Process Hazard Analyses of Control and Instrument Systems

摘要

The OSHA process safety management (PSM) and EPA risk management program (RMP) standards require that process hazards analyses (PHAs) be performed on processes that contain listed toxic or flammable chemicals. A number of PHA techniques are listed in both standards that can be used to satisfy this requirement. Typical PHA studies use analysis techniques such as hazard and operability (HAZOP), what-if, and checklists to review the hazards of a process. Typically, the PHA study reviews items such as deviations from normal process conditions of flow, temperature, pressure, etc. The influences of control and instrument system failures on the process system safety are usually considered indirectly. This paper reviews some of the considerations needed to conduct a PHA that includes control and instrument system failures. Information on (1) how to organize the review analysis team, (2) what type of documentation is needed, and (3) the special considerations needed in a control and instrument system review are included in this paper. The wide use by the chemical process industry of advanced programmable and electronic systems introduces a number of special considerations that must also be included in a control and instrument system review. These considerations are also discussed in this paper.