICI, U.K., and its use has since spread over six continents. In 1979, ARCO Chemical piloted its first HAZOP and since then, HAZOPs have become the backbone of the company's Process Hazards Review procedure.

Repeated use of the HAZOP technique since 1979 has resulted in an affirmation that to be “successful”, much more was needed than simply executing the HAZOP technique. Success is dependent upon the preparation and planning effort that precedes the HAZOP, and the follow-up activity that ensures implementation of study findings. Unlike the study technique, little information was available in 1979 on how to design the framework, or management system, that was needed to support the use of this tool.

The purpose of this paper is shift focus from executing the HAZOP technique to that framework, by presenting insights that have accumulated from using the technique in ARCO Chemical, especially during the period 1979 through 1986. These were the formative years, during which the company's advancement on the learning curve was most noticeable. These were the years that convinced the company that successful HAZOP studies do not just happen; success comes from building the right management system. Success must be defined and assured at each step in a Process Hazards Review procedure, of which executing the HAZOP technique is only one.