A PRACTICAL APPROACH TO FIRE AND EXPLOSION SAFETY RISK ASSESSMENT AND COMPLIANCE WITH THE DANGEROUS SUBSTANCES AND EXPLOSIVE ATMOSPHERES REGULATIONS (DSEAR) 2002 By Kevin James Dodd and Jon Lowe SYNOPSIS With the introduction of the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) 2002, fire and explosion safety is now a key element of an organisations demonstration of legal compliance. Organisations must now determine how best they can demonstrate compliance before 1st July 2006. This paper gives an overview of the requirements of DSEAR and seeks to describe practical methods to achieve compliance and, in particular, the production of a suitable and sufficient assessment of risk. 1.0 INTRODUCTION Fire and explosion legislation has long been present on the UK statute. For example the Explosives Act dates from 1875. Comparatively recent prescriptive regulation such as the Fire Precautions Act 1971, has been the foundation of fire legislation. However, over recent years the focus of regulation has changed. Health and safety legislation has now moved towards the requirement to identify hazard and assess risk. For example the Management of Health and Safety at Work Regulations 1999 (but first introduced in 1992) requires organisations to complete a suitable and sufficient assessment of the risks to which employees are exposed to at work, incorporating the provision of the Fire Precautions (Workplace) Regulations 1997. The Dangerous Substances and Explosive Atmosphere Regulations 2002 follow and build upon the provisions within these regulations. The aim of DSEAR 2002 is to ensure that organisations have: • Identified their fire and explosion hazards. • Assessed the risk presented by these hazards. • Developed technical and organisational measures to establish both control and mitigation. 2.0 OVERVIEW OF THE DANGEROUS SUBSTANCES AND EXPLOSIVE

ATMOSPHERES REGULATIONS 2002 The Dangerous Substances and Explosive Atmospheres Regulations 2002 came into force on 9 December 2002. These regulations implemented Directive 1999/92/EC (ATEX 137) of the European parliament and the Council of 16 December 1999 specified the minimum requirements for improving the safety and health of workers potentially at risk from explosive atmospheres (Official Journal of the European Communities; 2000). This directive is supported by Directive 94/9/EC (Official Journal of the European Communities, 1994) concerning equipment and protective systems intended for use in potentially explosive atmospheres [Reference 8]. In the United Kingdom this has been transposed as the Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres (EPS) Regulation 1996 (as amended) [Reference 3]. The regulatory framework is summarised in Figure 1.

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Figure 1 European and UK Regulatory Framework

The purpose of DSEAR 2002 is to protect people from the risks associated with dangerous substances that can cause fire, explosion or other energy releasing events. An ATEX dangerous substance can be defined as: a. A substance or preparation which is classified as (under the Dangerous Substance

Directive 67/548/EEC): b. A substance or preparation which because of its physicochemical or chemical properties and

the way it is used or present in the workplace creates a risk. c. Any dust, whether in the form of solid particles or fibrous materials or otherwise, which can

form an explosive mixture in air or an explosive atmosphere. In addition, the regulation defines an explosive atmosphere as a mixture with air, under atmospheric conditions. DSEAR 2002 requires an organisation to: • Assess the risk to people whose safety may be affected by the use or presence of a

dangerous substance. • Apply a hierarchy of control to potential risks from dangerous substances in the workplace. • Complete hazard area classification to an appropriate international standard ( • Establish provision to deal with accidents, incidents and emergency. • Provide information, instruction and training to all relevant personnel. • Identify pipes, tanks and containers which contain dangerous substances.

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In addition, before a workplace is first used an organisation must verify that it is safe. The transitional requirements for DSEAR 2002 are established within the Regulation. For equipment and protective systems already in place, organisations need to review existing risk assessments immediately. However, hazardous area classification may be completed before 30th June 2006. For plant modification organisations must comply with DSEAR at the time of the modification. New plants must comply with DSEAR immediately. Approved Codes of Practice have been issued in support of the regulation. In addition to these standards are also available – Table 1. Table 1 European Standards Supporting the Implementation of DSEAR 2002 Explosion hazard GAS DUST Basic principles and methodology

EN 1127-1 EN 1127-1

Area Classification EN 60079-10 EN 50281-3 Electrical Equipment Selection/design, installation EN 60079-14 EN 50281-1-2 Inspection, maintenance EN- 60079-17 EN 50281-1-2 Design and testing EN 50014-series EN 50281-series Non-Electrical Equipment Selection/design, testing EN 13463-1 series EN 13463-1-series

3.0 Compliance with the Dangerous Substances and Explosive Atmospheres

Regulations 2002 3.1 Introduction Compliance requires an organisation to demonstrate that systems and procedures have been developed and implemented to address each of the key elements of the regulation. Figure 2 presents a route map to compliance incorporating the key elements of the regulation. Three distinct phases have been identified: • An information gathering phase completed using gap analysis. • An implementation phase where risk is assessed and supporting ignition source assessment,

hazard identification, hazardous area classification are completed. • Completion phase where the results of the risk assessment are applied. Risk assessment is considered central. Hazard identification, ignition source assessment and hazardous area classification can support this study. These studies then inform the completion phase. Ultimately any inspection of mechanical and electrical equipment should be considered within risk assessment. However, the extent of inspection is dependant upon the hazardous area classification. Each element will be introduced and discussed in the following sections.

