Ptq Atex Article - Spring 2004

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The European Unions AtmosphresExplosibles (ATEX) Directivesbecame fully effective last summerthroughout the EU. More commonlyreferred to as ATEX, there are in fact twodifferent but complementary directives,

intended to reduce the hazards createdby explosive atmospheres within therefining and petrochemical processingindustry workplace. All processing facil-ities with operations located within theEuropean Union now have to complywith the requirements of these direc-tives. One of these directives is con-cerned with the supply of equipmentwhile the other deals with the protec-tion of workers.

It should be noted that these direc-tives only address the hazards associatedwith explosive atmospheres and do not

consider other hazards, for example tox-icological considerations.Collectively, the ATEX Directives

have the effect of turning what haduntil now been accepted best practicewithin the process industries intomandatory requirements. In addition toflammable liquids and vapours, com-bustible dusts have been specificallyincluded within the scope of dangeroussubstances. The definition of equipmentwithin these directives is also very broadand now includes mechanical equip-ment.

Traditionally, only the installation of

electrical equipment in potentiallyflammable atmospheres had been givenspecial consideration. The inclusion ofmechanical equipment presents one ofthe main compliance issues for bothequipment suppliers and users.

The equipment supply Directive94/9/EC, also known as ATEX 95, isintended to allow the free movement ofgoods throughout the EU by harmonis-ing the technical and legal requirementsfor equipment which is intended to beused in potentially explosive atmos-pheres. It applies to the placing on the

market, putting into service and designof this type of equipment. This directivehad a transitional period, which ended

on 30 June 2003. From this date manu-facturers and suppliers have to ensurethat any of their products, intended foruse within potentially explosive atmos-pheres, meet a series of specified essen-tial health and safety requirements,

have been assessed for conformity andare appropriately certified and marked.Manufacturers must also compile a tech-nical file for the equipment and, ifrequired, lodge a copy of this file withan appointed notified body.

From 30 June 2003, some categoriesof products have to be certified by anyof the notified bodies appointed by theEU member states. Notified bodiesinclude such organisations as BASEEFA,DEMKO, KEMA, INERIS, PTB, SIRA, andTV. Conformity with ATEX 95 meansthat equipment can be sold for use any-

where in the EU. It is important to notethat it is the use of the equipment with-in the EU that necessitates compliancewith this directive. Hence, equipmentexported from the EU need not comply.Conversely, equipment manufacturedoutside the EU must now comply if it isto be used within the EU.

This directive affects the operators ofhydrocarbon processing facilities, albeitindirectly, because of the way in whichit imposes duties upon their suppliers. Itmay also restrict an operators ability touse equipment that has been manufac-tured outside the EU. The definition of

equipment under this directive is verybroad and includes mechanical equip-ment (both rotating and static), such aspumps, compressors, fans and valves aswell as electrical equipment and instru-mentation.

The directive means that manufactur-ers in EU member states are, for the firsttime, set to work to common agreedstandards. A particular benefit is thatmanufacturers no longer have to gettheir equipment certified in more thanone EU country.

While ATEX 95 is concerned with the

design and specification of equipment,this directive directly affects the opera-tion of refining and petrochemical facil-

ities. Directive 99/92/EC, known asATEX 137, provides minimum require-ments within the workplace to improvethe safety and health protection ofworkers from the hazards of potentiallyexplosive atmospheres. It places specif-

ic duties on the employers. The direc-tive lays out a hierarchy of riskidentification and reduction measures.Operators must now demonstrate thatall the explosion risks within their facil-ities have been determined and thatappropriate measures have been putinto place to minimise and then con-trol these risks. In order to demonstratethat they are doing so, they must com-pile an Explosion Protection Documentfor the facility.

The risk assessment exercise com-mences with steps to identify the poten-

tially flammable substances within theworkplace and where possible to elimi-nate or reduce the risks presented by thesubstances. The next steps include theclassification of areas containingflammable substances into zones andthe installation of equipment suitablefor use within these zoned areas.

