EN 746-3:2021
(Main)Industrial thermoprocessing equipment - Part 3: Safety requirements for the generation and use of atmosphere gases
Industrial thermoprocessing equipment - Part 3: Safety requirements for the generation and use of atmosphere gases
This part of the EN 746 series specifies safety requirements for generation and use of protective and reactive atmosphere gases that are part of industrial thermo-processing equipment (TPE).
The general safety requirements common to TPE are provided in EN 746 1:1997+A1:2009 (see Introduction).
This part of the EN 746 series deals with significant hazards, hazardous situations and events relevant to the generation and use of protective and reactive atmosphere gases created by thermochemical reactions and their use in TPE that are part of TPE as listed in Clause 4 and Clause 5, when used as intended and under the conditions foreseen by the manufacturer.
This part of the EN 746 series covers:
- pipework downstream of and including the manual isolating valve,
- equipment for the generation of atmosphere gases,
- additional equipment for the use of atmosphere gases in TPE,
- safety devices, and
- functional requirements for safety related control system
for the generation and use of protective and reactive atmosphere gases.
It applies to the supply of atmosphere gas, source gas, inert gas and process liquids to TPE and their removal from TPE, confined to equipment integrated in the TPE.
This part of the EN 746 series also details the anticipated significant hazards associated with atmosphere gas systems and their use in TPE and specifies the appropriate preventative measures for the reduction or elimination of these hazards.
The pressure hazard of the piping and components covered by this standard is within the maximum pressure/size relationship of group 1 as described in Annex C.
This part of the EN 746 series:
- specifies the requirements to be met to ensure the safety of persons and property during installation, commissioning, start up, operation, shutdown and maintenance,
- does not cover the relevant risks involved in the flue gas ducting system when it is not considered a part of TPE,
- is not applicable to utility supply upstream of the TPE main disconnects,
- does not apply to TPE for semi-conductor devices,
- does not apply to TPE with atmosphere, such as air and flue gas from an over stoichiometric combustion,
- does not cover the decommissioning of the TPE,
- does not cover vacuum furnaces,
- does not cover blast furnaces, converters (in steel plants), boilers and equipment not covered under EN ISO 12100:2010.
- does not deal with the hazard of noise which is covered in EN 746 1:1997+A1:2009,
- is not applicable to generation and use of atmosphere gas in TPE and associated plant which is manufactured before the date of its publication, and
- gives the necessary requirements for the information for use.
A TPE designed according to this part of EN 746 series does not create any potentially explosive atmosphere in the area around the TPE and is not designed to be located in an area with a potentially explosive or hazardous atmosphere.
This part of the EN 746 series deals with significant hazards which are described in Annex A.
A table of typical protective and reactive gases is given in Annex B.
Industrielle Thermoprozessanlagen - Teil 3: Sicherheitsanforderungen für die Erzeugung und Anwendung von Schutz- und Reaktionsgasen
Dieser Teil der Normenreihe EN 746 legt die Sicherheitsanforderungen an die Erzeugung und Nutzung von Prozessgasen, die Teil einer industriellen Thermoprozessanlage (TPE) sind, fest.
Für TPE übliche allgemeine Sicherheitsanforderungen werden in EN 746 1:1997+A1:2009 festgelegt (siehe Einleitung).
Dieser Teil der Normenreihe EN 746 behandelt erhebliche Gefährdungen, Gefährdungssituationen und ereignisse, die mit der Erzeugung und Anwendung von Prozessgasen, die durch thermochemische Reaktionen erzeugt werden, und ihrer Anwendung in TPE zusammenhängen und die nach der Auflistung in Abschnitt 4 und Abschnitt 5 Teil von TPE sind, wenn diese wie beabsichtigt und in den vom Hersteller vorhergesehenen Bedingungen angewendet werden.
Dieser Teil der Normenreihe EN 746 behandelt:
Rohrleitungssysteme in Strömungsrichtung beginnend mit dem handbetätigtem Absperrventil,
Anlagen für die Erzeugung von Prozessgasen,
zusätzliche Anlagen zur Anwendung von Prozessgasen in TPE,
Sicherheitseinrichtungen, und
funktionale Anforderungen an sicherheitsbezogene Steuerungen
zur Erzeugung und Anwendung von Prozessgasen.
Er ist anzuwenden für die Versorgung von TPE mit Prozessgasen, Ausgangsgasen, Inertgasen und Prozessflüssigkeiten und deren Entfernung aus TPE. Er betrifft nur Anlagen, die in TPE integriert sind.
Dieser Teil der Normenreihe EN 746 gibt die zu erwartenden signifikanten Gefährdungen an, die bei Prozessgassystemen und ihrer Verwendung in TPE vorhanden sind, und legt die entsprechenden Vorsorgemaßnahmen zur Verringerung oder Beseitigung dieser Gefährdungen fest.
Die Druckgefährdung der Rohrleitungen und Komponenten, die in dieser Norm abgedeckt sind, liegt innerhalb des maximalen Druck-/Größenverhältnisses der Gruppe 1, wie in Anhang C beschrieben.
Dieses Teil der Normenreihe EN 746:
— legt die Anforderungen fest, die zur Sicherstellung der Sicherheit von Personen und Eigentum während der Installation, der Inbetriebnahme, dem Anfahren, dem Betrieb, der Abschaltung und der Instandhaltung zu erfüllen sind,
— behandelt nicht die relevanten Risiken, die Rauchgasanlage betreffen, wenn diese nicht als Teil der TPE betrachtet werden,
— ist nicht anzuwenden für die Versorgungsinfrastruktur, die den Haupttrenneinrichtungen der TPE vorgelagert ist,
— ist nicht anzuwenden für TPE für die Halbleiterfertigung,
— ist nicht anzuwenden für TPE mit Atmosphäre, wie etwa Luft und Rauchgas aus überstöchiometrischer Verbrennung,
— behandelt nicht die Außerbetriebnahme der TPE,
— behandelt nicht Vakuumöfen,
— gilt nicht für Hochöfen, Konverter (in Stahlwerken), Kessel und Anlagen, die nicht unter EN ISO 12100:2010 fallen
— behandelt kein Lärmgefährdungen; diese werden in EN 746 1:1997+A1:2009 behandelt,
— ist nicht auf die Erzeugung und Anwendung von Prozessgas in TPE und zugehörigen Anlagen anwendbar, die vor dem Veröffentlichungsdatum hergestellt werden, und
— beinhaltet auch notwendige Anforderungen für die Benutzerinformation.
Eine TPE, die nach diesem Teil der Normenreihe EN 746 konstruiert wurde, erzeugt im Bereich um sich herum keine potenziell explosionsfähige Atmosphäre. Sie ist auch nicht für die Aufstellung in einem Bereich mit explosionsfähiger oder gefährlicher Atmosphäre vorgesehen.
Dieser Teil der EN 746-Reihe befasst sich mit signifikanten Gefährdungen, die in Anhang A beschrieben sind.
Anhang B enthält eine Tabelle typischer Prozessgase.
Équipements thermiques industriels - Partie 3 : Prescriptions de sécurité pour la génération et l'utilisation des gaz d'atmosphère
La présente partie de la série des EN 746 spécifie les prescriptions de sécurité pour la génération et l'utilisation des gaz d’atmosphère protectrice et réactive qui font partie des équipements thermiques industriels (TPE).
Les prescriptions générales de sécurité communes aux TPE sont fournies dans l'EN 746 1:1997+A1:2009 (voir Introduction).
La présente partie de la série des EN 746 traite des phénomènes dangereux significatifs, des situations et des événements dangereux relatifs à la génération et à l'utilisation des gaz d’atmosphère protectrice et réactive créés par des réactions thermochimiques et leur utilisation dans les TPE qui font partie des TPE tels qu’énumérés à l’Article 4 et à l’Article 5, lorsqu'ils sont utilisés comme prévu et dans les conditions prévues par le fabricant.
La présente partie de la série des EN 746 couvre :
- la tuyauterie en aval du robinet de barrage à commande manuelle et y compris celui-ci,
- les équipements pour la génération des gaz d’atmosphère,
- les équipements supplémentaires pour l’utilisation des gaz d’atmosphère dans les TPE,
- les dispositifs de sécurité, et
- les prescriptions fonctionnelles pour le système de commande relatif à la sécurité
pour la génération et l'utilisation des gaz d’atmosphère protectrice et réactive.
Elle s’applique à la fourniture en gaz d’atmosphère, en gaz source, en gaz inerte et en liquides de procédé aux TPE et à leur évacuation des TPE, confinés aux équipements intégrés dans les TPE.
La présente partie de la série des EN 746 détaille également les phénomènes dangereux significatifs anticipés associés aux systèmes à gaz d'atmosphère et à leur utilisation dans les TPE et spécifie les mesures préventives appropriées pour la réduction ou l'élimination de ces phénomènes dangereux.
