In the last 20 years, process hazard analysis (PHA) techniques, particularly hazard and operability (HAZOP) studies, and formal maintenance and reliability methods, such as reliability centered maintenance (RCM) based on failure modes and effects analysis (FMEA), have developed in the chemical process industries. Often these techniques have been developed and promoted by different organizations within a company, and the studies are often done independently. In practice, HAZOP and FMEA techniques have much in common, and a combined study offers opportunities for greater efficiency and higher quality from both the process safety and reliability/maintenance point of view. In this paper, we will review the development of HAZOP and RCM methodologies at Rohm and Haas, and in the chemical process industry in general, and offer suggestions on how to integrate the two types of studies.


Hazard and operability (HAZOP) analysis has a well-deserved reputation for systematic and
thorough evaluation, and it has become the tool of choice in the chemical and hydrocarbon
processing industries for performing qualitative hazard/risk evaluations of processes. In
principle, both operability and reliability considerations have been a part of the HAZOP
methodology from its inception. Initially, many companies easily justified process hazard
analyses on the basis that the economic benefits of finding and correcting process
weaknesses through HAZOP far outweighed the cost of the analysis. Unfortunately, in
recent practice, regulatory compliance obligations and increased concern with major incident
prevention have resulted in a de-emphasis of the operability aspects of HAZOP in many
organizations. At the same time, the maintenance and reliability groups in many companies
have recognized the economic benefits of organized approaches to establishing maintenance
programs. Techniques such as reliability centered maintenance (RCM), based on failure
modes and effects analysis (FMEA), have been implemented to improve plant reliability and
maintenance cost-effectiveness. This has resulted in a duplication of effort by different
groups in the same organization, arising from separate RCM and HAZOP studies. Rohm
and Haas has successfully combined HAZOP studies with RCM studies to increase
efficiency and improve the quality of both reviews.

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