SIST EN ISO 14903:2025

Refrigerating systems and heat pumps - Qualification of tightness of components and joints (ISO 14903:2025)

This document specifies the qualification procedure for type approval of the tightness of hermetically sealed and closed components, joints and parts used in refrigerating systems and heat pumps as described in relevant parts of the ISO 5149 series, including metal flexible piping. It specifies the level of tightness of the component as a whole and its assembly as specified by the manufacturer. It specifies additional requirements for mechanical joints that can be recognized as hermetically sealed joints.
This document is applicable to joints of maximum DN 50 and components of internal volume of maximum 5 l and maximum weight of 50 kg.
It is applicable to the hermetically sealed and closed components, joints and parts (e.g. fittings, bursting discs, flanged or fitted assemblies) used in the refrigerating installations, including those with seals, whatever their material and design are.
This document does not apply to the tightness of flexible piping made from non-metallic material. This is covered in ISO 13971.
Components tested before the date of publication of this document and found to comply with ISO 14903:2017 are considered to comply with this document.

Kälteanlagen und Wärmepumpen - Qualifizierung der Dichtheit der Bauteile und Verbindungen (ISO 14903:2025)

Dieses Dokument legt ein Qualifizierungsverfahren für die Baumusterprüfung der Dichtheit von hermetisch dichten und geschlossenen Bauteilen, Verbindungen und Teilen fest, die in Kälteanlagen und Wärmepumpen verwendet werden, wie sie in relevanten Teilen der Normenreihe ISO 5149 beschrieben sind, einschließlich flexibler Rohrleitungen aus Metall. Es legt den Grad der Dichtheit des Bauteils als Ganzes sowie dessen Zusammenbau nach Angaben des Herstellers fest. Es legt zusätzliche Anforderungen an mechanische Verbindungen fest, die als hermetisch dichte Verbindungen anerkannt werden können.
Dieses Dokument ist anwendbar für Verbindungen von maximal DN 50 und Bauteile mit einem Innenvolumen von maximal 5 l und einem maximalen Gewicht von 50 kg.
Es ist anwendbar für hermetisch dichte und geschlossene Bauteile, Verbindungen und Teile (z. B. Fittings, Berstscheiben, geflanschte oder mit Verbindungsstücken hergestellte Baugruppen) anwendbar, die in Kälteanlagen verwendet werden, einschließlich solcher mit Dichtungen, unabhängig von ihrem Werkstoff und ihrer Ausführung.
Dieses Dokument ist nicht anwendbar für die Dichtheit von flexiblen Rohrleitungen aus nicht-metallischem Werkstoff. Dies wird in ISO 13971 behandelt.
Bauteile, die vor dem Veröffentlichungsdatum dieses Dokuments geprüft wurden und deren Übereinstimmung mit ISO 14903:2017 festgestellt wurde, werden als übereinstimmend mit diesem Dokument betrachtet.

Systèmes de réfrigération et pompes à chaleur - Qualification de l'étanchéité des composants et des joints (ISO 14903:2025)

Le présent document spécifie les procédures de qualification pour essai de type de l’étanchéité des composants, joints et éléments hermétiquement scellés et fermés, utilisés dans les systèmes de réfrigération et les pompes à chaleur comme décrits dans les parties pertinentes de la série ISO 5149, y compris les flexibles métalliques. Il spécifie le niveau d’étanchéité du composant dans son ensemble et de son assemblage comme spécifié par le fabricant. Il spécifie des exigences supplémentaires concernant les joints mécaniques susceptibles d’être considérés comme des joints hermétiquement scellés.
Le présent document s’applique aux joints de DN 50 maximum et aux composants d'un volume interne de 5 l maximum et d’un poids de 50 kg maximum.
Il est applicable aux composants, joints et éléments hermétiquement scellés et fermés (par exemple, raccords, disques de rupture ou d’éclatement, assemblages à brides ou à raccords) utilisés dans les installations de réfrigération, y compris ceux avec joints d’étanchéité, indépendamment de leur matière et de leur conception.
Le présent document ne s’applique pas à l’étanchéité des flexibles en matériaux non métalliques. Ils sont traités dans l’ISO 13971.
Les composants soumis à essai avant la date de publication du présent document et jugés conformes à l'ISO 14903:2017 sont considérés comme conformes au présent document.

