Hazard


Here we shall restrict consideration to safety and health considerations that can be built in while the design is developing rather than the detailed hazard and operability studies that take place in the later stages of design. The three major hazards in process plants are fire, explosion, and toxic release.  [c.255]

The first major hazard in process plants is fire, which is usually regarded as having a disaster potential lower than both explosion or toxic release. However, fire is still a major hazard and can, under the worst conditions, approach explosion in its disaster potential. It may, for example, give rise to toxic fumes. Let us start by examining the important factors in assessing fire as a hazard.  [c.255]

The hazard of an explosion should in general be minimized by avoiding flammable gas-air mixtures in the process. Again, this can  [c.258]

The third of the major hazards and the one with the greatest disaster potential is the release of toxic chemicals. The hazard posed by toxic release depends not only on the chemical species but also on the conditions of exposure. The high disaster potential from toxic release arises in situations where large numbers of people are briefly exposed to high concentrations of toxic material, i.e., acute exposure. However, the long-term health risks associated with prolonged exposure at low concentrations, i.e., chronic exposure, also present serious hazards.  [c.259]

The best way to deal with a hazard in a flowsheet is to remove it completely. The provision of safety systems to control the hazard is much less satisfactory. One of the principal approaches to making a process inherently safe is to limit the inventory of hazardous material, called intensification of hazardous material. The inventories we wish to avoid most of all are flashing flammable liquids or flashing toxic liquids.  [c.262]

Clearly, the potential hazard from runaway reactions is reduced by reducing the inventory of material in the reactor. Batch operation requires a larger inventory than the corresponding continuous reactor. Thus there may be a safety incentive to change from batch to continuous operation. Alternatively, the batch operation can be  [c.262]

Some operations need to be carried out at low temperature, which requires refrigeration. The refrigeration fluid might, for example, be propylene and present a major hazard. Operation of the process at a  [c.264]

Low pressure. Low pressures are not in general as hazardous as the other extreme operating conditions. However, one particular hazard that does exist in low-pressure plants handling flammable materials is the possible ingress of air with the consequent formation of a flammable mixture.  [c.267]

Safety indices, such as the Dow index, have been suggested as measures of safety. In these indices, the hazard associated with each material in the process is assessed and given a number based largely on judgment and experience. The numbers are weighted and combined to give an overall index for the process. The indices have no significance in an absolute sense but can be used to compare the relative hazards between two alternative designs. They are intended more for use in the later stages of design when more information is available. Detailed risk assessment, possibly including analysis of probabilities, also can be carried out in the later stages of design.  [c.268]

The major hazard from the release of flammable or toxic material  [c.268]

On the other hand, if the hazard is toxicity, process alternatives can be compared by assessing the mass of toxic material that would enter the vapor phase on release from containment, weighting the components according to their lethal concentration.  [c.269]

Thus, against this measure, the fire hazard is 3.5 times larger for operation at 150°C compared with operation at 100 C.  [c.270]

It is interesting to compare what might have been the conclusion if the inventory was in a reactor and not in a storage tank. If it is assumed, as an order of magnitude, that the reaction rate doubles for every lO C rise in temperature, then the rate of reaction at IhO C would be 32 times faster than that at 100°C. For the same reactor conversion, this would mean that the inventory would be 32 times smaller. Thus operation at higher temperatures brings increased hazard as far as the fraction of released material that vaporizes is concerned but a lower hazard as far as the inventory required to give the same reactor conversion is concerned. Overall, operation of the reactor at higher temperature would be preferred against these measures. However, other factors would need to be taken into consideration in a detailed assessment.  [c.270]

As the design progresses, it is necessary to carry out hazard and operability studies. These are generally only meaningful when the design has been progressed as far as the preparation of detailed flowsheets and are outside the scope of this text.  [c.272]

Kletz, T. A., Cheaper, Safer Plants, IChemE Hazard Workshop, 2d., IChemE, Rugby, U.K., 1984.  [c.272]

Pu (86 years) is formed from Np. Pu is separated by selective oxidation and solvent extraction. The metal is formed by reduction of PuF with calcium there are six crystal forms. Pu is used in nuclear weapons and reactors Pu is used as a nuclear power source (e.g. in space exploration). The ionizing radiation of plutonium can be a health hazard if the material is inhaled.  [c.318]

