Industrial thermoprocessing equipment - Part 3: Safety requirements for the generation and use of atmosphere gases

This part of 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).
NOTE   The general safety requirements common to TPE are provided in EN 746  1 (see Introduction).
This part of 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 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 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 I as described in Annex C.
This part of 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 deal with the hazard of noise which is covered in EN 746-1:2019,
-   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.
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 zudem die spezifischen Sicherheitsanforderungen an die Erzeugung und Nutzung von Schutz- und Reaktionsgasen, die, wie im Anwendungsbereich aufgelistet, Teil einer industriellen Thermoprozessanlage (TPE) sind, genauer fest.
ANMERKUNG   Für TPE übliche allgemeine Sicherheitsanforderungen werden in prEN 746 1 festgelegt (siehe Einleitung).
Dieser Teil der Normenreihe EN 746 behandelt erhebliche Gefährdungen, Gefährdungssituationen und -ereignisse, die mit der Erzeugung und Anwendung von Schutz- und Reaktionsgasen, 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:
—   Leitungssysteme in Strömungsrichtung beginnend mit dem handbetätigtem Absperrventil,
—   Anlagen für die Erzeugung von Schutz- und Reaktionsgasen,
—   zusätzliche Anlagen zur Anwendung von Schutz- und Reaktionsgasen in TPE,
—   Sicherheitseinrichtungen, und
—   funktionale Anforderungen an sicherheitsbezogene Steuerungen
zur Erzeugung und Anwendung von Schutz- und Reaktionsgasen.
Er gilt für die Versorgung von TPE mit Schutz- und Reaktionsgasen, Quellgasen, Inertgasen und Prozessflüssigkeiten und deren Entfernung aus TPE. Er betrifft nur Anlagen, die in TPE integriert sind.
Dieser Teil der Normenreihe EN 746 gibt im einzelnen signifikanten Gefährdungen an, die bei Schutz- und Reaktionsgassystemen 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 Kategorie I, 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 Risiken, die Rauchgasanlage betreffen, wenn diese nicht als Teil der TPE betrachtet werden,
—   gilt nicht für die Versorgungsinfrastruktur, die den Haupttrenneinrichtungen der TPE vorgelagert ist,
—   gilt nicht für TPE für die Halbleiterfertigung,
—   gilt nicht für TPE mit Atmosphäre, wie etwa Luft und Rauchgas aus überstöchiometrischer Verbrennung,
—   gilt nicht für die Außerbetriebnahme der TPE,
—   gilt nicht für Vakuumöfen,
—   behandelt kein Lärmgefährdungen; diese werden in prEN 746 1:2020 behandelt,
—   ist nicht auf die Erzeugung und Anwendung von Schutz- und Reaktionsgas 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 dazu ausgelegt, in einem Bereich mit einer potenziell explosionsfähigen oder gefährlichen Atmosphäre.
Anhang B enthält eine Tabelle typischer Schutz- und Reaktionsgase.

Équipements thermiques industriels - Partie 3 : Prescription de sécurité pour la génération et l'utilisation des gaz d'atmosphère

La présente partie de la série EN 746 spécifie les exigences de sécurité pour la génération et l'utilisation des gaz d’atmosphère protectrice et réactive qui font partie des équipements thermiques industriels (TPE).
NOTE   Les exigences générales de sécurité communes aux TPE sont fournies dans la prEN 746 1 (voir Introduction).
La présente partie de la série EN 746 traite des phénomènes dangereux, situations dangereuses et événements dangereux significatifs pertinents pour la génération et 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 dans l’Article 4 et l’Article 5, lorsqu'ils sont utilisés comme prévu et dans les conditions prévues par le fabricant.
La présente partie de la série 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 exigences fonctionnelles pour un 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 de gaz d’atmosphère, de gaz source, de gaz inerte et de liquides de procédé aux TPE et à leur retrait des TPE, confinés aux équipements intégrés dans les TPE.
La présente partie de la série 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 I telle que décrite dans l'Annexe C.
La présente partie de la série EN 746
-   spécifie les exigences 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,
-   n’est pas applicable à l’alimentation des utilités en amont des principaux dispositifs de déconnexion de TPE,
-   ne s’applique pas aux TPE pour les dispositifs semi-conducteurs,
-   ne s’applique pas aux TPE avec atmosphère, telle qu’air et fumées d’une combustion sur-stœchiométrique,
-   ne couvre pas la mise hors service des TPE,
-   ne couvre pas les fours sous vide,
-   ne traite pas du phénomène dangereux de bruit qui est couvert dans la prEN 746-1:2020,
-   n’est pas applicable à la génération et à l'utilisation des gaz d’atmosphère dans les TPE et l'installation associée qui est fabriquée avant la date de sa publication, et
-   donne les exigences nécessaires pour les informations pour l’utilisation.
Un TPE conçu selon la présente partie de la série EN 746 ne crée aucune atmosphère potentiellement explosive dans la zone entourant le TPE et n’est pas conçu pour être situé dans une zone avec une atmosphère potentiellement explosive ou dangereuse.
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

