Guidelines for the control of hazards arising from static electricity

Transcription

1 Model code of safe practice Part 21 Guidelines for the control of hazards arising from static electricity 3rd edition

2 EI MODEL CODE OF SAFE PRACTICE PART 21: GUIDELINES FOR THE CONTROL OF HAZARDS ARISING FROM STATIC ELECTRICITY Third edition February 2013 Published by ENERGY INSTITUTE, LONDON The Energy Institute is a professional membership body incorporated by Royal Charter 2003 Registered charity number

3 The Energy Institute (EI) is the leading chartered professional membership body supporting individuals and organisations across the energy industry. With a combined membership of over individuals and 300 companies in 100 countries, it provides an independent focal point for the energy community and a powerful voice to engage business and industry, government, academia and the public internationally. As a Royal Charter organisation, the EI offers professional recognition and sustains personal career development through the accreditation and delivery of training courses, conferences and publications and networking opportunities. It also runs a highly valued technical work programme, comprising original independent research and investigations, and the provision of EI technical publications to provide the international industry with information and guidance on key current and future issues. The EI promotes the safe, environmentally responsible and efficient supply and use of energy in all its forms and applications. In fulfilling this purpose the EI addresses the depth and breadth of energy and the energy system, from upstream and downstream hydrocarbons and other primary fuels and renewables, to power generation, transmission and distribution to sustainable development, demand side management and energy efficiency. Offering learning and networking opportunities to support career development, the EI provides a home to all those working in energy, and a scientific and technical reservoir of knowledge for industry. This publication has been produced as a result of work carried out within the Technical Team of the EI, funded by the EI s Technical Partners. The EI s Technical Work Programme provides industry with cost-effective, value-adding knowledge on key current and future issues affecting those operating in the energy sector, both in the UK and internationally. For further information, please visit The EI gratefully acknowledges the financial contributions towards the scientific and technical programme from the following companies BG Group Phillips 66 BP Exploration Operating Co Ltd Premier Oil BP Oil UK Ltd RWE npower Centrica Saudi Aramco Chevron Scottish Power ConocoPhillips Ltd Shell UK Oil Products Limited Dong Energy Shell U.K. Exploration and Production Ltd EDF Energy SSE ENI Statkraft E. ON UK Statoil ExxonMobil International Ltd Talisman Energy (UK) Ltd International Power Total E&P UK Limited Kuwait Petroleum International Ltd Total UK Limited Maersk Oil North Sea UK Limited Valero Murco Petroleum Ltd World Fuel Services Nexen Vattenfall However, it should be noted that the above organisations have not all been directly involved in the development of this publication, nor do they necessarily endorse its content. Copyright 2013 by the Energy Institute, London. The Energy Institute is a professional membership body incorporated by Royal Charter Registered charity number , England All rights reserved No part of this book may be reproduced by any means, or transmitted or translated into a machine language without the written permission of the publisher. ISBN Published by the Energy Institute The information contained in this publication is provided for general information purposes only. Whilst the Energy Institute and the contributors have applied reasonable care in developing this publication, no representations or warranties, express or implied, are made by the Energy Institute or any of the contributors concerning the applicability, suitability, accuracy or completeness of the information contained herein and the Energy Institute and the contributors accept no responsibility whatsoever for the use of this information. Neither the Energy Institute nor any of the contributors shall be liable in any way for any liability, loss, cost or damage incurred as a result of the receipt or use of the information contained herein. Hard copies can be obtained from: Portland Customer Services, Commerce Way, Whitehall Industrial Estate, Colchester CO2 8HP, UK. t: +44 (0) e: sales@portland-services.com Electronic access to EI and IP publications is available via our website, Documents can be purchased online as downloadable pdfs or on an annual subscription for single users and companies. For more information, contact the EI Publications Team. e: pubs@energyinst.org

4 CONTENTS Page Foreword....6 Acknowledgements Introduction and scope Background Scope How to use these guidelines Product characteristics and equipment requirements Product characteristics Equipment requirements Mechanical design Earthing and bonding Clothing and footwear Plastic surfaces Road and rail loading operations General Static electricity hazards Loading rates for road tanker loading Loading rates for rail loading Road and rail loading of lubricating oils Vehicle-to-vehicle transfers Receipt of additives and chemicals Storage tank operations General Tank filling with low conductivity liquids Tank filling with higher conductivity liquids Receiving product from multi-product pipelines Manual sampling and gauging of storage tanks General Static electricity hazard Sampling and gauging equipment Operating procedures Tank cleaning Ship and barge operations General Tank loading Low conductivity fuels Switch loading Contaminants Splash loading Ship-to-shore connections