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Figure 2 Route Map to Compliance

DSEARCompliance

Gap Analysis

HazardIdentification

Ignition SourceAssessment

Hazardous AreaClassification

Risk Assessment

Inspection / Testing/ Review of

Mechanical andelectrical

Equipment

EmergencyPlanning

Information /Training /Instruction

3.2 Gap Analysis The Health and Safety Executive has suggested that DSEAR complements the general duty to manage risks under the Management of Health and Safety at Work Regulations 1999. DSEAR expands upon existing duties to manage the hazards and risks associated with the release of dangerous substances and their potential to result in fire and explosion. The Health and Safety Executive further suggest that the ‘impact upon the diligent employer should be small’ (The Health and Safety Executive, 2004). It is reasonable to assume that many sites have existing systems in place to manage risks. A gap analysis is therefore considered to be an essential initial step to identify those systems that already do or can be used to demonstrate ATEX compliance. The gap analysis can then be used to develop a compliance programme. A gap analysis can be completed against a simple protocol developed from the regulation, supporting approved codes of practice and European Norm standards. A sites work processes can then be assessed against the criteria. The protocol itself can be simple or comprehensive depending upon the nature of an organisation. AK EHS & Risk has applied such protocols to a number of sites in both the UK and mainland Europe. In each case opportunities to demonstrate compliance through existing or modified systems were identified. However, in certain cases significant gaps in safety management systems were also identified. All this information assisted in the development of a programme to achieve compliance. 3.3 Risk Assessment 3.3.1 Introduction The requirement to complete a suitable and sufficient assessment of risk is central to DSEAR compliance. Risk assessment requires a risk to be: • Analysed to identify hazards and estimate risk. • Evaluated to determine whether tolerability criteria have been met.

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The assessment of fire and explosion risk may become quite onerous. However, the key components of a DSEAR risk assessment are identical to any other assessment of risk. These are summarised in Figure 3. Figure 3 Risk Assessment

A risk assessment under DSEAR is only necessary if a dangerous substance is or is liable to be present. The regulation stipulates that the following are considered: a. The hazardous properties of the substance. b. Information on safety provided by the supplier, including information contained in any

relevant safety data sheet. c. The circumstances of the work including:

i. The work processes and substances used and their possible interaction. ii. The quantity of each substance involved. iii. Where the work will involve more than one dangerous substance, the risk presented by

such substances in combination. iv. The arrangements for safe handling, storage and transport of dangerous substances

and of waste containing dangerous substances. d. Activities, such as maintenance, where there is the potential for a high level of risk. e. The effect of measures which have been or will be taken pursuant to these Regulations. f. The likelihood that an explosive atmosphere will occur and its persistence. g. The likelihood that ignition sources, including electrostatic discharges, will be present and

become active and effective. h. The scales of the anticipated effects of a fire or an explosion. i. Any places which are or can be connected via openings to places in which explosive

atmospheres may occur. j. Such additional safety information as the employer may need in order to complete the risk

assessment. Modifying the basic model presented in Figure 3 Risk Assessment and considering the requirement of the regulation, a DSEAR assessment can be considered as a series of logical steps (CEN, 2004): Step 1 Identify the fire and explosion hazard – the presence of a DSEAR dangerous

substance. Step 2 Identify the hazardous events leading to failure including the presence of a flammable /

explosive atmosphere and subsequent ignition. Step 3 Identify control established to ensure fire and explosion safety. Step 4 Estimate the risk by determining the likelihood of failure and extent of harm

(consequence). Step 5 Evaluate the risk to determine whether it is tolerable.

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Figure 4 summarises these concepts and introduces the specific consequence requirements for a DSEAR risk assessment. The consequences of the ignition of a flammable / explosive atmosphere can only be determined if the mechanism of harm is understood. A jet fire, for example, will have different consequences (or extent of harm) than a Boiling Liquid Expanding Vapour Explosion (BLEVE). In assessing these it is important to understand both the mechanism and the location of the release and safe guards in place. Figure 4 Summary of the Concepts and Requirements of a DSEAR Assessment

Presence ofDangerousSubstance

Hazard

Loss ofContainment

Hazardous events

Ignition JET FIRE

Generation ofvapour

UnconfinedIgnition

Rain out Pool formation Ignition POOL FIRE

Heats PressueVessel

FLASH FIRE

BLEVE

ConsquenceDeterminant

THERMAL RADIATION

THERMAL RADIATION

THERMAL RADIATION

THERMAL RADIATION

OVERPRESSUE

IntermediateConsquence

Evaporation andgeneration of

vapour cloud ordust cloudConfined

Ignition Explosion OVERPRESSUE

WithinContainment

Vapour / dust

These issues will be discussed further in the following sections. 3.3.2 Risk Analysis 3.3.2.1 Identification of Hazards The effective identification of hazards and hazardous events is the first stage of any risk assessment process. DSEAR defines a hazard as ‘those substances and preparations with the potential to create fires, explosions or other similar energetic events’. A dangerous substance must be present or liable to be present and form a mixture with air to combust. This determination is often simple for gases, vapours and mists but can be difficult for dusts. For dusts is may be necessary to complete detailed studies to determine if they are combustible. Physical testing may be appropriate or a review of the historical records to identify incidents involving the material. The hazard identification study should focus on where these dangerous substances are and / or could be located. Hazardous events are not merely associated with loss of containment events but also the presence of dangerous substance within containment. Organisations often have several techniques to do this. It is important that any technique does identify all the potential hazards associated with each dangerous substances. It may be that a single technique cannot or does not do this. The gap analysis will identify this. The depth of any hazard identification study will be determined by the nature and extent of the hazard. DSEAR covers both process and occupational safety risk. A comprehensive hazard study technique based upon the use of P&ID / EFD / PFD may be appropriate for the former but not for the latter. Task analysis may be more appropriate for the latter and not the former. It may be that both techniques need to be applied in order to demonstrate compliance.

