Hazard analyses preliminary

The preliminary hazard analysis (PHA) expands the preliminary hazard list by identifying additional hazards, analyzing identified hazards, recommending hazard controls, and determining the level of risk after the controls are 

The PHA is normally prepared by the system safety working group and reviewed by management review boards. 

Available project description information, historical data, and the PHL are used in preparing the PHA. 

Failure tpodes and effects analysis (FMEA) and energy trace and barrier analysis are the techniques recommended to aid in conducting PHAs. 

TTie PHL report is generally a narrative with a summary that highlights significant risks and recommendations. It should also contain a brief project description, a discussion of the PHL methodology used, including the risk assessment matrix, requirements for additional information, recommendations for follow-on studies or analyses, and the PHA worksheets. 

The Preliminary Hazard Analysis (PHA) is an analysis of the generic hazard groups present in a system, their evaluation, and recommendations for control (TAI 1989). The PHA is usually the first attempt in the system safety process to identify and categorize hazards or potential hazards associated with the operation of a proposed system, process, or procedure. In many instances, however, the PHA may be preceded with the preparation of aPreliminary Hazard List (PHL). The identification of hazards on a PHL can occur through the use of a variety of methods such as but not limited to 

After examining all available information, a PHL can then be prepared. Though not entirely necessary in the overall system safety program, a well-developed PHL can be expanded and further developed into the basis of a PHA. The methods used to develop 

Basic Guide to System Sc ety, tliird Edition. Jeffrey W. Vincoli. 

A PHA is the initial effort in identifying hazards which singly or in combination could cause an accident or undesired event. PHA is a system-safety analysis tool used to identify hazard sources, conditions, and potential accidents (Roland and Moriarty, 1990). At the same time, PHA establishes the initial design and procedural safety requirements to eliminate or control these identified hazardous conditions. A PHA is performed in the early stages of the conceptual cycle of system development. It can be performed by engineers, contractors, production line supervisors, or safety professionals. Management must always first look at any risk involved in the operation of the system. 

After identifying hazards and their resultant adverse effects, the analyst will rate each according to the Hazard Classification class, which could be one of four categories  

Roland and Moriarty (1990) show how to develop a Hazard Assessment Matrix to determine a Hazard Risk Index using frequency of occurrence and hazard category (see figure 9-3). 

The method requires the formation of an ad hoc team of personnel with appropriate level of familiarity with items such as equipment, substances, materials, and/or the process under consideration. The members of the team review with care the hazards occurrence in the area of their expertise and experience, and as a team they play the devil s advocate. 

This method is applied in the industry under quite different headings. The name used here refers to an established American technology, PHA, which was initially developed for military use. 

The aim of a preliminary hazard assessment is the dedicated analysis of the following areas of interest at a very early design stage  

The efficiency of the method is mainly influenced by the amount of information available at the time of application. The effort is usually rather limited. The user, however, should have a good training in process safety engineering in order to be able to apply this kind of evaluation in a more flexible way than the pure checklist method. Furthermore, it is highly recommended to include the later user of the plant into this analysis. This actually is a recommendation which is not limited to this method, but valid for numerous other methods described in the following. 

Basic Guide to System Safety, by Jeffrey W. Vincoli Copyright 2006 John Wiley Sons, Inc. 

List the nature of the condition (refer to Generic Hazard Group, If necessary). 

Describe what is CAUSING the stated condition to exist 

It allowed to go uncorrected, what will be the effect or effects of the hazardous condition  

Provide supporting comments and/or descriptions of rationale used to form conclusions 

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A critical assembly is a split bed on which fissionable material used to mock up up a separated reactor core that is stacked half on each half. One half is on roller guides so that the two halves may be quickly pulled apart if the neutron multiplication gets too high. Use the Preliminary Hazards Analysis method described in section 3,2.1 to identify the possible accidents that may occur and the qualitative probabilities and consequences. List the initiators in a matrix to systematically investigate the whole process. Don t forget human error. 

What if Approaches Hazind and Operability (HAZOP) Studies Preliminary Hazard Analysis (PLHA) Process Hazard Analysis (PHA)... 

To those already familiar with hazard/risk analysis methods, a "PHA" designates a Preliminary Hazard Analysis. Unfortunately, the PSM Rule uses these same letters to designate Process Hazard Analysis. In this document, PrHA will designate Process Hazard Analysis to avoid confusion with Preliminary Hazard Analysis. Note that other literature may be confusing on this issue. 

