PROCESS HAZARD ANALYSIS METHODS WITH EXAMPLES

0 PROCESS HAZARD ANALYSIS METHODS WITH EXAMPLES 

INTRODUCTION. The PSM Rule allows the use of several PrHA methods. DOE contractors should select the most appropriate methods for each facility or process and provide the rationale for their selections. Sometimes a combination of methods may be most appropriate. 

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Process Hazard Analysis (PHA) can be defined as the application of a systematic method to a process design in order to identify potential hazards and operating problems. It determines the causes and consequences of abnormal process conditions that arise from equipment failure, human error or other events. The goal is to determine whether opportunities exist to reduce the risks of the toll s hazards and then to implement warranted action items. The AJChE CCPS guideline Guidelines for Hazard Evaluation Procedures, Second Edition with Worked Examples is a good resource for fully detailed approaches to process hazard analysis. It provides an introduction to hazard evaluation as well as guidance on ... 

The term operability study should more properly be used for this type of study, though it is usually referred to as a hazard and operability study, or HAZOP study. This can cause confusion with the term hazard analysis or process hazard analysis (PHA), which is a similar but somewhat less rigorous method. Numerous books have been written illustrating the use of HAZOP Those by Hyatt (2003), AIChE (2000), Taylor (2000), and Kletz (1999a) give comprehensive descriptions of the technique, with examples. 

The HAZOP method is probably the most widely-used hazards analysis method. Even those who are not familiar with the hazards analysis process will often have heard of the term HAZOP, even if they are not really sure what it means. For example, when the PSM regulations in the USA were being promulgated in the early 1990s it was not unknown... 

Part II of this Basic Guide to System Safety presents and briefly discusses some of the more common system safety analytical tools used in the performance of the system safety function. Through example analyses of hypothetical mechanical and/or electrical systems, the reader should become familiar with each type of system safety analysis method or technique discussed. However, it must be understood that it is not within the limited scope of this volume to provide a detailed explanation of each of these methods and/or techniques. The intention is to merely introduce the reader to the various tools associated with the system safety process. The value of each concept in the analysis of hazard risk will vary according to the individual requirements of a given organization or company. 

In Chapter 1 structural design was outlined as a process of synthesis followed b an analysis of the likely hazards which might threaten the success of the propose structure. These hazards were split into three types, limit states, external randoi hazards, and human errors (Table 1.2). In this chapter, present calculatio techniques to deal with the first, the limit states, will be outlined and illustrate by the use of a simple worked example. However, in using these methods, cannot be emphasised too strongly that they deal with only part of the problen The designer must always remember that the possibility of human error and tl possibility of the occurrence of random hazards, such as fires and floods, are nc taken into account in these calculations. 

The specific process concern in this example is associated with an uncontrolled high level in the vessel and the consequences that would result from that. Detailed consequence analysis is not necessary for illustration of the method for demand identification and so for the illustration the hazardous event will be taken as high level in the separator with flow into the vapour line . 

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