Bulk Liquid Chemical Handling Guide for Plants, Terminals, Storage and Distribution Depots (BLCH) Guide First edition published 2012 ISBN: 978-1-85609-519-8 eBook ISBN: 978-1-85609-525-9 © The Chemical Distribution Institute British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library. Notice of Terms of Use All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the copyright holders. While the advice given in this book (Bulk Liquid Chemical Handling Guide for Plants, Terminals, Storage and Distribution Depots (BLCH) Guide) has been developed using the best information currently available, it is intended purely as guidance to be used at the user’s own risk. The authors and publishers accept no responsibility for the accuracy of any information or advice given in the document or any omission from the document or for any consequence whatsoever resulting directly or indirectly from compliance with or adoption of guidance contained in the document even if caused by failure to exercise reasonable care. This publication has been prepared to deal with the subject of Bulk Liquid Chemical Handling for Plants, Terminals, Storage and Distribution Depots. This should not however, be taken to mean that this publication deals comprehensively with all of the issues that will need to be addressed or even, where a particular issue is addressed, that this publication sets out the only definitive view for all situations. Cover images courtesy: ALGRANEL S.A. Getty Images istockphoto NERI Depositi Costieri Spa SEA-invest (www.sea-tankterminal.com) Terminales Portuarias S.L. Muelle de la Energía, s/n. (TEPSA) Printed and bound in Great Britain by Bell & Bain Ltd, Glasgow A Published by Witherby Publishing Group Ltd 4 Dunlop Square, Livingston, Edinburgh, EH54 8SB, Scotland, UK Tel No: +44(0)1506 463 227 Fax No: +44(0)1506 468 999 Email: [email protected] Web: www.witherbys.com iii This publication is to provide detailed guidance for the management and employees of terminals and for terminal inspectors when answering the questions of the Chemical Distribution Institute (CDI) – Terminal inspection protocol. The publication may also have educational value to professionals engaged in bulk liquid chemical handling in the wider industries of manufacturing, storage and distribution. The publication is explicitly not a reference for legislators to adopt as an Industry Standard, but recognises the requirements of all applicable legislation, and does not question or challenge the application or compliance with such legislation. The publication recognises industry good practice for the safe and secure handling of bulk liquid chemicals as provided by the various national, regional and international standard bodies and respected industry associations. The publication is non-prescriptive and sets-out to provide guidance on the various solutions and options to achieve an international level of consistency for safe and quality operational performance of bulk liquid chemical terminals and the handling of bulk liquid chemicals in associated transport and distribution industries. The publication is jointly produced by the Chemical Distribution Institute (CDI), Witherby Publishing Group and the Centre for Maritime & Industrial Safety Technology Limited (C-MIST). The publication has been developed using the best information currently available; it is intended to be used entirely at the user’s own risk. A v OVERVIEW OF THE CHEMICAL DISTRIBUTION INSTITUTE VISION Driven by the expertise of the world’s leading chemical manufacturers the Chemical Distribution Institute (CDI) sets out to be the global source for data, information and advice specific to marine transportation and storage of chemical products, whether that be in bulk or packaged form. GENERAL The CDI Foundation is a non-profit making and non-commercial organization funded by the chemical industry. CDI is responsible for the accreditation of inspectors and auditors to provide inspection and audit reports for use in the risk assessment process. CDI online databases provide facility to create, edit and interpolate the inspection and audit reports on a 24/7 global basis. The databases are maintained at secure sites in the Port of Rotterdam. CDI is a Dutch foundation operating from offices in the UK; audited accounts are filed annually with Companies House. The Foundation is governed by a Board of Directors elected from the chemical company participants and operates entirely within EU competition and US anti-trust law. The CDI schemes are each managed by Executive Boards, made up of individual representatives from the chemical company participants. Reporting to the Executive Boards are the Technical and Accreditation Committees, responsible for the inspection protocols, and the accreditation of inspectors and auditors. The committees are of split representation, their membership being 50% from chemical companies and 50% from supply chain companies. Additionally, there are the Quality Audit Committee and the Finance Committee. The Asia Pacific Panel (APP) holding the same status as an Executive Board reports directly to the Board of Directors. The multi-discipline panel engages with regional industry stakeholders and promotes the continued growth of CDI throughout the Asia Pacific region. There are over 300 inspectors and auditors accredited to conduct CDI inspections and audits around the world. In addition to meeting academic and industry experience criteria, the inspectors and auditors are trained, examined and performance monitored in the field. Training and examination is undertaken by Warsash Maritime Southampton and the Centre for Maritime and Industrial Safety Technology (C-MIST) at Heriot-Watt University Edinburgh. Accreditation certificates remain the property of CDI and individuals failing to meet the rigorous standards have their certification revoked. CDI has close relationships with European Chemical Industry Council (CEFIC), American Chemistry Council (ACC), Association of the Brazilian Chemical Industry (ABIQUIM), Association of International Chemical Manufacturers (AICM), Chemical and Allied Industries’ Association (CAIA), Gulf Petrochemical and Chemical Association (GPCA), Indian Chemical Council (ICC), Oil Companies International Marine Forum (OCIMF), International Liquid Terminals Association (ILTA), Bulk Liquids Industry Association Inc. (BLIA) and International Container Handling Coordination Association (ICHCA). ACC and CDI are party to a Memorandum of Agreement to cooperate on matters of mutual interest in promoting high levels of health, safety, environmental and security performance. The alliance between the U.S. Trade Association and Global Inspection & Audit Organization provides ACC Responsible Care® Partner companies the option of using the CDI-T and IMPCAS schemes to meet their Responsible Care certification requirements. Significantly, the collaboration between ACC and CDI extends the use of CDI-T and IMPCAS, already global systems, to North America. vi Bulk Liquid Chemical Handling Guide 1994, CDI-MARINE CDI-M was created by the chemical industry to improve the safety and quality performance of bulk liquid shipping. CDI-M now provides annual inspection reports on the world fleet of chemical and liquid petroleum gas tankers, over 700 ship operators with over 4000 ships participate in the scheme. The inspections are conducted by CDI-M Accredited inspectors located in ports around the world. CDI-M is an information provider to EQUASIS, the European Commission’s Quality in Shipping Campaign. Via the EQUASIS web site, ship inspection reports are available to the Port State authorities. 