EI 15 – Hazardous area classification
http://www.energyinst.org.uk/ei15
The EI’s Area Classification Working Group is currently in the process of undertaking the planned revision to Model code of safe practice Part 15: Area classification code for installations handling flammable fluids. The review will identify areas of the Model Code which require updating, leading to a 4th edition of the Model Code.
What is EI 15?
Model code of safe practice Part 15: The Area classification code for installations handling flammable fluids (EI 15, formerly referred to as IP 15) is a well-established, internationally accepted publication that provides methodologies for hazardous area classification around equipment storing or handling flammable fluids in the production, processing, distribution and retail sectors. It constitutes a sector-specific approach to achieving the hazardous area classification requirements for flammable fluids required in the UK by the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) 2002 and in doing so, provides much more detail than BS EN 60079-10 Electrical apparatus for explosive gas atmospheres: Classification of hazardous areas. Note that the scope of EI 15 excludes hazardous area classification arising from dusts.
This Model Code presents the following three complementary approaches for hazardous area classification:
- The direct example approach, which is limited to common facilities;
- The point source approach, where release rates are dependent on process conditions; and
- The risk-based approach.
The point source approach can be used for all situations; the risk-based approach is an optional methodology for secondary grade releases which may reduce the extent of the hazardous area determined by the point source approach.
EI 15 should be applied by process safety practitioners involved in hazardous area classification. The publication also provides a basis for both the correct selection of electrical equipment and the location of other sources of ignition in those areas.
EI 15 3rd edition
The 3rd edition of EI 15 (Model code of safe practice Part 15: Area classification code for installations handling flammable fluids, ISBN 978 0 85293 418 1) was published in July 2005. It provides, primarily, both technical and editorial clarification on issues that have been raised by users of the 2nd edition since its publication in 2002. In addition, further technical and editorial changes have been made. Yet, it is not anticipated that those changes will result in increased hazardous areas.
Model code of safe practice in the petroleum industry Part 15: Area classification code for installations handling flammable fluids
3rd ed., July 2005, ISBN 978 0 85293 418 0. Priced publication. Order from EI publications online.
Key technical changes in EI 15 3rd edition
The 3rd edition of EI 15 contains on page x, a summary of the key technical changes between the 2nd and updated editions of the Model Code. However, to assist those who are considering purchasing a copy or for users who want more information, a detailed listing has been prepared. Presented in a generalised form, this sets out additional information on the technical changes referenced to the page number and pertinent section, table or figure.
Area Classification Working Group
The Energy Institute’s area classification resources are developed by its Area Classification Working Group, as supported by other contributors. The Working Group would welcome the participation of additional upstream petroleum industry practitioners so as to ensure their continuing applicability of the resources to upstream operations. For further information contact Andrew Sykes (Secretary to the Area Classification Working Group) asykes@energyinst.org.uk t: +44 (0)20 7467 7148.
Technical queries
Users of IP 15 and its supporting publications seeking a consultant to provide technical support with carrying out hazardous area classifications should use the Consultant Database, maintained by the EI Library and Information Service.
 To seek clarification of technical issues included in IP15, contact the EI Library and Information Service. Note, however, that this is not a consultancy service and as it draws upon volunteers from the Working Group, it may take some time to respond to issues raised.
To facilitate the continuing technical development of EI 15, your technical feedback would be welcome.
Supporting publications
EI 15 is supported by four EI publications, which have influenced its technical development; they should be referred to where further guidance is required on particular aspects:
- A risk-based approach to hazardous area classification
- EI Research Report: Dispersion modelling and calculations in support of EI Model Code of Safe Practice Part 15: The area classification code for installations handling flammable fluids
- Predictions of minimum spark ignition energy and quenching distances for CH4/H2 and C3H8/H2 mixtures with air
- EI Research Report: Ignition probability review, model development and look-up correlations
A risk-based approach to hazardous area classification
This report provides a means for establishing the outer boundaries of Zone 2 hazardous areas, taking into account risks associated with contributory factors. It is applicable to hazardous area classification of upstream and downstream facilities handling flammable fluids using the point source approach described in Section 5 of EI 15.
A risk-based approach to hazardous area classification
1st ed., Nov 1998, ISBN 978 0 85293 238 5. Priced publication. Order from EI publications online.
Those wishing to take account of recent research on ignition probabilities, a factor that is used in the risk-based approach that is adopted in EI 15 should refer to EI Research Report: Ignition probability review, model development and look-up correlations.
EI Research Report: Dispersion modelling and calculations in support of EI Model Code of Safe Practice Part 15: The area classification code for installations handling flammable fluids
The second edition of EI Research Report: Dispersion analysis and calculations in support of EI Model Code of Safe Practice Part 15: The area classification code for installations handling flammable fluids provides the findings of additional research to further extend the dispersion modelling and calculation basis of EI Model Code of Safe Practice Part 15 Area classification code for installations handling flammable fluids (EI 15). It focuses on the following technical issues:
- Sensitivity analysis of ambient temperature, relative humidity, weather and surface roughness on dispersion characteristics from point sources for various fluid categories.
- Sensitivity analysis of the nature and ambient temperature of the underlying surface (e.g. concrete, dry soil), weather, and surface roughness on dispersion characteristics from pools of various diameters and depths, for various fluid categories.
- Determination of whether any existing EI 15 fluid categories apply to liquefied natural gas (LNG), or if it requires specific modelling and sensitivity analysis of parameters (hole diameter, release pressure, temperature, relative humidity, weather, surface roughness, surface type) to determine dispersion characteristics.
