Designing and operating safe chemical reaction processes HSG143

Health and SafetyExecutiveIntroduction1 This publication provides guidance on the assessment of chemical reactionhazards for batch and semi-batch processes, including selecting and specifying abasis of safety. It describes how to prevent and control the risk of thermal runawayaffecting people and the environment. It is aimed at those directly responsiblefor the development, design and operation of chemical plant and processes,particularly process chemists and process engineers. HSE has previously publishedguidance on this topic as a free leaflet. 12 The objectives of the publication are to:(a) increase awareness of potential chemical reaction hazards associated withchemical manufacture in batch and semi-batch processes;(b) help in the assessment of risks from chemical reactions, and advise onhow to prevent and control these risks;(c) provide a systematic approach for the design, operation and control ofchemical reactions in batch and semi-batch processes;(d) advise on safe management procedures and appropriate precautions toprevent or reduce injuries and damage caused to property or theenvironment associated with chemical manufacture; and(e) advise on maintenance, training and information needs to prevent andcontrol chemical reaction hazards.3 It is aimed at those directly responsible for the development, design andoperation of chemical plant and processes, particularly process chemists andprocess engineers.4 The guidance does not cover in any detail: continuous processes;environmental hazards; toxicological hazards; storage of raw materials and product;drying and formulation of products; size reduction processes; physical separationprocesses; or the transport of chemicals. Further guidance on some of theseaspects is available in the Further information section of this publication.Legal requirements5 Assessment by employers, of the risks to employees and others who may beaffected by the work activities, is one of the requirements of the Management ofHealth and Safety at Work Regulations1999 (MHSW). 26 This publication will help you in your assessment of the risks arising fromchemical reaction processes, and gives advice on how you may control these risks.7 This book also advises you on how to comply with relevant parts of the Healthand Safety at Work etc Act 1974 (HSW Act) 3 and, where applicable, with theProvision and Use of Work Equipment Regulations 1998 (PUWER), 4 the PressureSystems Safety Regulations 1999 (PSSR), 5 the Pressure Equipment Regulations1999 (PER), 6 the Control of Substances Hazardous to Health Regulations 1999(COSHH), 7 the Control of Major Accident Hazards 1999 (COMAH) 8 and otherrelevant legislation (see Appendix 1). The European Chemical Agents Directive(CAD) 9 requires you to avoid the conditions that can lead to harm from chemicallyunstable substances or mixtures. Legislation to implement the CAD requirements inDesigning and operating safe chemical reaction processes Page 5 of 64