1997, CDI-TERMINALS The CDI-T scheme was developed in 1997 and similar to the Marine scheme its purpose was to improve the safety and quality performance of bulk liquid storage terminals. Over 80 major chemical storage terminal companies are participant in the Terminals scheme. The CDI-T Accredited inspectors, regionally based, carry out the detailed management and technical inspections of liquid storage terminals on most continents of the world, with over 150 terminals inspected. 2002, INTERNATIONAL MARINE PACKED CARGO AUDIT SCHEME The IMPCAS is potentially the largest scheme of its kind in the world, with over 200 auditors based in the major container handling ports. Developed to provide audit reports on each category of service provider involved in the distribution supply chain, the scheme extends to include: Shipping Companies, Ships, Tank Container Operators, Container Freight Stations, Freight Forwarders, Agents, and Container Terminals. vii Contents Abbreviations xiii Acknowledgments xix VOLUME I 1 1. Chemicals and their Classification 3 1.1 Introduction 6 1.2 Regulatory Considerations 6 1.3 Basic Chemistry 7 1.4 Chemical Gases 9 1.5 Petrochemical Products 17 1.6 The Polymer Industry 18 1.7 Oleochemicals 19 1.8 Some Common Liquid Products Requiring Bulk Storage 20 1.9 Implications of Chemical Characteristics 20 1.10 Naming and Numbering Chemicals 29 1.11 Chemical Classification Systems 32 1.12 Material Safety Data Sheets (MSDS) 42 1.13 Special Information or Product Specific Requirements 53 References and Further Reading 55 2. Storage Tanks and Equipment 57 2.1 Introduction 59 2.2 Regulatory Considerations 60 2.3 Risk Assessment 61 2.4 Overview of Tank Types 62 2.5 Location and Layout of Tanks 65 2.6 General Tank Design and Construction 68 2.7 Pipework Systems and Pumps 77 2.8 Common Fittings and Fixtures 79 2.9 Earthing and Bonding 82 2.10 Gauging, Temperature Measurement and Sampling 83 2.11 Vapour and Emission Control 87 2.12 Bunds and Drains (also Referred to as Dikes) 90 2.13 Fire Safety 93 2.14 Operational Issues 94 2.15 Tank Cleaning 96 2.16 Inspection, Testing and Maintenance 100 References and Further Reading 100 3. Product Transfer Equipment 103 3.1 Introduction 105 3.2 Regulatory Considerations 105 3.3 Risk Assessment 105 3.4 General Considerations 106 3.5 Pumps 107 3.6 Pipes 113 3.7 Valves 116 3.8 Hoses 119 3.9 Loading Arms 122 viii Bulk Liquid Chemical Handling Guide 3.10 Couplings and Gaskets 127 3.11 Measuring Systems 128 3.12 Ancillary Equipment 129 3.13 Earthing and Bonding 130 3.14 Operational Issues 130 3.15 Inspection, Testing and Maintenance 132 References and Further Reading 132 4. Vapour and Emission Control 133 4.1 Introduction 135 4.2 Air Quality Management 135 4.3 Problems Associated with Emissions 136 4.4 Product Characteristics and Equipment Choice 138 4.5 Emissions Reduction Programmes 139 4.6 Sources of Emissions 140 4.7 Emission Monitoring and Control 150 4.8 Vapour Lines and Ancillary Equipment 153 4.9 Flame and Detonation Arresters 153 4.10 Blowers and Eductors 155 4.11 Inspection, Testing and Maintenance 156 4.12 Emissions from Incidents and Accidents 156 References and Further Reading 157 5. Jetty and Shipping 159 5.1 Introduction 161 5.2 Regulatory Considerations 162 5.3 Risk Assessment 163 5.4 Design and Construction 164 5.5 Jetty Infrastructure 167 5.6 Cargo Transfer Equipment 177 5.7 Waste Handling Facilities 186 5.8 Jetty Operations 187 5.9 Emergency Response 199 5.10 Jetty Security 203 5.11 Inspection, Testing and Maintenance 204 References and Further Reading 206 6. Road and Rail 207 6.1 Introduction 209 6.2 Regulatory and Terminal Considerations 209 6.3 Road and Rail Loading Station Risk Assessments 212 6.4 Loading and Unloading Infrastructure 213 6.5 Loading Station Product Transfer Equipment and Systems 219 6.6 Operations 226 6.7 Emergency Response 231 6.8 Security 232 6.9 Inspection, Testing and Maintenance 232 References and Further Reading 233 7. Warehousing and Drumming 235 7.1 Introduction 237 7.2 Regulatory Requirements 237 7.3 Risk Assessment and Management 239 7.4 Product Hazards and Classification 243 7.5 Dangerous Goods Packaging Requirements 250 7.6 Labelling of Drums and IBCs 255 7.7 Drumming 255 ix Contents 7.8 Warehouse and Infrastructure 265 7.9 Product Implications and Warehouse Types 270 7.10 Storage Arrangements 272 7.11 Training 274 7.12 Drum and IBC Filling 275 7.13 Warehousing Operations 276 7.14 Pallets 280 7.15 Fire Safety 282 7.16 Emergency Response 284 7.17 Security 286 7.18 Inspection, Testing and Maintenance 287 References and Further Reading 287 8. Hazardous Area Classification 289 8.1 Introduction 291 8.2 Regulatory Considerations 291 8.3 Hazardous Area Classification Systems 291 8.4 Fire and Explosion 296 8.5 Product Characteristics 298 8.6 Hazardous Area Classification – Assessing the Risk 300 8.7 Documentation 310 8.8 Overview of ATEX Requirements 310 8.9 Vehicles as Mobile Sources of Ignition 312 8.10 Inspection, Testing and Maintenance 315 References and Further Reading 316 VOLUME II 317 9. Fire Safety 319 9.1 Introduction 321 9.2 Regulatory Considerations 321 9.3 Classification of Fires 322 9.4 Terminal Fire and Explosion Hazard Areas 323 9.5 Fire-Related Hazards 324 9.6 Fire and Explosion Hazard Management (FEHM) 330 9.7 Fire Prevention 333 9.8 Fire and Flammable Vapour Detection 335 9.9 Fire Protection 338 9.10 Fire Response Strategies and Options 346 9.11 Inspection, Testing and Maintenance 347 References and Further Reading 348 10. Buildings 351 10.1 Introduction 353 10.2 Regulatory Considerations 353 10.3 Building Risk Assessments 354 10.4 Fires 357 10.5 Toxic Materials 357 10.6 Explosions 358 10.7 Management of Change 360 10.8 Terminal Layout and Buildings 360 10.9 General Ventilation Issues 365 10.10 Emergency Response 366 10.11 Security 367 10.12 Inspection, Testing and Maintenance 367 References and Further Reading 367 x Bulk Liquid Chemical Handling Guide 11. Solid and Liquid Waste 369 11.1 Introduction 371 11.2 Regulatory Compliance 371 11.3 Terminal Waste Inventory 372 11.4 Water Management 372 11.5 Sewers, Drains and Bunds 374 11.6 Water Collection and Treatment Facilities 378 11.7 Cleaning 379 11.8 Waste 380 11.9 Waste Handling 384 11.10 Carriage and Disposal of Hazardous Waste 386 11.11 Inspection, Testing and Maintenance 387 References and Further Reading 387 12. Electrical Equipment and Power Distribution 389 12.1 Introduction 391 12.2 Regulatory Considerations 391 12.3 Risk Assessment 392 12.4 System Drawings and Schedules 397 12.5 Substations and Switch Rooms 401 12.6 Cables and Ancillary Equipment 403 12.7 Motors and Ancillary Equipment 404 12.8 Lighting 404 12.9 Transportable and Portable Equipment 405 12.10 Alternative Energy Sources 406 12.11 Earthing and Static Protection 408 12.12 Cathodic Protection 411 12.13 Fire Safety 411 12.14 Emergency Response 412 12.15 Security Arrangements 413 12.16 Inspection, Testing and Maintenance 413 References and Further Reading 413 13. Traffic Circulation and Control 415 13.1 Introduction 417 13.2 Regulatory and Terminal Considerations 417 13.3 Traffic Circulation Risk Assessments 419 13.4 Vehicle Safety 421 13.5 General Design Principles for Roads and Facilities 423 13.6 General Traffic Management 429 13.7 Receipts and Deliveries 437 13.8 Driver Requirements and Control 440 13.9 Emergency Response 443 13.10 Security 443 13.11 Inspection, Testing and Maintenance 444 References and Further Reading 445 14. Personnel Safety 447 14.1 Introduction 449 14.2 Factors Affecting Health and Safety 450 14.3 Occupational Health Controls 455 14.4 Personal Protective Equipment 456 14.5 Job Safety Analysis 466 14.6 Permit to Work Systems 466 References and Further Reading 467 xi Contents 15. Emergency Response 469 15.1 Introduction 471 15.2 Regulatory Considerations 471 15.3 Assessment of Risks and Consequences 