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Hazardous area classification also offers an opportunity to achieve compliance. This is a requirement of the regulation where an explosive atmosphere is likely to be present (Health and Safety Executive, 2003). Hazardous area classification also requires that the point or location from which a flammable gas, vapour, liquid or dust may be released or is present and can form an explosive atmosphere to be identified and classified (British Standards Institute, 2003a). The initial step could also form the basis of a wider hazard identification step for DSEAR compliance. AK EHS & Risk has proposed a compliance programme based upon the development of hazardous area classification studies. This was possible as the site in question did not have such studies in place. It is essential, however, in demonstrating compliance a systematic approach must be adopted that can address all areas (both process and non-process) and hazards. For example a comprehensive process hazard review may not be sufficient. Simple occupational safety issues associated with the use of flammable materials in laboratories may not be captured. It may also be appropriate at this point to assess the frequency of such an event. This can be either qualitative or quantitative depending upon the nature of the hazard, but is associated with the Loss of Containment event only. 3.3.2.2 Ignition Source Assessment 3.3.2.2.1 Introduction DSEAR is explicit in requiring an analysis of ignition sources. The regulation stipulates that the likelihood that ignition sources will: • Be present. • Become active. • Be effective. The depth of any ignition source assessment will depend upon the nature and extent of the overall risk presented by the presence of a flammable / explosive atmosphere. However, each of these issues will be discussed further in section 3.3.2.2.2 and 3.3.2.2.3. By defining an area as hazardous (during risk assessment and formally in hazardous area classification) there is an assumption that a flammable and / or explosive atmosphere can be present, containment cannot be guaranteed and hence the only recourse is to prevent ignition. 3.3.2.2.2 Identification of Sources of Ignition DSEAR requires that the likelihood of an ignition source being present is assessed. All potential sources of ignition permanently located within or with the potential to be introduced into a defined hazardous area should therefore be identified and documented. These could be associated within permanent / temporary plant and equipment, process operations or merely the presence of people at the location. BE EN 1127-1 provides a potential list of generic ignition sources and ignition mechanisms [British Standards Institute, 1998], and these are reproduced in Appendix 1. Such a list could form the basis for any assessment. Equipment in particular, both electrical and non-electrical, can be a source of ignition and these will be discussed in more detail in section 3.3.2.2.4 and 3.3.2.2.5. 3.3.2.2.3 Assessment of the Likelihood of Ignition In addition to requiring that ignition sources are present, DSEAR also requires that they can become active and are effective. It may be that whilst an ignition source is present there is: • No foreseeable mechanism for it be active and ignite a flammable / explosive atmosphere. • Insufficient energy within the source to ignite the flammable / explosive atmosphere.

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Determining the likelihood of ignition is therefore important. It is reliant upon being able to match the ignition source with the location and extent of the flammable atmosphere and determining the ignition mechanism and capability of the source. This can be a difficult exercise to complete and the depth of study should once again be commensurate with the overall risk. A comprehensive assessment may be appropriate, where each potential source is identified, the likelihood of it being active determined and its potential compared with the properties of each flammable material. This study can be both qualitative and quantitative. For this type of study the following information may be required: • The minimum ignition energy of the dangerous substance. • The minimum ignition temperature of an explosive atmosphere. • The minimum ignition temperature of a dust layer. • Equipment failure mechanisms and data. • Probability of ignition. • Release rates. • Extent and quantity of the flammable atmosphere. A determination can then be made to the likelihood of ignition. However, it may be more appropriate to apply a simple qualitative work model. BS EN 1127 [British Standard Institute, 1998] presents a simple word model against which ignition sources can be assessed. These are: • High - Sources of ignition that can occur continuously or frequently. • Medium - Sources of ignition that can occur in rare situations. • Low - Sources of ignition which can only occur in very rare situation. It is recommended that if the likelihood of occurrence of an effective ignition source cannot be estimated then it presence should be assumed. This model assumes that the ignition source is effective. This simple model can be expanded further to incorporate effectiveness: • High – Strong ignition source. • Medium – Medium ignition source. • Low – Weak ignition source. Finally the flammable / explosive atmosphere must be able to reach the source of ignition. An assumption can be made that only ignition source within the maximum possible cloud dimensions will be considered. However, the probability of the cloud reaching a source of ignition could also be considered. 3.3.2.2.4 Electrical Equipment Electrical equipment has long been considered to present a potential ignition hazard. For this reason standards requiring hazardous areas to be classified and equipment to be designed for these areas to prevent ignition are long established. It is expected that within any DSEAR compliance programme the hazards and risk associated with electrical equipment will already be understood and addressed. Section 3.3.2.7.4 of this paper further discusses the concepts of the protection established for electrical equipment and the requirements for inspection and testing. 3.3.2.2.4 Mechanical Equipment DSEAR requires that all potential sources of ignition within a defined hazardous area are considered and hence mechanical equipment does need to be considered.

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Where mechanical equipment is new, then ATEX certified equipment should always be considered. In this way equipment designed for a particular hazardous zone can be specified and sourced. However, potential problems arise if ATEX certified equipment cannot be purchased or the site has existing mechanical equipment within a hazardous area. A demonstration of safety, through risk assessment will be required. One potential method to complete this is based upon BS EN 13463 and summarised in Figure 5. This method is based upon the identification a potential faults that could result in ignition. A hazardous area classification must first be completed as the depth of this assessment is based upon the zone in which the equipment is situated. Figure 5 Assessment of Mechanical Equipment

DetermineLikelihood

ReassessLikelihood

Identify AreaClassification

Group IICategory 1

Group IICategory 2

Group IICategory 3

Identify all potential ignition sourcesNormal operation

Identify all potentialignition sources

Expected Malfunction

Identify all potentialignition sources

Rare Malfunction

Identify all potentialmeasures to prevent

ignition

IdentifyConsequences Assess Risk

For example, equipment located within a zone 0 is required to be Category 1 and hence all potential ignition sources associated with a rare malfunction, expected malfunction and during normal operation should be identified. Control for these is then identified and options for improvement identified and assessed. The potential exists for this analysis to be incorporated into the wider risk assessment. 3.3.2.3 Frequency Assessment In the model discussed in Sections 3.3.2.1 and 3.3.2.2 and summarised in Figure 3 it can be seen that the likelihood of a fire and / or explosion is the product of: • The likelihood of a dangerous substance forming a flammable or explosive atmosphere. • The probability of ignition. However, there is a further factor that may need to be considered. To receive a specified level of harm from a hazard, people need to be within the hazard radius. It may be appropriate to consider the probability of this in any assessment. Once again a qualitative or quantitative approach may be adopted depending upon the nature of the hazard and incorporated into the overall frequency assessment.