Le phénomène dangereux engendré par la pression dans la tuyauterie et les composants couverts par la présente norme correspond à la relation pression maximale/dimensions de groupe 1 telle que décrite dans l'Annexe C.
La présente partie de la série des EN 746 :
- spécifie les prescriptions à satisfaire pour assurer la sécurité des personnes et des biens pendant l'installation, la mise en service, la mise en marche, l’utilisation, l’arrêt et la maintenance,
- ne couvre pas les risques pertinents impliqués dans le système de conduits de fumées lorsqu'il n’est pas considéré comme une partie de TPE,
- ne s'applique pas à l'alimentation en électricité en amont des sectionnements principaux des TPE,
- ne s’applique pas aux TPE pour les dispositifs semi-conducteurs,
- ne s’applique pas aux TPE avec atmosphère, tels que l’air et les gaz de combustion provenant d’une combustion sur-stœchiométrique,
- ne couvre pas la mise hors service des TPE,
- ne couvre pas les fours sous vide,
- ne couvre pas les hauts-fourneaux, les convertisseurs (dans les aciéries), les chaudières et les équipements non couverts par l’EN ISO 12100:2010.
- ne traite pas du phénomène dangereux engendré par le bruit qui est couvert dans l’EN 746-1:1997+A1:2009,
- ne s’applique pas à la génération et à l'utilisation des gaz d’atmosphère dans les TPE et lesinstallations associées qui sont fabriquées avant la date de sa publication, et
- donne les prescriptions nécessaires pour les informations pour l’utilisation.
Un TPE conçu conformément à la présente partie de la série des EN 746 ne crée aucune atmosphère potentiellement explosible dans la zone entourant le TPE et n’est pas conçu pour être situé dans une zone avec une atmosphère potentiellement explosible ou dangereuse.
La présente partie de la série EN 746 traite des phénomènes dangereux significatifs qui sont décrits dans l'Annexe A.
Un tableau des gaz d'atmosphère protectrice et réactive types est donné dans l’Annexe B.
Industrijska termoprocesna oprema - 3. del: Varnostne zahteve za pridobivanje in uporabo atmosferskih plinov
Ta del skupine standardov EN 746 določa varnostne zahteve za proizvodnjo in uporabo zaščitnih in reaktivnih atmosferskih plinov, ki so del industrijske opreme za termoprocesiranje (TPE).
OPOMBA: Splošne varnostne zahteve, ki so skupne za opremo za termoprocesiranje, so navedene v standardu EN 746 1 (glej Uvod).
Ta del skupine standardov EN 746 obravnava večje nevarnosti, nevarne situacije in dogodke v povezavi s pridobivanjem ter uporabo zaščitnih in reaktivnih atmosferskih plinov, ki nastanejo pri termokemičnih reakcijah (in njihovo uporabo v opremi za termoprocesiranje) in so del te opreme, kot je navedeno v točkah 4 in 5, če se uporabljajo v skladu s predvidenim namenom in pod pogoji, ki jih je predvidel proizvajalec.
Ta del skupine standardov EN 746 zajema:
– cevovod za ročnim zapornim ventilom in vključno z njim,
– opremo za pridobivanje atmosferskih plinov,
– dodatno opremo za uporabo atmosferskih plinov pri termoprocesiranju,
– varnostne naprave in
– funkcionalne zahteve za varnostni nadzorni sistem
pri pridobivanju ter uporabi zaščitnih in reaktivnih atmosferskih plinov.
Uporablja se za dobavo atmosferskega plina, izhodnega plina, inertnega plina in procesnih tekočin v opremo za termoprocesiranje oziroma iz nje, omejenega na opremo, vgrajeno v opremo za termoprocesiranje.
Ta del skupine standardov EN 746 podrobno opisuje tudi pričakovane večje nevarnosti, povezane s sistemi atmosferskih plinov in njihovo uporabo v opremi za termoprocesiranje, ter določa ustrezne preventivne ukrepe za zmanjšanje ali odpravo teh nevarnosti.
Nevarnost tlaka v ceveh in komponentah, ki jih zajema ta standard, je znotraj razmerja največjega tlaka/velikosti skupine I, kot je opisano v dodatku C.
Ta del skupine standardov EN 746:
– določa zahteve, ki jih je treba izpolniti za zagotovitev varnosti oseb in premoženja med montažo, pripravo, zagonom, delovanjem, zaustavitvijo in vzdrževanjem,
– ne zajema ustreznih tveganj, povezanih s sistemom kanalov za dimne pline, če niso del opreme za termoprocesiranje,
– se ne uporablja za oskrbo z napajanjem pred glavnim električnim stikalom opreme za termoprocesiranje,
– se ne uporablja za opremo za termoprocesiranje za polprevodniške naprave,
– se ne uporablja za opremo za termoprocesiranje z atmosfero, kot sta zrak in dimni plini zaradi prekomerno stehiometričnega zgorevanja,
– ne zajema razgradnje opreme za termoprocesiranje,
– ne zajema vakuumskih peči,
– ne obravnava nevarnosti hrupa, ki je zajet v standardu EN 746-1:2019,
– se ne uporablja za pridobivanje in uporabo atmosferskega plina v opremi za termoprocesiranje ter povezanih obratih, izdelanih pred datumom objave standarda, in
– podaja potrebne zahteve za informacije za uporabo.
Oprema za termoprocesiranje, zasnovana v skladu s tem delom skupine standardov EN 746, ne ustvarja potencialno eksplozivne atmosfere v okolici te opreme, in ni zasnovana tako, da bi jo bilo mogoče namestiti v območju s potencialno eksplozivno ali nevarno atmosfero.
Preglednica tipičnih zaščitnih in reaktivnih plinov je podana v dodatku B.
General Information
- Status
- Published
- Publication Date
- 14-Dec-2021
- Withdrawal Date
- 29-Jun-2022
- Technical Committee
- CEN/TC 186 - Industrial thermoprocessing - Safety
- Drafting Committee
- CEN/TC 186/WG 3 - Controlled atmospheres - Safety requirements
- Current Stage
- 6060 - Definitive text made available (DAV) - Publishing
- Start Date
- 15-Dec-2021
- Due Date
- 24-Oct-2021
- Completion Date
- 15-Dec-2021
Relations
- Effective Date
- 08-Aug-2018
Overview
EN 746-3:2021 - a CEN (European) standard - specifies safety requirements for the generation and use of protective and reactive atmosphere gases that are integrated into industrial thermoprocessing equipment (TPE). It addresses significant hazards, hazardous situations and events arising from thermochemical generation and use of atmosphere gases, and sets minimum safety measures for design, installation, commissioning, operation, shutdown and maintenance of TPE gas systems.
Key scope notes:
- Applies to pipework downstream of and including the manual isolating valve, atmosphere-gas generators, ancillary equipment, safety devices and safety-related control functions that are part of the TPE.
- Covers supply and removal of atmosphere gas, source gas, inert gas and process liquids integrated in the TPE.
- Excludes utility supply upstream of TPE main disconnects, semiconductor TPE, vacuum furnaces, blast furnaces, boilers, certain flue systems, and equipment manufactured before publication.
Key topics and technical requirements
EN 746-3:2021 focuses on practical, safety-driven technical requirements, including:
- Pipework and connections: material selection, marking, tightness, purge/drain provisions and condensate management for downstream piping.
- Atmosphere gas generation: requirements for endothermic/exothermic generators, burners, reaction mixtures and post-treatment.
- Safety devices and controls: mandatory safety devices, flame detection, pressure relief, flame arrestors and isolation of safety devices.
- Functional safety: specification of safety-related control system performance (SIL/PL considerations and verification approaches are supported by informative annexes).
- Change-of-atmosphere procedures: purge strategies (purge gas, self‑ignition, burning, evacuation) and interface requirements to exhaust systems.
- Hazard analysis and verification: identification of significant hazards (Annex A), typical atmosphere gases (Annex B), allowed maximum pressure (Annex C) and verification/commissioning checks.
- Information for use: marking, user manuals, commissioning, inspection, maintenance and operating instructions.
Applications and users
This standard is essential for stakeholders involved in industrial heat‑treating and thermoprocessing where controlled atmospheres are used:
- Furnace and TPE manufacturers and system integrators
- Plant engineers, maintenance teams and safety managers
- Health & safety authorities and machinery conformity assessors
- Contractors and service providers for installation, commissioning and retrofit work
Typical industries: heat treatment, metallurgy, brazing/soldering, sintering, surface engineering and other processes that rely on protective or reactive atmosphere gases.