Safety performance is measured by companies in many different ways, but one common method is by recording the number of accidents, or lost time incidents (LTI). An LTI is an incident which causes a person to stay away from work for one or more days. Another measure might be the monetary cost of a safety incident. Many techniques are applied to improve the company s safety performance, such as writing work procedures and equipment standards, training staff, performing safety audits, and using hazard studies in the design of plant and equipment. These are all very valid and important techniques, but one of the most effective methods of influencing safety performance is to raise the level of safety awareness in staff.  [c.65]

The practising engineer has an excellent opportunity to influence the safety of operations by applying techniques such as hazard and operability studies (HAZOP) to the design of plant layout and equipment. This technique involves determining the potential hazard of an operation under normal and abnormal operating conditions, and considering the probability and consequences of an accident. This type of study is now commonly applied to new platform design and to the evaluation of refurbishment on existing platforms. Some examples of innovations in platform design which has resulted from this type of study are  [c.66]

In both safety and environment issues, the engineer should try to eliminate the hazard at source. For example, one of the most hazardous operations performed in both the offshore and onshore environments is transport, amongst which helicopter flying has the most incidents per hour of exposure. At feasibility study stage in, say, an offshore development, the engineer should be considering alternatives for reducing the flying exposure of personnel. Options to consider might include  [c.67]

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  [c.69]

A common operation in practical organic chemistry is the separation of an organic compound from a solution or suspension in a liquid by shaking with a second solvent in which the organic compound is soluble and which is immiscible (or nearly immiscible) with the liquid containing the substance. The liquid is generally water, so that the subsequent discussion will be concerned with extraction from this medium. The solvents generally employed for extraction are diethyl ether, di-iso-propyl ether, benzene, chloroform, carbon tetrachloride, and petroleum ether. The solvent selected will depend upon the solubility of the substance to be extracted in that solvent (compare Section 1,22) and upon the ease with which the solvent can be separated from the solute. Diethyl ether, owing to its powerful solvent properties and its low boiling point (35°) thus rendering its removal extremely facile, is very widely used its chief disadvantage lies in the great fire hazard attending its use, but this may be reduced to a minimum by adopting the precautions given in Section 11,14. The fire hazard is reduced also by employing di-wo-propyl ether (b.p. 67 5°), but this solvent is much more expensive than diethyl ether.  [c.149]

Other sources of hazard arise from the handling of such chemicals as concentrated acids, alkalis, metallic sodium and bromine, and in working with such extremely poisonous substances as sodium and potassium cyanides. The special precautions to be observed will be indicated, where necessary, in the experiments in which the substances are employed, and will also be supplied by the demonstrator. The exercise of obvious precautions and cautious handling will in most cases reduce the danger to almost negligible proportions. Thus, if concentrated sulphuric acid should be accidentally spilled, it should be immediately washed with a liberal quantity of water or of a solution of a mild alkali.  [c.206]

Wider passages are provided for vapours and the comparatively narrow tubes, which are usually fitted through holes bored in cork or rubber stoppers, are absent this considerably diminishes danger in violent reactions and also tends to give better results in distillation under reduced pressure as well as diminishing the hazard of choking.  [c.207]

The radioactivity presents no appreciable hazard.  [c.46]

Bromine is the only liquid nonmetallic element. It is a heavy, mobile, reddish-brown liquid, volatilizing readily at room temperature to a red vapor with a strong disagreeable odor, resembling chlorine, and having a very irritating effect on the eyes and throat it is readily soluble in water or carbon disulfide, forming a red solution, is less active than chlorine but more so than iodine it unites readily with many elements and has a bleaching action when spilled on the skin it produces painful sores. It presents a serious health hazard, and maximum safety precautions should be taken when handling it.  [c.98]

The waste streams created by utility systems tend, on the whole, to be less environmentally harmful than process waste. Unfortunately, complacency would be njisplaced. Even though utility waste tends to be less harmful than process waste, the quantities of utility waste tend to be larger than those of process waste. This sheer volume can result in a greater environmental impact than process waste. Gaseous combustion products contribute in various ways to the greenhouse effect, acid rain, and can produce a direct health hazard due to the formation of smog (see Fig. 10.1). The aqueous waste generated by utility systems also can be a major problem if it is contaminated.  [c.291]

The prime global authority is the International Maritime Organisation. The IMO sets the standards and guidelines for the removal of offshore installations. The guidelines specify that installations in less than 75 meters of water with substructures weighing less than 4,000 tons be completely removed from the site. Those in deeper water must be removed to a depth of 55 meters below the surface so that there is no hazard to navigation. In some countries the depth to which structures have to be removed has already been extended to 100m.  [c.365]

E.N. Hogert, E.N., 1993, Tesis Doctoral, Universidad de Buenos Aires, Argentina.  [c.659]

