Major hazard

A series of major accidents at manufacturing sites and storage installation has focused the attention of national governments on the need to control the planning and operation of sites where there is the potential for a major accident. That is, those sites posing a substantial threat to the employees, the public and the environment. 

In the United Kingdom this is covered by the Control of Major Accident Hazards Regulations 1999 (COMAH), set up by the HSE (Health and Safety Executive) to implement the Seveso II directive of the EC (European Union) see www.hse.gov.uk. The COMAH regulations supersede the previous CIMAH (1984) regulations, set up under Seveso I. 

Other countries have set up similar regulations for the control of major hazards. 

The aim of the COMAH regulations is to prevent major accidents involving dangerous materials from occurring and to mitigate the effects on people and the environment. 

The regulations require industrial companies to report on the operation of dangerous installations, and on the storage of dangerous materials. 

In the United Kingdom an advisory committee was set up by the Health and Safety Executive (HSE) to review the problem and recommend procedures for the control of these sites, HSE (1976, 1979). Subsequently, a series of directives and amendments on this subject were issued by the European Economic Commission (EEC), and the EEC directives were implemented in the UK by the publication of the Control of Major Industrial Accident Hazards Regulations, 1984 (the CIMAH regulations). 

Prepared, and kept up to date, an emergency plan covering procedures to deal with a major incident. 

In preparing the report for the HSE the company would usually prepare a safety case assessing the nature and degree of the hazard and the consequences of an incident. This would include details of the measures taken to alleviate the hazard and the consequences of an accident. The preparation of safety cases is covered by Lees and Ang (1989). 

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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. ... 

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. 

The second of the major hazards is explosion, which has a disaster potential usually considered to be greater than fire but lower than toxic release. Explosion is a sudden and violent release of energy. 

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. 

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... 

The major hazard from the release of flammable or toxic material... 

The results of the Flixborough investigation made it clear that the large inventory of flammable material in the process plant contributed to the scale of the disaster. It was concluded that limitations of inventory should be taken as specific design objectives in major hazard installations. It should be noted, however, that reduction of inventoiy may require more frequent and smaller shipments and improved management. 

CIA 1990. A Approach to the Categorization of Process Plant Hazard and Control Building Design. Prepared by Working Group 3 of the Major Hazards Steering Group. Issued by the Safety Committee of the Chemical Industry Safety and Health Council of the Chemical Industries Association, Eondon. 

In Steps 2 through 5 of Figure 5 you will use subjective judgment to consider whether the situation involves major hazards, familiar processes, large consequence potential, or frequent accidents. The... 

C. G. Ramsey, R. Sylvester-Evans, and M. A. English, Siting and Layout of Major Hazardous Installations, /. Ghem. E. Symposium Series No. 71, 1982. 

Elealth and Safety Executive Advisory Committee on Dangerous Substances (EISE), Major Hazard Aspects of the Transport of Dangerous Substances, London HMSO, 1991. 

Societies concern with air quality has evolved from medieval times, when breathing smelting fumes was a major hazard, to where we are today (see Chapter 1). In modem society, a parallel effort has been under way to improve air quality in the outside or ambient air, which is the focus of this book, and in the industrial occupational setting in manufacturing and other traditional jobs. A combination of events is moving many countries to consider the quality of air in other locations where we live parts of our lives. Attention is now being refocused on "indoor" air quality. 

Consultation distances (in relation to major hazard and other sites, e.g. LPG, chlorine, for land use planning) HSE assessments for consultation distances for major hazard installations. Chapter 5 in Safety Cases (Lees and Ang, 1989)... 

Major hazard aspects of the transport of dangerous substances 1991 Recommendations for training users of non-agricultural pesticides Health surveillance under COSHH. Guidance for employers Anaesthetic agents. Controlling exposure under COSHH Risk assessments of notified new substances... 

Regulate the design and operation of defined major hazard installations. All necessary measures are required to prevent and limit the consequences of major accidents. Operators of upper-tier sites must produce a detailed Safety Report those of lower-tier sites must prepare a Major Accident Prevention Policy. 

Chemical Reactivity - Reactivity with Water Reacts violently with water as a dry solid or when dissolved in ether. The hydrogen produced by the reaction with water is a major hazard and necessitates adequate ventilation Reactivity with Common Materials Can burn in heated or moist air Stability During Transport Normally stable imstable at high temperatures Neutralizing Agerus for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

Viruses are the 2nd most problematic pathogen, behind protozoa. As with protozoa, most waterborne viral diseases don t present a lethal hazard to a healthy adult. Waterborne pathogenic viruses range in size from 0.020-0.030 jtim, and are too small to be filtered out by a mechanical filter. All waterborne enteric viruses affecting humans occur solely in humans, thus animal waste doesn t present much of a viral threat. At the present viruses don t present a major hazard to people drinking surface water in the U.S., but this could change in a survival situation as the level of human sanitation is reduced. Viruses do tend to show up even in remote areas, so a case can be made for eliminating them now. 