5 6.2.6 Maximum flow rates for sea loading Sampling and gauging General First-foot sampling Line clearing using water or gas Water Gas Tank cleaning Handling liquids and solids in containers General Static electricity hazard Intermediate bulk containers (IBCs) Metal or equivalently dissipative plastic IBCs IBCs made of an insulative material surrounded by a conductive enclosure, grid or coating Catalyst filling and handling Filling station operations General Forecourt surface and filling station equipment design - earthing and bonding Forecourt surface Tanks, metal (conductive) pipes, electrical equipment and dispensers Plastic pipes Additional earthing considerations for plastic pipes Mixed metallic and plastic pipe types at a single site Mixed plastic pipe types at a single site Fuel deliveries Fuelling of vehicles Diesel vehicles Petrol vehicles Filling containers Small containers Large containers Refuelling with LPG or CNG Maintenance and testing activities General Draining lines Clearing product out of lines by using air or nitrogen Grit blasting Static electricity hazards Tank cleaning General High pressure, high velocity water washing Cleaning with hydrocarbon jets Steam cleaning Steam leaks Paint spraying Meter proving

6 10 Aircraft fuel handling General Static dissipator additive (SDA) Hoses Hose types Making hose connections to the aircraft Earthing and bonding Refuelling vehicle systems Hydrant-dispenser systems Earthing the aircraft Bonding requirements for other equipment Making bonding connections to the aircraft Fuelling light aircraft and helicopters Pipeline operations Flow rates limits Aircraft fuelling Personnel LPG and LNG systems Offshore operations...86 Annexes: Annex A Explanation of static electricity A.1 General...89 A.2 Static electrical charge...89 A.3 Rate of generation...91 A.4 Dissipation and discharge A.4.1 Dissipation A.4.2 Spark, brush and corona discharges A.5 Incendive discharges...97 A.6 Spark gap...98 A.7 Ignition by static electrical discharge A.8 Control of ignition hazards A.8.1 Generation...99 A.8.2 Accumulation...99 A.8.3 Spark gap A.8.4 Flammable vapours A.8.5 Conclusions Annex B Model assessment of ignition risk B.1 General Annex C Glossary of terms Annex D References

7 FOREWORD This Model Code provides an explanation of the static electricity ignition risk as it relates to operations in the petroleum industry, and provides technical guidance for the more frequent operations which will help to reduce the inadvertent ignition of flammable atmospheres due to static electricity. The third edition of this Model Code provides new and revised information on: how to use the guidelines in the context of a risk assessment, the influence of bio-components (only a preliminary warning highlighting potential risk is possible at present), a more detailed discussion of earthing and bonding requirements for filling stations and aircraft fuelling, personal protective equipment (PPE), including footwear, filling IBCs, the use of plastics for underground piping at filling stations, fuelling with LPG and CNG (brief information only), tank cleaning, meter proving, liquefied natural gas (brief information only), and upstream operations (brief information only). In addition, the information on electrical equipment which was not directly relevant to static electricity hazards has been removed and the arrangement of sections has been reorganised to put the general information on static electricity hazards into an Annex. Minor changes to the Model Code have also been made in several places in order to increase alignment with other publications and standards. The information contained in this publication is provided as guidance only and while every reasonable care has been taken to ensure the accuracy of its contents, the EI and the technical representatives listed in the acknowledgements, cannot accept any responsibility for any action taken, or not taken, on the basis of this information. The EI shall not be liable to any person for any loss or damage which may arise from the use of any of the information contained in any of its publications. The above disclaimer is not intended to restrict or exclude liability for death or personal injury caused by own negligence. Suggested revisions are invited and should be submitted to the Technical Department, Energy Institute, 61 New Cavendish Street, London, W1G 7AR, e: technical@energyinst.org 6

