Equipment by Hazard Potential

Critical Consequences—Class 1. Containment equipment or the critical instruments serving that equipment whose failure would result in uncontrolled releases of dangerous materials, situations resulting in accidental fires or explosions, reportable environmental releases including closing of nearby highways or shelter in place for community members, personal injury, death, or major property or major production loss. 

pressure vessels, piping or rotating equipment containing highly hazardous or flammable chemicals are easily identified by experienced operations personnel as Class 1 equipment. These containment systems must be inspected in some effective manner on a priority basis. 

Critical instruments assigned to Class 1 include those necessary to avoid a failure that may cause the perils listed above or instruments that fail to warn of upset conditions that may result in perils. Testing of these instrument systems may be mandated by regulatory agencies, in-house technical safety review committees, HAZOP studies, or designated as critical by operations supervisors. All of these shutdown systems and alarms must be prooftested in accordance with a proper schedule. [8] 

Serious Consequences—Class 2. Equipment or the critical instruments serving equipment whose failure could possibly cause, or fail to warn of upset conditions, uncontrolled releases of dangerous materials, situations that could result in accidental fires and explosions. Furthermore these failures could result in serious conditions involving environmental releases, property or production losses, or other non-life-threMening situations. These particular pieces of equipment, the safety shutdown systems and the alarms that serve this equipment e given a slightly lower priority. However, they are also inspected, tested, or prooftested on a regular schedule, but may be allowed to have some leniency in compli iee. 

A Class 2 list might include equipment that typically does not contain highly hazardous chemicals, but may under abnormal conditions contain such chemicals. It may also include utility systems such as cooling tower operations, compressed air or refrigeration systems whose failure could create significant upsets. 

Chemical plant equipment—including tanks, pressure vessels, piping, rotating equipment, vent systems, and safety instrumentation—should be identified and categorized into different degrees of hazard potential. Classification systems could be simple or very complex. A complex system could be a matrix of increasing severity ratings on one axis and the 

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The scope to alter both the efficiency and safety of application through control of the fate of applied material has been explored in a classification of application equipment by hazard (Parkin et al., 1994). Application techniques as well as equipment are required to be taken into account for such a classification, which covers all four possible distinct styles of application i.e. direct, liquid, solid and space. The direct style of application, which is typified by the need to bring treated items into intimate contact with pesticide, is exemplified by admixture processes, e.g. seed treatments. Direct applications take place under highly controllable conditions and often within relatively confined environments, which can potentially mitigate the exposure risks from applied material (presented either in... 

Since the chemical industry operates by handling potentially hazardous materials safely, safety has always been an important consideration for chemical engineers. Engineers have never been able to discharge their professional responsibility only by designing efficient equipment or developing efficient processes. Today society has expanded that traditional responsibility to include environmental and community protection. The chemical industry s operations and products should not have an unacceptable impact upon its neighbors, its customers, or the environment. 

A safety trip can be incorporated in a control loop, as shown in Figure 5.29a. In this system the level control instrument has a built-in software alarm that alerts the operator if the level is too low and a programmed trip set for a level somewhat lower than the alarm level. However, the safe operation of such a system will be dependent on the reliability of the control equipment, and for potentially hazardous situations it is better practice to specify a separate trip system, such as that shown in Figure 5.29b, in which the trip is activated by a separate low-level switch. Provision must be made for the periodic checking of the trip system to ensure that the system operates when needed. 

However, the paint manufacturer, through measurement of airborne levels of the specific material, has determined that the material is controlled well below recommended or required airborne levels. Thus some regulated airborne levels are in compliance, or judged of a low hazard potential and there is no need for the use of a dust respirator. Therefore, the appropriate protective equipment would be gloves, safety glasses and synthetic apron. This corresponds with a personal protective designation of "C". A manufacturer would then put C" on the element. This is known as the "derived personal protective equipment." NPCA would like to remind paint manufacturers that the needs of different work sites within a plant will vary. Personal protection equipment assignments should be determined by the specific needs of a plant or work site rather than the establishment of one company wide standard. 

