System safety concept processes

Facility System Safety (FSS), which is the application of system safety concepts to the facility acquisition process, has recently gained acceptance throughout the Department of Defense and most recently within the Department of Army with the conception of SAFEARMY 1990. The Army s goal is to fully integrate the total system safety, human factors, and health hazard assessments into continuous comprehensive evaluation of selected systems and facilities. The Chemical Research Development and Engineering Center (CRDEC) has mandated appropriate levels of system safety throughout the lifecycle of facility development for many reasons. These include ... 

Participating in the design process presents opportunities for upstream involvement by safety professionals, using system safety concepts. 

The system safety concept involves a planned, disciplined, systematically organized and before-the-fact process characterized as the identify-analyze-control method of safety [p. 9]. 

System safety concepts promote the establishment of policies and procedures that are to achieve an effective, orderly and continuous hazards management process for the design, development, installation, and maintenance, of all facilities, materials, hardware, equipment, tooling, and products, and for their eventual disposal. 

The system safety discipline will require the timely identification and subsequent evaluation of the hazards associated with this operation, before losses occur. The hazards must then be either eliminated or controlled to an acceptable level of risk in order to accomplish the goal of relocating the hazardous chemicals. In short, the system safety process will identify any corrective actions that must be implemented before the task is permitted to proceed. The fly-fix-fiy approach discussed earlier has also been described as an after the fact attempt to improve operational safety performance. In contrast, the system safety concept requires before the fact control of system hazards. 

The OSHA Process Safety Standard incorporates many system safety concepts. Also see Chapter 24. For example, the standard calls for an experienced team to identify and analyze hazards (process hazard analysis or PHA) using one or more of the following methods ... 

Organizational interfaces may pose other problems. When management does not take responsibility for decision making in the process, functional and system safety groups may be at odds with each other. Management perception is another difficulty. System-safety concepts are more abstract than those in many other disciplines. Therefore, it is important for the safety professional to structure the program so its impact is clear. 

For new products, facilities, equipment, and processes, and for their subsequent alteration, the time and place to efficiently and effectively avoid, eliminate, or control hazards is in the design or redesign processes. Participating in those processes presents opportunities for upstream involvement by safety professionals, using system safety concepts. 

Companies may wish to develop workshops to train potential team members in the inherent safety review process. The workshop can provide background information on inherent safety concepts, the extensive systems required to manage hazardous materials, and information on the inherent safety review process. Videos, problems, examples, and team exercises can be included to enliven the education process. 

Implementing an inherent safety review process is one mechanism companies can use to institutionalize inherent safety. The review process should integrate well with company systems for process safety management, new product development, and project execution. Safety, health, and environmental considerations in the new product or process development effort can be strengthened via the introduction of the inherent safety review. Companies may also build inherently safer design concepts into their existing process safety management system and process hazard reviews. 

Management systems for chemical process safety are comprehensive sets of policies, procedures, and practices designed to ensure that barriers to major incidents are in place, in use, and effective. The management systems serve to integrate process safety concepts into ongoing activities of everyone involved in operations— from the chemical process operator to the chief executive officer. 

LOPA is a semi-quantitative tool for analyzing and assessing risk. This method includes simplified methods to characterize the consequences and estimate the frequencies. Various layers of protection are added to a process, for example, to lower the frequency of the undesired consequences. The protection layers may include inherently safer concepts the basic process control system safety instrumented functions passive devices, such as dikes or blast walls active devices, such as relief valves and human intervention. This concept of layers of protection is illustrated in Figure 11-16. The combined effects of the protection layers and the consequences are then compared against some risk tolerance criteria. 

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. 

One of the most critical steps in establishing the appropriate role and settings of the individual safety systems will be the risk assessment analysis, the process in which engineers consider and analyse all possible conditions in order to select the most appropriate safety concept, which ensures safe operation under all possible circumstances and scenarios (see Section 13.4). 

In application of inherent safety concepts, I2SI indexing system is used for quantification of process units and equipment response. 

When objective measurement of performance capacities has been incorporated into many clinical trials, concepts and tools from human performance engineering can facilitate the selection of variables and shed some Hght on issues noted above. In either safety- or efficacy-oriented studies, study variable selection can be characterized as a two-step process (1) identification of the factors in question (Table 82.1) and (2) selection of the relevant performance capacities to be measured and associated measurement instruments. This Hnk between these two steps often represents a challenge to researchers for a number of reasons. First, duality in terminology must be overcome. Concerns about an intervention are typically initially identified with negative terms such as dizziness and not in terms of performance capacities such as postural stability. Human performance models based on systems engineering concepts [Kondraske, 1995] can be used to facilitate the translation of both formal and lay terms used to identify adverse effects to relevant performance capacities to be measured, as shown in Table 82.1. 

The STAMP (Systems-Theoretic Accident Model and Process) model of accident causation is built on these three basic concepts—safety constraints, a hierarchical safety control structure, and process models—along with basic systems theory concepts. All the pieces for a new causation model have been presented. It is now simply a matter of putting them together. 

This Safety Concept of a Self-Sustaining PEM Hydrogen Electrolyzer System is the base for the generation of large scale electrolysis systems and is subject for modification and optimization during the ongoing development and production processes [6]. 

Forasassi, G., Guerrini, B. and Petrangeli, G. (1997) Comparison of some passive safety concepts in nuclear and process industry systems , Post-SMIRT 14 International Seminar 18 Passive Safety Eeatures in Nuclear Installations, 25-7 August, Pisa. 

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