SIST EN ISO 15875-3:2026

SLOVENSKI STANDARD
01-januar-2026
Cevni sistemi iz polimernih materialov za napeljave z vročo in hladno vodo -
Zamreženi polietilen (PE-X) - 3. del: Fitingi (ISO 15875-3:2025)
Plastics piping systems for hot and cold water installations - Crosslinked polyethylene
(PE-X) - Part 3: Fittings (ISO 15875-3:2025)
Kunststoff-Rohrleitungssysteme für die Warm- und Kaltwasserinstallation– Vernetztes
Polyethylen (PE-X)– Teil3: Formstücke (ISO 15875-3:2025)
Systèmes de canalisations en plastique pour les installations d'eau chaude et froide -
Polyéthylène réticulé (PE-X) - Partie 3: Raccords (ISO 15875-3:2025)
Ta slovenski standard je istoveten z: EN ISO 15875-3:2025
ICS:
23.040.45 Fitingi iz polimernih Plastics fittings
materialov
91.140.60 Sistemi za oskrbo z vodo Water supply systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 15875-3
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2025
EUROPÄISCHE NORM
ICS 23.040.45; 91.140.60 Supersedes EN ISO 15875-3:2003, EN ISO 15875-
3:2003/A1:2020, EN ISO 15875-3:2003/A2:2021
English Version
Plastics piping systems for hot and cold water installations
- Crosslinked polyethylene (PE-X) - Part 3: Fittings (ISO
15875-3:2025)
Systèmes de canalisations en plastique pour les Kunststoff-Rohrleitungssysteme für die Warm- und
installations d'eau chaude et froide - Polyéthylène Kaltwasserinstallation - Vernetztes Polyethylen (PE-X)
réticulé (PE-X) - Partie 3: Raccords (ISO 15875- - Teil 3: Formstücke (ISO 15875-3:2025)
3:2025)
This European Standard was approved by CEN on 23 October 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 15875-3:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 15875-3:2025) has been prepared by Technical Committee ISO/TC 138
"Plastics pipes, fittings and valves for the transport of fluids" in collaboration with Technical Committee
CEN/TC 155 “Plastics piping systems and ducting systems” the secretariat of which is held by NEN.
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 April 2026, and conflicting national standards shall be
withdrawn at the latest by April 2026.
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 15875-3:2003, EN ISO 15875-3:2003/A1:2020, EN ISO 15875-
3:2003/A2:2021.
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 15875-3:2025 has been approved by CEN as EN ISO 15875-3:2025 without any
modification.
International
Standard
ISO 15875-3
Second edition
Plastics piping systems for hot
2025-10
and cold water installations —
Crosslinked polyethylene (PE-X) —
Part 3:
Fittings
Systèmes de canalisations en plastique pour les installations
d'eau chaude et froide — Polyéthylène réticulé (PE-X) —
Partie 3: Raccords
Reference number
ISO 15875-3:2025(en) © ISO 2025

ISO 15875-3:2025(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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 15875-3:2025(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 2
3.1 Terms and definitions .2
3.1.1 General .2
3.1.2 Mechanical fittings .3
3.2 Symbols .4
4 Generic requirements, instructions and explanations. 4
4.1 Designation PE-X .4
4.2 Application classes, design pressures and pipe dimension classes restrictions .4
4.3 Application classes — Responsibility of the purchaser or specifier .4
4.4 Use of the parts of the ISO 15875 series .5
4.5 Completeness of tests .5
4.6 Test result interchangeability restriction .5
5 Material characteristics . 5
5.1 Plastics fitting body material subjected to hydrostatic stress .5
5.2 Plastics material of auxiliary fittings parts subjected to mechanical stress .8
5.3 Metallic fitting body material .8
5.4 Influence on water intended for human consumption .8
6 General characteristics . 8
6.1 Appearance .8
6.1.1 Appearance of plastic fittings .8
6.1.2 Appearance of metal fittings .9
6.2 Opacity .9
7 Geometrical characteristics . 9
7.1 General .9
7.1.1 Overview .9
7.1.2 Nominal diameter(s) .9
7.1.3 Angles .9
7.1.4 Threads .9
7.2 Dimensions of sockets for electro-fusion fittings .9
7.3 Dimensions of metallic fittings — Minimum wall thickness of fittings made of copper
alloys .11
8 Mechanical characteristics of plastics fittings .11
8.1 General .11
8.2 Fitting made from a PE-X material . 12
8.3 Fitting made from plastics material other than PE-X and specified by an ISO standard
according to Annex B . 13
8.4 Fitting made from plastics material not specified by an ISO standard according to
Annex B .14
9 Physical and chemical characteristics .15
9.1 Physical and chemical characteristics of plastics fittings . 15
9.1.1 Thermal stability . 15
9.1.2 Degree of crosslinking and Melt flow rate .16
9.2 Physical and chemical characteristics of metallic fittings .16
9.2.1 Fittings made of copper alloys — Resistance to stress corrosion .16
9.2.2 Fittings made of copper alloys — Resistance to dezincification .16
9.2.3 Metallic fittings made from cast alloys — Tightness test .17
10 Sealing elements . 17