471 15.4 Emergency Preparedness 472 15.5 Emergency Response Plans (ERP) 475 15.6 Post Incident Cleanup and Recovery 490 15.7 Information and Training 491 15.8 Resources (Manpower/Equipment/Materials) 492 15.9 Security Arrangements 493 15.10 Inspection, Testing and Maintenance 493 References and Further Reading 495 16. Security 497 16.1 Introduction 499 16.2 Regulatory Considerations 499 16.3 Security Risk Assessment 500 16.4 Security Plan 501 16.5 Security Performance Standards 501 16.6 Security Training 501 16.7 Site Security 502 16.8 Security and the Carriage of Dangerous Goods 511 16.9 Pipeline Security 513 16.10 Jetty Security 515 16.11 CCTV Cameras 518 16.12 Computer and Document Security 519 16.13 Security Against Insider Activities 521 16.14 Security and Emergency Response 521 16.15 Inspection, Testing and Maintenance 522 References and Further Reading 522 17. Management of the Terminal 523 17.1 Level 1 – Policies and Procedures 527 17.2 Level 2 – Objectives and Management Plans 535 17.3 Level 3 – Operational Disciplines 541 Empty drums/ packaging Labs, Samples, QC Single flow traffic Gate house Administration RoadTruck loading Pre-inspection Vapour treatment Control room Key Waste handling Seagoing Warehouse B A W = Weighbridge ABC = Bulk storage areas = Gate = Loading gantries C Fill Water treatment BargesBarge jetty Parking W W Parking Offsite parking Truck loading Railloading W Volume I 1CHAPTER CHEMICALS AND THEIR CLASSIFICATION 4 Bulk Liquid Chemical Handling Guide, Vol 1 1. Chemicals and their Classification 3 1.1 Introduction 6 1.2 Regulatory Considerations 6 1.3 Basic Chemistry 7 1.3.1 Organic and Inorganic Compounds 7 1.3.2 Organic Chemicals 7 1.3.3 Inorganic Chemicals 9 1.4 Chemical Gases 9 1.4.1 States of Matter 10 1.4.2 Gases – Properties and Rules 11 1.4.3 First Stage – Gas to Liquid 12 1.4.4 Gases and Vapours 13 1.4.5 Saturated Vapour Pressure (SVP) 13 1.4.6 Common Chemical Gases 16 1.5 Petrochemical Products 17 1.6 The Polymer Industry 18 1.7 Oleochemicals 19 1.8 Some Common Liquid Products Requiring Bulk Storage 20 1.9 Implications of Chemical Characteristics 20 1.9.1 Physical Properties 20 1.9.2 Chemical Properties 22 1.9.3 Fire and Explosion 23 1.9.4 Solubility 27 1.9.5 Isomers 29 1.10 Naming and Numbering Chemicals 29 1.10.1 IUPAC Name 30 1.10.2 Synonyms 30 1.10.3 UN Number 30 1.10.4 CAS (Chemical Abstracts Service) Registry Number 30 1.10.5 EC (European Commission) Number 30 1.10.6 Supplier’s Catalogue Number 32 1.11 Chemical Classification Systems 32 1.11.1 Globally Harmonized System (GHS) (the Purple Book) 32 1.11.2 OSHA Hazard Communication Standard (HCS) 36 1.11.3 National Fire Protection Association (NFPA) 36 1.11.4 International Maritime Dangerous Goods (IMDG) Code 39 1.11.5 International Bulk Chemical (IBC) Code 40 1.11.6 The Federation of Oils, Seeds and Fats Associations (FOSFA) 41 1.12 Material Safety Data Sheets (MSDS) 42 1.12.1 Requirements and Use 42 1.12.2 Accuracy and Quality of Information 43 1.12.3 GHS MSDS Format 43 1.13 Special Information or Product Specific Requirements 53 References and Further Reading 55 20 Bulk Liquid Chemical Handling Guide, Vol 1 1.8 Some Common Liquid Products Requiring Bulk Storage Product Butyl Acrylate Ethylene Glycol (fibre grade, industrial grade and antifreeze grade) Acetic Acid Sulphuric Acid Ethyl Acrylate Toluene Caustic Soda Base Oil Potable Alcohol Benzene N-Butanol Ethanol Methanol Phenol Isobutanol Vinyl Acetate Monomer (VAM) Styrene Monomer Butyl Glycol Ether Monopropylene Glycol 2-Ethylhexyl Acrylate Ethyl Acetate Acrylonitrile Propylene Oxide Propionic Acid Table 1.2 – Some common products that require bulk storage 1.9 Implications of Chemical Characteristics The characteristics that chemicals exhibit under various conditions are highly significant to their handling and storage. For example, the level of reactivity of a particular substance determines the possible hazards or consequences of any reaction. The physical and chemical properties of a substance directly impact safe handling and storage practices, including decisions on what type of pump or valve should be selected. Therefore, it is crucial to have a broad understanding of some of the implications posed by chemical characteristics. Chemical characteristics can be separated into two categories: ?Physical properties ?chemical properties. 1.9.1 Physical Properties A physical property is any aspect of an object or substance, such as boiling point, that can be measured or perceived without changing its identity. For example, the boiling of liquid water (H2O) into gas is a physical property since the chemical property of the water remains unchanged, only its physical state has changed. Since differences between the physical properties of chemicals may affect the way that they are handled and stored, reference should always be made to the supplier’s technical information and MSDS. There are many important physical properties that should be carefully considered when handling chemicals to prevent dangerous conditions arising, including: ?Viscosity ?density ?saturated vapour pressure. 1.9.1.1 Viscosity Viscosity is a measure of a fluid’s resistance to flow. The less viscous a fluid, the greater its ease of movement. A highly viscous fluid will flow less readily. Temperature has an important effect on the viscosity of a material. Liquids and gases are both fluid, so both can flow, but temperature changes affect their viscosity values differently. For a gas, an increase in the temperature increases the chemical’s viscosity, ie at higher temperatures a gas’s ability to flow is reduced and it becomes ‘thicker’. For liquids, as the temperature increases, the viscosity decreases, ie at higher temperatures liquids tend to flow more easily. For example, honey and syrups flow more readily when heated and, in cold weather, engine oil and hydraulic fluids can thicken, which can significantly affect the performance of machinery. 21 Chemicals and their Classi?cation GasTemperature (°C) Hydrogen9.0 Hydrogen08.4 27 LiquidViscosity mPa.s Glycerine 10014.8 Glycerine30612 Glycerine201410 Glycerine012070 As temperature increases, viscosity of gases increases As temperature increases, viscosity of liquids decreases Table 1.3 – Viscosity changes with temperature for liquids and gases There are two measures of fluid viscosity - dynamic and kinematic. Dynamic (or absolute) viscosity This is a measure of the resistance to flow of a fluid under an applied force. Kinematic viscosity This is the ratio of the viscosity of a fluid to its density and is calculated by dividing the dynamic viscosity value of a chemical by its density. Kinematic Viscosity (cSt) Temperature (°C) 1000.000 100.000 Mercury Water Oil SAE 10 Oil no.3 Air Hydrogen Helium 10.000 1.000 0.100 0.010 0102030405060708090100 Figure 1.15 – Kinematic viscosities for some common gases and fluids 1.9.1.2 Density The density of a fluid (whether liquid or gas) is very important in terms of the handling and storage of chemicals since, among other factors, it determines the choice of storage and handling equipment and fire-fighting procedures. For example, if the relative density of a liquid is less than 1 (see Table 1.1), the material is lighter than water and so will require alternative fire- fighting measures to be available. It is also important in terms of transport because it determines weight and storage capacity. The relative density or specific gravity (SG) of a liquid is defined as the ratio of density of the material to the density of water at a specified temperature. Liquid SG=Density of liquid Density of water The density of water is about 1 g/cm3. Many have an SG that is >1.0, which means they are heavier than water and so will sink. For example, glycerine