Related standards
- EN 746-1:1997+A1:2009 - general safety requirements for TPE (complements EN 746-3)
- ISO 13577-3:2016 - related international guidance (EN 746-3:2021 is based on this)
- ISO 13577-4:2014 - protective systems for TPE
- EN ISO 12100:2010 - general machine safety principles
- Annex ZA of EN 746-3 maps applicability to EU Machinery Directive 2006/42/EC.
Keywords: EN 746-3:2021, industrial thermoprocessing equipment, atmosphere gases safety, protective gases, reactive gases, TPE safety, CEN standard, gas generator safety, purge procedures, SIL PL.
Frequently Asked Questions
EN 746-3:2021 is a standard published by the European Committee for Standardization (CEN). Its full title is "Industrial thermoprocessing equipment - Part 3: Safety requirements for the generation and use of atmosphere gases". This standard covers: This part of the EN 746 series specifies safety requirements for generation and use of protective and reactive atmosphere gases that are part of industrial thermo-processing equipment (TPE). The general safety requirements common to TPE are provided in EN 746 1:1997+A1:2009 (see Introduction). This part of the EN 746 series deals with significant hazards, hazardous situations and events relevant to the generation and use of protective and reactive atmosphere gases created by thermochemical reactions and their use in TPE that are part of TPE as listed in Clause 4 and Clause 5, when used as intended and under the conditions foreseen by the manufacturer. This part of the EN 746 series covers: - pipework downstream of and including the manual isolating valve, - equipment for the generation of atmosphere gases, - additional equipment for the use of atmosphere gases in TPE, - safety devices, and - functional requirements for safety related control system for the generation and use of protective and reactive atmosphere gases. It applies to the supply of atmosphere gas, source gas, inert gas and process liquids to TPE and their removal from TPE, confined to equipment integrated in the TPE. This part of the EN 746 series also details the anticipated significant hazards associated with atmosphere gas systems and their use in TPE and specifies the appropriate preventative measures for the reduction or elimination of these hazards. The pressure hazard of the piping and components covered by this standard is within the maximum pressure/size relationship of group 1 as described in Annex C. This part of the EN 746 series: - specifies the requirements to be met to ensure the safety of persons and property during installation, commissioning, start up, operation, shutdown and maintenance, - does not cover the relevant risks involved in the flue gas ducting system when it is not considered a part of TPE, - is not applicable to utility supply upstream of the TPE main disconnects, - does not apply to TPE for semi-conductor devices, - does not apply to TPE with atmosphere, such as air and flue gas from an over stoichiometric combustion, - does not cover the decommissioning of the TPE, - does not cover vacuum furnaces, - does not cover blast furnaces, converters (in steel plants), boilers and equipment not covered under EN ISO 12100:2010. - does not deal with the hazard of noise which is covered in EN 746 1:1997+A1:2009, - is not applicable to generation and use of atmosphere gas in TPE and associated plant which is manufactured before the date of its publication, and - gives the necessary requirements for the information for use. A TPE designed according to this part of EN 746 series does not create any potentially explosive atmosphere in the area around the TPE and is not designed to be located in an area with a potentially explosive or hazardous atmosphere. This part of the EN 746 series deals with significant hazards which are described in Annex A. A table of typical protective and reactive gases is given in Annex B.
This part of the EN 746 series specifies safety requirements for generation and use of protective and reactive atmosphere gases that are part of industrial thermo-processing equipment (TPE). The general safety requirements common to TPE are provided in EN 746 1:1997+A1:2009 (see Introduction). This part of the EN 746 series deals with significant hazards, hazardous situations and events relevant to the generation and use of protective and reactive atmosphere gases created by thermochemical reactions and their use in TPE that are part of TPE as listed in Clause 4 and Clause 5, when used as intended and under the conditions foreseen by the manufacturer. This part of the EN 746 series covers: - pipework downstream of and including the manual isolating valve, - equipment for the generation of atmosphere gases, - additional equipment for the use of atmosphere gases in TPE, - safety devices, and - functional requirements for safety related control system for the generation and use of protective and reactive atmosphere gases. It applies to the supply of atmosphere gas, source gas, inert gas and process liquids to TPE and their removal from TPE, confined to equipment integrated in the TPE. This part of the EN 746 series also details the anticipated significant hazards associated with atmosphere gas systems and their use in TPE and specifies the appropriate preventative measures for the reduction or elimination of these hazards. The pressure hazard of the piping and components covered by this standard is within the maximum pressure/size relationship of group 1 as described in Annex C. This part of the EN 746 series: - specifies the requirements to be met to ensure the safety of persons and property during installation, commissioning, start up, operation, shutdown and maintenance, - does not cover the relevant risks involved in the flue gas ducting system when it is not considered a part of TPE, - is not applicable to utility supply upstream of the TPE main disconnects, - does not apply to TPE for semi-conductor devices, - does not apply to TPE with atmosphere, such as air and flue gas from an over stoichiometric combustion, - does not cover the decommissioning of the TPE, - does not cover vacuum furnaces, - does not cover blast furnaces, converters (in steel plants), boilers and equipment not covered under EN ISO 12100:2010. - does not deal with the hazard of noise which is covered in EN 746 1:1997+A1:2009, - is not applicable to generation and use of atmosphere gas in TPE and associated plant which is manufactured before the date of its publication, and - gives the necessary requirements for the information for use. A TPE designed according to this part of EN 746 series does not create any potentially explosive atmosphere in the area around the TPE and is not designed to be located in an area with a potentially explosive or hazardous atmosphere. This part of the EN 746 series deals with significant hazards which are described in Annex A. A table of typical protective and reactive gases is given in Annex B.
EN 746-3:2021 is classified under the following ICS (International Classification for Standards) categories: 25.180.01 - Industrial furnaces in general. The ICS classification helps identify the subject area and facilitates finding related standards.
EN 746-3:2021 has the following relationships with other standards: It is inter standard links to EN 746-3:1997+A1:2009. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
EN 746-3:2021 is associated with the following European legislation: EU Directives/Regulations: 2006/42/EC; Standardization Mandates: M/396. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
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Standards Content (Sample)
SLOVENSKI STANDARD
01-marec-2022
Nadomešča:
SIST EN 746-3:2000+A1:2009
Industrijska termoprocesna oprema - 3. del: Varnostne zahteve za pridobivanje in
uporabo atmosferskih plinov
Industrial thermoprocessing equipment - Part 3: Safety requirements for the generation
and use of atmosphere gases
Industrielle Thermoprozessanlagen - Teil 3: Sicherheitsanforderungen für die Erzeugung
und Anwendung von Schutz- und Reaktionsgasen
Équipements thermiques industriels - Partie 3 : Prescription de sécurité pour la
génération et l'utilisation des gaz d'atmosphère
Ta slovenski standard je istoveten z: EN 746-3:2021
ICS:
25.180.01 Industrijske peči na splošno Industrial furnaces in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN 746-3
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2021
EUROPÄISCHE NORM
ICS 25.180.01 Supersedes EN 746-3:1997+A1:2009
English Version
Industrial thermoprocessing equipment - Part 3: Safety
requirements for the generation and use of atmosphere
gases
Équipements thermiques industriels - Partie 3 : Industrielle Thermoprozessanlagen - Teil 3:
Prescriptions de sécurité pour la génération et Sicherheitsanforderungen für die Erzeugung und
l'utilisation des gaz d'atmosphère Anwendung von Schutz- und Reaktionsgasen
This European Standard was approved by CEN on 24 October 2021.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 746-3:2021 E
worldwide for CEN national Members.
