Hazard principles

A more recent concept which could have significant impact on future designs is that of inherent safety (12). This basic principle states that what is not there cannot be blown up or leak into the environment. Thus, the idea is to avoid the hazard in the first place. 

Preventive Explosion Protection The principle of preventive explosion protection comprises the reliable exclusion of one of the requirements necessary for the development of an explosion. In pictorial terms, therefore, at least one of the sides of the hazard triangle shown in Figure 26-33 will be broken open. 

FIG. 26-33 Hazard triangle principle of preventive explosion protection. 

The selection of materials to be used in design dictates a basic understanding of the behavior of materials and the principles that govern such behavior. If proper design of suitable materials of construction is incorporated, the eqiiipment should deteriorate at a uniform and anticipated gradual rate, which will allow scheduled maintenance or replacement at regular inteivals. If localized forms of corrosion are characteristic of the combination of materials and environment, the materials engineer should still be able to predict the probable life of equipment, or devise an appropriate inspection schedule to preclude unexpected failures. The concepts of predictive, or at least preventive, maintenance are minimum requirements to proper materials selection. This approach to maintenance is certainly intended to minimize the possibility of unscheduled production shutdowns because of corrosion failures, with their attendant possible financial losses, hazard to personnel and equipment, and resultant environmental pollution. 

Understanding the chemistry of the process also provides the greatest opportunity in applying the principles of inherent safety at the chemical synthesis stage. Process chemistry greatly determines the potential impact of the processing facility on people and the environment. It also determines such important safety variables as inventory, ancillary unit operations, by-product disposal, etc. Creative design and selection of process chemistry can result in the use of inherently safer chemicals, a reduction in the inventories of hazardous chemicals and/or a minimization of waste treatment requirements. 

Process Safety Management (PSM) A program or activity involving the application of management principles and analytical techniques to ensure the safety of chemical process facilities. Sometimes called process hazard management. Each principle is often termed an element or component of process safety. 

An elementary introduction to chemistry is given in Chapter 3 this serves only to provide background and for more advanced consideration reference will be necessary to specific text books, e.g. as listed in the Bibliography. A brief discussion of the relevance of physicochemical principles to hazard identification is given in Chapter 4. Relevant toxic and flammable properties, and summaries of appropriate precautions to cater for them during handling, use and disposal, are provided in Chapters 5 and 6, respectively. Reactive hazards are discussed in Chapter 7. The special problems with cryogenic materials and chemicals under pressure, typified by compressed... 

This chapter provides a brief insight into selected fundamental principles of matter as a background to the appreciation of the hazards of chemicals. 

Hazards can often be foreseen from basic physicochemical principles, as summarized below. 

This chapter provides an insight into general principles associated with the transportation of hazardous substances reference is made to selected regulations for illustrative purposes. 

Strong, C.B., and Irvin, T.R. (1995) Emergency Response and Hazardous Chemical Management Principles and Practices (Advances m Environmental Management Senes), St Lucie Press. 

Whilst the hazards identified, and the principles and practice for the control of risks are universal, i.e. they are independent of location, in order to assist quick-reference an appendix of relevant contemporaneous UK legislation has been added as a guide together with a much-expanded Bibliography in Chapter 19. Finally, for convenience of use, the Index has been enlarged. 

The PHI-TEC II adiabatic calorimeter as shown in Figure 12-17 was developed by Hazard Evaluation Laboratory Ltd. (UK). The PHI-TEC can be used both as a high sensitivity adiabatic calorimeter and as multi-purpose vent sizing device [17,18]. The PHI-TEC employs the principles established by DIERS and includes advanced features compared to the VSP. It also provides important information for storage and handling and provides useful insight into the options suitable for downstream disposal of vented material. 

When reviewing the materials of construction consider external corrosion concerns. Chloride stress cracking of stainless steel can be initiated by insulation capturing chlorides or insulation that contains chlorides (stainless steel should be primed). A weather barrier is needed. The principle here is to understand the potential hazards and their mechanisms. 

The safety status of the process should be periodically reviewed against the guiding principles for the original design. Monitoring of add-ons can detect potentially dangerous modifications. Process hazards analysis or process safety audits are useful tools for this review. Documentation of inherently safer principles is critical to ensure that future changes don t nullify the positive features of the initial installation. 

During process hazard reviews, evaluate each safety critical device or procedure to see if the device or procedure can be eliminated by applying inherently safer principles. Consider the existing plant, the next plant, and the plant after next. 

Bayer (Pilz, 1995) uses a procedure based on hazard analysis, focusing on the application of inherent safety principles to reduce or eliminate hazards. 

Dow (Sheffler, 1996 Gowland, 1996a,b) describes the use of the Dow Fire and Explosion Index (Dow, 1994b) and the Dow Chemical Exposure Index (Dow, 1994a) as measures of inherent safety, along with the use of inherently safer design principles to reduce hazards. 

The Rohm and Haas Major Accident Prevention Program (Ren-shaw, 1990 Berger and Lantzy, 1996 Hendershot, 1991a) is based on potential accident consequence analysis and uses checklists based on inherently safer design principles to identify ways to eliminate or reduce hazards. 

Reducing and eliminating hazards and their associated risks is the second major objective. Applying inherent safety principles early in the product/process development effort provides the greatest opportunity to achieve the objectives of the inherent safety review process for the project at hand. If these principles are applied late in the effort the results may have to be applied to the project after next as the schedule may not permit implementation of the results. 

Let s look at another example a small-scale voluntary cleanup that might take place in the lot behind a factory, or a tank being removed at a corner gas station. Although we have the same considerations, these projects are on a smaller scale and will create less of a hazardous condition. The same principles that exist at the large job still should be adhered to on the small job. The work zone should be delineated and controlled to protect workers or the public from entering the work zone. For the small job, caution tape, snow fence, or traffic cones can be used effectively. 

Training for other activities such as deactivation and D D may not fall under the hazardous waste definition. As previously mentioned, the authors believe that, in many cases, applying hazardous waste principles based on a hazard-based approach will help to provide a safe worksite and add value to these activities. These activities may involve hazard abatement processes, such as chemical lab packing, asbestos, lead, mercury, or... 

The harmful effects of industrial emissions are not confined to the workers but extend beyond the plant boundary line. Chemically-induced diseases among workers exposed to industrial chemicals are a warning sign of the risks to which a larger population is also being exposed usually the chemical hazards are in principle similar in the occupational and general environment. However, occasionally environmental exposures can be qualitatively different from the occupational environment and may also cause deleterious health effects in the general population. 

The final element in management s communication of a desire to reduce human error is the identification and elimination of error-likely situations. Every task is an opportunity for a human error, but some situahons represent greater risks than others. Identifying these high-risk situations is not easy and an expertise in applying human factors principles to the workplace is an essential prerequisite for this identification. Eliminating these hazardous situations is often relatively simple once they have been identified. In some cases it may be appropriate to provide error-tolerant systems, which are those that facilitate identification of and recovery from the errors. 

Numerous other highly reactive oxofluoro-sulfur compounds have been prepared but their chemistry, though sometimes hazardous because of a tendency to explosion, introduces no new principles. Some examples are ... 

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