has an SG of 1.263 (at 25°C) and mercury has an SG of 13.6 (at 25°C). However, materials that are lighter than water, ie with an SG <1.0, will float. For example, natural gasoline has an SG of 0.713 (at 15.5°C) and kerosene has an SG of 0.820 (at 15.5°C). Vapour SG (or vapour relative density)=Density of vapour Density of air The relative density of a vapour (or gas) is the density of a fixed volume of the vapour in relation to the same volume of a standard, in this case air, and measured at a standard temperature and pressure. Liquefied Gases Specific Gravity Liquid Specific Gravity Vapour Ammonia0.6170.59 1.3 Butadiene0.6271.87 iso-Butane0.5632.01 n-Butane0.5832.01 Chlorine1.4142.45 Ethane0.3561.04 Ethylene0.6100.97 Ethylene oxide0.8851.52 Hydrogen0.0700.07 Methane0.4150.55 Nitrogen0.8080.97 Oxygen1.1401.10 Propane0.5801.52 Propylene (Propene) 0.5221.45 Vinyl chloride0.9192.15 Table 1.4 – Specific gravity (SG) of some liquefied gases 22 Bulk Liquid Chemical Handling Guide, Vol 1 Knowing the vapour relative density (or vapour SG) is useful in predicting whether a material is heavier or lighter than air and is valuable in avoiding potentially hazardous conditions. For example, ether is much heavier than air (SG vapour = 2.55) and this means it could flow across decks and jetties and may reach an ignition source. Vapour density would influence the degree to which the vapour would rise or sink and collect in low points such as bunds or drains. Where there is a fire, under certain conditions the resulting up draught can result in low level vapours, that are significantly heavier than air, being carried upwards into the fire. 1.9.1.3 Saturated Vapour Pressure (SVP) 100 50 0 0102030405060708090100 temperature (°C) When the atmospheric pressure is 100 kPa (1 atm), and the SVP starts to rise as a result of increasing temperature, the water starts to boil at 100°C. If the external pressure is reduced to about 30 kPa (0.3 atm), the boiling point of water reduces to about 70°C. SVP (kPa) Figure 1.16 – Graph of SVP for water (See Section 1.4.5) An important property to be considered when handling chemicals is the saturated vapour pressure (SVP), which is particularly relevant when flammable and toxic products are handled due to: ?The product reaching boiling point when the SVP is the same as the atmospheric pressure ?there being an increased rate of evaporation as the SVP rises ?there being an increase in the SVP as the product temperature rises. 1.9.2 Chemical Properties Unlike physical properties, which do not change the chemical nature of a substance, chemical properties of substances change the chemical nature of the substance during a reaction, resulting in a new substance or substances with different properties. Some generalisations can be made for the handling and storage of bulk products with regard to their chemical properties, but since these are only indications, the supplier’s technical information and the MSDS should always be consulted. There are several chemical properties of substances and many are interlinked, which will affect the measures taken for safe and efficient bulk handling and storage of chemicals. Some examples with particular relevance to the handling and storage operations are: ?Reactivity ?flammability and combustibility ?toxicity ?pH. 1.9.2.1 Reactivity Some chemicals are more reactive than others and their reactivity can be influenced by a number of factors including temperature and pressure. In general, increases in temperature and pressure encourage reactions to take place. In many cases the process involves the production of heat and, if this occurs in a closed system, the rising temperature will also increase the pressure. This can create a risk of explosion and a release of toxic gases. The reactivity of a chemical is also based on the number of other substances with which it reacts, how much of the total chemical present takes part in the reaction and how quickly this occurs. 1.9.2.2 Flammability and combustibility Flammable and combustible liquids evaporate and form a vapour and it is the mixture of air and vapour that is flammable. This can take place when containers are left open, leaks or spills occur, or the liquids are heated. The flashpoint is the lowest temperature at which a liquid can release sufficient vapour to form an ignitable mixture with air. Vapour mixed with air can ignite when exposed to a spark or a flame. 23 Chemicals and their Classi?cation The difference between a flammable and a combustible liquid is the ease (ie temperature) with which the substance burns or supports burning and is a measure of its potential hazard. Flammable liquids form flammable vapours at temperatures <38°C (100°F), about the same as a hot summer’s day. Extremely flammable liquids form vapour at <23°C (73°F), which approximates to normal room temperature. A combustible liquid is any liquid with a flashpoint >38°C (100°F) but <93°C (200°F). There are different systems used to classify liquids as flammable or combustible, so it is important to use the local classification system See Figure 1.18. Combustion byproduct contaminants are also a danger and may have very different properties to the original flammable material. Byproducts include fumes, gases, smoke and dust particles, some of which may be toxic. The handling of flammable liquids and their vapours may cause health hazards from ingestion, inhalation or skin contact. Health effects vary depending on the particular chemical, the chemical concentration and the route of exposure. Dangers include toxicity, reactivity or corrosivity of the material. 1.9.2.3 Toxicity Toxicity effects are dose dependent and there is a relationship between concentration level, duration and method of exposure. For example, carbon dioxide (CO2) is normally present in fresh air at between 0.036% and 0.039%. At 1%, with prolonged exposure, it can cause drowsiness. However, at a concentration of approximately 8% a loss of consciousness occurs in as little as 5–10 minutes. The LD50 figure of a chemical (see Section 1.12.3) is frequently used as a general indicator of the acute toxicity of a substance. The LD50 is usually determined for both oral (swallowing) and dermal (skin) exposure, and is usually expressed in milligrams of chemical per kilogram of body weight (mg/kg). The lower the LD50 value of a substance, the greater its toxicity. For example, a shellfish poison (saxitoxin) has an LD50 value of 0.8 mg/kg and is highly toxic, producing the syndrome paralytic shellfish poisoning, whereas sucrose (table sugar) has an LD50 value of 30,000 mg/kg and is practically non-toxic. When comparing a chemical with a low LD50 to one with a high LD50 the low LD50 chemical is not necessarily a more dangerous chemical, but is simply more toxic. 1.9.3 Fire and Explosion The basic difference between a fire and an explosion is the rate of the reaction. A fire reaction can continue over a long period, but an explosion is a reaction of short duration. Fire During combustion, the rate of energy release is in balance with the dissipation of this energy. This means that, over time, a limiting rate of reaction is reached. This can be observed in Figure 1.17 with the combustion line levelling off. Time Explosion Combustion Rate of Reaction Figure 1.17 – Typical rate of reaction vs time for explosion/combustion rates Explosion During an explosion, the products of combustion remain in the reaction zone, meaning that the temperature and pressure continue to rise. The rate of reaction increases exponentially until all the reactants are consumed. 