Hladilni sistemi in toplotne črpalke - Ocena tesnosti sestavnih delov in spojev (ISO 14903:2025)

Ta dokument določa postopek kvalifikacije za tipsko odobritev tesnosti hermetično zatesnjenih in zaprtih sestavnih delov, spojev ter delov, ki se uporabljajo v hladilnih sistemih in toplotnih črpalkah, kot je opisano v ustreznih delih skupine standardov ISO 5149, vključno s kovinskimi upogljivimi cevmi. Določa stopnjo tesnosti sestavnega dela kot celote in njegove montaže, kot jo je določil proizvajalec. Določa tudi dodatne zahteve za mehanske spoje, ki jih je mogoče prepoznati kot hermetično zatesnjene spoje.
Ta dokument se uporablja za spoje velikosti največ DN 50 in sestavne dele z notranjo prostornino največ 5 l in največjo težo 50 kg.
Uporablja se za hermetično zatesnjene in zaprte sestavne dele, spoje ter dele (npr. fitinge, razpočne plošče, prirobnice ali vgrajene sklope), ki se uporabljajo v hladilnih napravah, vključno z vsemi tesnili, ne glede na njihov material in obliko.
Ta dokument se ne uporablja za tesnost upogljivih cevi iz nekovinskih materialov. To je zajeto v standardu ISO 13971.
Za sestavne dele, ki so bili preskušeni pred datumom objave tega dokumenta in izpolnjujejo zahteve standarda ISO 14903:2017, se šteje, da so v skladu s tem dokumentom.

General Information

• Status: Published
• Public Enquiry End Date: 06-Nov-2023
• Publication Date: 03-Feb-2025
• ICS: 27.080 - Heat pumps
• ICS: 27.200 - Refrigerating technology
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 30-Jan-2025
• Due Date: 06-Apr-2025
• Completion Date: 04-Feb-2025
• Ref Project: EN ISO 14903:2025 - Refrigerating systems and heat pumps - Qualification of tightness of components and joints (ISO 14903:2025)

Relations

• Revises: SIST EN ISO 14903:2017 - Refrigerating systems and heat pumps - Qualification of tightness of components and joints (ISO 14903:2017)
• Effective Date: 12-Apr-2023

Standards Content (Sample)

SLOVENSKI STANDARD
01-marec-2025
Hladilni sistemi in toplotne črpalke - Ocena tesnosti sestavnih delov in spojev (ISO
14903:2025)
Refrigerating systems and heat pumps - Qualification of tightness of components and
joints (ISO 14903:2025)
Kälteanlagen und Wärmepumpen - Qualifizierung der Dichtheit der Bauteile und
Verbindungen (ISO 14903:2025)
Systèmes de réfrigération et pompes à chaleur - Qualification de l'étanchéité des
composants et des joints (ISO 14903:2025)
Ta slovenski standard je istoveten z: EN ISO 14903:2025
ICS:
27.080 Toplotne črpalke Heat pumps
27.200 Hladilna tehnologija Refrigerating technology
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 14903
EUROPEAN STANDARD
NORME EUROPÉENNE
January 2025
EUROPÄISCHE NORM
ICS 27.080; 27.200 Supersedes EN ISO 14903:2017
English Version
Refrigerating systems and heat pumps - Qualification of
tightness of components and joints (ISO 14903:2025)
Systèmes de réfrigération et pompes à chaleur - Kälteanlagen und Wärmepumpen - Qualifizierung der
Qualification de l'étanchéité des composants et des Dichtheit der Bauteile und Verbindungen (ISO
joints (ISO 14903:2025) 14903:2025)
This European Standard was approved by CEN on 10 January 2025.

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, Türkiye 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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14903:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 14903:2025) has been prepared by Technical Committee ISO/TC 86
"Refrigeration and air-conditioning" in collaboration with Technical Committee CEN/TC 182
“Refrigerating systems, safety and environmental requirements” 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 July 2025, and conflicting national standards shall be
withdrawn at the latest by July 2025.
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 ISO 14903:2017.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations 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, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 14903:2025 has been approved by CEN as EN ISO 14903:2025 without any modification.