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3.3.2.6 Estimation of Consequence of Fire and Explosion The focus of a DSEAR assessment is the impact upon safety of dangerous substance. The potential outcome on the ignition of any loss of containment event should be considered (Figure 3). To do this the intermediate consequence and the consequence determinant should be identified. In addition, the scale of any impact, will to a certain extent, be determined by the quantity of material involved. This should always be considered as this also informs the ‘extent of harm’. 3.3.2.7 Identification of Control 3.3.2.7.1 General The identification of control is fundamental to the risk assessment process. The regulation requires that the ‘effect of measures which have been or will be taken pursuant to these Regulations’ should be considered. This requires that the measures for explosion protection to be identified and their effectiveness assessed. Measures can be both technical and organisational. 3.3.2.7.2 Measures for Explosion Protection During the risk assessment process the measures established for fire and explosion protection should be formally identified and their effectiveness assessed. Measures can be considered to: • Prevent the formation of an explosion atmosphere. • Avoid the ignition of an explosive atmosphere. • Mitigate the consequences of an explosive atmosphere. Within this framework, organisational measures are typically taken where technical measures are insufficient or where technical measures cannot alone ensure or maintain protection. It is essential that the assessment considers both. To do this effectively it is useful to address these separately. Hazardous area classification can be considered as a protection measure within this context and this is discussed further. 3.3.2.7.3 Hazardous Area Classification Hazardous area classification is an explicit requirement of DSEAR. Workplaces, where an explosive atmosphere may occur should be classified into hazardous (zones) or non hazardous places on the basis of the frequency and duration of the occurrence of an explosive atmosphere – Table 2.

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Table 2 Definitions of zones GAS, VAPOURS, MIST DUST Zone Zone 0 Place in which an explosive atmosphere

consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is present continuously or for long periods or frequently.

20 A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is present continuously, or for long periods or frequently.

1 Place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is likely to occur in normal operation occasionally.

21 A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation occasionally.

2 Place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

22 A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

There are exiting European Norm standards (British Standards Institute, 2003a & 2000) ’for completing these studies and these may be supported by industry codes of practice. For example the institute of petroleum and the Institution of Gas Engineers have both issued codes of practice in support of hazardous area classification: • Area Classification Code for Installations Handling Flammable Fluids Part 15 of the Institute of

Petroleum model Code of Safe Practice in the Petroleum Industry (Institute of Petroleum, 2002).

• Recommendation IGE/SR/25, Hazardous Area Classification of Natural Gas Installations (Institution of Gas Engineers, 2000).

Industry codes of practices may be used where they are more applicable to the materials under consideration (British Standards Institute, 2003a). The Approved Code of Practice issued in support of DSEAR (Health and Safety Executive, 2003) suggests that hazardous area classification should be completed as an integral part of risk assessment. This enables control over ignition sources to be formally assessed. Furthermore integration of risk assessment enables: • The quantity of material to be assessed which may negate the requirement for hazardous area

classification. • The criticality of ventilation to be formally assessed. 3.3.2.7.4 Concepts of Protection There are standards to ensure that ignition sources cannot arise. Common concepts of protection, associated standards and brief descriptions are detailed in Appendix B. The equipment is assessed against general requirements in addition to the concept of protection specific requirements. Essential Health and Safety Requirements need to be satisfied for ATEX certification and compliance with concepts of protection aids this process. Alternatively equipment is designed and assessed against the Essential Health and Safety Requirements (EHSR) without applying concepts of protection.

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The standards detailed are currently in use but there is a possibility that all the European references with soon follow the 60079 numbering system as used for Hazardous Area Classification EN 60079-10. In addition to the standards presented in Appendix B there are further methods of protection specifically for combustible dust based on several methods of protection used for gases and vapours, as detailed in Table 3. Table 3 Further Concepts of Protection Ex tD Protection by enclosure. Ex iD Intrinsic safety. Ex pD Pressurised. Ex mD Encapsulation.

The standards for concepts of protection are continually being updated and revised, therefore continuous reviews are required. 3.3.3 Risk Evaluation The risk evaluation stage uses the outcome of the risk analysis to determine whether the tolerable risk has been achieved. The depth of this study will depend upon the nature of the hazard. Once a frequency and consequence have been determined to each event it is then necessary to determine whether these risks are tolerable. The HSE offer guidelines on numerical values that can be used to describe the tolerability limits for a fatality. The guidelines suggest the upper limit of the Tolerable if ALARP region is 1x10-3 and the lower limit is 1x10-6, (Health and Safety Executive, 2001). This suggests that a quantitative or semi-qualitative approach should be used. For example the risk matrix is a well-used tool to present risks in relation to the HSE’s tolerability criteria. However, in order to be able to do this the matrix may need to be calibrated against the HSE criteria. It should also be recognised that this criterion applies to all of the risks that a person may be exposed to at work, not just the risks from flammable & explosive hazards. However, this approach may not be appropriate to the hazards under assessment. A purely qualitative approach may be considered, but once again the criteria for decision making should be established and recorded. Risk evaluation provides the basis for determining whether additional control or mitigation is necessary. Control is discussed in Section 3.2.2.7 and at this point further measures for explosion protection need to be considered. These may be either technical or organisation preventative or mitigation measures. Options for improvement should be considered within the context of the existing risk assessment. Certain options will reduced the frequency of harm others will mitigate the consequences. Within in any framework developed it is useful that the following hierarchy is considered: • Eliminate hazard. • Substitute hazard. • Control risk. • Mitigate the detrimental effects.