Operators must be able to show thatthey are using appropriate managementsystems including the training of per-sonnel and work control measures, forexample permit to work procedures.Workplaces and work equipment,including warning devices, must be

designed, operated and maintained withdue regard for the avoidance of leakageand the prevention of ignition sources.

Existing workplaces are subject to athree-year transitional period. Work-places used for the first time after 30June 2003 and all modifications to exist-ing plants after this date must complywhen they are brought into use. Work-places already in use before 1 July 2003are required to be in compliance withthis directive by 30 June 2006.

Area classification

The processing industry undertakes theprocessing and handling of large quanti-ties of flammable materials, frequently

M ech anical equipm ent andth e ATEX Directives

European U nion requirem ents for operating mech anical equipm ent in potentiallyflammable atmospheres present major compliance issues for users and suppliers.

This article provides guidelines for the ap propriate m easures to ensure com plian ce

Andy Hollins

ABB Engineeri ng Services

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well above their flash point tempera-tures. Responsible operators alreadyhave in place risk assessment studiessuch as process hazard reviews andHAZOPs, which seek to address theseissues.

The nature of the business means thatthere is effectively little scope for substi-tution with less flammable substancesand generally minimal opportunity toreduce the quantities of the flammable

materials. Loss of containment in pro-cessing plants consequently has thepotential to create flammable atmos-pheres. Combustible dusts are not gen-erally a problem in such facilities.

ATEX 137 requires that areas contain-ing hazardous substances are classifiedinto zones on the basis of frequency andduration. Area classification is, however,a long established procedure within therefining ad petrochemical industries.But the directive has the effect of turn-ing this good practise into a formalrequirement.

Existing standards, for example EN6007910, give guidance on carryingout the studies, although until now onlythe electrical and instrumentationengineers had any real interest in theoutcome. Going forward, the mechani-cal engineers for both rotating and stat-ic equipment will need to understandthe implications of the area classifica-tion upon their equipment located with-in hazardous areas. The different zonesfor potentially explosive vapours anddusts, together with much simplifieddefinitions of frequency and persistenceare shown in Table 1.

Since 1 July 2003 only equipmentcomplying with ATEX 95 can beinstalled in a hazardous area. Equip-ment is divided into groups and cat-egories with differing requirements fordesign, testing, certification and docu-mentation. The equipment groups areeasily understood. Group I equipmentis intended only for use in hazardousareas in mines while Group II equip-ment is for use in hazardous areas inother locations. Equipment fromGroup II is, consequently, suitable foruse within refining and petrochemical

facilities.The equipment categories are apotential source of confusion. It was

decided that there could be no suchthing as a category zero and that there-fore the equipment categories should benumbered 1, 2 and 3. This is despite thefact that the vapour zones are designat-ed 0,1 and 2. The use of equipment ofthe different categories of equipmentwithin hazardous areas is restricted asalso shown in Table 2.

Although responsible operators willhave existing area classification draw-

ings they should now review them toensure they are up to date and theyshould be able to produce documenta-tion. For example, minutes of the areaclassification review meetings, support-ing these drawings, which show howthe extent of the zones was determined.Operators who in the past relied on theblanket zoning of whole plant areasshould seek to establish the necessaryextent of individual zones. Otherwise,they are likely to incur unnecessarycosts, particularly with regard to theirmechanical equipment.

In the past, electrical engineers fre-quently employed blanket zone 1 as ameans of ensuring that electrical appar-atus suitable only for installation inzone 2 areas was not inadvertentlyinstalled in a zone 1 area. The associatedcost penalty being regarded as modestwhen compared with the potential risk.In comparison, mechanical equipmentdoes not have the same potential levelof inter-changeability. Additionally, theprocurement and ongoing maintenancecosts of category 2 mechanical equip-ment is likely to be significantly higherthan for category 3 equipment.

New equipmentIt is the users responsibility to correctlyspecify equipment for installation inhazardous areas on their facilities. The

supplier is responsible for the design,testing, certification and marking of theequipment that they supply. Operatorswill need to have amended their pur-chasing procedures and possibly alsotheir project processes so as to ensurethat from now on only ATEX certifiedequipment is purchased for installationin zoned areas.