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 7
2 Normative references . 8
3 Terms and definitions .10
4 Safety requirements and/or protective/risk reduction measures .13
4.1 General .13
4.2 Pipework .13
4.2.1 General .13
4.2.2 Connections .14
4.2.3 Unconnected pipework .15
4.2.4 Galvanic cells .15
4.2.5 Flexible tubing and couplings .15
4.2.6 Marking of pipework .15
4.2.7 Soundness/Tightness .15
4.2.8 Condensate drains .16
4.2.9 Purge points .16
4.2.10 Blow-off and breather pipes or conduits .16
4.2.11 Pressure relief devices and flame arrestors on pipework .16
4.2.12 Pressure oscillations .16
4.2.13 Combustible gas by-pass .17
4.2.14 Isolation of required safety devices .17
4.2.15 Vents .17
4.3 Required safety devices .17
4.3.1 Atmosphere gas control equipment .17
4.3.2 Other safety devices .21
4.4 Requirements for the use of atmosphere gases .22
4.4.1 Prevention of potential ignitable atmospheres .22
4.4.2 Monitoring of TPE doors movements .23
4.4.3 Supervision of the means of ignition at the point of combustible atmosphere gas
discharge .23
4.4.4 Emergency safety purge .23
4.5 Change of atmosphere .24
4.5.1 General .24
4.5.2 Purge with purge gas .24
4.5.3 Purge with self-ignition .25
4.5.4 Change of atmosphere by burning .25
4.5.5 Purge by evacuation .26
4.6 Interfaces to exhaust systems for combustible or toxic atmosphere gases .26
4.6.1 Exhaust of burned gases .26
4.6.2 Gathering of gases without burning and a closed system .27
5 Additional requirements for the generation of atmosphere gases .27
5.1 General .27
5.2 Gas and process liquid supplies .28
5.2.1 Air supplies .28
5.2.2 Reaction mixture supplies. 28
5.2.3 Generated atmosphere gas distribution . 28
5.3 Flame detection . 28
5.4 Burners generating exothermic gases . 29
5.5 Special requirements for different types of generator . 29
5.5.1 Requirements for endothermic generators . 29
5.5.2 Requirements for exothermic generators . 29
5.6 Post-treatment of generated atmosphere gases . 30
6 Verification of the safety requirements and/or measures . 30
7 Information for use . 34
7.1 General . 34
7.2 Marking . 34
7.3 Instruction handbook . 35
7.3.1 General . 35
7.3.2 Description of equipment . 35
7.3.3 Inspection procedures . 35
7.3.4 Commissioning, start-up and operating procedures . 36
7.3.5 Shutdown procedures . 37
7.3.6 Maintenance procedures . 37
7.3.7 Documentation . 38
Annex A (informative) List of significant hazards . 39
Annex B (informative) Typical protective and reactive atmosphere gases . 41
Annex C (normative) Allowed maximum pressure . 43
Annex D (informative) Principle procedures for the change of atmosphere. 48
Annex E (informative) Examples for the determination of safety integrity level SIL and
performance level PL using the risk graph method . 49
Annex F (informative) Basic configuration of piping system of TPE using protective or
reactive atmosphere gases . 61
Annex G (informative) Overview of the terms defined in ISO 13574 (Vocabulary) . 63
Annex ZA (informative) Relationship between this European Standard and the essential
requirements of Directive 2006/42/EC aimed to be covered . 70
Bibliography . 72
European foreword
This document (EN 746-3:2021) has been prepared by Technical Committee CEN/TC 186 “Industrial
thermoprocessing - Safety”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by June 2022, and conflicting national standards shall be
withdrawn at the latest by June 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 746-3:1997+A1:2009.
Based on EN 746-3:1997+A1:2009, ISO 13577-3 was developed in 2016. This ISO standard differs
considerably from the original EN 746-3:1997+A1:2009. The contents of this completely renewed
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association, and supports essential requirements of EU
Directive(s) / Regulation(s).
For relationship with EU Directive(s) / Regulation(s), see informative Annex ZA, which is an integral part
of this document.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
Introduction
This document is a type-C standard as stated in EN ISO 12100:2010.
This document is of relevance, in particular, for the following stakeholder groups representing the market
players with regard to machinery safety:
— machine manufacturers (small, medium and large enterprises);
— health and safety bodies (regulators, accident prevention organizations, market surveillance etc.).
Others can be affected by the level of machinery safety achieved with the means of the document by the
above-mentioned stakeholder groups:
— machine users/employers (small, medium and large enterprises);
— machine users/employees (e.g. trade unions, organizations for people with special needs);
— service providers, e.g. for maintenance (small, medium and large enterprises);
— consumers (in case of machinery intended for use by consumers).
The above-mentioned stakeholder groups have been given the possibility to participate at the drafting
process of this document.
The machinery concerned and the extent to which hazards, hazardous situations or hazardous events are
covered are indicated in the Scope of this document.
When requirements of this type-C standard are different from those which are stated in type-A or type-B
standards, the requirements of this type-C standard take precedence over the requirements of the other
standards for machines that have been designed and built according to the requirements of this type-C
standard.
Industrial furnaces and associated thermo-processing equipment (TPE) generally consists of the
following components:
— processing chamber (e.g. steel construction with lining and/or refractory);
— heating systems;
— protective system;
— control and instrumentation system/operator-control level.
EN 746-1:1997+A1:2009 provides the general safety requirements common to TPE. This part of the
EN 746 series details in addition specific safety requirements for generation and use of protective and
reactive atmosphere gases that are part of TPE as listed in the scope. These requirements establish the
minimum acceptable requirements for safety functions required for various processes. Where a process
is not part of the TPE, the requirements do not apply.
For example, the minimum requirements for the opening and closing of doors on a TPE does not apply to
TPE that do not have doors in their design.
NOTE As stated in its scope, EN 746-1:1997+A1:2009 does not cover blast furnaces, converters (in steel plants),
boilers and equipment not covered under EN ISO 12100.
The requirements of protective system are specified in ISO 13577-4:2014.
If a general provision of EN 746-1:1997+A1:2009 counters provisions in this part of the EN 746 series,
the provisions of this part of EN 746 take precedence.
It is assumed that TPE will only be operated and maintained by trained personnel.
1 Scope
This part of the EN 746 series specifies safety requirements for generation and use of protective and
reactive atmosphere gases that are part of industrial thermo-processing equipment (TPE).
The general safety requirements common to TPE are provided in EN 746-1:1997+A1:2009 (see
Introduction).
This part of the EN 746 series deals with significant hazards, hazardous situations and events relevant to
the generation and use of protective and reactive atmosphere gases created by thermochemical reactions
and their use in TPE that are part of TPE as listed in Clause 4 and Clause 5, when used as intended and
under the conditions foreseen by the manufacturer.
This part of the EN 746 series covers:
— pipework downstream of and including the manual isolating valve,
— equipment for the generation of atmosphere gases,
— additional equipment for the use of atmosphere gases in TPE,
— safety devices, and
— functional requirements for safety related control system
for the generation and use of protective and reactive atmosphere gases.
It applies to the supply of atmosphere gas, source gas, inert gas and process liquids to TPE and their
removal from TPE, confined to equipment integrated in the TPE.
This part of the EN 746 series also details the anticipated significant hazards associated with atmosphere
gas systems and their use in TPE and specifies the appropriate preventative measures for the reduction
or elimination of these hazards.
The pressure hazard of the piping and components covered by this standard is within the maximum
pressure/size relationship of group 1 as described in Annex C.
This part of the EN 746 series:
— specifies the requirements to be met to ensure the safety of persons and property during installation,
commissioning, start up, operation, shutdown and maintenance,
— does not cover the relevant risks involved in the flue gas ducting system when it is not considered a
part of TPE,
— is not applicable to utility supply upstream of the TPE main disconnects,
— does not apply to TPE for semi-conductor devices,
— does not apply to TPE with atmosphere, such as air and flue gas from an over stoichiometric
combustion,
— does not cover the decommissioning of the TPE,
— does not cover vacuum furnaces,
— does not cover blast furnaces, converters (in steel plants), boilers and equipment not covered under
EN ISO 12100:2010.
— does not deal with the hazard of noise which is covered in EN 746-1:1997+A1:2009,
— is not applicable to generation and use of atmosphere gas in TPE and associated plant which is
manufactured before the date of its publication, and
— gives the necessary requirements for the information for use.
A TPE designed according to this part of EN 746 series does not create any potentially explosive
atmosphere in the area around the TPE and is not designed to be located in an area with a potentially
explosive or hazardous atmosphere.
This part of the EN 746 series deals with significant hazards which are described in Annex A.
