Design process procedures

Nuclear power has achieved an excellent safety record. Exceptions are the accidents at Three Mile Island in 1979 and at Chernobyl in 1986. In the United States, safety can be attributed in part to the strict regulation provided by the Nuclear Regulatory Commission, which reviews proposed reactor designs, processes appHcations forUcenses to constmct and operate plants, and provides surveillance of all safety-related activities of a utiUty. The utiUties seek continued improvement in capabiUty, use procedures extensively, and analy2e any plant incidents for their root causes. Similar programs intended to ensure reactor safety are in place in other countries. 

In a similar manner to the design process for packed columns, the physical characteristics and the performance specifications can be calculated theoretically for open tubular columns. The same protocol will be observed and again, the procedure involves the use of a number of equations that have been previously derived and/or discussed. However, it will be seen that as a result of the geometric simplicity of the open tubular column, there are no packing factors and no multi-path term and so the equations that result are far less complex and easier to manipulate and to understand. 

Designs should be based on knowledge of what the human body (and human nature) will do. Include educated operators in design reviews. The HAZOP methodology for process hazard analysis offers an excellent opportunity to identify design and procedural opportunities for inherently safer systems. After all, the OP in HAZOP stands for operability (COPS, 1992). For example, a safe start-up procedure that requires the operator to walk up and down the stairs three times to manipulate valves in the correct sequence can be made inherently safer by locating the valves so that operator has to walk up the stairs only once during the start-up. 

A team consists of two or more people that know the process technology, design, operating procedures, practices, alarms, emergency procedures, test and maintenance procedures, routine and non-routine tasks. They must consider authorization and procurement of parts and supplies, safety and health standards, codes, specifications and regulations. The team leader provides m.iriagcment and goals to the process the team and consultants construct and interpret the analyses. 

Daily work procedure characterization for each worker must be outlined early in the design process. 

Halpin and Tsai [3-17] developed an interpolation procedure that is an approximate representation of more complicated micromechanics results. The beauty of the procedure is twofoldr-First. it is simple, so it can readily be used in the design process. Second, it enables the generalization of usually limited, although more exact, micromechanics results. Moreover, the procedure is apparently gnltp accurate if the fiber-volume fraction (Vf) does not approach one. ... 

Some of the essential attributes of the laminate design process with optimization concepts were described in general terms. The process is indeterminate, unlike that for a metal plate. An iterative procedure must be used to guide a design toward satisfaction of the design requirements. 

The other main application area for predictive error analysis is in chemical process quantitative risk assessment (CPQRA) as a means of identifying human errors with significant risk consequences. In most cases, the generation of error modes in CPQRA is a somewhat unsystematic process, since it only considers errors that involve the failure to perform some pre-specified function, usually in an emergency (e.g., responding to an alarm within a time interval). The fact that errors of commission can arise as a result of diagnostic failures, or that poor interface design or procedures can also induce errors is rarely considered as part of CPQRA. However, this may be due to the fact that HEA techniques are not widely known in the chemical industry. The application of error analysis in CPQRA will be discussed further in Chapter 5. 

The "Capital Projects Design Review Procedures" element of process safety management assures that the design, the equipment and the construction are properly reviewed for all new projects. Process safety review procedures should be involved with the project from its inception. One method of illustrating the various phases of a project is shown in Figure 8.1 (Figure 5-1 from CCPS, 1989a). 

After tlie system has been defined, a hazard evaluation technique can be used to identify different types of hazards within tlie system components and to propose possible solutions to eliminate the hazards. This topic is treated in more detail in the next t o chapters. These procedures are e.xtremely useful in identifying system modes and failures that can contribute to the occurrence of accidents diey should be an integral part of different phases of process development from conceptual design to installation, operation, and maintenance. The hazard evaluation tecliniques tliat are useful in tlie preliminary and detailed stages of tlie design process include ... 

Zanker has presented a graphical technique for determining the fouling resistance (factor) for process or water fluid systems based on selected or plant data measurements, as shown in Figures 10-43A, 10-43B, and 10-43C. The design determination procedure presented by ZankeD is quoted here and used by permission from Hydrocarbon Processing... 

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