1.9.3.1 Requirements for a fire or explosion Before a fire or explosion can take place, the three elements that must be present, commonly referred to as the ‘fire triangle’, are: ?A flammable material capable of supporting combustion (fuel) ?a source of ignition with sufficient energy to initiate combustion (heat) 24 Bulk Liquid Chemical Handling Guide, Vol 1 ?an adequate supply of oxygen, usually air (oxidizer). Fire Triangle FuelOxygen Heat An extension to the fire triangle is the fire tetrahedron, where a fourth element, a chemical chain reaction between the three elements, has been added. The removal of any of the elements will prevent or extinguish a fire. Fire Tetrahedron Heat FuelOxygen Chain reaction Possible sources of ignition include: ?Direct flame or sparks from sources such as matches or lighters, fires, faulty electrical equipment and maintenance activities ?electrostatic discharge from activities such as product transfer activities and indirect lightning strikes ?hot surfaces from sources such as vehicle exhausts, faulty equipment and heating equipment ?combustion due to reactions such as those from mixing incompatible materials, runaway product polymerization and spontaneous combustion. 1.9.3.2 Flammable range When a flammable material is mixed with air, there needs to be a certain concentration of fuel (flammable substance) within the mixture for it to burn. The flammable range is the range of concentrations of a particular substance within air that may catch fire or explode. For example, a mixture of hydrocarbon gas and air cannot ignite and burn unless its composition lies within the flammable range. The proportion of combustible material in the mixture is expressed as a percentage by volume of vapour in air, and is delineated by the upper and lower flammability limits. Lower flammable limit (LFL) or lower explosive limit (LEL) Below the lower limit of the flammability range, known as the lower flammable limit (LFL), there is insufficient flammable material in the mixture to support combustion. The LFL refers to the leanest mixture that can sustain a flame Upper flammable limit (UFL) or upper explosive limit (UEL) The upper flammable limit (UFL) refers to the point above which there is insufficient air to generate or support combustion. The UFL gives the richest flammable mixture. Hydrocarbon Flammability Limits (% by volume) LowerUpper Methane5.016.0 Ethane3.016.0 Propane2.010.0 Butane1.59.0 Pentane1.08.0 Hexane1.17.5 H2S4.345.0 Table 1.5 – Limits of flammability of various petroleum vapours in air (standard conditions) In air, the flammability limits of a substance depend on the initial temperature and pressure. Standard tests are carried out at 25°C and 1 atm. When the initial temperature is increased the flammable range widens, with the LFL reducing and the UFL increasing. Similarly, an increase in the oxygen concentration broadens the flammable range (lowering the LFL and raising the UFL), leading to an increase in flammability. Adding an inert gas to the air mixture narrows the range (raising the LFL and lowering the UFL) and reduces flammability. Changes in the initial pressure, in the case of hydrocarbons in air, do not change the LFL significantly, but the UFL will increase. 55 Chemicals and their Classi?cation References and Further Reading EEC Dangerous Substances Directive 67-548-EEC Annex VI Classification on the basis of Physicochemical Properties [Figure 1.18] EI Model Code of Practice Part 19 Annex B - IP Classification of Petroleum & its Products [Figure 1.18] European Regulation (EC) No 1272/2008 on Classification, Labelling and Packaging of Substances and Mixtures (CLP Regulation) [1.11.1.2] IMDG 2008 Edition 2.3.2.5 Hazard Grouping based on Flammability [Figure 1.18] International Bulk Chemicals (IBC) Code International Maritime Dangerous Goods (IMDG) Code International Safety Guide for Oil Tankers and Terminals (ISGOTT) [1.9.3.3] ISGOTT 5th Edition 1.2.6 Flammability Classification of Petroleum [Figure 1.18] Material Safety Data Sheet/Safety Data Sheet (MSDS/SDS) National Fire Protection Association (NFPA) – www.NFPA.org NFPA 30 Flammable & Combustible Liquids Code Ch 4 Definition & Classification of Liquids [Figure 1.18] NFPA 704 Standard System for the Identification of the Hazards of Materials for Emergency Response [1.11.3] OSHA 1910.106 Flammable and Combustible Liquids [Figure 1.18] SOLAS Chapter VII – Carriage of dangerous goods [1.11.5] Tanker Safety Training Liquefied Gases (2007, Witherby Publishing Group) [1.11.1-9] The European Directive on Safety Data Sheets (2001/58/EC) [1.12] The Federation of Oils, Seeds and Fats Associations (FOSFA) – www.fosfa.org The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The International Code for the Construction and Equipment of Ships carrying Dangerous Chemical in Bulk (IBC Code) [1.11.5] The International Convention for the Prevention of Pollution from Ships 73/78 (MARPOL) [1.11.5] OSHA Hazard Communication Standard 29 CFR 1910.1200 (HCS) [1.11.2] The US Department of Labor, Occupational Safety and Health Administration (OSHA) – www.osha.gov 2CHAPTER STORAGE TANKS AND EQUIPMENT 58 Bulk Liquid Chemical Handling Guide, Vol 1 2. Storage Tanks and Equipment 57 2.1 Introduction 59 2.2 Regulatory Considerations 60 2.2.1 Local Legislation and Regulations 60 2.2.2 International Standards and Codes of Practice 61 2.3 Risk Assessment 61 2.3.1 Site Risk Assessments 61 2.3.2 Management of Change 62 2.4 Overview of Tank Types 62 2.4.1 Fixed Roof Tanks 62 2.4.2 Internal Floating Roof Tanks 63 2.4.3 External Floating Roof Tanks 65 2.4.4 Horizontal Tanks 65 2.5 Location and Layout of Tanks 65 2.5.1 General Site Layout 65 2.5.2 Safety Distances 66 2.6 General Tank Design and Construction 68 2.6.1 General 68 2.6.2 Materials of Construction 69 2.6.3 Corrosion Protection 70 2.6.4 Tank Foundations 72 2.6.5 Tank Bases, Shells and Roofs 74 2.6.6 Stairs, Ladders and Walkways 75 2.7 Pipework Systems and Pumps 77 2.7.1 Pumps, Valves and Pipelines 77 2.7.2 Pipeline Pressure Relief Systems 79 2.8 Common Fittings and Fixtures 79 2.8.1 Tank Fittings 80 2.8.2 Heaters 81 2.8.3 Tank Cladding and Insulation 81 2.8.4 Agitators 82 2.9 Earthing and Bonding 82 2.9.1 Lightning Protection 82 2.9.2 Earthing and Bonding 83 2.10 Gauging, Temperature Measurement and Sampling 83 2.10.1 Automatic Level Gauges and Temperature Measurement 84 2.10.2 Manual Dipping, Temperature Measurement and Sampling 84 2.10.3 Tank Capacity, High and Low Level Alarms and Shut-off Valves 84 2.11 Vapour and Emission Control 87 2.11.1 Flammable Vapour Issues 88 2.11.2 Quality Issues 89 2.11.3 Emissions and Vapour Control Systems 89 2.12 Bunds and Drains (also Referred to as Dikes) 90 2.12.1 Bund Design and Containment Requirements 91 2.12.2 Bund Wall Design and Height 91 2.12.3 Drains and Valves 92 2.13 Fire Safety 93 2.13.1 General 93 2.13.2 Detection and Alarm Systems 93 2.13.3 Water Systems 94 2.13.4 Foam Systems 94 2.14 Operational Issues 94 2.14.1 Product Movement and Requirements 94 2.14.2 Tank and Equipment Choice 95 2.14.3 General Operational Requirements 95 2.15 Tank Cleaning 96 2.15.1 General 96 2.15.2 Cleaning Procedures 97 2.15.3 Inspection and Recommissioning 99 2.16 Inspection, Testing and Maintenance 100 References and Further Reading 100 77 Storage Tanks and Equipment 2.7 Pipework Systems and Pumps This is also covered in Chapter 3 - Product Transfer Equipment. 