A table of typical protective and reactive gases is given in Annex B.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 7-1:1994, Pipe threads where pressure-tight joints are made on the threads — Part 1: Dimensions,
tolerances and designation
ISO 49:1994, Malleable cast iron fittings threaded to ISO 7-1
EN 88-1:2011+A1:2016, Pressure regulators and associated safety devices for gas appliances - Part 1:
Pressure regulators for inlet pressures up to and including 50 kPa
EN 88-2:2007, Pressure regulators and associated safety devices for gas appliances - Part 2: Pressure
regulators for inlet pressures above 500 mbar up to and including 5 bar
EN 161:2011+A3:2013, Automatic shut-off valves for gas burners and gas appliances
EN ISO 228-1:2003, Pipe threads where pressure-tight joints are not made on the threads - Part 1:
Dimensions, tolerances and designation (ISO 228-1:2000)
EN 331:2015, Manually operated ball valves and closed bottom taper plug valves for gas installations for
buildings
EN 334:2019, Gas pressure regulators for inlet pressure up to 10 MPa (100 bar)
EN 746-1:1997+A1:2009, Industrial thermoprocessing equipment - Part 1: Common safety requirements
for industrial thermoprocessing equipment
EN 746-2:2010, Industrial thermoprocessing equipment - Part 2: Safety requirements for combustion and
fuel handling systems
EN 751-1:1996, Sealing materials for metallic threaded joints in contact with 1st, 2nd and 3rd family gases
and hot water - Part 1: Anaerobic jointing compounds
EN 751-2:1996, Sealing materials for metallic threaded joints in contact with 1st, 2nd and 3rd family gases
and hot water - Part 2: Non-hardening jointing compounds
EN 1643:2014, Safety and control devices for gas burners and gas burning appliances - Valve proving
systems for automatic shut-off valves
EN 1854:2010, Pressure sensing devices for gas burners and gas burning appliances
EN 10241:2000, Steel threaded pipe fittings
EN 10242:1994, Threaded pipe fittings in malleable cast iron
EN ISO 5817:2014, Welding - Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding
excluded) - Quality levels for imperfections (ISO 5817:2014)
ISO 7005-1:2011, Pipe flanges — Part 1: Steel flanges for industrial and general service piping systems
ISO 7005-2:1988, Metallic flanges — Part 2: Cast iron flanges
EN ISO 8434-1:2018, Metallic tube connections for fluid power and general use - Part 1: 24° cone connectors
(ISO 8434-1:2018, Corrected version 2018-10)
ISO 8434-2:2007, Metallic tube connections for fluid power and general use — Part 2: 37 degree flared
connectors
ISO 8434-3:2005, Metallic tube connections for fluid power and general use — Part 3: O-ring face seal
connectors
EN ISO 10352:2020, Fibre-reinforced plastics - Moulding compounds and prepregs - Determination of mass
per unit area and fibre mass per unit area (ISO 10352:2020)
EN ISO 12100:2010, Safety of machinery - General principles for design - Risk assessment and risk reduction
(ISO 12100:2010)
EN 14382:2019, Gas safety shut-off devices for inlet pressure up to 10 MPa (100 bar)
ISO 13574:2015, Industrial furnaces and associated processing equipment — Vocabulary
ISO 13577-4:2014, Industrial furnace and associated processing equipment — Safety — Part 4: Protective
systems
EN ISO 13849-1:2015, Safety of machinery - Safety-related parts of control systems - Part 1: General
principles for design (ISO 13849-1:2015)
EN ISO 19879:2021, Metallic tube connections for fluid power and general use - Test methods for hydraulic
fluid power connections (ISO 19879:2021)
EN 60204-1:2018, Safety of machinery - Electrical equipment of machines - Part 1: General requirements
EN 60730-2-5:2015, Automatic electrical controls - Part 2-5: Particular requirements for automatic
electrical burner control systems
EN 61508-1:2010, Functional safety of electrical/electronic/programmable electronic safety-related
systems - Part 1: General requirements
This document is impacted by the amendments EN 10242:1994/A1:1999 and EN 10242:1994/A2:2003.
EN 61508-2:2010, Functional safety of electrical/electronic/programmable electronic safety-related
systems - Part 2: Requirements for electrical/electronic/programmable electronic safety-related systems
EN 61508-3:2010, Functional safety of electrical/electronic/programmable electronic safety-related
systems - Part 3: Software requirements
EN 61508-4:2010, Functional safety of electrical/electronic/programmable electronic safety-related
systems - Part 4: Definitions and abbreviations
EN 61508-5:2010, Functional safety of electrical/electronic/programmable electronic safety-related
systems - Part 5: Examples of methods for the determination of safety integrity levels
EN 61508-6:2010, Functional safety of electrical/electronic/programmable electronic safety-related
systems - Part 6: Guidelines on the application of IEC 61508-2 and IEC 61508-3
EN 61508-7:2010, Functional safety of electrical/electronic/programmable electronic safety-related
systems - Part 7: Overview of techniques and measures
EN 61511-1:2017, Functional safety - Safety instrumented systems for the process industry sector - Part 1:
Framework, definitions, system, hardware and application programming Requirements
EN 61511-1:2017/A1:2017, Functional safety - Safety instrumented systems for the process industry sector
- Part 1: Framework, definitions, system, hardware and application programming Requirements
EN 61511-2:2017, Functional safety - Safety instrumented systems for the process industry sector - Part 2:
Guidelines for the application of IEC 61511-1
EN 61511-3:2017, Functional safety - Safety instrumented systems for the process industry sector - Part 3:
Guidance for the determination of the required safety integrity levels
EN 62061:2005, Safety of machinery — Functional safety of safety-related electrical, electronic and
programmable electronic control systems (IEC 62061:2005)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13574:2015 and the following
apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
NOTE See Annex G for the list of terms specified in ISO 13574:2015.
This document is impacted by the amendments EN 62061:2005/A1:2013 and EN 62061:2005/A2:2015.
3.1
safety shutdown
function that takes the TPE out of operation and brings it in a defined safe state
Note 1 to entry: The definition is different from safety shutdown according ISO 13574:2015, 2.166 which is
applicable to ISO 13577-2:2014 and EN 746-2:2010.
3.2
flame failure
loss of flame from the normally detected position by any cause other than the action of de-energising the
automatic shut-off valves system
Note 1 to entry: The term is used in ISO 13577-2 and EN 746-2:2010.
3.3
gas generator
equipment that converts or modifies a fluid or a mixture of fluids (gaseous or liquid) into a gas which can
be utilized as the controlled atmosphere within the thermo-processing equipment
3.4
endothermic generator
gas generator that produces atmosphere gas by an endothermic reaction
3.5
exothermic generator
gas generator that produces atmosphere gas by an exothermic reaction
3.6
combustible atmosphere gas
any gas mixture that is capable of forming ignitable mixtures with air or oxygen under the conditions of
temperature and pressure used in the process, according to the lower explosion level (LEL) of the actual
gas mixture
3.7
inert gas
non-combustible gas which will not support combustion and does not react at all
Note 1 to entry: Nitrogen, helium and argon are typical inert gases.
3.8
purge gas
gas which can be used to purge a TPE
Note 1 to entry: A purge gas can safely be used for pre- and post-purging of cold and hot enclosures of TPE.
Note 2 to entry: Typically, purge gases are nitrogen, argon, helium and lean exothermic gas.
3.9
safety purge volume
volume of purge gas needed to displace either air or a combustible gas from a furnace chamber/enclosure
to achieve a volume fraction of 1 % or less oxygen and/or a non-combustible atmosphere gas and/or
25 % of the lower flammability limit
Note 1 to entry: Typically, this will be a volume equal to five times the volume of the thermo-processing
equipment chamber to be purged, if the purging gas is an inert gas.
Note 2 to entry: Non-combustible atmosphere gas as defined in 3.6.
3.10
multi-turn valve
valve which, in order to operate from the fully closed to the fully open position, requires a number of
revolutions of the operating key or handwheel to be completed
3.11
safe ignition temperature
minimum temperature at which spontaneous, safe auto-ignition of combustible gases occurs
Note 1 to entry: The safe ignition temperature has been established at 750 °C.
3.12
toxic atmosphere gas
gas which, in addition to having asphyxiating properties, also acts as a poison
3.13
internal gas generator
gas generator integrated into or directly connected to a TPE
3.14
gas control equipment
centralized mounting of components such as: pipework, safety components, pressure and flow
accessories, assembled in a functional unit
3.15
atmosphere gas
gas that is supplied into or formed in TPE in accordance with a defined specification for thermo-
processes
Note 1 to entry: Atmosphere gas is used to react with the material processed or to avoid a reaction with the
material processed.
3.16
process liquids
liquids that are supplied to TPE to create an atmosphere gas
4 Safety requirements and/or protective/risk reduction measures
4.1 General
Protective and reactive atmosphere gases in TPE are used to react with the material processed or to avoid
a reaction with the material processed. Protective and reactive atmosphere gases are fed into the TPE at
determined points and are discharged out of the TPE at determined points too.
Protective and reactive atmosphere gases shall only be used in TPE that has been constructed to avoid
leakage of the protective and reactive atmosphere gases out of the TPE or ambient air into the TPE.
Machinery shall comply with the safety requirements and/or protective/risk reduction measures of this
clause. In addition, the machine shall be designed according to the principles of EN ISO 12100:2010 for
relevant but not significant hazards which are not dealt with by this document.
Electrical circuits shall be designed in accordance with EN 60204-1:2018.
A risk assessment according to EN ISO 12100:2010 shall be carried out. Safety functions shall be designed
in accordance with ISO 13577-4:2014, where the use of standards for functional safety EN 62061:2005,
EN ISO 13849-1:2015, EN 61511-1:2017, EN 61511-1:2017/A1:2017, EN 61511-2:2017,
EN 61511-3:2017, EN 61508-1:2010, EN 61508-2:2010, EN 61508-3:2010, EN 61508-4:2010,
EN 61508-5:2010, EN 61508-6:2010 and EN 61508-7:2010 is included. Annex E provides information
for the determination of the SIL or PL of safety-related functions covered in this part of EN 746 series.