As far as electrical apparatus is con-cerned, the ATEX requirements are

nothing new for both suppliers andusers, with only some changes to exist-ing labelling and certification proce-dures. Electrical engineers have beendealing with the issue of the safe opera-tion of equipment in potentiallyflammable atmospheres for about 30years and the standards and equipmentcertification procedures are well estab-lished.

EN 60079-14 covers the selectionand installation of electrical apparatusfor use in hazardous areas. The differ-ent types of protection for electrical

apparatus are widely understood bymanufacturers and the notified bodiesand are covered by the EN 500XX seriesof standards.

In contrast, many of the equivalentstandards for mechanical equipment,the EN 13463 series, are still at the draftstage. EN 13463-1 covering basicmethod and requirements was pub-lished in 2001. EN 13463-5 coveringprotection by constructional safety andEN 13463-8 protection by liquid immer-sion were published towards the end of2003. Of the remaining draft standards,EN 13463-6 covering control of ignition

sources has been subject to substantialrevision and is potentially of interest tothe operators of existing facilities.

For electrical apparatus the mostnoticeable change will be in the labelaffixed to the apparatus. Hazardous areamarkings are an entirely new feature onmechanical equipment. An example ofa typical ATEX equipment label isshown in Figure 1. Certified equipmentfor use within the EU now has to carryboth an Ex mark denoting compli-ance with the ATEX 95 Directive and aCE mark, which signifies that the

equipment complies with all relevantEU Directives.As well as carrying the correct label,

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Vapours Dusts Frequency of Approximate durationflam mab le atm osp he re ( ho urs/ ye ar)

Zone 0 Zone 20 Continuously >1000

Zone 1 Zone 21 Intermittently 10 to 1000

Zone 2 Zone 22 Abnormally


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new equipment must be supplied with acertificate of compliance. Again, haz-ardous area equipment certificates forelectrical apparatus are nothing new,while Ex certificates for mechanicalequipment is a new phenomenon. Thecertificates should be read and under-stood by the operator. Most ATEX certi-fied mechanical equipment comes witha conditional certificate requiring specif-ic operating and/or maintenanceregimes for the certification to be valid.

While there were bound to be someinitial problems with the certification ofnew mechanical equipment, many ofthe manufacturers supplying mechani-cal equipment for use on chemical pro-cessing plants are now able to supplyATEX certified equipment. The same istrue for spares and components. Forexample, ATEX certified mechanicalseals are readily available from themajor manufacturers.

There are, however, likely to be resid-ual issues with one-off and specialistitems of mechanical equipment andwith the importation of equipmentfrom outside the EU. Should they wishto, operators are allowed to import un-certified equipment into the EU, butbefore they can use this equipment in ahazardous area they must undertake allof the duties assigned to the supplierunder the ATEX 95 Directive.

Control of ignition sourcesThe ATEX Directives permit existing

equipment to be used indefinitely pro-vided that the operator can show thatthis equipment is safe for use in thezone in which it is located. Spare partsthat were in stock before 1 July 2003 canbe used providing that they do notrequire substantial modification.

For installed certified electrical equip-ment, demonstrating suitability for on-going use should be relativelystraightforward. This can be based onthe fact that the apparatus was manu-factured and certified to existing stan-dards, which addressed the ignitionsource potential of that particular type

of item. Activities will typically includethe following steps: Inspecting the apparatus to checkthat it is correct for the zone and to con-firm that it has been maintained in goodcondition The replacement, where necessary,with apparatus appropriate to the zone The repair of any defects identifiedduring the inspections Documentation of the above steps.

The first step is important, particular-ly as the zoning may have changed sincethe equipment was installed. Inspection

regimes for electrical apparatus locatedwithin hazardous areas are given in EN60079-17.

For existing mechanical equipmentthe route to demonstrating safety ismuch less clear-cut. The equipment willnot have been designed and built tostandards, which directly addressed thepotential for the equipment to createignition sources. Many of the mechani-cal items within refining facilities willhave been built in accordance with theAPI standard for that type of equipment.In essence, these standards capture thepetroleum industries operating experi-ence and establish the design featuresnecessary for reliable operation at therequired throughput.