2.7.1 Pumps, Valves and Pipelines All pumps, pipes, valves and connections to the tank should be constructed of steel, designed in accordance with the relevant tank and fire safety standards and, where required, adequately bonded and earthed. The type of pump and any electrical equipment should be compatible with the zone in which they will operate. Pumps Pumps are ignition sources due to the electrical cables, connections and motor and the potential for mechanical seal failures. Where flammable products are stored, the pumps should be sited outside the bund in accordance with the flammable area classification and zone requirements. The most commonly used pumps at chemical storage facilities are centrifugal pumps and, for more viscous products, various types of positive displacement pumps. Issues to consider when selecting and installing pumps include: ?Performance specifications and suitability to service and flow required ?adequate Kw rating for all performance points over the operational range ?a motor, electrical cables and switches meeting the hazardous area zone requirements ?all pump connections and components to be earthed ?location of connections for ease of maintenance or replacement ?isolation valves on the inlet and outlet side of the pump to allow for ease of removal or replacement ?a strainer fitted on the suction side to protect the pump from damage ?pipe connections that avoid misalignment and stress to the pump seals and casing ?where required, and for all positive displacement pumps, an automatic pressure bypass or relief system ?low or no flow protection or cut-out ?high temperature protection or cut-out ?high pressure protection or cut-out ?a means of checking the pressure on the pump outlet ?adequate bunding or spill containment. Figure 2.15 – Centrifugal pump Valves For volatile products, valve choice should take into consideration the degree of fugitive emission release. Where bonnet valves are used, they should be bolted rather than screwed. For flammable products, the valves should be inherently fire safe, all-metal gate valves or soft-seated valves that have been fire tested. The valves should be of cast steel or fire rated. Ductile or cast iron should not be used in critical positions as they may fail due to the application of cold water streams during a fire. Where valves are used for isolation or shut-off, they should be capable of maintaining a liquid- tight seal when the piping system is disconnected on the discharge end of the valve. Valves with bolts extending from flange to flange outside the valve body or wafer valves should not be used for isolation without special fire protection. Where check valves are used to control the direction of flow, they should not be relied on for complete positive shut-off of reverse flow. Consideration should be given to the installation of check valves on the discharge side of pumps or on pump bypass piping. 78 Bulk Liquid Chemical Handling Guide, Vol 1 Particularly where hazardous products are involved, consideration should be given to the installation of valves on the tank that can be remotely operated and are fail-closed. Where remotely operated valves are used, the closure time should be set with due consideration given to the effects of pressure surge. Valves should have some form of indication to show whether they are fully or partially open or closed. Figure 2.16 – Tank delivery pipeline with gate valve and thermal relief system Pipelines The pipeline diameter should be sized to achieve the required flow rate, which for flammable products should normally not exceed 7 m/sec. Apart from the potential for static electricity buildup, higher flows can result in hydraulic surges and internal erosion in the pipelines. Gusset platesTank wall PipeDrain holes Figure 2.17 – Tank pipeline showing strengthening gussets An assessment should be conducted to determine the pros and cons of installing the pipelines above or below ground. Local regulations may specify aboveground or buried pipelines for different applications. Aboveground pipeline characteristics include: ?Easier access for inspection, testing and maintenance ?leaks are quickly and easily identified Figure 2.18 – Tank pipeline with spring loaded support ?changes or modifications are less complicated ?there is more flexibility of movement in all planes ?misalignment or stress due to movement or settling of structures such as foundations, tanks or bund walls is easier to identify and rectify ?pipelines and support structures can obstruct movement of operational and maintenance staff and equipment 79 Storage Tanks and Equipment ?pipelines are more affected by ambient temperatures and radiant heat with additional expansion and thermal relief requirements ?greater risk of damage by fire. The pipeline layout should be as uncomplicated as possible and should: ?Have a minimum of connections, fittings and valves ?avoid dead legs ?be adequately supported ?be protected against corrosion ?have surge protection where required. Inlet pipes should terminate internally near the bottom of the tank to minimise turbulence and the generation of vapours and/or static electricity. 2.7.2 Pipeline Pressure Relief Systems Thermal pressure relief valves should be installed where there is the potential for pressure buildup where the product is blocked in, such as between closed valves, check valves and pumps. Discharge from the pressure relief valve should be directed to a low pressure receptacle or pipeline where the relief pressure will not interfere with the downstream conditions. Adjusting screw Disc Base Inlet Outlet Spring Figure 2.19 – Thermal relief valve There should be a one way check valve on the downstream side of the pressure relief valve, and isolation valves on either side of the pressure relief valve and check valve. The isolation valves should have visible indication of their open or closed status and should be able to be locked in the open position. The isolation valves allow the pressure relief valve and check valve to be easily removed for inspection, testing or maintenance, without having to clean the entire product pipeline. Figure 2.20 – Positive displacement pump with pressure relief system 2.8 Common Fittings and Fixtures Fittings above the highest liquid level should be vapour tight when closed and fittings below the highest liquid level should be both liquid and vapour tight. For flammable products, all equipment should meet the standards for the zone in which they will operate. Other factors to be considered include: ?Product physical and chemical characteristics ?operating environment and climatic conditions ?local emission standards ?local fire safety standards ?product quality and sampling requirements ?earthing and bonding ?inspection, testing and maintenance requirements. 80 Bulk Liquid Chemical Handling Guide, Vol 1 2.8.1 Tank Fittings Manholes Manholes should be large enough to allow tank entry while wearing full PPE and breathing apparatus, typically 600 mm inside diameter. For vertical tanks there should be at least one manhole close to the tank base and one on the roof. Depending on tank size, it is good practice to have two or more manholes close to the tank base, which will facilitate tank ventilation and provide an additional means of emergency access or escape. Figure 2.21 – Manhole Connecting manholes to davit arms will allow easier and safer fitting and removal of heavy manholes and will reduce the risk of damage to gaskets during the fitting process. Procedures should be in place to ensure that the manhole bolts are tightened in the correct sequence and to the correct torque settings. This is particularly important when special gaskets, which can be easily damaged, are used. Vents All tanks should be fitted with open vents, conservancy vents or P/ V valves. The vents should be sized according to the relevant standard, which allows for: ?A combination of the highest outbreathing rate due to high ambient temperatures and the maximum product filling rate ?a combination of the highest inbreathing rate due to falling ambient temperatures and the maximum product emptying rate. Figure 2.22 – Conservancy vent Pressure Guide post Pallet stem Pallet assembly Mesh screen Seat Vacuum Pallet stem Weather hood Guide post Mesh screen Pallet assembly Seat Figure 2.23 – P/ V valve Tanks should be fitted with emergency venting that allows for overpressure relief from abnormal operating conditions and radiant heat from fires. Tanks fitted with a frangible roof do not require an emergency relief vent. Some tanks with internal floating roofs are fitted with air circulation vents that prevent the development of flammable vapours in the tank headspace. 