International
Standard
ISO 14903
Third edition
Refrigerating systems and heat
2025-01
pumps — Qualification of tightness
of components and joints
Systèmes de réfrigération et pompes à chaleur — Qualification de
l'étanchéité des composants et des joints
Reference number
ISO 14903:2025(en) © ISO 2025
ISO 14903:2025(en)
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 14903:2025(en)
Contents  Page
Foreword .iv
Introduction .v
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
4  Symbols . 3
5 Test requirements . 3
6  Requirements for sealed systems . . 7
7  Test procedures . 7
7.1 General .7
7.2 Sampling .7
7.3 Test temperature .7
7.4 Tightness test .8
7.4.1 General .8
7.4.2 Tightness level control .9
7.5 Requirements for joints .10
7.5.1 Test samples .10
7.5.2 Torque .10
7.5.3 Reusable joint .11
7.5.4 Requirements for hermetically sealed joints .11
7.6 Pressure-temperature vibration tests (PTV) .11
7.6.1 General .11
7.6.2 Samples .11
7.6.3 Test equipment and arrangements .11
7.6.4 Method: Combined pressure-temperature cycle test with a separate vibration
test. 12
7.7 Operation simulation .17
7.8 Freezing test .17
7.9 Additional pressure test for hermetically sealed joints .18
7.10 Vacuum test .19
7.11 Compatibility screening test .19
7.11.1 General .19
7.11.2 Test fluids . . .19
7.11.3 Test specimens .19
7.11.4 Test setup parameters . 20
7.11.5 Test procedure. 20
7.11.6 Pass/fail criteria for sealing elements .21
7.12 Fatigue test for hermetically sealed joints .21
8  Test report .22
9  Information to the user .22
Annex A (informative)  Equivalent tightness control levels .23
Bibliography .29

iii
ISO 14903:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by the European Committee for Standardization (CEN) Technical Committee
CEN/TC 182, Refrigerating systems, safety and environmental requirements, in collaboration with ISO
Technical Committee TC 86, Refrigeration and air-conditioning, Subcommittee SC 1, Safety and environmental
requirements for refrigerating systems, in accordance with the Agreement on technical cooperation between
ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 14903:2017), which has been technically
revised.
The main changes are as follows:
— update of the test procedure:
— PTV test:
— deletion of previous method 1 "Combined pressure-temperature cycle test with integrated
vibration test";
— update of previous method 2 "Combined pressure-temperature cycle test with a separate
vibration test".
— pressure test: modification of the test pressure specification;
— modification of Figure 2 "Test procedure": the compatibility test is moved out of the tightness test;
— deletion of previous Annex B "Test arrangements".
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
ISO 14903:2025(en)
Introduction
This document is intended to characterize the tightness stresses of joints of maximum DN 50 and components
of internal volume of maximum 5 l and maximum weight of 50 kg met during their operations, following the
fitting procedure specified by the manufacturer. This document is also intended to specify the minimal list
of necessary information to be provided by the supplier of a component to the person in charge of carrying
out this procedure.
v
International Standard ISO 14903:2025(en)
Refrigerating systems and heat pumps — Qualification of
tightness of components and joints
1  Scope
This document specifies the qualification procedure for type approval of the tightness of hermetically
sealed and closed components, joints and parts used in refrigerating systems and heat pumps as described
in relevant parts of the ISO 5149 series, including metal flexible piping. It specifies the level of tightness
of the component as a whole and its assembly as specified by the manufacturer. It specifies additional
requirements for mechanical joints that can be recognized as hermetically sealed joints.
This document is applicable to joints of maximum DN 50 and components of internal volume of maximum 5 l
and maximum weight of 50 kg.
It is applicable to the hermetically sealed and closed components, joints and parts (e.g. fittings, bursting
discs, flanged or fitted assemblies) used in the refrigerating installations, including those with seals,
whatever their material and design are.
This document does not apply to the tightness of flexible piping made from non-metallic material. This is
covered in ISO 13971.
Components tested before the date of publication of this document and found to comply with ISO 14903:2017
are considered to comply with this document.
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 175, Plastics — Methods of test for the determination of the effects of immersion in liquid chemicals
ISO 1817, Rubber, vulcanized or thermoplastic — Determination of the effect of liquids
ISO 5149-1, Refrigerating systems and heat pumps — Safety and environmental requirements — Part 1:
Definitions, classification and selection criteria
ISO 20485:2017, Non-destructive testing — Leak testing — Tracer gas method
3  Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5149-1 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/