Having undertaken the area classifica-tion review, ATEX 137 requires that riskassessments be carried to show that igni-

tion sources have been identified andeither eliminated or effectively con-trolled. It follows that one of the majorconsequences of these directives is thatthe operators now have to carry out therisk assessment of uncertified equip-ment located within their hazardousareas for potential sources of ignitionand provide the technical and theorganisational measures required toeliminate or reduce the identified risksto an acceptable level.

At this point, it may not be clear howthe installation and operation ofmechanical equipment can lead to theintroduction of potential ignitionsources within a zoned area. EN 1127-1lists 13 potential groups of ignition

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sources. Of these, the most commonassociated with the types of equipmentto be found in refining and petrochemi-cal plants are hot surfaces, flames, hotgases, mechanically generated sparks

and static electricity. Other mechanicalplant items have a similar potential togenerate ignition sources.

Operators will need to be able todemonstrate that the equipment in usewithin the zoned areas does not result inactive ignition sources. The tolerabilityof active ignition sources varies accord-ing to the zone in which the equipmentis located. The requirements are out-lined as:

Zone 0/20: In normal operation and

resulting from expected malfunctions,and resulting from rare malfunctions Zone 1/21: In normal operation andresulting from expected malfunctions Zone 2/22: In normal operation (nomalfunctions).

Equipment located in zone 0 requiresthe highest level of protection frompotentially active ignition sources whilethat installed in zone 2 areas requiresthe lowest. Hence the required level ofprotection is proportionate to the likeli-hood of a flammable atmosphere beingpresent.

Having identified the potential igni-tion sources associated with themechanical equipment it is then neces-sary to identify how they are to be elim-inated or controlled. Once this has beencompleted, any necessary modificationscan be progressed and the required mit-igating measures can then be imple-mented. The risk assessments need to bedocumented since they will form part ofthe overall Explosion Protection Docu-ment. Any necessary inspections canthen be undertaken and recorded. Therange of mitigating measures includes:

Maintenance and operational proce-dures Process operator checks Maintenance inspections and records Condition monitoring regimes Instrumented trips and alarms Hardware protection devices (such astorque limiters).

Inspections for mechanical equip-ment mirror those for certified electricalequipment. The inspection points havebeen identified during the ignitionsource risk assessment. They involveconfirming the specification of theequipment, checking its condition and

confirming that the necessary mitigat-ing measures are in place.

Processing facilities will typicallyhave thousands of installed plant itemsoperating within their zoned areas, rep-resenting a significant challenge tooperators.

To meet this need ABB EngineeringServices has developed an ignitionsource risk assessment methodologythat identifies any effective ignitionsources created by the operation ofequipment in hazardous areas. The ne-cessary mitigating measures are then

selected to reduce the residual risk to anacceptable level. The methodologyenables full credit to be taken for the

mitigation provided by the mainte-

nance and operating procedures, whichthe operator already has in place togeth-er with the protection provided by exist-ing hardware and instrumentedprotective systems.

The outcome of the assessment isthen summarised in the risk assessmentreport for the item of equipment and ininspection sheets to enable the user toimplement and manage the requiredmitigating measures. The methodologyenables the equipment user to demon-strate compliance with the ATEX direc-tives. The focus is on minimising the

ongoing cost of compliance for theoperator while reducing the risk of igni-tion to the necessary level. The method-ology also makes use of software tools toundertake the risk assessment of largevolumes of equipment in a cost effectivemanner.

Repairs and m odificationsThe repair of electrical apparatus is cov-ered by EN 60079-19. It is supported byrecognised training schemes for techni-cians and approved contractors. Cur-rently, there is no equivalent standardfor mechanical equipment. But essential-

ly, any repairs to mechanical equipmentshould return it to its original condition.Care needs to be exercised to ensure thatmaterials specifications and dimensionaltolerances are achieved and that the cor-rect re-build procedures are followed.While operators frequently choose to usecontractors to undertake these activitieson their behalf, they cannot transfertheir responsibilities under the directivesfor protecting their employees.