100 Bulk Liquid Chemical Handling Guide, Vol 1 2.16 Inspection, Testing and Maintenance This is also covered in Chapter 17 - Management of the Terminal. General The inspection, testing and maintenance of storage tanks and associated equipment and infrastructure should only be carried out by personnel who are fully qualified and trained in these tasks. They should comply with regulations and site health, safety and environmental requirements and also be aware of the hazards and risks posed by the products stored and the operations being conducted nearby. The terminal should have detailed procedures covering inspection, testing and maintenance activities for the tanks and there should be ready access to all relevant and up-to-date documentation required for performance. References and Further Reading National Fire Protection Association (NFPA) BS 2654 Appendix F Specification for manufacture of vertical steel welded non-refrigerated storage tanks with butt-welded shells for the petroleum industry. (Withdrawn. Replaced by BS EN 14015:2004) API 650 Welded Tanks for Oil Storage, 11th Edition, 2007 API 607 Fire Test for Soft-Seated Ball Valves, 4th Edition. 1993 API Std 653 Tank Inspection, Repair, Alteration and Reconstruction, 4th Edition, 2009 API Std 620 Design and Construction of Large, Welded, Low-pressure Storage Tanks, 11th Edition, 2008 API Std 2000 Venting Atmospheric and Low-pressure Storage Tanks, 6th Edition, 2009 (Identical Adoption of international standard ISO 28300:2008) API Std 2015 Requirements for Safe Entry and Cleaning of Petroleum Storage Tanks, 6th Edition, 2001, reaffirmed 2006 API Std 2016 Guidelines and Procedures for Entering and Cleaning Petroleum Storage Tanks, 1st Edition, 2001, Reaffirmed 2006 API Publ 2026 Safe Access/Egress Involving Floating Roofs of Storage Tanks in Petroleum Service, 2nd Edition, 1998, reaffirmed 2006 API RP 2350 Overfill Protection for Storage Tanks in Petroleum Facilities, 2nd Edition, 2005 API Std 2610 Design, Construction, Operation, Maintenance & Inspection of Terminal and Tank Facilities, 2nd Edition, 2005 API RP 12R1 Recommended Practice for Setting, Maintenance, Inspection, Operation and Repair of Tanks in Production Service, 5th Edition, 1997, reaffirmed 2008 API RP 575 Inspection of Atmospheric & Low Pressure Storage Tanks, 2nd Edition, 2005 NFPA 30 Flammable and Combustible Liquids Code 2012 Edition, 2011 NFPA 68 Standard on Explosion Protection by Deflagration Venting, 2007 Edition, 2007 EEMUA 180 Frangible Roof Joints for Fixed Storage Tanks: Guide for Designers and Users, 2007 EEMUA 159 Users’ Guide to the Inspection, Maintenance and Repair of Above ground Vertical Cylindrical Steel Storage Tanks (2003, 3rd Edition with corrigenda & Amendment February 04 To Vol 1 and January 2005 to Vol 2) Energy Institute Design, Construction and Operation of Petroleum Distribution Installations. Model Code of Safe Practice in the Petroleum Industry, Part 2, 3rd Edition, 2005 Energy Institute Model of Safe Practice Part 16: Tank cleaning and safety code, 3rd Edition, 2008 101 Storage Tanks and Equipment Institute of Petroleum Vapour Recovery Hazards Bulletin, 2002 CIRIA Chemical Storage Tank Systems – good practice. Guidance on design, manufacture, installation, operation, inspection and maintenance (C598), 2003 HSG 176 The Storage of Flammable Liquid in Tanks (1998) (HSE/UK) Safety and Environmental Standards for Fuel Storage Sites. Buncefield Standards Task Group (BSTG) Final Report – July 2009 Recommendations on the Design and Operation of Fuel Storage Sites. Buncefield Major Incident Investigation Board – 03/07 The Buncefield Incident 11 December 2005. The Final Report of the Major Incident Investigation Board – 2008 3CHAPTER PRODUCT TRANSFER EQUIPMENT 104 Bulk Liquid Chemical Handling Guide, Vol 1 3. Product Transfer Equipment 103 3.1 Introduction 105 3.2 Regulatory Considerations 105 3.3 Risk Assessment 105 3.3.1 Onsite Assessment 106 3.3.2 Offsite Assessment 106 3.3.3 Management of Change 106 3.4 General Considerations 106 3.4.1 Degree of Automation 106 3.4.2 Dedicated and Shared Systems 107 3.4.3 Labelling and Marking 107 3.5 Pumps 107 3.5.1 General 107 3.5.2 Pump Location Considerations 108 3.5.3 Containment and Drainage 108 3.5.4 Product Characteristics and Pump Selection 108 3.5.5 Types of Pumps 109 3.5.6 Pump Equipment 109 3.5.7 Pump Protection Systems 111 3.6 Pipes 113 3.6.1 General 113 3.6.2 Types of Piping 113 3.6.3 Product Pipes 113 3.6.4 Vapour Pipes 113 3.6.5 Flame and Detonation Arresters 114 3.6.6 Pipe Installation 114 3.6.7 Pigging Stations 114 3.6.8 Hose Exchanges/Switching Stations 116 3.7 Valves 116 3.7.1 General 116 3.7.2 Types of Valves 116 3.7.3 Operations and Valve Applications 117 3.7.4 Blinds and Flanges 117 3.7.5 Materials of Construction 118 3.7.6 Implication of Product Characteristics 118 3.7.7 Operational Requirements and Valve Choice 118 3.7.8 ROSOVs (Remotely Operated Shut-Off Valves) 118 3.8 Hoses 119 3.8.1 General 119 3.8.2 Types of Hoses 120 3.8.3 Implications of Product Characteristics 120 3.8.4 Operational Requirements and Hose Choice 120 3.8.5 Cleaning Hoses 121 3.8.6 Inspection, Testing and Maintenance of Hoses 122 3.9 Loading Arms 122 3.9.1 General 122 3.9.2 Loading Arm Connecting Systems 125 3.9.3 Implications of Product Characteristics 126 3.9.4 Operational Requirements and Loading Arm Choice 126 3.9.5 Cleaning Loading Arms 126 3.10 Couplings and Gaskets 127 3.10.1 General 127 3.10.2 Types of Couplings 127 3.10.3 Operations and Coupling Choice 127 3.10.4 Implications of Product Characteristics 127 3.10.5 Gaskets 127 3.11 Measuring Systems 128 3.11.1 Standards and Regulations 128 3.11.2 Types of Measuring Systems 128 3.11.3 Implications of Product Characteristics 129 3.11.4 Operations and Measuring System Choice 129 3.11.5 Inspection and Calibration Requirements 129 3.12 Ancillary Equipment 129 3.12.1 Sample Points and Valves 129 3.12.2 Blowing and Drain Points and Valves 129 3.12.3 Pressure Gauges 129 3.12.4 Strainers 129 3.12.5 Filters 129 3.13 Earthing and Bonding 130 3.13.1 General 130 3.13.2 Product Characteristics and Implications 130 3.13.3 Insulating Flanges 130 3.13.4 Inspection and Testing 130 3.14 Operational Issues 130 3.14.1 Product Movement and Characteristics 130 3.14.2 Product Characteristics and Transfer Equipment Choice 131 3.14.3 Operations 131 3.14.4 Transfer Rates 131 3.14.5 Monitoring and Control 132 3.15 Inspection, Testing and Maintenance 132 References and Further Reading 132 113 Product Transfer Equipment 3.6 Pipes 3.6.1 General The operation and function of each piping system should be clearly understood under normal conditions, during startup, during shutdown and during any failure. 3.6.2 Types of Piping Pipes and piping components are normally manufactured to meet the requirements of national standards. (See references at the end of this chapter.) Consideration should be given to the need for additional corrosion allowance, depending on the nature of the product or operating environment. Welded pipe Electrically welded pipe should not be used where internal corrosion is expected. It should only be used in low pressure lines. Seamless pipe Seamless pipe is a wrought steel tube without a welded seam that is generally used in high pressure lines. Seamless pipe is used in critical locations and where there are severe operating conditions. 