ISO 14903:2025(en)
3.1
mass flow rate
Q
m
value of the leak mass flow rate at any point of the component
Note 1 to entry: The mass flow rate is expressed in grams per year (g/a).
3.2
volume flow rate
Q
value of the leak volume flow rate at any point of the component
Note 1 to entry: The volume flow rate is expressed in Pascal cubic metres per second (Pa∙m /s).
3.3
product family
group of products that have the same function, technology and material for each functional part and sealing
materials
3.4
closed joint
joint other than hermetically sealed joints where there is no movement between the sealing surfaces except
for service purposes
EXAMPLE Flanged joints.
3.5
closed component
component other than hermetically sealed components where there is no movement between the sealing
surfaces except for service purpose
EXAMPLE Stop valves, service ports, pressure-relief valves.
3.6
hermetically sealed joint
joint that is made tight by welding, brazing or a similar permanent connection
3.7
hermetically sealed component
component that is made tight by welding, brazing or a similar permanent connection
3.8
permanent joint
joint which cannot be disconnected except by destructive methods
[SOURCE: Pressure Equipment Directive 2014/68/EU]
3.9
reusable joint
joint made without replacing the sealing material in general procedure
Note 1 to entry: In some cases, the tube is used as sealing material (e.g. flared joint).
3.10
same base material
material belonging to the same group
EXAMPLE Steel group, aluminium and aluminium alloy group, or copper group.
Note 1 to entry: Subgroups of these material groups are considered to be same base materials (refer to EN 14276-1 and
EN 14276-2).
ISO 14903:2025(en)
4  Symbols
Symbol Denomination Unit
percentage deviation of the minimum and maximum torque from the average of the
D —
K
minimum and maximum torque, (K − K )/(K + K )
max min min max
f frequency of vibrations Hz
average torques of the respective joint standard, if specified. Otherwise, average of K
min
K Nm
ave
and K
max
K maximum torque used for testing a joint Nm
test_max
K minimum torque used for testing a joint Nm
test_min
required maximum torques of the respective joint standard if specified; otherwise, the
K Nm
max
maximum torque values supplied by the manufacturer
required minimum torques of the respective joint standard if specified; otherwise, the
K Nm
min
minimum torque values supplied by the manufacturer
L length of tube mm
n number of cycles in temperature and in pressure —
n number of cycles in pressure —
n number of cycles in vibration —
n total number of cycles in temperature and in pressure —
total
N number of samples —
P tightness test pressure bar
P maximal pressure of cycle bar
max
P minimal pressure of cycle bar
min
PS maximal allowable pressure bar
P nominal set pressure of the device bar
set
Q volume flow rate Pa⋅m /s
Q mass flow rate g/a
m
s vibration displacement (peak to peak value) mm
T maximal temperature of cycle °C
max
T minimal temperature of cycle °C
min
5 Test requirements
The tests that shall be applied to component bodies and joints used in refrigerating systems and heat pumps
are given in Table 1 and in Table 2.
When a component can be connected with different types of joints, one of these joints shall be tested with the
component according to Table 1. The other possible types of joints shall be tested independently according
to Table 2.
Figure 1 illustrates the principle of a component and a joint.