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3.4 Inspection and Testing of Mechanical Equipment 3.4.1 Electrical Equipment 3.4.1.1 Inspection Inspection of electrical equipment is detailed in an European Standard, EN 60079-17 (British Standards Institute, 2003b). This standard is intended to be applied by users, and covers factors directly related to the inspection and maintenance of electrical installations within hazardous areas only. It does not include conventional requirements for electrical installations, nor the testing and certification of electrical apparatus. When conducting an inspection of electrical equipment in hazardous areas, the following up-to-date documentation is required:

a) the classification of hazardous areas (reference EN 60079-10). b) apparatus group and temperature class. c) records sufficient to enable the explosion-protected equipment to be maintained in

accordance with its type of protection (e.g. equipment type, spares, technical information, manufacturers’ instructions, etc).

The inspection and maintenance of equipment installations should be carried out by competent personnel. The competent inspection and maintenance team should conduct an initial inspection before plant or equipment is brought into service. To ensure installations remain in a satisfactory condition for continued use within the associated hazardous areas either: a) Regular periodic inspections, or b) Continuous supervision by skilled personnel, and, c) Maintenance. should be carried out by the inspection and maintenance team. In addition, where replacement, repair, modification or adjustment is applicable further inspection is necessary to ensure the installation remains suitable for the environment. There are different types and grades of inspection. The interrelationships are detailed in Table 4.

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Table 4 Inspection Type and Grade INSPECTION TYPE INSPECTION GRADE Type Description Grade Description Initial • Conducted to ensure

installation is correct. • This inspection can be done

by the manufacturer. • This inspection should also

consider the period between future inspections

Detailed An inspection which encompasses those aspects covered by CLOSE INSPECTION and in addition identifies those defects, which will only be apparent by opening-up the equipment.

Close An inspection which encompasses those aspects covered by VISUAL INSPECTION and in addition, identifies those defects which will be apparent only by the use of access equipment (e.g. ladders and tools).

Periodic • Conducted periodically to evaluate the status of equipment.

• Periodically evaluated on a regular basis. o Fixed equipment -

maximum 3 year interval o Mobile equipment -

maximum 1 year interval • Detailed inspection

conducted if internal damage is suspected.

Visual An inspection which identifies, without the use of access equipment or tools, those defects which will be apparent to the naked eye.

Detailed As detailed previously.

Close As detailed previously.

Sample • Periodic inspection may be done on a sample basis for numerous similar items (e.g. JBs & luminaires).

• This is used at the discretion of the inspection team.

• Used to monitor if environment is problematic.

Visual As detailed previously.

Close As detailed previously. Continuous supervision

• This is used on a regular basis in the normal course of work.

• Prevents designated inspection.

• Issues relating to personnel integrity.

Visual As detailed previously.

The results of all initial, periodic, sample and continuous supervision inspections shouldl be recorded. Methods of recording vary but generally the information gathered will be fairly standard. EN 60079-17 provides check lists for common types of protection concepts (i.e. Flameproof, intrinsic safety, increased safety, etc) and most recording systems are based around these tables. Information required for an effective inspection includes: • Details of installation. • Evidence of Hazardous Area Classification review. • Apparatus group and temperature classification. • Equipment certificates (especially when special conditions are indicated). • Inspection date. • Inspector. • Type and grade of inspection. • Inspection schedule (Reference check lists detailed in EN 60079-17). • Additional information.

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The requirements for continuous supervision by skilled personnel are not as rigorous. Generally the records of inspection shall include: • A history of maintenance activities with the reason for such activities. • Verification of the effectiveness of the continuous supervision approach. • Information on defects found and remedial action taken. The records are usually part of normal maintenance documentation. However, the interrogation arrangements for the system must then be suitable to achieve the concepts detailed above. 3.4.1.2 Maintenance The general condition of all equipment shall be noted when conducting an inspection and appropriate remedial measures shall be taken where necessary (e.g. replacement of missing bolts). Care shall be taken, however, to maintain the integrity of the type of protection provided for the equipment; this may require consultation with the manufacturer (e.g. replacement bolts for a flameproof enclosure might require a specific grade). The advent of ATEX equipment ensures that equipment is supplied with instructions; these instructions will highlight maintenance requirements for the item of equipment. Replacement parts, if required, will be detailed in the instructions (or on the certificate) and shall be replaced in accordance with the safety documentation. For example, if a luminaire lamp is replaced with a higher wattage lamp this could effect the temperature classification of the equipment and could lead to ignition of an explosive atmosphere. Alterations to apparatus shall not be carried out without appropriate authorization where they adversely affect the safety of the apparatus as stated in the safety documentation (e.g. certificate or instructions). EN 60079-17 does not provide generic information for types of equipment maintenance as this information should be provided by the manufacturer. This information will be available for equipment post ATEX but it might be harder to find pre ATEX. Some of the main areas to be considered for general maintenance will relate to the environmental conditions in which the equipment is located. Some of the key elements to consider are corrosion, ambient temperature, ultraviolet radiation, ingress of water, accumulation of dust or sand, mechanical effects and chemical attack. Equipment maintenance shall always consider the type of protection. For example, flameproof equipment relies heavily on the mechanical strength and construction of the enclosure/flamepaths, therefore maintenance such as skimming a corroded flamepath could invalidate the type of protection if not conducted under the requirements of the certification. In these situations advice should be sort from the manufacturer or experts. 3.4.1.3 Mechanical Equipment Mechanical equipment standards are unavailable at present for inspection and maintenance but ATEX certified equipment should be supplied with instructions as required for electrical equipment. Therefore, until standards and /or guidance is provided mechanical equipment should be inspected and maintained following the same principles laid down for electrical equipment. EN 60079-17 only covers the main concepts of protection and relies on the inspection/maintenance team adapting the principles used for other electrical equipment, thus this approach should be taken for mechanical equipment. The check lists detailed in EN 60079-17 are based on generic questioning and the design requirements of the concepts of protection. Published and draft mechanical equipment design standards are available, and hence inspection schedules can be produced. In addition, input from manufacturers and users of the equipment should be considered where appropriate.