8 ACKNOWLEDGEMENTS This publication was prepared at the request of the EI s Electrical Committee by Harold Walmsley (Harold Walmsley Electrostatics Ltd). It was subsequently reviewed and developed by the members of the Electrical Committee. At the time of publication the Electrical Committee comprised: Duncan Crichton Bob Emmerson Terry Hedgeland Glyn Jenkins Ian Neve Tom Ramsey John Stevens Andrew Sykes Stephen Wilkinson Leigh Williams BP Exploration Shell U.K. Limited Consultant Valero Energy Limited Total Lindsey Oil Refinery ExxonMobil BPA EI Phillips 66 Limited Health & Safety Executive The EI wishes to record its appreciation of the work carried out by the members of the Electrical Committee and to recognise the contribution made by those individuals, companies and organisations that provided comments during technical review of earlier drafts. Technical editing and project coordination was undertaken by Andrew Sykes (EI). 7

9 1 INTRODUCTION AND SCOPE 1.1 BACKGROUND Static electricity is a phenomenon that will be familiar to most people. When the atmosphere is dry, small electric shocks are commonly experienced after walking across synthetic materials, or removing synthetic clothing. Very seldom are these small electric shocks dangerous or life threatening. However, it is worth noting that an electric shock that can be felt would probably cause ignition of a flammable atmosphere if it were present. Static electricity can be generated in the work environment. In the petroleum industry, the possibility of an electrical discharge or spark occurring when flammable atmospheres are present poses an ignition hazard that could threaten the safety of personnel. Work to understand static electricity hazards and prevent incidents has been undertaken in numerous studies and the general principles for controlling these hazards are now well understood. However, as the industry evolves, the specific details of products, equipment and operations change and consequently, incidents have still occurred. This Model Code has been updated to provide improved guidance on how to control and minimise the risks associated with static electricity. It is intended to complement other publications and standards (e.g. those issued by API, BSI, CEN, CENELEC, IEC, ISGOTT, ISGINTT, etc.) and provide additional guidance for operational areas where incidents continue to be reported. It is also intended that use of this Model Code will aid the petroleum industry in meeting their duties under the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) SCOPE The scope of this Model Code covers static electricity hazards in the petroleum industry. The main focus is on downstream operations (the handling of refined products and components) because this is where most of the hazards will potentially occur. However, a brief summary on possible upstream (exploration and production) issues is also provided. This Model Code provides: a general explanation of the relevant aspects of static electricity; information to guide the evaluation of static electricity hazards in a risk assessment; information on relevant product characteristics and equipment requirements, and measures for controlling static electricity in particular operations. Guidance on specific measures is provided in the following areas: road and rail loading and unloading; product storage and transfer, including sampling and gauging; ship and barge loading and unloading; product deliveries; filling station operations; barrel, drum and container filling, and aircraft fuel handling. 1 The Offshore Installations (Prevention of Fire and Explosion, and Emergency Response) Regulations 1995 (PFEER) apply to offshore installations. It is intended that using the guidance in this Model Code will assist in complying with these regulations, specifically Regulation 9. 8

10 Adoption of the specific measures in this Model Code should help reduce the likelihood of an inadvertent ignition of a flammable atmosphere in the operations concerned. The general guidance provides an opportunity to understand hazard processes, so that potential hazards can be identified in new operations or with new equipment designs and change can be managed appropriately. Users should recognise that even the specific measures described in this Model Code provide only an overview of the methods for controlling static electricity hazards. The detailed implementation of the measures at any particular site depends on local considerations. The appropriate implementation should be determined by including a consideration of static electricity issues in a site risk assessment, such as that required under DSEAR (onshore) and PFEER 2 (offshore). Users are recommended to perform risk assessments on their operations to determine the most appropriate way to apply the guidance in this Model Code. General electrical safety hazards are not included in the scope of this Model Code; however, information on electrical equipment (which may be used for static electricity protection) is provided in EI Model code of safe practice Part 1: The selection, installation, inspection, and maintenance of electrical and non electrical apparatus in hazardous areas. Hazardous areas are used for controlling ignition hazards from electrical and mechanical equipment, but can also assist in controlling static electricity hazards. Guidance on hazardous area classification can be found in EI Model code of safe practice Part 15: Area classification code for installations handling flammable fluids. 2 One method of satisfying the requirements of PFEER is by the application of DSEAR. 9