3.6.3 Product Pipes Pipelines should avoid dead legs and have drainage facilities at the lowest point. Where the drainage point is fitted with a valve, it should be further protected with a blank flange or cap. All product pipelines, connections and gaskets should be compatible with the full range of products transferred through them. If pipelines are used for transferring multiple products it should be possible for them to be safely and efficiently pigged. Flow rates All pipelines should be sized to match the transfer system requirements or limitations, including the maximum velocity for flammable products. Any pipe insulation should be weatherproofed and protected from moisture and spills to avoid corrosion. Some pipelines need to be heated (usually through steam or electric tracing) to prevent freezing in harsh climates or to assist flow rate of viscous products. Steam tracing may be: ?External, where steam pipes run alongside the product pipeline, either as a separate system or as an integral part of the pipe ?jacketed, where the product pipeline runs inside an outer pipe containing steam. This method may be used where high temperatures or closely regulated temperatures are required. With electric trace heating, an electrical heating cable is wound round or run along the length of the product pipeline. The cable and the pipeline are insulated with lagging material. This type of heating must be carefully controlled to prevent overheating or electric sparks. All forms of trace heating should conform to the standards required by the zone classification of the area that the pipe runs through. 3.6.4 Vapour Pipes Vapour pipelines, hoses and fittings should be of the same standard as those used for products. Hoses or other combustible material should not be used as vapour pipelines for flammable products. Factors to be considered when choosing and installing vapour pipelines include: ?Dedicated or shared use ?vapour characteristics such as condensation and polymerisation potential ?ambient temperature implications ?vapour flow requirements and pressure drop ?isolation capability and clearing or cleaning requirements ?pressure monitoring and control ?emergency shutdown and isolation requirements. 114 Bulk Liquid Chemical Handling Guide, Vol 1 3.6.5 Flame and Detonation Arresters Flame arresters are installed on equipment or vapour pipelines to prevent the unrestricted propagation of flame through flammable gas or vapour mixtures and to absorb heat from unburnt gas. (See references at the end of this chapter.) Procedures should be in place to check the valve specifications, particularly if there has been a change of product. The flame arresters should be fitted on both sides of vapour lines and as close as is practical to the equipment they are protecting. Consideration should be given to: ?Checks to confirm that the flame arrester is suited to the product characteristics ?product implications and requirement for oversizing when mounted vertically ?condensation and knock-out drums ?vapour solidification or polymerisation potential ?pressure monitoring facilities and alarms to identify and notify of blockages or restrictions ?isolation valves for inspection, testing or maintenance. 3.6.6 Pipe Installation If pipework is not adequately supported, the weight of product may cause sagging, distortion, loosening of connections and damage to valves. All parts of the pipeline, including pipe supports and bridges, should be regularly inspected to ensure the structures are sound and there is no leaking or corrosion. Suitable barriers and warning signs should be erected to help protect pipelines near traffic routes. Overhead pipes must have sufficient advance warning for oncoming drivers in the form of height warning signs and audible or visual alarms. All underground pipelines should be regularly pressure tested to check for leaks. All pipelines, whether buried in the ground, exposed to the atmosphere or submerged in water, are susceptible to corrosion. Common ways of controlling corrosion on pipelines are: ?Protective coatings and linings ?cathodic protection ?materials selection. Environmental assessment is an essential part of corrosion control and reducing moisture or improving drainage can be a simple and effective way to reduce the potential for corrosion. Where practicable, a level of environmental protection can be obtained by running pipelines in impermeable concrete channels. These should be fitted with access hatches to permit inspection and maintenance. Unless there is no alternative, pipework should never be run through the side or floor of a bund as this may compromise the strength of the bund and encourage leaking. Pipe installation and components Pipe joints are often the point of leakage on pipework systems, so the number of joints should be minimised, where practical. Joints can be permanently welded for high integrity systems, or flanged, screwed or compression fittings may be used. Piping will experience a certain amount of thermal expansion, which is compensated for by expansion joints, either a bend or loop fabricated from pipe, or a mechanical joint. Pipe joints, depending on the frictional characteristics of their components, should only be used where leakage can be controlled by the operation of a valve outside the fire risk area and the mechanical strength and integrity of the joint is not dependent on the resilience of a combustible material. 3.6.7 Pigging Stations Pigs are used to clear pipelines. They are put into the pipeline through pig launchers. 115 Product Transfer Equipment The type of pig used will depend on the product and equipment characteristics. Pigs may be suitable for single or multiple uses. Procedures and equipment needs to be in place to: ?Ensure the correct type of pig is used ?allow for the safe removal, storage, cleaning or disposal of used pigs. The design, location and operation of the pigging systems will depend on the equipment and product. Consideration should be given to: ?Design, layout and ease of access to the pig launchers and receivers so that insertion and removal of pigs to be carried out in a safe and efficient manner ?all closures having pressure indicators or built-in safety locks that prevent them being opened while the trap is pressurised ?pig trap location, which should be as close as possible to the vessel being cleared into Pig signal Receiver Main Vent PRV Closure Kicker lineThrottle Launcher Drain Figure 3.4 – Example of pig launcher and pig receiver Figure 3.5 – Pig receiver showing ‘pig home indicator’ (spring loaded arrangement) with interlock to prevent opening under pressure ?the pig receiver and piping configuration design should prevent air or nitrogen from entering the ship tank, shore tank or other receiving vessel when the lines are cleared ?locating the pigging stations in an area with sufficient secondary or additional remote capacity to contain the largest credible spill ?location of portable pig launchers or receivers and supports required. Safety considerations include: ?Pigging of flammable products should only be conducted using nitrogen ?the air or nitrogen supply used for pigging operations should be equipped with pressure indication and control, and signs showing allowable pressures ?the air and nitrogen supply should be clearly marked and labelled and fitted with unique couplings to avoid incorrect usage ?for products that are flammable, toxic, corrosive or odorous, if line depressurising is necessary, special vapour treatment facilities may be required ?there should be a safety shower with eyewash facilities located close by. 116 Bulk Liquid Chemical Handling Guide, Vol 1 3.6.8 Hose Exchanges/Switching Station