CAUTION — Toxic hazards for persons occur at lower concentrations than hazards by generation of
ignitable atmospheres.
NOTE Requirements for maximum allowable concentrations values are identified by national regulations.
The choice of materials shall consider the specific properties of the engaged gas and liquids (e.g. non-
ferrous metals are not suitable for NH and natural rubber is not suitable for natural gas).
For basic configuration of piping system of TPE using atmosphere gas, see Annex F.
4.2 Pipework
4.2.1 General
The pipework design shall take into account the composition and properties (e.g. pressure, temperature,
corrosiveness, specific gravity, velocity) of gas and liquids and the need for venting, purging and cleaning.
Due to durability, steel is the preferred material for pipes and components but where appropriate and
the same safety levels can be achieved, then other materials may be utilized. Such materials and
conditions of service shall be specified in the instruction handbook.
Oscillations which may cause damage to pipework, components or safety systems shall be prevented (by
firm anchoring and/or use of flexible couplings).
Pipework shall be arranged so that safe isolation of atmosphere gas and process liquids to all parts of the
TPE can be guaranteed
NOTE An example is shown in Figure F.1.
The isolation method shall be clearly identified (e.g. by removable spool piece painted in red, blanking
plate), and provision for blanking opened pipes shall be provided secured against loss (e.g. by an attached
chain).
For steel pipes, compliance with EN ISO 3183:2019, EN 13480-2:2017, or EN 10255 is considered
appropriate. For copper pipes, compliance with EN 1057 is considered appropriate. Copper soldering
connections shall not be used for gas carrying parts where the temperature could exceed 100 °C .
Threaded pipe fittings shall comply with EN 10241:2000 or EN 10242:1994 .
Use of brass or other copper alloy components in contact with ammonia or dissociated ammonia is not
allowed.
4.2.2 Connections
Pipework connections shall be metallic and shall be of threaded, compression, press fittings, flanged,
welded or brazed types. The number of connections shall be kept to a minimum.
Threaded connections shall be used only for the following pressure/diameter combinations:
— pressures up to 15 kPa and diameters up to DN 100;
— pressures up to 200 kPa and diameters up to DN 50;
— pressures up to 500 kPa and diameters up to DN 25;
— pressures up to 1 MPa and diameters up to DN 15.
For other combinations of pressures and diameters, connections shall be made by means of welded
flanges or welded joints. The number of connections shall be kept to a minimum.
For fittings according to ISO 49:1994, the following limitations shall be observed:
— fittings are class “A”;
— maximum allowed pressure is 50 kPa;
— for dimensions DN 25 or less, the maximum pressure is 500 kPa.
Where the equipment has a threaded connection, this thread shall comply with EN ISO 228-1:2003 or
ISO 7-1:1994, as appropriate. The use of threads complying with EN ISO 228-1:2003 is limited to
diameter up to DN 50. In the case of threads according to EN ISO 228-1:2003, the tightness shall be
ensured by a ring gasket. Hemp shall not be used in threaded connections unless reinforced with a
suitable sealant.
Sealants for threads according to ISO 7-1:1994 shall comply with EN 751-1:1996 or EN 751-2:1996 as
appropriate.
Other threaded connections shall only be used providing they ensure tight connections and are suitably
identified.
The design of pipework shall be such as to avoid tensile loading of the joints.
Compression fittings shall comply with EN ISO 8434-1:2018, ISO 8434-2:2007 and ISO 8434-3:2005 or
EN ISO 19879:2021. They shall only be used for pressures up to 500 kPa and diameters up to 42 mm.
Where press fitting according to EN ISO 10352:2020 are used, they shall comply with the application
restrictions (e.g. temperature, vibration, gas, liquids).
Paragraph is not in the body text of ISO 13577-3.
Paragraph is not in the body text of ISO 13577-3.
Any pipe passing through an unventilated space shall not have a connection except welded joints.
Flanges shall comply with ISO 7005-1:2011 and ISO 7005-2:1988 as appropriate.
Arc welding shall comply with EN ISO 5817:2014, quality Level C.
4.2.3 Unconnected pipework
Any unconnected pipework shall be plugged, capped or blank flanged by means of metallic parts.
4.2.4 Galvanic cells
Corrosion in pipelines can be caused by the unintentional formation of a galvanic cell. Galvanic cells are
formed when materials with different electrochemical potentials are conductively connected (e.g. copper
screw in an aluminium sheet, stainless steel sheet screwed to steel sheet). This shall be taken into account
when selecting the material for piping.
4.2.5 Flexible tubing and couplings
Flexible tubing shall comply with the general requirements of 4.2.1, together with the following:
— shall be as short as practicable;
— shall be suitable for the maximum and minimum working temperatures;
— shall be suitable for a pressure 1,5 times the working operating pressure (with a minimum of 15 kPa),
at the maximum and minimum working temperatures;
— shall have a directly accessible, upstream manual shut-off valve;
— shall be mounted in such a way as to avoid distortion, whiplash and damage;
— shall have end fittings as integral parts of the tubing;
— shall be constructed from suitable material both metallic and/or non-metallic selected for the
application duty and not be easily damaged.
— Couplings for removable equipment shall ensure a gastight connection with the equipment
connected and disconnected.
4.2.6 Marking of pipework
Marking of pipework is required which enable medium and flow direction to be identified.
NOTE Identification of gas pipework is dealt with by national regulations.
4.2.7 Soundness/Tightness
The pipework shall be tight and shall be designed to withstand the internal pressure. After assembly, the
pipework shall be submitted to its test pressure and tested for tightness. The test pressure shall be not
less than 1,1 times the maximum working pressure at any point with a minimum of 5 kPa.
The external leakage rate shall not give rise to a dangerous condition, combustible and/or toxic, in the
foreseen circumstances of the equipment or installation. The frequency of testing to determine the
external leakage shall be specified in the instruction handbook.
3 3
NOTE It is generally agreed that an external leak rate of ~1 dm (n)/h for gas or 1 cm (n)/h for methanol will
not create a dangerous condition in typical ventilated industrial installation. The actual leak rate will depend upon
the volume, number of connections, test gas, number of valves and component parts contained.
The external leak rate test method shall take into account the volume, number of connections, test gas,
number of valves and component parts contained and temperature. Methods of testing shall include
spray bubble leak identification and/or pressure decay test.
4.2.8 Condensate drains
In cases where condensates can create a hazard, means shall be provided at the lowest points of the
equipment for draining any condensate. When moist gases are being used, condensate drains of a suitable
type shall be installed. Any condensate drains, siphons, etc. shall be in a position such that they can be
easily checked. Combustible condensates shall be collected by an appropriate means (e.g. piped into a
container).
Valves in condensate drains shall be suitably plugged, capped or blank flanged by metallic parts.
4.2.9 Purge points
Means shall be provided to facilitate purging of pipework during commissioning and maintenance to
prevent the forming of an ignitable atmosphere or build-up of flammable substances.
All distribution pipework and storage vessels for atmosphere gas shall be designed so that purging
procedures in accordance with 4.5 or in such a manner which excludes the simultaneous presence of
combustible gas/air mixtures and an ignition source can be done. Each purging point shall be provided
with a valve which shall either
— be fitted with a device to prevent unauthorised operation, or
— be blanked off during normal operation of the plant.
4.2.10 Blow-off and breather pipes or conduits
Where blow-off or breather pipes or conduits are fitted on regulators or relief valves or vent valves,
adequate means shall be provided to facilitate the venting of gas from the system to a safe discharge area.
In case breathers or blow-off pipes are gathered, the cross section of the collector shall be suitable to
evacuate simultaneously total flow rates of the exhaust sources.
4.2.11 Pressure relief devices and flame arrestors on pipework
For equipment designed for situations in which flash-backs can occur, flame arrestors and/or pressure
relief devices shall be fitted.
Pressure relief devices shall be designed to yield at a pressure below the design pressure of the pipework
and shall be positioned such that the discharge flow and the pressure relief device does not constitute a
risk to the equipment, personnel or third parties.
A flash-back shall trigger an alarm. The required measures after a flash-back shall be described in the
instruction handbook.
4.2.12 Pressure oscillations
The pipework shall be designed so as to avoid the possibility of gas velocities and pressure fluctuations
causing oscillations which could cause damage to pipework, components or safety systems (e.g. by
designing the correct sizing of pipes or using pressure regulators).
4.2.13 Combustible gas by-pass
By-passes shall not be fitted in parallel with any item of safety equipment.
This requirement shall not apply to valve proving systems (see EN 1643:2014 ) on automatic shut-off
valves.