If several processes require PrHAs, the PrHAs must be prioritized. A preliminary hazard analysis (PHA) may be used to determine and document the priority order for conducting PrHAs. At a minimum, the PSM Rule requires the prioritization to consider the potential severity of a chemical release, the number of potentially affected employees, and the operating history of the process, including the frequency of past chemical releases and the age of the process. 

Partial what-if analyses for the two example processes described in Section 4.0 are shown in Tables 4.9 and 4.10. Although for actual, more complex analyses, the what-if tables for each line or vessel would be separate, for these examples, a single table was developed. A preliminary hazard analysis (PHA) would identify that the intrinsic hazards associated with HF are its reactivity (including reactivity with water, by solution), corrosivity (including carbon steel, if wet), toxicity via inhalation and skin contact, and environmental toxicity. The N2 supply system pressure is not considered in this example. The specific effects of loss of containment could be explicitly stated in the "loss of HF containment" scenarios identified. Similarly, the effects of loss of chlorine containment, including the reactivity and toxicity of chlorine, could be specified for the second example. 

A designer, as part of his facility design analysis, should perform a hazards analysis or risk assessment of the various processes which will be conducted within the facility in order to determine what potential thermal dangers or threats exist to personnel and equipment. A hazards analysis or risk assessment will provide for the identification of potential hazards and of the necessary corrective actions/measures to prevent or control the hazard. Early in the design of a facility, the processes and equipment may be conceptual and at this stage, a preliminary hazards analysis can be performed. It is early in the design that a preliminary hazards analysis can be most helpful because its... 

Assessment. An analysis of the hazards present in this laboratory show the most significant hazard to be the release of vapor CSM from engineering controls and into the workplace. The significance of this hazard mandates further efforts in system safety in the form of a Preliminary Hazard List (PHL) and a Preliminary Hazard Analysis (PHA). The user must in this instance take an active role in the design review process. 

Preliminary Hazard Analysis. The next step in the process is the development of a PHA. This analysis is the core of the FSS program and as such is vital in eliminating or reducing the inherent hazards associated with this laboratory operation. The PHA is used to further analyze the data identified in the PHL. This enhances the hazard control data base and provides specific recommended corrective action for the resolution of hazardous conditions. A combination of the informational sources used in the PHL development and any additional design information should be used in PHA development. 

Preliminary Hazard Analysis Description. The incorporation of this information into a PHA entry is shown as Table II. This entry describes the proposed actions needed to eliminate or control the hazard (column 6), the risk assessment code assigned after controls (column 7), and the identification of applicable codes and standards (column 8). 

Other possible preliminary safety analysis methods are concept safety review (CSR), critical examination of system safety (CE), concept hazard analysis (CHA), preliminary consequence analysis (PCA) and preliminary hazard analysis (PHA) (Wells et al., 1993). These methods are meant to be carried out from the time of the concept safety review until such time as reasonably firm process flow diagrams or early P I diagrams are available. 

Several qualitative approaches can be used to identify hazardous reaction scenarios, including process hazard analysis, checklists, chemical interaction matrices, and an experience-based review. CCPS (1995a p. 176) describes nine hazard evaluation procedures that can be used to identify hazardous reaction scenarios-checklists, Dow fire and explosion indices, preliminary hazard analysis, what-if analysis, failure modes and effects analysis (FMEA), HAZOP study, fault tree analysis, human error analysis, and quantitative risk analysis. 

PA PCP PCR PFA PGB PHA PID PLC PMACWA PMD POTW ppm PRH PRR psi psig PTFE PVDF PWS picric acid pentachlorophenol propellant collection reactor perfluoroalkoxy product gas burner preliminary hazards analysis proportional integral differential controller programmable logic control Program Manager for Assembled Chemical Weapons Assessment projectile mortar demilitarization (machine) publicly owned treatment works parts per million projectile rotary hydrolyzer propellant removal room pounds per square inch pounds per square inch gauge polytetrafluoroethylene (Teflon) polyvinylidene fluoride projectile washout system... 

The EDS II test program includes testing and design studies needed for a preliminary design of a full-scale pilot plant, a preliminary hazard analysis, development of a full-scale cost estimate, and a schedule for construction and operation of a facility employing the AEA technology. 

Preliminary Hazard Analysis (commonly used in the defense and aerospace industry)... 

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