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3.4.1.4 Inspection and Maintenance Team / Individual Training Skilled personnel conducting inspection and maintenance within a hazardous area shall be provided with sufficient training to enable familiarity with the installation which they attend. This training shall include any plant, equipment, operational or environment conditions which relate to their understanding of the needs of the explosion protection of equipment. Where any alterations or changes to the process or installation are effected, this information shall be provided to the skilled personnel in a manner which supports their function as part of the continuous supervision process. Where necessary, training in the concepts of continuous supervision shall be provided together with refresher or reinforcement seminars. The knowledge requirements of the technical person with executive function shall include a full understanding of the provisions of EN 60079-10 (hazardous area classification) and EN 60079-14 (equipment selection and installation). Personnel competence is extremely important and should not be overlooked when training personnel to conduct the inspection and maintenance functions required by EN 60079-17. This has a direct link to human factors assessments which are becoming more prominent in hazardous environments. 3.5 Emergency Arrangements The requirement to establish emergency arrangements has been a longstanding requirement of UK legislation. The Management of Health and Safety at Work Regulations 1999 (Health and Safety Executive, 2003) require that procedures for ‘serious and imminent danger and for danger areas’ are established. It is therefore expected that the majority of sites will have systems in place to address emergencies. It may be that within any compliance programme there is an action to review these arrangements following the completion of the assessment of risk. There are additional requirements within DSEAR that the emergency arrangements should address. There is a requirement to coordinate fire and explosion safety where more than one employer occupies a site. This duty does apply to emergency arrangements. The risk assessment therefore needs to consider this type of situation and within these assessments determine whether other employers can be affected. In addition, there is also a requirement for verification of explosion safety following modification of existing plant and for new plant. The effectiveness of emergency arrangements do need to be assessed at this stage. It is therefore useful in any design project to consider this requirement as the project progresses. 3.6 Information, Training and Instruction The Health and Safety Executive (2003) stipulate the information that needs to be provided to employees. This includes: • The identity of the dangerous substances which could be present. • The type and extent of the risks. • Significant findings of risk assessment. • The control and mitigation measures adopted. • Procedures for dealing with accidents / emergencies. It is evident from the above that much of this information is generated during a compliance programme. It is therefore possible to generate this as the programme progresses. It is also important to note, that where risks can affect other employees from other employers that this is identified and appropriate information instruction / training is provided at induction. Finally, information / training / instruction may be an important organisation measure to prevent and / or mitigate risk. Where this is the case the risk assessment should refer to this explicitly.

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4.0 Discussion Section 3 introduced the key elements of DSEAR compliance. The information present in Section 3.3.2 (Risk Assessment) can be considered as key to any compliance programme. Risk assessment is the principal demonstration required by the regulation. Furthermore, it is this risk assessment process which informs other key elements of the compliance programme. Without an effective assessment of risk, emergency planning arrangements cannot be developed, employees cannot be trained and critical mechanical / electrical equipment cannot be inspected. DSEAR can be considered as establishing a layer of defence (LOD) for each of the elements of the risk assessment. For DSEAR to apply there must first be a source of hazard within the workplace. The first layer of protection can therefore be considered to be design procedures, inspection / maintenance system or perhaps even the principals of inherent SHE. Following the release of a material, an explosive atmosphere must be able to form and ignite. Once again there will be a layer of defence to prevent this. This LOD may include the inspection of electrical and mechanical equipment against an appropriate standard of the results of the risk assessment. Finally following ignition someone needs to be present to be harmed. A final layer, principally of mitigation measures but also prevention measures can be established. The risk assessment process described in Section 3 gives guidance for each of these stages and can be used to identify existing systems and inform improvement. This concept has been summarised in Figure 6. Figure 6 Summary of Compliance Requirements

SOURCE OF HAZARD

WORKPLACE

PRESENCE OF ANEXPLOSIVE

ATMOSPHERE

PRESENCE OF ANIGNITION SOURCE

(ACTIVE ANDEFFECTIVE)

IGNITION OF ANEXPLOSIVE

ATMOSPHERE

PRESENCE OFSOMEONE WHO

COULD BE HARMED

HARM

LOD

1

LOD

2

LOD

3

Technical preventionmeasures for release andignition

Organizational preventionmeasures for release

Hazardous AreaClassification

Technical mitigationmeasuresOrganizational preventionmeasuresOrganizational mitigationmeasures.

Design procedures - inherentSHERisk assessment techniquesManagement of change

6.0 Conclusion The paper has discussed a potential route to compliance and has introduced tools to achieve this. A compliance programme and hence the tools used will be dependant upon the nature and extent of the hazard and risk and ultimately what the organisation decides is suitable and sufficient. The Health and Safety Executive has suggested that DSEAR complements the general duty to manage risks under the Management of Health and Safety at Work Regulations 1999. However, despite this DSEAR may still present a challenge to some organisations. Others organisations may determine that compliance can be demonstrated within their existing systems. DSEAR, in common with recent health and safety legislation is focussed upon demonstrating that measures are in place to guarantee the safety of employees and other who may be affected, and this may not be in place. It is also possible that organisations have yet to assess the hazard presented by mechanical equipment located with a defined hazardous area. A potential method is presented to assist organisations achieve this.