4.2.14 Isolation of required safety devices
Required safety devices (e.g. pressure switche
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La norme EN 746-3:2021 fixe des exigences de sécurité essentielles pour la génération et l'utilisation de gaz d'ambiance protecteurs et réactifs dans le cadre des équipements de thermoprocessing industriel (TPE). Son champ d'application est bien défini, abordant les dangers significatifs associés aux gaz d'ambiance créés par des réactions thermo-chimiques, tout en clarifiant leur mise en œuvre dans les TPE conformément aux conditions prévues par les fabricants. Les points forts de cette norme résident dans sa capacité à définir des exigences claires pour la sécurité des personnes et des biens lors de l'installation, de la mise en service, du fonctionnement et de l'entretien des systèmes de gaz d'ambiance. En intégrant des exigences pour les équipements de génération de gaz d'atmosphère, les dispositifs de sécurité, ainsi que les systèmes de contrôle liés à la sécurité, cette norme garantit non seulement la protection contre les dangers associés aux gaz d'ambiance, mais propose également des mesures préventives adaptées pour les réduire ou les éliminer. Un autre aspect notable de la norme est sa spécificité concernant les équipements intégrés au TPE, limitant ainsi son application à la fourniture de gaz d'atmosphère dans des conditions de fonctionnement idéales. Elle exclut également certains systèmes et situations, comme les installations de chaudières, les fours à vide, et les systèmes de gaz d'échappement qui ne sont pas considérés comme faisant partie du TPE, permettant ainsi une concentration sur les équipements de TPE spécifiques. La norme EN 746-3:2021 se distingue également par sa capacité à traiter les approbations de conception qui ne créent pas d’atmosphère potentiellement explosive, garantissant un environnement de travail sûr et exempt de risques dus aux gaz d'ambiance. De plus, les annexes fournissent des précisions utiles, y compris une table des gaz protecteurs et réactifs typiques, qui enrichit la compréhension et l'application des exigences de sécurité. En somme, EN 746-3:2021 représente un document essentiel pour les professionnels du secteur, leur offrant une base solide pour développer des systèmes de thermoprocessing sûrs et conformes aux exigences réglementaires en matière de sécurité des gaz d'ambiance.
Die Norm EN 746-3:2021 stellt eine wesentliche Grundlage für die Sicherheit bei der Generation und Nutzung von Schutz- und Reaktionsatmosphärengasen in der industriellen Thermoprozessausrüstung (TPE) dar. Der Umfang dieser Norm ist klar definiert und umfasst spezifische Anforderungen, die für die Handhabung von gases, die durch thermochemische Reaktionen erzeugt werden, von Bedeutung sind. Ein zentraler Stärke dieser Norm ist ihre Fokussierung auf signifikante Gefahren sowie die gefährlichen Situationen, die beim Einsatz von Atmosphärengasen entstehen können. Sie behandelt nicht nur die sicherheitstechnischen Anforderungen an die Pipelines, das zusätzliche Equipment für die Nutzung von Atmosphärengasen und Sicherungsgeräte, sondern auch funktionale Anforderungen an sicherheitsrelevante Steuerungssysteme. Die Norm sorgt somit für eine umfassende Betrachtung der Sicherheitsaspekte, die beim Betrieb von TPE zu beachten sind. Ein weiterer wichtiger Aspekt der EN 746-3:2021 ist die Detaillierung der zu erwartenden signifikanten Gefahren, die mit Atmosphärengassystemen verbunden sind. Die Norm spezifiziert präventive Maßnahmen, die zur Reduzierung oder Eliminierung dieser Risiken erforderlich sind. Dabei wird auch der Druckgefahr in den behandelten Leitungen und Komponenten Rechnung getragen und entsprechende Grenzwerte gemäß den Anforderungen der Gruppe 1 in Anhang C aufgestellt. Die Relevanz der Norm ergibt sich aus ihrem gezielten Ansatz, Sicherheit während der Installation, Inbetriebnahme, Betrieb und Wartung von TPE zu gewährleisten. Trotz ihrer umfassenden Regelungen werden klar die Bereiche ausgeschlossen, die nicht unter die Norm fallen, wie zum Beispiel die Risiken im Zusammenhang mit Abgasleitungen, die nicht als Teil von TPE angesehen werden. Das schafft Klarheit für Anwender und stellt sicher, dass nur die relevanten Risiken adressiert werden. Zusammenfassend bietet die EN 746-3:2021 eine solide Grundlage, um die Sicherheit in der industriellen Thermoprozessausrüstung zu garantieren. Durch die systematische Behandlung von Risiken und die spezifizierten Sicherheitsanforderungen trägt sie maßgeblich zum Schutz von Personen und Eigentum bei und ist damit von großer Bedeutung für die Industrie, die mit Atmosphärengasen arbeitet.
SIST EN 746-3:2022の標準は、産業用熱処理機器における保護および反応性雰囲気ガスの生成と使用に関する安全要件を明確に定めています。この標準は、EN 746シリーズの重要な一部であり、熱化学反応によって生成されるガスが、どのように安全に取扱われるべきかを詳細に記述しています。 この標準の範囲は広く、温度処理機器(TPE)の構成要素である大気ガスの供給、源ガス、惰性ガスおよびプロセス液体の供給に加え、これに関連する土台となる設備や安全装置についても言及しています。具体的には、手動隔離弁を含む配管や、ガス生成設備、ガス使用のための追加機器、そして安全関連の制御システムの機能要件が含まれます。このような詳細な要件が示されているため、特に産業界において、作業者及び設備の安全性を高めることに貢献しています。 標準は、特にTPEにおける大気ガス関連の重要な危険、危険な状況、出来事を扱っており、それに伴う予防策を具体化しています。これにより、工場内での大気ガスシステムが引き起こす可能性のある重大なリスクを効果的に低減または排除するための指針が提供されています。 また、この標準は適用範囲に制限を設けており、TPEの主要な電源装置からのユーティリティ供給や、真空炉、ブラスター炉、半導体デバイス用のTPEに関しては適用されないことが明記されています。これにより、特定の状況下でのリスクを明確にし、誤解を避ける点でも優れています。 さらに、この標準に準拠して設計されたTPEは、周囲に潜在的な爆発雰囲気を生じさせないことが強調されており、設置場所の安全性を高めています。また、標準の附属書Aに記載されている重大な危険についても言及されているため、より包括的なリスク管理が可能です。 以上の点から、SIST EN 746-3:2022は、産業用熱処理機器における大気ガスの安全な生成と使用に関する決定的な標準であり、その重要性はますます高まっていると言えるでしょう。
EN 746-3:2021 표준은 산업 열처리 장비의 안전 요구사항을 세부적으로 규정한 문서로, 특히 보호 및 반응 대기 가스의 생성 및 사용에 관한 안전 절차를 다루고 있습니다. 이 표준은 열처리 장비(TPE)에서 발생할 수 있는 주요 위험 요소와 위험한 상황에 대한 조치를 명시하여, TPE 사용 시 예상되는 사고를 미연에 방지하는 데 중점을 둡니다. 이 표준의 강점 중 하나는 보호 및 반응 대기 가스의 안전한 생성을 보장하기 위한 구체적인 요구사항을 제공함으로써, 산업 현장에서의 안전성을 크게 향상시키는 데 기여한다는 점입니다. 파이프라인, 장비, 안전 장치 및 안전 관련 제어 시스템의 기능적 요구사항을 세분화하여 설명하며, TPE 전반에 걸쳐 안전한 운영을 도모할 수 있습니다. 특히, 이 표준은 THP와 관련된 대기 가스 시스템의 심각한 위험을 평가하고 이에 대한 예방 조치를 효과적으로 제시합니다. EN 746-3:2021은 TPE의 설치, 시운전, 운영, 정지 및 유지보수 시 개인과 재산의 안전을 보장하기 위한 필수 요구 사항을 정리하여, 사용자에게 실질적인 안전 지침을 제공합니다. 이 표준의 적용은 TPE 주 연결 차단기 이전의 유틸리티 공급이나 반도체 장치에 사용되는 TPE와 같은 특정 상황에는 해당되지 않지만, 산업 열처리 장비에서 발생할 수 있는 다양한 대기 가스와 관련된 안전 문제를 포괄적으로 다루고 있습니다. 결론적으로, EN 746-3:2021은 산업 열처리 장비에서 보호 및 반응 대기 가스의 안전한 사용과 관련하여 매우 중요한 역할을 하는 표준으로, TPE 사용 시 발생할 수 있는 위험을 체계적으로 규명하고 이에 대한 대응책을 마련함으로써, 산업의 안전성을 한층 강화하는 데 중점을 두고 있습니다.