ISO 14903:2025(en)
a) According to Table 1
b) According to Table 1
c) According to Table 2
Key
1 joint 4 component body joint
2 component body 5 extension pipe
3 pipe
Figure 1 — Principle of component body joint and joining of components

ISO 14903:2025(en)
Table 1 — Requirements for component bodies
Requirements
PTV test Additional test for hermeti-
Chemical
(pres- cally sealed components
Components (including valves)
Tightness Operation  compatibility
sure-temper- Freezing test Vacuum test
test simulation with mate-
ature-vibra-
Pressure test Fatigue test
rials
tion)
Subclause 7.4 7.6 7.7 7.8 7.11 7.10 7.9 7.12
Component bodies having only per-
manent joints: brazing and welding
YES NO NO NO NO NO NO NO
Same base materials
Components having permanent
a
joints: brazing and welding
YES YES NO NO NO NO NO NO
Not same base materials
Component bodies having other YES
YES
permanent joints (e.g. glue, perma- if operating
YES YES NO if non-metallic YES YES YES
nent compression fittings, expansion temperature
parts
joints) below 0 °C
YES
if any external
YES
stems, shaft YES
Component bodies with non-perma- if operating
YES YES seals or if non-metallic YES Not applicable Not applicable
nent joints temperature
removable or parts
below 0 °C
replaceable
parts
YES
YES
Capped valves and capped service if operating
YES YES YES if non-metallic YES YES YES
ports for sealed systems temperature
parts
below 0 °C
YES
Safety valves YES YES NO NO if non-metallic Not applicable Not applicable Not applicable
parts
Flexible piping Test according to ISO 13971
By exception, compressors that conform to the requirements of EN 12693 or IEC 60335-2-34 only need to be subjected to the following test:
—  joints connecting to other parts of the refrigerating systems;
—  chemical compatibility test for all gaskets (sight glass, etc.).
a
PTV tests are not required if destructive and non-destructive tests of EN 13134 are carried out.
NOTE Other qualifications for this chemical compatibility done according to other standards are equivalent.

ISO 14903:2025(en)
Table 2 — Requirements for the joining of components
Requirements
PTV test Chemical  Additional test for hermeti-
Joints and parts
Tightness (pressure- Operation  compatibility  cally sealed joints
Freezing test Vacuum test
test temperature- simulation with mate-
Pressure test Fatigue test
vibration) rials
Subclause 7.4 7.6 7.7 7.8 7.11 7.10 7.9 7.12
Permanent joints for piping: brazing
and welding
YES NO NO NO NO NO NO NO
Same base materials
Permanent joints for piping: brazing
and welding
YES YES NO NO NO NO NO NO
Not same base materials
Other permanent joints for piping
(e.g. glue, permanent compression YES YES NO YES YES YES YES YES
fittings, expansion joints)
YES, if sealing
Non-permanent joints for piping YES YES YES YES YES Not applicable Not applicable
material
Gaskets and sealing NO NO NO NO YES NO Not applicable Not applicable

ISO 14903:2025(en)
6  Requirements for sealed systems
Sealed systems shall be constructed with components that have their tightness control level qualified as
A1 or A2 as per Table 3 or Table 4. These components and joints shall be subjected to the relevant tests as
specified in Table 1 and Table 2.
7  Test procedures
7.1 General
The components, joints and part shall pass the tightness test before the other tests are executed. The
different tests are shown in Figure 2.
Figure 2 — Test procedure
7.2 Sampling
The largest, the smallest and any random samples in between of the product family shall be subjected to the
test as required in Table 1 or Table 2. The samples used for the pressure-temperature vibration test (7.6)
and for the operation simulation (7.7) shall be the same. For each of the other tests (7.8, 7.9, 7.10, 7.11, 7.12),
different samples may be used.
7.3 Test temperature
Test temperature (ambient and gas) shall be 15 °C to 35 °C, unless otherwise specified as the test conditions.

