Plant hazard analysis steps

Logical steps for plant hazard analysis (PHA) method selection. 

Step 0 In Fig. V/4-1 -4 1, it has been shown that LOPA starts from plant hazard analysis (PHA)/HAZOP results. This is the normal case, but it could be started afresh also. In both the cases, it is necessary to fix up the scope and boundary as... 

The first step in the acceptance process is the identification of the environment within which the pre-developed software will have to work. This environment is determined by the system-level safety function as described in the system requirements specification. Also the interface and performance requirements, as well as the safety category should be contained in the system requirements specification. This means, that during the establishment of the plant safety design base a risk and hazards analysis has been performed which rendered the categories of safety functions to be implemented by pre-developed software. This risk and hazard analysis - in spite of being out of the scope of I C engineering - has been taken as the first of four acceptance criteria that should be applied to pre-developed software independently of its safety category. 

Including risk analysis steps in the planning phase of the maintenance of equipment important for safety is considered to be a good practice. A standardized method may be used, addressing all potential hazards (nuclear safety, industrial safety and radiation protection). The method is based on tools that are user friendly and transparent in application (work formulas, simple to use interactive computer sequences). For an overall risk picture at plant level, a PC based risk monitor programme may be used. The information from this planning phase is then used to verify that proper precautions are being identified and implemented. 

The hazards analysis should also give consideration to reliability and troubleshooting issues. The processing steps on a typical platform are usually quite simple therefore, process optimization may not be as important to the overall economics as it would be for an onshore chemical plant or refinery. What is important, however, is operations should not be interrupted. Therefore, it is useful if the hazards analysis can be oriented to identify potential production stoppages and any appropriate follow-up troubleshooting techniques. 

In this study detailed fault trees with probability and failure rate calculations were generated for the events (1) Fatality due to Explosion, Fire, Toxic Release or Asphyxiation at the Process Development Unit (PDU) Coal Gasification Process and (2) Loss of Availability of the PDU. The fault trees for the PDU were synthesized by Design Sciences, Inc., and then subjected to multiple reviews by Combustion Engineering. The steps involved in hazard identification and evaluation, fault tree generation, probability assessment, and design alteration are presented in the main body of this report. The fault trees, cut sets, failure rate data and unavailability calculations are included as attachments to this report. Although both safety and reliability trees have been constructed for the PDU, the verification and analysis of these trees were not completed as a result of the curtailment of the demonstration plant project. Certain items not completed for the PDU risk and reliability assessment are listed. 

The data show that the half-ester, the caprylene recycle material and finished goods each contain less than one % of the original perchloric acid charge determined as chlorides. Preliminary analysis with samples both from laboratory and pilot plant operations indicated that there was no serious perchloric acid carry-back encountered with recycle of recovered acid-ester and unreacted caprylene. We therefore assumed that no hazardous build up of perchloric acid in the reaction step would be expected. The results of these studies may be summarized as follows ... 

A Fimctional Process Analysis (FRA) is first undertaken to identify hazards and their causes in terms of technical and human elements using plant diagrams, safety procedures, incident records and inter-views/observations of operational people. Bow-tie diagrams can be used to develop a graphical representation of hazards and potential barriers that can prevent or mitigate failure consequences. The next step involves the analysis of human-related barriers (e.g., operator visual checks, operator procedures etc) in Older to identify possible task deviations and human errors that may diminish the efficiency of barriers or make them fad. The analysis of human barriers and task deviations is done with the support of Task... 

The initial position of the analysis must be problem oriented and technically meaningful. For example, a plant should not be tested from the viewpoint of the fire hazard emanating from it if such a risk is not significant in practice. Determinations of specifications of the initial analysis position call for high requirements, since by means of these specifications the key points for all subsequent steps are established, and neglecting important aspects could have serious consequences. 

The basic steps involved in an external flooding analysis are similar to those followed for internal flooding in the individual plant examination. However, the focus of attention is on areas, which due to their location and grading may be susceptible to external flood damage. This requires information on such items as dykes, surface grading, locations of structures and locations of equipment within the structures. It is expected that the generic envelope will bound site hazard parameters. 

In broad terms, the process for producing a specification for a safe design involves hazard identification (HAZID), which asks what sort of accidents do we need to worry about , followed by detailed analysis to identify the magnitude of potential accidents. From a safety perspective, a most important step is the clear and robust definition of the safety functional requirements, i.e., the requirements for the control and protection systems on the completed plant. The history of accidents involving design failures shows a frequent root cause to be inaccurate or inadequate definition of the safety functional requirements (see Fig. 2.3). 

The present paper is focused on the implementation of the risk analysis within a major hazard plant. The main innovative aspect of the paper is the proposal of a new combination rule of information supplied by experts with relation to each BE. The aggregation step is a critical phase of the whole procedure consisting of the following steps ... 

A pesticide-contaminated Superfund site and a coal-burning electric power plant illustrate the general principles involved in hazard identification, the first step in the risk-assessment process Identify hazardous chemicals to which people might be exposed, the pathways by which exposure might occur, and the populations and subpopulations that are at risk. Once hazards have been identified, the risks they pose can be assessed. Risk is a combination of exposure and toxicity (Figure 1.1). An assessment of risk continues with an analysis of the degrees to which at-risk populations are exposed to chemicals of concern. 

To summarize, a lot of work has been done in the field of fluorination reactions in microfluidic devices. Concerning the deoxofluorination with hazardous DAST, the development of a process from laboratory to pilot plant scale with inline process analysis was nicely demonstrated. Later on, the scope of substrates and fluorinating agents was broadened and inline purifications were introduced on laboratory scale. Thus, the microfluidic devices were a good tool to establish substance libraries. In the case of radiolabeling with [ F] fluoride ions, the chapter focused on recent advances in continuous-flow microfluidic procedures. However, the miniaturization for a continuous processing of all necessary preparation steps remains a major challenge. 

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