Given that the new research augments, but does not invalidate, several technical issues in the first edition, and that no further technical work has been carried out on other work items, the first edition of the report is entirely replicated as Addendum 1.
The findings of the report will be reviewed by the Area Classification Working Group to see how the new research affects the continuing technical integrity of pertinent aspects of the third edition of EI 15.
The information in this publication should assist process safety engineers, safety advisors, designers, or others with responsibility for hazardous area classification to better determine the extent of hazardous areas in a consistent manner for specific fluid and process, weather and environment dependent values.
The information is internationally applicable provided it is read, interpreted and applied in conjunction with relevant national and local requirements.
EI Research Report: Dispersion analysis and calculations in support of EI Model Code of Safe Practice Part 15: The area classification code for installations handling flammable fluids
2nd edition, Nov 2007, ISBN 0 978 85293 489 0. Priced publication. Order from EI publications online.
Predictions of minimum spark ignition energy and quenching distances for CH4/H2 and C3H8/H2 mixtures with air
This report considers when gas streams containing hydrogen as a component should be treated as hydrogen for the purposes of specifying electrical equipment. The particular properties of hydrogen require very specialised electrical equipment to be used to prevent ignition. Given that many industrial gas streams contain hydrogen mixed with hydrocarbon gases, engineers have to decide whether equipment designed for hydrogen duty is needed (i.e. gas group IIC) or whether equipment designed to the less stringent standards for hydrocarbon gas groups IIA or IIB is suitable. This report provides the justification for the cut-off value of hydrogen concentration used when specifying gas group IIC equipment for gas mixtures, referenced in EI 15.
Predictions of minimum spark ignition energy and quenching distances for CH4/H2 and C3H8/H2 mixtures with air
1st ed., May 2002, ISBN 978 0 85293 354 1. Priced publication. Order from EI publications online.
EI Research Report: Ignition probability review, model development and look-up correlations
The probability of flammable releases igniting on facilities, both onshore and offshore, is a key factor in determining the risks such installations present to people, assets and the environment, and is therefore one of the key considerations when carrying quantified risk assessments (QRAs) for safety cases or safety reports.
This EI Research Report provides the findings of a United Kingdom Offshore Operators Association (UKOOA)/ Health and Safety Executive (HSE)/ Energy Institute (EI) co-sponsored project undertaken by ESR Technology to improve the modelling of ignition probabilities in onshore and offshore installation QRAs. Specifically, the report reviews current data and models; includes a model for assigning ignition probabilities in QRAs; and, provides through look-up correlations a simple basis and guidance for assigning ignition probabilities to generic scenarios.
The comprehensive report includes a free CD-Rom that comprises three workbooks: two provide the ignition probability model in both single scenario and multirun formats; whereas, the third workbook enables users to look up charts of ignition probabilities for generic scenarios.
EI Research Report: Ignition probability review, model development and look-up correlations is intended to help safety practitioners, risk analysts and designers to evaluate more rigorously the risk of hydrocarbons igniting on oil and gas installations. Whilst it primarily addresses release rates typical of major hazard scenarios, the report is also relevant to release rates of a few kg/s, which are typical of hazardous area classification scenarios. In addition, the report and one workbook include look-up correlations for specific installations (e.g. FPSO, riser, storage, pipeline, etc.), substances (e.g. gas, LPG, flammable liquid, etc.) and environments (e.g. rural, industrial, within tank farm, etc.), which makes it particularly relevant to those applying the risk-based approach.
Whilst the report focuses on major hazard momentum driven releases, it can also be applied to the smaller release rates typical of hazardous area classification.
EI Research Report: Ignition probability review, model development and look-up correlations
1st ed., Jan 2006, ISBN 978 0 85293 454 8. Priced publication. Order from EI publications online.
The research was launched in March 2006 at IChemE’s Hazards XIX Process safety and environmental protection What do we know? Where are we going? The paper Plant specific ignition probability model and correlations for use in onshore and offshore QRA is included in the symposium proceedings, which are available from IChemE (Symposium proceedings No. 151, ISBN 13 978 0 85295 492 8).
To assist any future revision the sponsors of the research welcome users submitting comments (e.g. on the performance of the model and the look-up correlations) or suggestions for improvement to the Energy Institute’s Technical Department.
Use of EI 15
The Energy Institute has sanctioned in 2006 reproduction of some aspects of EI 15 by the Environmental Services Association in two publications entitled Area classification for landfill gas extraction, utilisation and combustion and Area classification for leachate extraction, treatment and disposal.
Two papers presented at IChemE’s Hazards XIX Process safety and environmental protection What do we know? Where are we going? referred extensively to the EI 15 methodology. The papers Experiences and issues in ATEX and DSEAR compliance and Area classification methodology for hydrogen-cooled alternators in power stations are included in the symposium proceedings, which are available from IChemE (Symposium proceedings No. 151, ISBN 13 978 0 85295 492 8).
IGEM IGE/SR/25 (Communication 1665) Hazardous area classification of natural gas installations
The EI sells selected IGEM titles, including IGE/SR/25 (Communication 1665) Hazardous area classification of natural gas installations.
IGE/SR/25 provides a procedure for hazardous area classification around installations handling natural gas. It takes a pragmatic approach to the determination of safe dispersion distance and present the results in the form of tables – there is no need to consider differences in gas composition or temperature and it is not necessary to determine the flow rate that coincides with the peak distance. The Recommendations address both ideal and non-ideal venting, and enclosures that have, respectively, adequate; less than adequate and poor ventilation.
IGE/SR/25 Hazardous area classification of natural gas installations
2000. Priced publication. Order from EI publications online.
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