ISO 14903:2025(en)
7.4 Tightness test
7.4.1 General
The tightness of components and joints shall be tested according to the following test pressures.
For pressure relief devices: P = 0,88 × P to 0,9 × P
set set
For all other components and joints: P = 1,00 × PS to 1,02 × PS
Q ≤ requirements for actual tightness control level A1 – A2
(hermetically sealed components) or B1 – B2 for all other
components
The maximum required tightness control level is specified for helium at 10 bar and +20 °C as a reference.
The actual tightness control levels can be calculated (e.g. for other test fluids or pressures) by using the
stated calculation formulae (Annex A).
The maximum tightness control level depends on the size of the tested component or joint. Tightness control
levels are specified in accordance with the joints used in Table 3.
Table 3 — Tightness control level according to joints nominal diameter
Joints DN Tightness control levels
Hermetically sealed joints ≤ 50 A1
Closed joints ≤ 50 B1
For components, the tightness control level depends on the component internal volume and the type of
component as specified in Table 4.
Table 4 — Tightness control level according to components volume
Component volume
Components Tightness control levels
l
0 up to 1,0 A1
Hermetically sealed com-
ponents
> 1,0 A2
Closed components 0 up to 2,0 B1
Closed components > 2,0 up to 5,0 B2
The manufacturer can choose more stringent tightness control level if adequate.
The tightness criteria are given in Table 5.
Table 5 — Equivalence of test gas flow according to tightness control levels
Helium reference  Equivalent iso‑bu-
Equivalent air leak
Tightness control
leak tane leak
Component type level at +20 °C,
Q Q Q
m
10 bar
3 3
Pa⋅m /s Pa⋅m /s g/a
−7 −7
A1 ≤ 7,5 × 10 ≤ 8 × 10 ≤ 1,5
Hermetically sealed
−6 −7
A2 ≤ 1 × 10 ≤ 11 × 10 ≤ 2,0
−6 −7
B1 ≤ 1 × 10 ≤ 11 × 10 ≤ 2,0
Closed
−6 −6
B2 ≤ 2 × 10 ≤ 2,1 × 10 ≤ 4,0
NOTE The equivalent iso-butane leak is calculated as gas. At +20 °C and 10 bar, iso-butane is in the liquid phase. See R-600a in
Table A.1.
ISO 14903:2025(en)
7.4.2  Tightness level control
7.4.2.1  Test method
NOTE 1 EN 1779 gives guidance on the criteria for method and technique selection.
The tightness control level of joints and components shown in Table 3 and Table 4 shall be measured by the
vacuum chamber technique which sum all leak.
It is preferable to use tracer gas technique as specified in ISO 20485:2017, 9.8.
The component to be tested is pressurized with the tracer gas and placed in the vacuum chamber in which
the sum of all components leak is measured.
The following procedure shall be carried out to measure the tightness control level:
— connect the vacuum chamber to the detector;
— connect the component to the tracer gas pressure generator (in the vacuum chamber) (see Figure 3);
— close the vacuum chamber and start the leak detector (and if necessary add a vacuum pump);
— adjust and calibrate the leak detector according to ISO 20485:2017, 8.2.1;
— measure the residual signal in the vacuum chamber and the component without helium pressure;
— adjust the test pressure in the component;
— measure the leak signal of the component;
NOTE 2 This signal is the total flow of the tracer gas from the component measured by the leak detector.
— calculate the leak level according to the formula given in ISO 20485:2017, 8.3.7.
If joints and/or components are tested together, the total level shall fulfil the most stringent tightness
control level of the individual joint or component.
Key
1 tracer gas (P) 4 test object
2 vacuum 5 calibrated leak
3 mass spectrometric leak detector
Figure 3 — Principle of tightness control — Tracer gas

ISO 14903:2025(en)
7.4.2.2  Alternative test methods
Two alternative methods may be applied.
a) Alternative method 1
The control by pressure technique by accumulation according to ISO 20485:2017, 9.5.2, can be used to
measure the leak rate of the component.
b) Alternative method 2
Bubble test methods shown in Figure 4 can be acceptable for tightness control level B, provided that the
method is capable of measuring the actual leakage rate. The bubble test methods shall be carried out
in accordance with EN 1593. The accuracy of the selected method shall be verified and conform to the
requirements for actual tightness control level. If this method is used, the following requirements shall
be applied:
1) the test object shall be subjected to an internal air pressure = PS (maximum allowable pressure).
Reduced pressure is not acceptable;
2) the test object shall be immersed in water;
3) the test object shall be exposed to atmospheric pressure;
4) the test shall be performed at normal ambient temperature;
5) the period of time between bubbles leaving the test object shall be more than 60 s.