General Information

Status
Not Published
Current Stage
5060 - Closure of Vote - Formal Approval
Due Date
23-Sep-2021
Completion Date
23-Sep-2021

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SLOVENSKI STANDARD
oSIST prEN 746-3:2020
01-marec-2020
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: prEN 746-3
ICS:
25.180.01 Industrijske peči na splošno Industrial furnaces in general
oSIST prEN 746-3:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 746-3:2020
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oSIST prEN 746-3:2020
DRAFT
EUROPEAN STANDARD
prEN 746-3
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2020
ICS 25.180.01 Will supersede 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:

Prescription de sécurité pour la génération et Sicherheitsanforderungen für die Erzeugung und

l'utilisation des gaz d'atmosphère Anwendung von Schutz- und Reaktionsgasen

This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee

CEN/TC 186.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are

aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without

notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 746-3:2020 E

worldwide for CEN national Members.
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oSIST prEN 746-3:2020
prEN 746-3:2020 (E)
Contents Page

European foreword ............................................................................................................................................ 4

Introduction .......................................................................................................................................................... 5

1 Scope .......................................................................................................................................................... 6

2 Normative references .......................................................................................................................... 7

3 Terms and definitions ......................................................................................................................... 9

4 Safety requirements and measures.............................................................................................. 10

4.1 General.................................................................................................................................................... 10

4.2 Pipework ................................................................................................................................................ 11

4.2.1 General.................................................................................................................................................... 11

4.2.2 Connections ........................................................................................................................................... 12

4.2.3 Unconnected pipework ..................................................................................................................... 12

4.2.4 Galvanic cells ........................................................................................................................................ 12

4.2.5 Flexible tubing and couplings ........................................................................................................ 13

4.2.6 Marking of pipework ......................................................................................................................... 13

4.2.7 Soundness/Tightness ........................................................................................................................ 13

4.2.8 Condensate drains .............................................................................................................................. 13

4.2.9 Purge points .......................................................................................................................................... 13

4.2.10 Blow-off and breather pipes or conduits ................................................................................... 14

4.2.11 Pressure relief devices and flame arrestors on pipework ................................................... 14

4.2.12 Pressure oscillations ......................................................................................................................... 14

4.2.13 Combustible gas by-pass .................................................................................................................. 14

4.2.14 Isolation of required safety devices ............................................................................................. 14

4.2.15 Vents ........................................................................................................................................................ 14

4.3 Required safety devices .................................................................................................................... 15

4.3.1 Atmosphere gas control equipment ............................................................................................. 15

4.3.2 Other safety devices ........................................................................................................................... 18

4.4 Requirements for the use of atmosphere gases ....................................................................... 19

4.4.1 Prevention of potential ignitable atmospheres ....................................................................... 19

4.4.2 Monitoring of TPE doors movements .......................................................................................... 20

4.4.3 Supervision of the means of ignition at the point of combustible atmosphere gas

discharge ................................................................................................................................................ 20

4.4.4 Emergency safety purge ................................................................................................................... 21

4.5 Change of atmosphere ....................................................................................................................... 21

4.5.1 General.................................................................................................................................................... 21

4.5.2 Purge with purge gas ......................................................................................................................... 22

4.5.3 Purge with self-ignition .................................................................................................................... 22

4.5.4 Change of atmosphere by burning ................................................................................................ 23

4.5.5 Purge by evacuation ........................................................................................................................... 23

4.6 Interfaces to exhaust systems for combustible or toxic atmosphere gases .................. 24

4.6.1 Exhaust of burned gases ................................................................................................................... 24

4.6.2 Gathering of gases without burning and a closed system .................................................... 24

5 Additional requirements for the generation of atmosphere gases .................................. 25

5.1 General.................................................................................................................................................... 25

5.2 Gas and process liquid supplies..................................................................................................... 25

5.2.1 Air supplies ........................................................................................................................................... 25

5.2.2 Reaction mixture supplies ............................................................................................................... 25

5.2.3 Generated atmosphere gas distribution .................................................................................... 25

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prEN 746-3:2020 (E)

5.3 Flame detection ................................................................................................................................... 26

5.4 Burners generating exothermic gases ........................................................................................ 26

5.5 Special requirements for different types of generator ......................................................... 26

5.5.1 Requirements for endothermic generators .............................................................................. 26

5.5.2 Requirements for exothermic generators ................................................................................. 27

5.6 Post-treatment of generated atmosphere gases ..................................................................... 27

6 Verification of the safety requirements and/or measures .................................................. 27

7 Information for use ............................................................................................................................ 31

7.1 General ................................................................................................................................................... 31

7.2 Marking .................................................................................................................................................. 31

7.3 Instruction handbook ....................................................................................................................... 32

7.3.1 General ................................................................................................................................................... 32

7.3.2 Description of equipment ................................................................................................................ 32

7.3.3 Inspection procedures ...................................................................................................................... 32

7.3.4 Commissioning, start-up and operating procedures ............................................................. 33

7.3.5 Shutdown procedures ....................................................................................................................... 34

7.3.6 Maintenance procedures ................................................................................................................. 34

7.3.7 Documentation .................................................................................................................................... 34