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7.0 References British Standards Institute; 2003a, BS EN 60079-10:2003 Electrical Apparatus for Explosive Gas Atmospheres – Part 10: Classification of hazardous areas; BS EN 60079-10:2003. British Standards Institute, 2003b, Electrical apparatus for explosive gas atmospheres – Part 17: Inspection and maintenance of electrical installations in hazardous areas (other than mines), BS EN 60079-17. British Standards Institute, 2002, BS EN 50281-3:2001, Equipment for the use in the presence of combustible dust – Part 3: Classification of areas where combustible dusts are or may be present, British Standards Institute, BS EN 50281-3:2001. British Standards Institute, 1998, BS EN 1127-1:1998 Explosive atmospheres – Explosion prevention and protection Part 1: Basic concepts and methodology, British Standards Institute, BS EN 1127-1:1998. CEN, 2004, Methodology for Risk Assessment of Protective Systems for Intended Use in Potentially Explosive Atmospheres, TC 305 WI 00305082. Health and Safety Executive, 2004, The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR), Implementing the Chemical Agents Directive 98/24/EC (CAD) and the Explosive Atmospheres Directive 99/92/EC (ATEX 137). Available from: http://www.hse.gov.uk/spd/dsear.htm [Accessed 18 November 2004. Health and Safety Executive; 2003, L138, The Dangerous Substances and Explosive Atmospheres Regulations 2002, Approved Code of Practice and Guidance, L138. Health and Safety Executive, 2001, Reducing Risk, Protecting People. Institute of Petroleum, 2002, Area Classification Code for Installations Handling Flammable Fluids Part 15 of the Institute of Petroleum model Code of Safe Practice in the Petroleum Industry, 2nd Edition. Institution of Gas Engineers, 2000, Safety Recommendation IGE/SR/25, Hazardous Area Classification of Natural Gas Installation, IGE/SR/25. Official Journal of the European Communities; 2000, Directive 1999/92/EC of the European parliament and the Council of 16 December 1999 on minimum requirements for improving the safety and health of workers potentially at risk from explosive atmospheres. Official Journal of the European Communities, 1994, Directive 1994/9/EC of 23 March 1994 on the approximation of the laws of the member states concerning equipment and protective systems intended for use in potentially explosive atmospheres. Word count excluding Appendices - 6869

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Appendix A Ignitions Sources Ignition Source Mechanism Hot surfaces. Hot or heated surfaces generated by mechanical or machinery processes.

All moving parts (bearing, shaft passages, glands), tight housing of moving parts etc. Inherent hot or heated surfaces such as radiators, drying cabinets, heating coils. Hot surfaces generated by exothermic chemical reactions. Equipment, protective systems or components that convert mechanical energy into heat, e.g. friction clutches, mechanically operating brakes. A layer of dust or combustible solid in contact with a hot surface and ignited by the hot surface can also act as an ignition source.

Mechanically generated sparks / Thermite reactions.

As a result of friction, impact or abrasion particles become separated from solid materials and become hot. If these particles consist of oxidisable materials (e.g. iron, steel), they can burn thus reaching higher temperatures. Deposited dust in contact with sparks can smoulder and thus be a secondary ignition source. The ingress of foreign materials into equipment can cause sparking. Rubbing friction between ferrous metals and between ceramics can generate hot spots and sparks. Impacts between rust and light metals (e.g. aluminium, magnesium), and their alloys can initiate thermite reactions. Light metals such as Titanium and Zirconium can generate sparks upon impact or friction with any hard material in the absence of rust.

Naked flames and hot gases / liquids (including hot particles).

Flames are associated with combustion reactions at temperatures of more than 1000°C. Hot gases include the products of reaction or heated gases. Glowing solid particles can also be produced in dusty or sooty flames. Welding beads (which occur when welding or cutting) are sparks with a very large surface and hence the most effective source of ignition.

Electrical apparatus. Electrical sparks and hot surfaces can occur as sources of ignition. Electrical sparks can be generated: • When electrical circuits are opened and closed. • By loose connections. • By stray currents.

Stray electrical currents, cathodic corrosion protection.

Stray currents can flow in electrically conductive systems or parts of systems: • As a result of short circuit or a short circuit to earth owing to faults in electrical installations. • As a result of magnetic induction (near electrical installations with high current or radio frequency). • As a result of lightning. • If parts of a system able to carry current are disconnected, connected or bridged (even in the case of a slight potential difference)

and explosive atmosphere can be ignited as a result of an electric spark and / or arcs. In addition, ignition can occur due to heating up of these current paths.

• With cathodic corrosion protection the above ignition risks are present. However, if sacrificial anodes are used ignition risk due to electrical sparks are unlikely (unless anodes are Al or Mg).

Static electricity. The discharge of charged, insulated conductive parts can lead to incendive sparks. Non conductive materials will include most plastics. Brush discharges, cone discharges from bulk material and cloud discharges are also possible. Brush discharges can ignite almost all explosive gas and vapour atmospheres. In addition ignition of explosive dust / air atmospheres

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Ignition Source Mechanism by brush discharges cannot be discounted. Whilst all discharges can ignite all types of explosive atmosphere this is dependant upon their discharge energy.

Lightning. If lightning strikes an explosive atmosphere ignition will always occur. There is also a possibility of ignition due to the high temperatures reached by lightning conductors. Large currents flow from lightning strikes and these can produce sparks in the vicinity of the point of impact. In the absence of lightning strikes thunderstorms can cause high induced voltages in equipment, protective systems and components.

Radio frequency electromagnetic waves (104 – 3x1012 Hz)..