Key
1 water
2 test object
3 air pressure (PS)
Figure 4 — Principle of tightness control — Bubble method
7.5  Requirements for joints
7.5.1 Test samples
All joints tested shall be tested in the final form as the customer receives the part.
All joints shall be subjected to the tests as indicated in Table 2.
7.5.2  Torque
Where relevant, tube joints shall be tested both at the minimum torque, K , and the maximum torque,
test_min
K , specified in Table 6.
test_max
NOTE For a reusable joint with a thread connection, this implies that two sets of samples are used for the tests of
Table 2, one set tested at K and one set tested at K .
test_min test_max
ISO 14903:2025(en)
Table 6 — Torque for the test, K and K
test_min test_max
K K
test_min test_max
If D ≥ 20 % K K
K min max
If 20 % > D 0,8 × K 1,2 × K
K ave ave
7.5.3  Reusable joint
If the joints to be tested are reusable, the following steps shall be taken before the test:
a) fit the joints to tubes to be connected and tighten the joints to the maximum torque, K , specified
test_max
in Table 6;
b) loosen the joints and take the tubes completely apart;
c) repeat a) and b) four more times.
NOTE This implies that before starting the tests of Table 2, all samples are assembled and disassembled five times,
each time with the sealing material changed and applying K torque.
test_max
7.5.4  Requirements for hermetically sealed joints
The joint shall not be opened without the use of special tools.
NOTE Special tools are other than screw-drivers, parallel wrenches, simple gripping tool, etc.
The joint shall not be reusable without replacing the sealing material in normal use. In case the sealing
material is the tube, including that the tube is deformed during the sealing process, the deformed part of the
tube shall not be reusable for sealing purposes.
7.6  Pressure‑temperature vibration tests (PTV)
7.6.1 General
In order to qualify the tightness level, joints and components shall be subjected to the pressure-temperature
and vibration tests as specified below.
7.6.2 Samples
For the combined cycle test, the number of samples is determined based on tightness control level according
to Table 7.
Table 7 — Test parameters
Tightness control level Number of samples
A1, B1 3
A2, B2 2
7.6.3 Test equipment and arrangements
7.6.3.1 Equipment
Test equipment shall be composed of:
a) regulated enclosure for environment tests, able to maintain temperatures varying regularly between
T and T ;
min max
b) pressure device, connected to the joints, capable of producing a pressure that varies between P and P ;
min max
ISO 14903:2025(en)
c) vibration generator, to make the specified frequency and amplitude;
d) pressure control system capable of controlling the pressure with an accuracy of ±5 %;
e) temperature control system capable of controlling the temperature inside of the test enclosure with an
accuracy of ±5 K;
f) temperature sensor capable of monitoring the temperature (T , T ) of the component or joint
max min
subjected to the test.
The temperature sensor shall be adhered to the surface of the sample on the item with the biggest
weight concentration of the pressure bearing part in order to ensure that the sample has reached the
specified temperature values. Where the pressure bearing part is made from metallic and non-metallic
materials, the sensor shall be fixed on the non-metallic material.
The sensor can be fixed to the sample by soldering or with adhesives, whichever is more appropriate,
depending on the material of the sample.
Another method, proven to have the same performance as the thermocouple can be applied.
g) cycle counter of temperature and pressure;
h) test equipment to perform tightness test according to 7.4.
7.6.3.2 Test arrangements
The test samples shall be mounted as shown in Figure 7 in accordance with the number of joints to be tested
and with the dimension of the climatic enclosure in which the tests are carried out.
The tube section shall have a diameter and dimensional tolerances such as specified by the manufacturer of
the joint.
The assembly of the joints on the tube shall be carried out following the fitting instructions of the
manufacturer.
For the pressure test, one end of a tube shall be connected to the pressure generator; the other end shall be
tightly closed.
7.6.4  Method: Combined pressure‑temperature cycle test with a separate vibration test
7.6.4.1  Requirements for the combined pressure‑temperature cycle test
The samples shall be subjected to a specified number n of cycles of temperature and pressure, between
maximal values (T , P ) and minimal values (T , P ), and n cycles of pressure between maximum
max max min min 2
value (P ) and minimum value (P ) with fixed temperature value (T ).
max min max
The test characteristics to be applied to the components are given in Table 8.
A typical temperature-pressure cycle is given in Figure 5.
NOTE The shape of the curve is theoretical.