The EN 746-3:2021 standard is a crucial document for ensuring safety in industrial thermoprocessing equipment (TPE) by outlining comprehensive safety requirements related to the generation and use of protective and reactive atmosphere gases. The scope of the standard encompasses the significant hazards, hazardous situations, and events associated with these gases, particularly in the context of thermochemical reactions relevant to TPE operations. One of the key strengths of this standard is its explicit detailing of components involved in the generation and use of atmosphere gases, which includes pipework, generation equipment, and safety devices. This thorough delineation helps manufacturers establish safety protocols and systems effectively, ensuring that critical safety measures are in place throughout the lifecycle of the equipment, from installation to maintenance. The relevance of EN 746-3:2021 is underscored by its focus on both preventative measures and the functional requirements for safety-related control systems. By specifying these requirements, the standard aids in mitigating risks associated with atmosphere gas systems in TPE, thereby enhancing operational safety and efficiency. Notably, the standard also provides guidance on handling notable hazards such as pressure and safety risks specific to atmosphere gases, which are critical in avoiding dangerous situations during TPE operation. By clearly stating the limitations of applicability, such as exclusions for various types of furnaces and processes not covered by EN ISO 12100:2010, it clarifies the scope and specific circumstances under which the requirements should be applied. Furthermore, the standard's directives ensure that TPE designed in compliance with EN 746-3 does not create potentially explosive atmospheres in its operational environment, which is vital for protecting personnel and property. The inclusion of a table detailing typical protective and reactive gases serves as a quick reference for users, enhancing the practical application of the standard. Overall, EN 746-3:2021 serves as an essential framework for the safe generation and use of atmosphere gases in industrial thermoprocessing equipment, addressing significant hazards and outlining the necessary safety measures to protect both users and the environment.
The article discusses the safety requirements for the generation and use of protective and reactive atmosphere gases in industrial thermoprocessing equipment (TPE). It specifies the hazards and events related to the generation and use of these gases, as well as the equipment and devices involved. The article also outlines the preventative measures to reduce or eliminate these hazards. It clarifies that the standard does not cover certain areas such as flue gas ducting systems, utility supply upstream of the TPE main disconnects, and TPE for semiconductor devices. Additionally, it does not address noise hazards and is not applicable to TPE manufactured before the publication of the standard. The article includes a table of typical protective and reactive gases.
기사 제목: EN 746-3:2021 - 산업용 열처리 장비 - 제 3부: 공기 가스 생성 및 사용에 대한 안전 요구 사항 기사 내용: 이 EN 746 시리즈의 이 부분은 산업용 열처리 장비 (TPE)의 일부인 보호 및 반응성 대기 가스의 생성 및 사용에 대한 안전 요구 사항을 명시합니다. TPE에 공통적으로 적용되는 일반적인 안전 요구 사항은 EN 746 1:1997 + A1:2009에서 제공됩니다 (서문 참조). 이 EN 746 시리즈의 이 부분은 TPE에서 발생하는 열화학 반응으로 생성되는 보호 및 반응성 대기 가스의 생성 및 사용과 관련된 중요한 위험, 위험 상황 및 사건을 다룹니다. 제조업자가 예상한 용도와 조건에서 의도된 대로 사용될 때, 제 4 조 및 제 5 조에 나열된 TPE의 일부인 경우를 다룹니다. 이 EN 746 시리즈의 이 부분은 다음을 다루고 있습니다. - 수동 분리밸브 이하의 배관, - 대기 가스 생성 장비, - TPE에서 대기 가스 사용을 위한 추가 장비, - 안전 장치, 및 - 보호 및 반응성 대기 가스의 생성 및 사용을 위한 안전 관련 제어 시스템의 기능 요구 사항. 이는 TPE에 공급되는 대기 가스, 원료 가스, 비활성 기체 및 공정용 액체와 이를 TPE에 통합된 장비에 한정된 범위 내에서 제고합니다. 이 EN 746 시리즈의 이 부분은 또한 대기 가스 시스템과 TPE에서 사용되는 것과 관련된 예견되는 중요한 위험을 설명하고, 이러한 위험을 감소 또는 없애기 위한 적절한 예방 조치를 명시합니다. 이 표준이 다루는 배관 및 구성 요소의 압력 위험은 부록 C에서 설명하는 그룹 1의 최대 압력/크기 관계 범위 내에 있습니다. 이 EN 746 시리즈의 이 부분은 다음 사항을 다룹니다. - 설치, 취급, 시작, 운영, 정지 및 유지 보수 중에 인명 및 재산의 안전을 보장하기 위해 충족해야하는 요구 사항을 명시합니다. - TPE의 일부로 간주되지 않는 배기 가스 배관 시스템과 관련된 관련 위험을 다루지 않습니다. - TPE 주요 차단기 이전의 유틸리티 공급에는 적용되지 않습니다. - 반도체 장치용 TPE에는 적용되지 않습니다. - 공기 및 과량의 연소에서 생성 된 배기 가스와 같은 대기를 사용하는 TPE에는 적용되지 않습니다. - TPE의 폐기를 다루지 않습니다. - 진공로를 다루지 않습니다. - 블라스트 피어나 변환기 (강철 공장), 보일러 및 EN ISO 12100:2010에 포함되지 않은 장비를 다루지 않습니다. - EN 746 1:1997 + A1:2009에서 다루는 소음 위험을 다루지 않습니다. - TPE 및 해당 설비에서 생성 및 사용되는 대기 가스에는 출판일 이전에 제조 된 것에 적용되지 않으며, - 사용 설명서에 필요한 요구 사항을 제공합니다. 이 EN 746 시리즈의 이 부분에 따라 설계된 TPE는 TPE 주변에 잠재적으로 폭발성 대기를 생성하지 않으며, 잠재적으로 폭발성이거나 위험한 대기가 있는 장소에 배치되도록 설계되어 있지 않습니다. 이 EN 746 시리즈의 이 부분은 부록 A에 설명된 중요한 위험과 관련됩니다. 부록 B에는 일반적인 보호 및 반응성 가스의 테이블이 제공됩니다.
記事のタイトル：EN 746-3:2021 - 産業用熱処理装置 - 第3部：雰囲気ガスの生成および利用の安全要求事項 記事内容：このEN 746シリーズの一部は、産業用熱処理装置（TPE）の一部である保護および反応性雰囲気ガスの生成および利用の安全要求事項を規定しています。 TPEに共通する一般的な安全要件はEN 746 1:1997+A1:2009で提供されています（参照）。 このEN 746シリーズの一部は、熱化学的反応によって生成される保護および反応性雰囲気ガスの生成およびTPEでの使用に関連する重大な危険、危険な状況、およびイベントを扱っています。製造業者が意図した使用方法と条件で使用される場合、TPEの一部としてリストされたTPE（第4条および第5条に記載）に適用されます。 このEN 746シリーズの一部は以下をカバーしています。 -手動切断バルブを含む配管 -雰囲気ガス生成装置 -TPEでの雰囲気ガスの使用のための追加装置 -安全装置 -保護および反応性雰囲気ガスの生成および使用に関連する安全関連制御システムの機能要件 これはTPEへの雰囲気ガス、原料ガス、不活性ガス、およびプロセス液の供給およびTPEからの除去に適用され、TPEに統合された機器に限定されます。 このEN 746シリーズのこの部分は、雰囲気ガスシステムおよびTPEでの使用に関連する予想される重大な危険を詳述し、これらの危険の削減または排除に適切な予防措置を指定します。 この規格でカバーされる配管および構成部品の圧力リスクは、付録Cで説明されるグループ1の最大圧力/サイズの関係に範囲内です。 このEN 746シリーズのこの部分は次の項目を扱っています。 -インストール、立ち上げ、運転、停止、メンテナンス中に人や財産の安全を保証するために満たすべき要件を指定します。 -TPEの一部でない排気ガスダクトシステムに関連するリスクは扱われません。 -TPEの主な分離切断装置の上流の公益事業供給には適用されません。 -半導体装置用のTPEには適用されません。 -空気や過剰燃焼からの排気ガスなどの雰囲気を持つTPEには適用されません。 -TPEの廃棄処分は扱われません。 -真空炉は扱われません。 -ブラスト炉、コンバータ（鉄鋼プラント）、ボイラー、およびEN ISO 12100:2010でカバーされない装置は扱われません。 -EN 7461:1997+A1:2009で扱われる騒音の危険は扱われません。 -この規格の発行日前に製造されたTPEおよびそれに関連する施設での雰囲気ガスの生成と使用には適用されません。 -使用情報に必要な要件を提供します。 このEN 746シリーズのこの部分に準拠したTPEは、TPE周辺に潜在的な爆発性の雰囲気を作り出すことはなく、潜在的に爆発性または危険な雰囲気のある場所に配置するために設計されていません。 このEN 746シリーズのこの部分は、付録Aに記載されている重大な危険に対処しています。 付録Bには一般的な保護および反応性ガスの一覧表が記載されています。
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