Objective
The objective of this code of practice is to provide guidance in the setting up of an administrative, legal and technical system for the control of major hazard installations. It seeks to protect workers, the public and the environment by:
Preventing major accidents from occurring at these installation;
Minimising the consequences of a major accident on site and off site, for example by:
Arranging appropriate separation between major hazard installations and housing and other centres of population nearby such as hospitals, schools and shops; and
Appropriate emergency planning.
Application and uses
1.2.1. This code applies to major hazard installations which are usually identified by means of a list of hazardous substances, each with an associated threshold quantity, in such a way that the industrial installation brought within the scope of the definition are recognised as those requiring priority attention, i.e. they have the potential for causing a very serious incident which is likely to affect people, both on site and off site, and the environment. The list and threshold quantities of hazardous substances should reflect national priorities.
1.2.2. In order to facilitate step-wise implementation of the provisions of this code of practice, the competent authorities may for a transitional period establish increased threshold quantities for the implementation of particular components of the code.
1.2.3. Excluded from the scope of this code of practice are nuclear hazards and those of a strictly nature, both of which are likely to have existing comprehensive controls of their own. In addition, the code excludes the transportation of hazardous chemicals since its control and management are different from those at static sites.
1.2.4. This code addresses the activities necessary for competent authorities to establish a major hazard control system, and calls for attention to be paid to them by:
competent authorities such as governmental safety authorities and government inspectorates;
local authorities;
works managements;
workers and workers’ representatives;
police;
fire authorities;
health authorities;
suppliers of technologies involving major hazards;
other local organisations developing on particular national arrangements.
1.2.5. Depending on the type and quantity of hazardous substance present, the kinds of major hazard installation covered by this code may include:
chemical and petrochemical works;
oil refineries;
sites storing liquefied petroleum gas (LPG);
major storages of gas and flammable liquids;
chemical warehouses;
fertiliser works;
water treatment works using chlorine.
Definitions
1.3.1. In this code, the following terms have the meanings hereby assigned to them:
Accident consequence analysis: An analysis of the expected effects of an accident, independent of frequency and probability.
Check-list analysis: A method for identifying hazards by comparison with experience in the form of a list of failure modes and hazardous situations.
Code of practice: A document offering practical guidance on the policy, standard-setting and practice in occupational and general public safety and health for use by governments, employers and workers in order to promote safety and health at the national level and at the level of the installation. A code of practice is not necessarily a substitute for existing national legislation, regulations and safety standards.
Competent authority: A Minister, government department or other public authority with the power to issue regulations, orders or other instructions having the force of law.
Emergency plan: A formal written plan which, on the basis of identified potential accidents at the installation together with their consequences, describes how such accidents and their consequences should be handled either on site or off site.
Emergency services: External bodies which are available to handle major accidents and their consequences both on site and off site, e.g. fire authorities, police, health services.
Event tree analysis: A method for illustrating the intermediate and final outcomes which may arise after the occurrence of a selected initial event.
Failure mode and effects analysis: A process of hazard identification where all known failure modes of components or features of a system are considered in turn and undesired outcomes are noted.
Fault tree analysis: A method for representing the logical combinations of various system status which lead to a particular outcome (top event).
Hazard: A physical situation with a potential for human injury, damage to property, damage to the environment or some combination of these.
Hazard analysis: The identification of undesired events that lead to the materialization of the hazard, the analysis of the mechanisms by which those undesired events could occur and usually the estimation of the extent, magnitude and relative likelihood of any harmful effects.
Hazard assessment: An evaluation of the results of a hazard analysis including judgements as to their acceptability and, as a guide, comparison with relevant codes, standards, laws and policies.
Hazard and operability study (HAZOP): A study carried out by application of guide words to identify all deviations from design intent having undesirable effects on safety or operability, with the aim of identifying potential hazards.
Hazardous substance: A substance which by virtue of its chemical, physical or toxicological properties constitutes a hazard.
Hot work: An activity involving a source of ignition such as welding, brazing or spark-producing operations.
Major accident: An unexpected, sudden occurrence including, in particular, a major emission, fire or explosion, resulting from abnormal developments in the course of an industrial activity, leading to a serious danger to workers, the public or the environment, whether immediate or delayed, inside or outside the installation and involving one or more hazardous substances.
Major hazard installation: An industrial installation which stores, processes or produces hazardous substances in such a form and such a quantity that they posses the potential to cause a major accident. The term is also used for an installation which has on its premises, either permanently or temporarily, a quantity of hazardous substance which exceeds the amount prescribed in national or state major hazard legislation.
Operational safety concept: Strategy for process control, incorporating a hierarchy of monitoring and controlling process parameters and of protective action to be taken.
Preliminary hazard analysis (PHA): A procedure for identifying hazards early in the design phase of a project before the final design has been established. Its purpose is to identify opportunities for design modifications which would reduce or eliminate hazards, mitigate the consequences of accidents, or both.
Rapid ranking method: A means of classifying the hazards of separate elements of plant within an industrial complex, to enable areas for priority attention to be quickly established.
Risk: The likelihood of an undesired event with specified consequence occurring within a specified period or in specified circumstances. It may be expressed either as a frequency (the number of specified events in unit time) or as a probability (the probability of a specified event following a prior event), depending on the circumstances.
Risk management: The whole of actions taken to achieve, maintain or improve the safety of an installation and its operation.
Safety audit: A methodical in-depth examination of all or part of a total operating system with relevance to safety.
Safety report: The written presentation of the technical, management and operational information covering the hazards of a major hazard installation and their control in support of a justification for the safety of the installation.
Safety team: A group which may be established by the works management for specific safety purposes, e.g. inspections or emergency planning. The team should include workers, their representatives where appropriate, and other persons with expertise relevant to the tasks.
Threshold quantity: That quantity of a listed hazardous substance present or liable to be present in an installation which, if exceeded, results in the classification of the installation as a major hazard installation.
Workers: All employed persons.
Works management: Employers and persons at works level having the responsibility and the authority delegated by the employer for taking decisions relevant to the safety of major hazard installations. When appropriate, the definition also includes persons at corporate level having such authority.
Basic principles
1.4.1. Major hazard installations possess the potential, by virtue of the nature and quantity of hazardous substances present, to cause a major accident in one of the following general categories:
the release of toxic substances in tonnage quantities which are lethal or harmful even at considerable distances from the point of release;
the release of extremely toxic substances in kilogram quantities which are lethal or harmful even at considerable distances from the point of release;
the release of flammable liquids or gases in tonnage quantities which may either burn to produce high levels of thermal radiation or form an explosive vapour cloud;
the explosion of unstable or reactive materials.
1.4.2. Apart from routine safety and health provisions, special attention should be paid by competent authorities to major hazard installations by establishing a major hazard control system.
1.4.3. For each country having major hazard installations, competent authorities should establish such a major hazard control system. This should be implemented at a speed and to an extent dependent on the national financial and technical resources available.
1.4.4. The works managements of each major hazard installation should strive to eliminate all major accidents by developing and implementing an integrated plan of safety management.
1.4.5. Works management should develop and practice plans to mitigate the consequences of accidents which could occur.
1.4.6. For a major hazard control system to be effective, there should be full co-operation and consultation, based on all relevant information, among competent authorities, works managements, and workers and their representatives.