Technical requirements Sound engineering practice, essential requirements tarticle 3t The directive includes a particular technical requirement with respect to equipment which presents only a minor pressure hazard. For such equipment the essential requirements and the certification procedures are not applicable. Instead the so-called sound engineering practice of one of the Member States must be applied. That practice must ensure that design and manufacture takes into account all relevant factors influencing safety during the intended lifetime. The equipment must be accompanied with adequate instruetions for use and must bear the identification of the manufacturer. The CE-marking shall not be applied for such equipment.  [c.941]

Classific.atinn and conformity a.s.se.s.sment of the equipment tarticles 9 and 101 For the purpose of conformity assessment the directive distinguishes between hazard categories 1 to IV, whereby category 1 relates to the lowest risk. To each of these categories adequate modules have been assigned. In the lowest risk category 1 the module A has been attributed which foresees no intervention of the notified body whilst categories II to IV impose an ascending intervention of that body. As referred to earlier, a choice is given to the manufacturer to select either a procedure based on product control or based on quality assurance systems. Finally, in order to add to the flexibility already inherent in the New Approach, the modules attributed to a higher hazard category may be used in lower categories.  [c.942]

Special calorimeters have been developed to make thennal hazard evaluations. In an exothemiic chemical reaction there is the possibility of a runaway reaction occurring where the energy released from the reaction increases the temperature with a consequent increase in tire reaction rate, thus increasing the release of energy. If there are insufficient resources to remove the generated energy, hazardous temperature and pressure regimes can be encountered. An accelerating rate calorimeter or ARC, initially developed at Dow Chemical, is available connnercially to study such thennal hazards. A schematic diagram is shown in figure Bl.27.12. The reaction vessel consists of a spherical bomb that can withstand pressures greater than 20 MPa and temperatures to 770 K. The calorimeter operates in an adiabatic mode under computer control in a heat-wait-seek mode. After the reaction comes to thennal equilibrium the rate of temperature rise due to the reaction is detennined. If this is less tlian a preset value the calorimeter temperature is increased in steps and the process repeated until the reaction rate is sufficient to give the preset temperature rise. The chemical reaction then proceeds at its own rate and the temperature and pressure recorded. From these measurements the kinetic parameters are detennined and used to establish the conditions that could lead to a ninaway reaction. A problem with this calorimeter is that the massive vessel required to withstand the pressure has a heat capacity well in excess of the heat capacity of the reactants. This problem can be overcome by having a thin-walled vessel within the bomb and the pressure in the space between the reaction vessel and the bomb is automatically controlled to the pressure in the calorimeter.  [c.1917]

Carbon dio.xide has the adv antages that in use (a) adverse chemical reactions are extremely unhkely, (b) there is no electrical hazard, and (c) damage to apparatus is minimal.  [c.529]

It must be borne in mind that in spite of the fact that the solvents have normal boiling points below 90-95°, they cannot always be completely removed by heating on a steam or water bath when they form part of mixtures with less-volatile liquids. Simple distillation may lead to mixtures with higher boiling points than the individual solvents, so that separation of the latter may not be quite complete. In such cases the distillation should be completed with the aid of an air bath (Fig. 77,5,3) or an oil bath the Are hazard is considerably reduced since most of the solvent will have been removed.  [c.90]

Great care must be taken in handling sodium hydride and experimental details for its manipulation with comparative safety are given below. Sodium hydride is a white, crystalline, free-flowing powder it must be kept in air-tight containers for protection against moisture and oxygen. The hermetically sealed tin in which it is supplied may be opened without hazard in ordinary dry air and the solid rapidly transforred from the container to a reaction vessel. If exposed to the air unduly, traces of sodium hydroxide formed on the surface render the material hygroscopic rapid absorption of atmospheric moisture may then take place, and the heat generated by the reaction with water may suffice to ignite the solid. The fire is not violent and may be extinguished readily by excluding air either by the application of an asbestos blanket or by the use of anhydrous sodium carbonate carbon dioxide and carbon  [c.922]


See pages that mention the term Hazard : [c.257]    [c.404]    [c.340]    [c.69]    [c.656]    [c.659]    [c.659]    [c.659]    [c.659]    [c.659]    [c.659]    [c.560]    [c.2608]    [c.293]    [c.918]    [c.1111]    [c.107]   
Hazardous chemicals handbook Изд.2 (2002) -- [ c.3 , c.14 , c.259 ]

Surface production operations Ч.2 (1999) -- [ c.0 ]