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David Woolgar DSEAR and gas safety
- 1. DSEAR & GasSafety 1
- 2. Introduction David Woolgar Chartered Gas Engineer Chair of ADBA Working Group Member of IGEM Gas Safety panel Independent consultant in AD and Biogas 10 years at Biogen leading the design and commissioning of AD plants David Woolgar Consulting
- 3. Agenda What isDSEAR Overview of Legislation & Regulations Site owners / operators responsibilities Examples David Woolgar Consulting
- 4. Regulatory Background EUDirectives ATEX ATmospheres EXplosibles ATEX 137 Workplace Directive - Protection of workers in potentially explosive areas Assess workplace for presence of potentially hazardous zones and classify them Prepare Explosion Protection Document (EPD) ATEX 95 The Equipment Directive - Equipment for use in potentially explosive areas Standards for Electrical and Mechanical Equipment and Protection Systems Ex & CE marked David Woolgar Consulting
- 5. Regulatory Background EUDirectives transposed in UK Law by DSEAR & EPS Dangerous Substances and Explosive Areas Regulations Identify Dangerous Substances at workplace Carry out Risk Assessment Reduce Risk Classify Hazardous Areas Inform & Train staff Equipment and Protective Systems for Use in Potentially Explosive Atmospheres Regulations Sets out different protection concepts David Woolgar Consulting
- 6. Biogas Plant Whosupplied your plant Was it an EU supplier Lots of very good German, Dutch, Danish suppliers Probably complied with EU Directive – suitable for UK Market Possibly some gaps with respect to details of UK regulation David Woolgar Consulting
- 7. Identification of DangerousSubstances Dangerous Substance – Liquids, Gases, Vapours, Solids, Dusts That can form explosive atmospheres when mixed with air. Note - not Harmful Substance – COSHH Gases – Biogas, Biomethane, Ammonia, H2S, LPG Liquids – Diesel, Lube Oil, Solvents Dust – Digestate Dryer David Woolgar Consulting
- 8. Identification of DangerousSubstances Biogas is a fuel supplies fires forms explosive mixtures. Biogas safety is about containment and dispersion of leaks Leaks are expected David Woolgar Consulting
- 9. Risk Assessment Regulation5 requires employers and the self-employed to assess risks to employees and others whose safety may be affected by the use of presence of dangerous substances at work. This is an iterative process with the following steps as risks are identified and reduced, protected and mitigated. Identify safe work methods, maintenance requirements, emergency procedures, training requirements David Woolgar Consulting
- 10. Reduce Risk Regulation6 sets out how the risk to safety from dangerous substances should be eliminated or reduced. Hierarchy of controls Reduce quantities – minimum storage of biogas before use Avoid or minimise releases – secure containment, flare rather than vent Control release in safe place – vent at high level for safe dispersion, purge point Prevent formation of explosive atmosphere – ventilation Avoid ignition sources including static – ATEX equipment, equipotential bonding David Woolgar Consulting
- 11. Mitigate consequences offire or explosion Reduce employees exposed to risk – control access, work permits, isolations Avoid propagation of fire – separation zones, barriers Explosion protection – physical strength, separation PPE David Woolgar Consulting
- 12. Practical Measures toReduce Risk Technical Design – Self closing sample valves and caps Isolate vibration Separation of equipment Ventilation Natural ventilation – locate equipment outdoors Forced ventilation - CHP Control of Ignition sources Equipment for use in Hazardous Areas David Woolgar Consulting
- 13. Practical Measures toReduce Risk Organisational Training – understanding of what a Zone is Procedures – Site Rules, methods of work Inspections – check equipment Maintenance – isolations, purging Permit to Work – hot work Control of Change – review with design, HAZOP David Woolgar Consulting
- 14. Classify Hazardous Areas-Zones Hazardous areas are classified into zones as follows: Zone 0: An area in which an explosive gas atmosphere is present continuously or for long periods. Zone 1: An area in which an explosive gas atmosphere is likely to occur in normal operation. Zone 2: An area in which an explosive gas atmosphere is not likely to occur in normal operation and, if it occurs, will only exist for a short time. Zone of Negligible Extent David Woolgar Consulting
- 15. Record Hazardous Areas Produce a drawing – Zoning diagram Place warning signs where explosive atmospheres may occur. Black letters on a yellow background. Mark pipes and containers with contents of dangerous substance David Woolgar Consulting