EM waves are emitted by all systems that generate or use radio frequency electrical energy e.g. radio transmitters, industrial / medical RF generators for heating, drying, hardening, welding, cutting. All conductive parts located in the radiation field function as receiving aerials. If the field is powerful enough and if the receiving aerial is sufficiently large these conductive parts can cause an ignition in an explosive atmosphere – the received radio-frequency

Electromagnetic waves from 3x1011 – 3x1015 Hz.

Focussed energy in this spectral range can become a source of ignition through absorption by the explosive atmosphere or solid surface. Under certain circumstances this radiation of intense light is so intense that following absorption by dust particles these become a source of ignition in an explosive atmosphere. Examples include sunlight, lasers. It is also worth noting that equipment that generates intense lights sources (e.g. lamps, lasers, electric arcs) can themselves be sources of ignition).

Ionizing radiation. Ionizing radiation generated by X-ray tubes and radioactive substances can ignite explosive atmospheres (especially those with dust particles). In addition, the radioactive source itself can heat up to such an extent that the minimum ignition energy of the explosive atmosphere is exceeded. Ionizing radiation can cause chemical decomposition or other reactions, which can lead to the generation of highly reactive radicals or unstable compounds, and this can cause ignition (Note: these reactions can also create explosive atmospheres, e.g. radiolysis of water generating hydrogen and oxygen).

Utrasonics. In the use of ultrasonic sound waves solid or liquid substances absorb a large portion of the emitted energy. As a result substances exposed to ultrasonics can warm up so in extreme cases, ignition may be induced.

Adiabatic compression and shock waves.

The high temperatures generated during adiabatic compression in shock waves can ignite explosive atmospheres (and deposited dusts). The temperature increase depends upon the pressure ratio and not the pressure difference. Shock waves are generated during the sudden relief of high pressure gases into pipelines.

Exothermic reaction including self ignition of dusts.

Exothermic reactions can act as an ignition source when the rate of heat exceeds the rate of heat loss to the surroundings. Reactions include; Pyrophoric substances with air, Alkali metals with water, Self ignition of combustible dusts, Self heating of feedstuffs induced by biological processes, Decomposition of organic peroxides, Polymerisation, Those induced by catalysts, Copper with acetylene, Hydrogen peroxide with heavy metals, Aluminium / rust exposed to impact or friction, Sugar / chlorate exposed to impact or friction.

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Appendix B Concepts of Protection Concept Standard Cat Brief description Ex o Oil immersion

EN 50015 2 Type of protection in which the electrical apparatus or parts of the electrical apparatus are immersed in a protective liquid in such a way that an explosive atmosphere which may be above the liquid or outside the enclosure cannot be ignited.

Ex p Pressurised EN 50016 2 Technique of applying protection as to an enclosure in order to prevent the formation of an explosive atmosphere inside the enclosure by maintaining an overpressure against the surrounding atmosphere, and where necessary by using dilution.

Ex q Powder filling EN 50017 2 Type of protection in which the parts capable of igniting an explosive atmosphere are fixed in position and completely surrounded by filling material to prevent the ignition of an external explosive atmosphere.

Ex d Flameproof Enclosure

EN 50018 2 Type of protection in which the parts which can ignite an explosive atmosphere are placed in an enclosure which can withstand the pressure developed during an internal explosion of an explosive mixture and which prevents the transmission of the explosion to the explosive atmosphere surrounding the enclosure.

Ex e Increased safety

EN 50019 2 Type of protection in which additional measures are applied so as to give increased security against the possibility of excessive temperatures and of the occurrence of arcs and sparks inside and on external parts of electrical apparatus which does not produce arcs or sparks in normal service.

Ex i Intrinsic safety EN 50020 1 (ia) 2 (ib)

Type of protection where circuits in which any spark or any thermal effect produced in the conditions specified in EN 50020, which include normal operation and specified fault conditions, is not capable of causing ignition of a given explosive gas atmosphere.

Ex n Type of protection “n”

EN 50021 3 Type of protection applied to electrical apparatus such that, in normal operation and in certain abnormal conditions specified by EN 50021, it is not capable of igniting a surrounding explosive

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Concept Standard Cat Brief description atmosphere. This type of protection is broken into the following types: nA – non-sparking. nC – enclosed break. nR – restricted breathing. nL – energy limited. nP – simplified pressurisation.

Ex m Encapsulation EN 50028 - Type of protection applied to electrical apparatus such that surrounding explosive atmospheres are excluded from ignition sources by a compound.

Basic methods and requirements

EN 13463-1

1, 2 or 3

Risk assessment and application of supporting standards as listed below where necessary.

Ex fr Flow restricted enclosure

prEN 13463-2

- Type of protection relies on tight seals of the enclosure to restrict the breathing of the enclosure

Ex d Flameproof enclosure

prEN 13463-3

- Type of protection as detailed for electrical apparatus Ex d.

Ex g Inherent safety

prEN 13463-4

- Type of protection relies on low potential energy.

Ex c Constructional safety

EN 13463-5

- Type of protection in which constructional measures are applied so as to protect against the possibility of ignition from hot surfaces, sparks and adiabatic compression generated by moving parts.

Ex b Control of ignition sources

prEN 13463-6

- Type of protection that relies on a device to control all ignition sources, e.g. thermal sensors and shutdown devices.

Ex p Pressurisation prEN 13463-7

- Type of protection as detailed for electrical apparatus Ex p.

Ex k Liquid immersion

EN 13463-8

- Type of protection in which potential ignition sources are made ineffective or separated from the explosive atmosphere by either totally immersing them in a protective liquid, or by partially immersing and continuously coating their active surfaces with a protective liquid in such a way that an explosive atmosphere which may be above the liquid, or outside the equipment enclosure cannot be ignited.

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