Impurities or the delayed addition of a catalyst causes inhibition or delayed initiation resulting in accumulation in the reactors. The major hazard from accumulation of the reactants is due to a potentially rapid reaction and consequent high heat output that occurs when the reaction finally starts. If the heat output is greater than the cooling capacity of the plant, the reaction will run away. The reaction might commence if an agitator is restarted after it has stopped, a catalyst is added suddenly, or because the desired reaction is slow to start. 

Wells, G., Major Hazards and Their Managements, Institution of Chemieal Engineer (IChemE), 1997. 

More inclusive is Table 3.3.1 -3 which is appropriate at depth into the analysis. The major headings in this table address major hazardous subject areas,. iccideni mitigation, protection and repair. I or example, under the first major heading, "Storage of Raw Materials, Products, Intermediates," listed are confinement measures, release nicclumi.sms (valves), procedures for safe operation and limitations that must be observed for safety. 

Holden, P. L. and A, B, Reeves, 1985, Fragment Hazards from Failures of Pressurized Liquified Gas Assessment and Control of Major Hazards, / Chem. E Symposium Senes No. 

MHIDAS, 1992, Major Hazard facident Data Service, Safety and Reliability Business, UKAEA, distributed by Silverplate Information Inc. 

The major hazard on the site as a whole was the storage and use of chlorine. So much attention was devoted to this that other hazards received less attention than they should have. 

In the United Kingdom, the Health and Safety at Work Act (1974) and regulations made under it require occupiers to provide a safe plant and system of work and adequate instruction, training, and supervision. In the European community, occupiers of major hazard sites are required to produce a safety case, which describes how hazards have been assessed and are kept under control. Many other countries have similar legislation, though standards of enforcement vary. 

When deflagration venting is nsed, a major hazard of concern is the fireball (flame clond consisting of bnrning gases and/or dnst) discharged from the vent. This can cause harm to personnel or process eqnipment and... 

Health and Safety Executive. 1979. Second Report. Advisory Committee Major Hazards. U.K. Health and Safety Commission, 1979. 

A flash fire is the nonexplosive combustion of a vapor cloud resulting from a release of flammable material into the open air, which, after mixing with air, ignites. In Section 4.1, experiments on vapor cloud explosions were reviewed. They showed that combustion in a vapor cloud develops an explosive intensity and attendant blast effects only in areas where intensely turbulent combustion develops and only if certain conditions are met. Where these conditions are not present, no blast should occur. The cloud then bums as a flash fire, and its major hazard is from the effect of heat from thermal radiation. 

Consequently, if none of these conditions is present, no blast effects are to be expected. That is, under fully unconfined and unobstructed conditions, the cloud bums as a flash fire, and the major hazard encountered is heat effect from thermal radiation. 

The project began with an extensive evaluation of 900 reported incidents involving failures of fixed pipework on chemical and major hazard plant. As part of the analysis a failure classification scheme was developed which considered the chief causes of failures, the possible prevention or recovery mechanism that could have prevented the failure and the underlying cause. The classification scheme is summarized in Figure 2.13. A typical event classification would be... 

Hurst, N. W., Bellamy, L. J., Wright, M. S. (1992). Research Models of Safety Management of Onshore Major Hazards and Their Application to Offshore Safety. Proceedings of a Conference on Major Hazards Onshore and Offshore. IChemE Symposium Series No. 130. Rugby, UK Institution of Chemical Engineers. 

Major system upset Major hazard to facilities Major hazard to personnel Orderly process shutdown necessary... 

This reaction is indeed a major hazard in Xe/F chemistry, since Xe03 is highly explosive, and the complete exclusion of moisture is therefore essential (see p. 165 of ref. 10). Interestingly, the maximum yield of Xe03 is 33% rather than the 50% that would be expected from a simple disproportionation of 2Xe Xe -I- Xe", and the following reaction sequence has been suggested to explain this ... 

One of the major hazards of narcotic administration is respiratory depression, widi a decrease in the respiratory rate and depth. The most common adverse reactions include light-headedness, dizziness, sedation, constipation, anorexia, nausea, vomiting, and sweating. When diese effects occur, die primary healdi care provider may lower die dose in an effort to eliminate or decrease die intensity of die adverse reaction. Otiier adverse reactions tiiat may be seen witii die administration of an agonist narcotic analgesic include ... 

Performance requirements, environmental issues, and avaUabUity/cost of the material will mainly drive material requirement in the future. In order to face the huge tire wastage problem causing major hazards to the environment, future development in mbbery materials will be focused on development of thermoplastic polymer so that used polymer could be recovered by thermal treatment and separation, biological degradation by radiation/addition of chemical into the mbber compound that could be activated by exposure to radiation and development of biopolymer. 

Difficult to measure accurately and deal with effectively, organic pollutants continue to be a major hazard in the environment. Significantly expanded, the second edition of Organic Pollutants An Ecotoxicological Perspective describes the mechanistic basis of ecotoxicology, using major groups of pollutants as illustrative examples. It also explores the problem of complex mixtures of chemicals. 

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