Risk analysis equipment

Design procedures are developed with the intention of improving the safety of equipment. Tools used in this step are hazard and operability studies and quantitative risk analysis (ORA). The following scheme may be used ... 

Chemical Process Quantitative Risk Analysis Process Equipment Reliability Data, with Data Tables Technical Management of Chemical Process Safety (Plant)... 

In some situations, a risk analysis (perhaps quantitative) may be of value in selecting from the options. Use of the risk analysis can reveal both critical equipment and critical procedures. Once the critical issues are identified, design to accommodate them. 

The Chemical Process Industry (CPI) uses various quantitative and qualitative techniques to assess the reliability and risk of process equipment, process systems, and chemical manufacturing operations. These techniques identify the interactions of equipment, systems, and persons that have potentially undesirable consequences. In the case of reliability analyses, the undesirable consequences (e.g., plant shutdown, excessive downtime, or production of off-specification product) are those incidents which reduce system profitability through loss of production and increased maintenance costs. In the case of risk analyses, the primary concerns are human injuries, environmental impacts, and system damage caused by occurrence of fires, explosions, toxic material releases, and related hazards. Quantification of risk in terms of the severity of the consequences and the likelihood of occurrence provides the manager of the system with an important decisionmaking tool. By using the results of a quantitative risk analysis, we are better able to answer such questions as, Which of several candidate systems poses the least risk Are risk reduction modifications necessary and What modifications would be most effective in reducing risk ... 

When using failure rate data for a CPQRA, the ideal situation is to have valid historical data from the identical equipment in the same application. In most cases, plant-specific data are unavailable or may carry a level of confidence that is too low to allow those data to be used without corroborating data. Risk analysts often overcome these problems by using generic failure rate data as surrogates for or supplements to plant-specific data. Because of the uncertainties inherent in risk analysis methodology, generic failure rate data are frequently adequate to identify the major risk contributors in a process or plant. 

Although maintenance systems contain some of this information, engineering, purchasing, and operating department records may be required to find the remainder. Also, equipment maintenance records may be in several file locations since they are usually organized by components and component modules that may differ from equipment boundaries established for risk analysis. 

Hazard and Risk Analysis Consideration should be given to identifying process hazards as early as possible in the process equipment design, so that measures can be taken to reduce or eliminate the hazards. Inherently safer design strategies, such as minimize, substitute, moderate, and simplify, should be implemented. 

The ideal solution is to perform a risk analysis for each item in a facility to determine the probable maximum fire and explosive range the location may produce. The calculations and expense to accomplish such a task today does not appear to justify a unilateral application to every piece of equipment at a facility. Consequentially the use of a spacing table for a facility design provides for an economical and expedient solution. This is especially important when several options on the layout of the facility are available. However in some instances the use of risk analysis may demonstrate less spacing is necessary that what a spacing chart requires. 

Various methods are available to limit the damage from the effects of an explosion. The best options are to provide some pre-installed or engineered features into the design of the facility or equipment that allow for the dissipation or diversion of the effects of a blast to nonconsequential areas. Wherever these mechanisms are used the overpressure levels utilized should be consistent with the risk analysis estimates of the WCCE incident. 

Failure rate data generated from collecting information on equipment failure experience at a facility are referred to as facility-specific or field failure rate data. Facility-specific data contain failure rates specific to equipment (e.g., a certain valve or pump in use at a facility by manufacturer, make, model, and serial number) and are cataloged accordingly. The collection of facility-specific data from internal operations for use in a risk analysis is desirable because such data reflect the practices, environmental factors, and other reliability influences specific to the equipment under study. The ideal situation is to have valid historical data from identical equipment, in the identical application, functioning under the identical operating and maintenance conditions. Where these are not available, but data on similar equipment are, then they may be used with appropriate judgment. 

Evaluation of the cleanliness of the equipment involves measuring the residue left on a known area of the equipment. This is done by marking off a known area and then swabbing the area with a good solvent for the residue. Laboratory measurements quantify the amount of residue in the swabbed area after cleaning so that the quantity of residue left in the equipment can be estimated. If the estimate of the residue is below the maximum calculated from the risk analysis above, then the equipment has been adequately cleaned. 

Dow s Fire and Explosion Risk Analysis Program provides a step-by-step, objective evaluation of the realistic fire, explosion, and reactivity potential of process equipment and its contents. The procedure allows calculation of the damage that would probably result from, and the areas which could be exposed to, fire or explosion generated in the process unit being evaluated. Management can then decide unit spacing needed to protect people from injury and to keep potential property and equipment damage to acceptable levels. 

Interwoven with all these topics are the crucial areas of safety (see Figure 2), risk analysis, plant and equipment design, process control and process economics. A practising chemical engineer will often find that the data he/she requires is either unreliable or incomplete3 and, hence, he/she must make sound judgements based on mathematics, physics and chemistry to determine appropriate simplifying assumptions, while at... 

The application of standards in crop protection machines is an in rortant contribution to the availability of well performing equipment thus improving the safety of the operators, environmental protection and, at the same time, the quality of agricultural products. Standards offer the highest benefits when there are national regulations such as is the case of the EU Machine Directive. This Directive could be a first important step and may offer protection to farmers ffom cheap, low quality machinery carrying a CE stamp based only on approximate risk analysis. 

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