Many chemicals and combinations of chemicals are potentially dangerous if handled carelessly. Likewise, improper manipulation of certain pieces of equipment leads to potentially hazardous situations. However, with proper precautions, accidents can be avoided. The following safety precautions are by no means complete, but should increase your awareness of how to experiment defensively just as you must learn to drive defensively. ... 

Once the hazards were identified, the severity of each hazard was evaluated by considering the worst-case loss associated with the hazard. In the example, the losses are evaluated for each of three categories humans (H), mission (M), and equipment (E). Initially, potential damage to the Earth and planet surface environment was included in the hazard log. In the end, the environment component was left out of the analysis because project managers decided to replace the analysis with mandatory compliance with NASA s planetary protection standards. A risk analysis can be replaced by a customer policy on how the hazards are to be treated. A more complete example, however, for a different system would normally include environmental hazards. 

Dropped objects (usually from deck cranes) are a major hazard on offshore platforms. If they fall on the deck, they can hurt workers and/or seriously damage equipment (with the potential for a catastrophic event). If the dropped object is heavy and it falls into the sea, it can be traveling quite fast by the time it reaches the seabed, especially in deepwater. Consequently the dropped object can cause substantial damage to subsea equipment—with the potential for causing a serious environmental problem. 

In contrast only general requirements are formulated in the field of process plants. This is explained by fact that we have to deal with a great variety of different plants and equipment, which impedes the formulation of specific requirements. Following these general requirements potential hazards are identified for different equipments by systematic investigations (vid. Chap. 9) and the necessary protective equipments are conceived. The basis is given by the following classification of potential accidents (cf. [20]). 

A method to evaluate, authorize, implement, communicate, and document changes to process technology, chemicals, equipment, procedures, facilities, buildings, or organizations as to their potential for hazards, potential consequential loss, the magnitude of the potential risk, and the impact on facility operation. Control by means of elimination or mitigation of the hazards and/or the consequences should then be implemented to minimize potential risk. See Figure M.l for a flowchart of a typical MOC procedure. 

The U.S. Army Corps of Engineers requires contractors who perform construction work for the federal government to prepare a safety and occupational health plan (SOH). The idea is to analyze the potential work on a specific job or project and to plan accident prevention measures for each phase and component of the work. The plan includes work performed by subcontractors. It includes contractor hazard control measures. The plan must include frequent and regularly scheduled safety inspections of work sites, materials and equipment by competent persons. 

If other means of controls prove to be impossible or infeasible, the use of personal protective equipment by employees may become necessary. Such control methods, however, do not reduce or eliminate the source of the potential hazard and are the least preferred choice for controlling exposure. Personal protective equipment includes air-purifying and air-supplying respirators, hearing protection to reduce noise exposures, eye and face protection and gloves, boots and other impervious clothing. 

Consider now the situation in Figure 27.7(b) with an open grounding conductor. Even with a direct ground-fault between a Une conductor and the machine frame, no fault current occurs because there is no return path to the neutral of the transformer. As a result, the circuit breaker wiU not trip and the system will continue to operate as if no fault existed. Even if the vehicle frame were in direct contact with earth, rather than insulated by the tires, the magnitude of fault current would probably still be insufficient to cause circuit-breaker tripping. In either case, the equipment frame would be elevated to a hazardous potential. 

All of the actinide elements, with the exception of uranium and thorium, are radioactive to such a degree that handling requires spedal equipment and shielded facilities [9,10]. The special containment and manipulation techniques for work with the actinide elements are necessitated by the potential health hazards to the investigator and other occupants of the laboratory. Containment in the form of glove boxes is now standard, and these are available through normal commercial channels. Shielded facilities are more specialized, and, for the most part, are found in laboratories devoted to the study or processing of the actinide elements. 

Fire and uncontroUed polymerization are a concern in the handling of chloroprene monomer. The refined monomer is ordinarily stored refrigerated under nitrogen and inhibited. This is supported by routine monitoring for polymer formation and vessel temperature. Tanks and polymerization vessels are equipped for emergency inhibitor addition. Formalized process hazard studies, which look beyond the plant fence to potential for community involvement, are routine for most chemical processes. 

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