Annex A (informative) List of significant hazards .................................................................................. 35

Annex B (informative) Typical protective and reactive atmosphere gases ................................. 37

Annex C (normative) Allowed maximum pressure ............................................................................... 39

Annex D (informative) Principle procedures for the change of atmosphere ................................ 44

Annex E (informative) Examples for the determination of safety integrity level SIL and

performance level PL using the risk graph method ............................................................... 45

Annex F (informative) Basic configuration of piping system of TPE using protective or

reactive atmosphere gases .............................................................................................................. 57

Annex G (informative) Overview of the terms defined in ISO 13574 (Vocabulary) .................. 59

Annex ZA (informative) Relationship between this European Standard and the essential

requirements of Directive 2006/42/EC aimed to be covered ............................................ 66

Bibliography ....................................................................................................................................................... 68

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oSIST prEN 746-3:2020
prEN 746-3:2020 (E)
European foreword

This document (prEN 746-3:2020) has been prepared by Technical Committee CEN/TC 186 “Industrial

Thermoprocess Equipment - Safety”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede 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

EN 746-3:2020 are based on ISO 13577-3:2016.

This document has been prepared under a mandate given to CEN by the European Commission and the

European Free Trade Association, and supports essential requirements of EU Directive(s).

For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this

document.
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oSIST prEN 746-3:2020
prEN 746-3:2020 (E)
Introduction
This part of the EN 746 series is a Type C-Standard as defined in EN ISO 12100.

The machinery concerned and the extent, to which hazards, hazardous situations and events are covered,

is indicated in the scope of this part of the EN 746 series.

When provisions of this type C standard are different from those which are stated in type A or B

standards, the provisions of this type C standard take precedence over the provisions of the other

standards, for machines that have been designed and built according to the provisions 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.

prEN 746-1:2020 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, prEN 746-1:2020 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 prEN 746-11:2020.

If a general provision of prEN 746-1:2020 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.

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oSIST prEN 746-3:2020
prEN 746-3:2020 (E)
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).

NOTE The general safety requirements common to TPE are provided in prEN 746-1 (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 I 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 deal with the hazard of noise which is covered in prEN 746-1:2020,

— 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.
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oSIST prEN 746-3:2020
prEN 746-3:2020 (E)

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.
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 pressures up to 100 bar

prEN 746-1:2020, Industrial thermoprocessing equipment - Part 1: Common safety requirements for

industrial thermoprocessing equipment (ISO 13577-1:2016)

prEN 746-2:2020, Industrial thermoprocessing equipment – Part 2: Safety requirements for combustion

and fuel handling systems (ISO 13577-2:2014)

prEN 746-11:2020, Industrial furnaces and associated processing equipment — Safety — Part 11:

Protective 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, Valve proving systems for automatic shut-off valves for gas burners and gas appliances

EN 1854:2010, Pressure sensing devices for gas burners and gas burning applications

EN 10241:2000, Steel threaded pipe
EN 10242:1994 , Threaded pipe fittings in malleable cast iron

This document is impacted by the amendments EN 10242:1994/A1:1999 and EN 10242:1994/A2:2003.

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oSIST prEN 746-3:2020
prEN 746-3:2020 (E)

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 or industrial and general purpose 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)

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 10352:2010, Fibre-reinforced plastics — Moulding compounds and prepregs—Determination of

mass per unit area (ISO 10352:2010)

EN ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk

reduction (ISO 12100:2010)

EN 14382:2019, Safety devices for gas pressure regulating stations and installations — Gas safety shut-off

devices for inlet pressures up to 100 bar

ISO 13574:2015, Industrial furnaces and associated processing equipment — Vocabulary (ISO 13574:2015)

EN ISO 13849 (all parts), Safety of machinery — Safety-related parts of control systems (ISO 13849)

EN ISO 19879:2010, Metallic tube connections for fluid power and general use — Test methods for

hydraulic fluid power connections (ISO 19879:2010)

EN ISO 23553-1:2014, Safety and control devices for oil burners and oil-burning appliances - Particular

requirements - Part 1: Automatic and semi-automatic valves (ISO 23553-1:2014)

EN 60204-1:2018, Safety of machinery — Electrical equipment of machines — Part 1: General

requirements (IEC 60204-1:2016)

EN 60730-2-5:2015, Automatic electrical controls — Part 2-5: Particular requirements for automatic

electrical burner control systems (IEC 60730-2-5:2013)

EN 61508 (all parts), Functional safety of electrical/electronic/programmable electronic safety-related

systems (IEC 61508 (all parts))

EN 61511 (all parts), Functional safety — Safety instrumented systems for the process industry (IEC 61511

(all parts))

EN 62061:2005 , Safety of machinery — Functional safety of safety-related electrical, electronic and

programmable electronic control systems (IEC 62061:2005)

This document is impacted by the amendments EN 62061:2005/A1:2013 and EN 62061:2005/A2:2015.

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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 http://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.
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 and prEN 746-2:2020.
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 prEN 746-2:2020.
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.

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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 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.
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Protective and reactive atmosphere gases shall only be used in TPE that has been constructed to avoid

leakage of the prot
...

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