Operators need to be careful aboutmodifying their equipment. For exam-ple, modifications to certified electrical

equipment will invalidate the certifica-tion. Under the directives, modifica-tions can still be undertaken but in

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ATEX Directives

ATEX 95: European Union directive

1994/9/EC.

ATEX 137: European Union directive

1999/92/EC.

EN 1127-1: Explosive atmospheres

explosion prevention and protection

Part 1: Basic concepts and

methodology.

EN 13463-1: Non-electrical

equipment for potentially explosive

atmospheres

Part 1: Basic method & requirements.



atmospheres

Part 5: Protection by constructional

safety.



atmospheres

Part 6: Protection by control of i

ignition sources. (Draft Standard).



atmospheres

Part 8: Protection by liquid

immersion.

EN 60079-10: Electrical apparatus forexplosive gas atmospheres

Part 10: Classification of hazardous

areas.

EN 60079-14: Electrical apparatus for

explosive gas atmospheres

Part 14: Electrical installations in

hazardous areas (other than mines).



Part 17: Inspection and maintenance

of electrical installations in hazardous

areas (other than mines).



Part 19: Repair and overhaul for

apparatus used in explosive

atmospheres (other than mines or

explosives).

Care needs to be exercised

to ensure that materials

specifications and

dimensional tolerances are

achieved. . . While operatorsfrequently choose to use

contractors to undertake

these activities on their

behalf, they cannot transfer

their responsibilities under

the directives for protecting

their employees


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these circumstances the operator may have toundertake all the duties placed upon equipmentmanufactures by the ATEX 95 Directive.

Minimising explosion effectsATEX 137 accepts that even after the risks havebeen reduced and controlled as previously out-lined, there could still be a residual risk of explo-sions within the workplace. The directive requiresthat the operator protect the workforce by havingthe appropriate measures in place to minimise theeffects of explosions. These range from escape andevacuation plans, fire detection and fire fightingsystems to explosion containment, venting andsuppression systems.

The intention throughout is to limit the scale ofany incident and minimise the number of employ-ees that may be harmed.

Operators will already have such systems andprocedures in place. They will, however, need toreview the adequacy of their existing measures totake into account the outcome of the risk assess-ment exercises, particularly where these identify

new risks. This will be required as part of theirExplosion Protection Document for the facility.

ConclusionOperators in the refining and petrochemical sectorhave had to address the issues of handlingflammable substances from the outset. Over theyears, companies operating in this sector have beenat the forefront of implementing procedures anddeveloping standards and best practice to reducethese risks. The avoidance of explosions and firesis, after all , good business. Consequently, operatorswith facilities located within EU member states andwho have been routinely using industry standard

best practices will find that they already have inplace many of the procedures and much of thedocumentation needed for compliance with therequirements of the ATEX Directives, the mainexception to this being the issues related to theoperation of mechanical equipment in potentiallyflammable atmospheres.

The ATEX Directives have legal force within theEU by virtue of being passed into national law byeach of the EU member states. In particular, itneeds to be understood that compliance with theminimum requirements of Directive 1999/92/ECdoes not in itself guarantee compliance with therelevant national law. Individual member stateshave the ability to introduce more stringent mea-

sures within their own law, providing that they arecompatible with Article 137. This article does notconsider all of the aspects of the ATEX Directives.For the avoidance of doubt, following the stepsdiscussed in the article will not in itself be suffi-cient to comply with either the ATEX Directives orthe relevant national law.

Andy Hollinsis a senior consult ant wit h ABB Engineer-

ing Services, wi th specific interests in process plant reli-

ability and the safe operation of mechanical

equipment. He graduat ed from Cambridge University

wit h a degree in engineering. He is currently working

wi th clients to address ATEX compliance issues associ-ated with t heir mechanical equipment .

E-mail: andy.hollin [email protected]

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Ptq Atex Article - Spring 2004

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