System safety tasks hazard analysis/control

Safety and reliability of chemical process plants are such important issues, they deserve the best techniques to prevent problems occurring. To minimize risks resulted from operating problems and hazardous events, process system safety and reliability analysis is often employed. This is a rigorous approach undertaken to improve system reliability and safety. The approach consists of three main tasks hazard identification, risk estimation, and risk control. 

Hierarchical Approach is a simple but powerful methodology for the synthesis of process flowsheets. It consists of a top-down analysis organised as a clearly defined sequence of tasks grouped in levels. Each level solves a fundamental problem as, number of plants, input/output structure, reactor design and recycle structure, separation system, energy integration, environmental analysis, safety and hazard analysis, and plantwide control. At each level, systematic methods can be applied for the synthesis of subsystems, as chemical reaction, separations, or heat exchangers network. 

The next task is an analysis showing that no control system failure can cause an initiating event that can result in a hazard. If control system failure can initiate a hazardous sequence, then safety instrumented functions MUST NOT be designed into common equipment without detailed quantitative risk analysis. That language in the standard is strong and clear. Most of the time, initiating event analysis shows a problem with combined control and safety. 

The safety community provides expertise in hazard identification, analysis, and control techniques. TTie safety representative may serve as the primary advisor to the chairperson in articulating system safety goals, tasks, and responsibilities. The safety representative frequently has the job of writing or drafting documents generated by the SSWG. 

The JSA, then, is a specialized approach of task analysis that takes an existing job and analyzes its tasks to specifically identify hazards encountered in the work environment. At the very least, the JSA does have a place within the system safety process as a tool to evaluate the hazards or risks of an existing task or function during the operation phase of the project life cycle. Here we see another connection between the principal elements of the industrial safety process and one of the basic objectives of the system safety effort, namely, that the JSA tries to eliminate or control the risk of hazard exposure in a given task during the life of the project. 

The job hazard analysis (JHA) is the foundation for any successful safety management system. A safety culture can only exist when a full understanding of ongoing jobs, steps, and tasks are defined and the various hazards and associated risk are managed and controlled. As such, the JHA is an essential element in assessing the depth and scope of risk within the organization. 

Derived from task analysis or work study, job safety analysis, whether effected as part of work study or not, can do much to eliminate the hazards of a job. The analysis identifies every single operation in a job, examines the specific hazards and indicates remedial measures necessary. It involves the examination of a number of areas, including permit to work systems, influences on behaviour, the operator training required and the degree of supervision and control necessary. Job safety analysis can feature as part of a workplace risk assessment. 

Once a task has been identified as hazardous, controls need to be applied. For complex tasks, analysis may be required to sort out the component parts of what is actually going to be done. This can result in task improvements and risk reduction. A formal technique for doing this is known as job safety analysis, which has developed from work study practices. Essentially, the task is observed, and broken down into steps or stages which are then examined for the level of risk involved (Table 6.1). Control measures are then worked out, and the paperwork is then used to generate a written safe system of work. Naturally, the tasks selected need to be reviewed at intervals to make sure that the analysis and solutions remain valid over time. 

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