ISO 14903:2025(en)
Key
1 temperature
2 pressure
Figure 5 — Temperature‑pressure cycle test with a separate vibration test
Table 8 — Test parameters
Parameters Value
n 50
n 200
T minimum temperature as specified by the manufacturer or −40 °C if this is not specified
min
T maximum temperature as specified by the manufacturer or +140 °C if this is not specified
max
P atmospheric pressure
min
for safety valves, P = 0,85 × P
max set
P
max
a
for other components 1,0 × PS
a
1,0 × PS is proposed because of safety issue for test on big component. In the method, the number of cycles and the level of
vibration are extended to compensate for the reduced pressure.
The test fluid shall not be a liquid.
7.6.4.2  Procedure
The following procedure shall be followed:
— Fit the test items on a test-bed in accordance with the instructions of the manufacturer.
— Fix the test parameters (n , n , T , T , P , P ) in accordance with Table 8.
1 2 max min max min
— Subject the test items to the test pressure according to Table 8.
— Check the tightness of the joints in order to detect leaks before test.
— Tighten again the joints that leak according to the instructions of the manufacturer.
— Execute the operation simulation according to 7.7.
— Place the joints in the climatic enclosure and subject them to n and n pressure and temperature cycles
1 2
in accordance with Figure 5 and Table 8.

ISO 14903:2025(en)
7.6.4.3  Vibration test
7.6.4.3.1 General
The component and joints shall be subjected to a vibration test.
Perform the sinusoidal and random vibration test on the same sample.
The frequency measurement shall be made on the component.
An example of vibration assembly for joint is given in Figure 6.
Key
1 joint
3 pipe
L length (200 mm, only for joints)
Figure 6 — Vibration assembly for joint
Examples of vibration assembly for component are given in Figure 7.

ISO 14903:2025(en)
a) Example of horizontal joint b) Example of extension pipe
c) Example of angled joint d) Example of single‑joint component
Key
1 joint
2 extension pipe
3 component body
Figure 7 — Vibration assembly for components
The samples are fixed according to the manufacturer’s instructions. Otherwise, the main body of the sample
should be fixed as close as possible to the joint.
7.6.4.3.2  Procedure
The following procedure shall be applied:
— Before testing, execute the operation simulation according to 7.7.
— Fit the test items on a test-bench in accordance with the instructions of the manufacturer.
— Fix the test parameters for components in accordance with Table 9 and Table 10 (see also Figure 8).
— Subject the samples to the vibration test according to the numbers of tests specified in the respective tables.
— At the end of the vibrations test, subject the samples to the tightness test specified in 7.4. The pass-fail
criteria shall be the tightness control levels according to the test gas shown in Table 5.
7.6.4.3.3  Sinusoidal loading
NOTE Sinusoidal testing is based on IEC 60068-2-6 testing procedures.

ISO 14903:2025(en)
The components shall meet the specifications given in Table 9.
Table 9 — Test parameters for sinusoidal vibration
Parameters Value
Frequency range 10 Hz to 200 Hz
Acceleration 0,7 g
Sweep speed 1 octave/min
a
Number of excitation directions 3 (x-y-z)
Duration 2 h in each direction
a
Numbers of excitation directions can be reduced to two on symmetric shaped components.
7.6.4.3.4  Random loading
NOTE Random testing requirement covers installations near the source of vibration.
Table 10 — Test parameters for random testing
a
Acceleration PSD  Acceleration PSD
Frequency
2 2 2
Hz
(m/s ) /Hz g /Hz
20 2,88 0,03
Value 150 1,92 0,02
1 000 0,38 0,004
Acceleration (RMS) 3,1 g
Duration 2 h
a
The power spectral density is illustrated in Figure 8.
Key
X frequency, in Hz
2 2
Y acceleration PSD, in (m/s ) /Hz
Figure 8 — Power Spectral Density (PSD)

ISO 14903:2025(en)
7.7  Operation simulation
The operation of maintenance and operating shall be carried out according to Table 11.
Table 11 — List of operations
Components Operations Maintenance and operating
Component body with non-per- Ten times before n , ten times before
...