- 16. Control of IgnitionSources Lightning strikes. Open flames. This varies from a lit cigarette to welding activity. Mechanically generated friction sparks. More than one red hot spark is often necessary in order to have an effective ignition source. Electric sparks. For example, a bad electrical connection or a faulty pressure transmitter. The electric energy content of the spark determines the effectiveness of the ignition source. High surface temperature. This can be the result mechanical friction in a stuffing box or bearing, or boiler flue. Electrostatic discharge. Static electricity can be generated by a rotating belt or a non-conductive liquid flowing through a filter screen. David Woolgar Consulting
- 17. Inform & TrainStaff Induction Site Rules Training Risk assessment Operating and Maintenance instructions David Woolgar Consulting
- 18. Equipment for usein Hazardous Areas Equipment used in Hazardous Areas must be suitable for the Zone class, selected on requirements of Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations. in zone 0 - category 1 equipment, in zone 1 - category 1 or 2 equipment, in zone 2 - category 1, 2 or 3 equipment. This applies to both electrical and mechanical equipment David Woolgar Consulting
- 19. Protection Types -Physical Protection can be broadly seen as 2 types Physical – the equipment is built in a specific way: 8 variants Ex ma – encapsulation – Category 1 Ex d – flameproof enclosure – Category 2 Ex e – increased safety – Category 2 Ex o – oil immersion – Category 2 Ex n – non sparking – Category 3 Ex pz – pressurised enclosure – Category 3 Must be installed as specified in certificate / instructions David Woolgar Consulting
- 20. Example Motor Exd David Woolgar Consulting
- 21. Protection Types –Intrinsic Safety This is a protection system for instrumentation Limits the electrical and thermal energy in the circuit Separated from normal power circuit by IS Barrier 3 levels of protection - Ex ia, ib & ic for Zones 0, 1 & 2. The instruments and the IS Barrier must be certified Requires circuit documentation IS circuits should be identified and segregated David Woolgar Consulting
- 22. Protection Types –Intrinsic Safety David Woolgar Consulting
- 23. Example Instrument David WoolgarConsulting
- 24. Equipment Certification &Marking Equipment for use in the EU will have both the εx and CE marks Equipment for use in Zone 0 and Zone 1 must be 3rd party certified Equipment built to the requirements of EPS will carry the explosion protection symbol in a hexagon, It will show the equipment category number (1, 2 or 3), the letter G and/or D depending on whether it is intended for use in gas or dust atmospheres or both, and other essential safety information. David Woolgar Consulting
- 25. Equipment Marking David WoolgarConsulting
- 26. Management of ATEXEquipment BS 60079:17 Inspections and Maintenance Keep a record of equipment and certification ATEX Register Set up schedule of periodic inspection Use competent person to inspect and maintain ATEX equipment Test critical instruments - Buncefield David Woolgar Consulting
- 27. Hazardous Area Management Inspect gas system - IGEM recommend 6 monthly Identify and rectify any leaks Check key valves – isolation valves Review effect on Hazardous Areas of any modifications Consider effect on Hazardous Areas of any maintenance tasks David Woolgar Consulting
- 28. Questions David Woolgar Consulting DavidWoolgar david@davidwoolgarconsulting.co.uk
Editor's Notes
- #3 David Woolgar Chair of the group took over from Terry Brown Been a member of the group from the early days Involved in AD since the early 90s most recently designing and commissioning foodwaste plants at Biogen Now an independent consultant focussing on AD and Biogas.
- #9 I apologise that this slide is going to end up being very dense – I hope the information will be useful when the slides are circulated. The legal requirements are set out in DSEAR and ATEX but I have heard concerns that there is not a lot of technical guidance on how to build and maintain safe biogas systems. There is excellent technical guidance published by the Institution of Gas Engineers and Managers. The original guidance was developed by British Gas and following privatisation was taken over by IGEM and maintained and expanded by the professional engineering members. These are documents produced by gas engineers for industrial users. I admit to a bias – I have been involved in these documents for the past 15 years but I commend them to designers and operators. I am currently on the panel updating the guidance on hazardous areas and risk assessment.