iii
ISO 15875-3:2025(en)
11 Performance requirements . . 17
12 Marking . . 17
12.1 General requirements .17
12.2 Minimum required marking .17
Annex A (normative) Dimensional requirements for metallic fittings . 19
Annex B (normative) ISO standards defining plastics material to be used for components in hot
and cold applications inside buildings .21
Annex C (normative) Plastics material of auxiliary fitting parts subjected to mechanical stress .22
Bibliography .25

iv
ISO 15875-3:2025(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 Technical Committee ISO/TC 138, Plastics pipes, fittings and valves for the
transport of fluids, Subcommittee SC 2, Plastics pipes and fittings for water supplies, in collaboration with the
European Committee for Standardization (CEN) Technical Committee CEN/TC 155, Plastics piping systems
and ducting systems, in accordance with the Agreement on technical cooperation between ISO and CEN
(Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 15875-3:2003), which has been technically revised.
It also incorporates the Amendments ISO 15875-3:2003/Amd. 1:2020 and ISO 15875-3:2003/Amd. 2:2021.
— clarification has been added concerning plastics fitting body material not identical to PE-X due to a
distinction between:
— plastics fitting body material not identical to PE-X, but specified by other ISO documents;
— plastics fitting body material not identical to PE-X and not specified by other ISO documents;
— a new clause for plastics material of auxiliary fittings parts subjected to mechanical stress in 5.2;
— a 2 500 h at 95 °C confirmation test has been introduced in 5.1.2, 5.1.3 and 5.1.4.
A list of all parts in the ISO 15875 series can be found on the ISO website.
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.

v
ISO 15875-3:2025(en)
Introduction
The ISO 15875 series specifies the requirements for a piping system consisting of pipe, fitting and the
jointing made of it, when the pipe is made from crosslinked polyethylene (PE-X). The ISO 15875 series
consists of ISO 15875-1, ISO 15875-2, ISO 15875-2 and ISO 15875-5, and covers the requirements and related
test methods for all components used in the system (e. g. pipes and fittings). In addition, the ISO 15875 series
includes requirements and related test methods to verify the performance and compatibility of the jointing
of components.
The piping system is intended to be used for hot and cold water installations.
In respect of potential adverse effects on the quality of water intended for human consumption, caused by
the product covered by the ISO 15875 series:
— the ISO 15875 series provides no information as to whether the product may be used without restriction
in any of the Member States of the EU or EFTA;
— it should be noted that, while awaiting the adoption of verifiable European criteria, existing national
regulations concerning the use and/or the characteristics of this product remain in force.
Requirements and test methods for materials and components, other than fittings, are specified in
ISO 15875-1 and ISO 15875-2. Characteristics for fitness for purpose (mainly for joints) are covered in
ISO 15875-5. ISO/TS 15875-7 gives guidance for the assessment of conformity.
This document specifies the characteristics of the fittings.
At the date of publication of this document, standards for piping systems of other plastics materials used for
the same application include
— the ISO 15874 series,
— the ISO 15875 series,
— the ISO 15876 series,
— the ISO 15877 series,
— the ISO 21003 series, and
— the ISO 22391 series.
vi
International Standard ISO 15875-3:2025(en)
Plastics piping systems for hot and cold water installations —
Crosslinked polyethylene (PE-X) —
Part 3:
Fittings
1 Scope
This document specifies the characteristics of fittings for crosslinked polyethylene (PE-X) piping systems
intended to be used for hot and cold water installations within buildings for the conveyance of water,
whether or not intended for human consumption (domestic systems) and for heating systems under design
pressures and temperatures according to the class of application (see ISO 15875-1:—, Table 1).
This document also specifies the test parameters for the test methods referred to herein.
This document is applicable to fittings made from PE-X or other plastics or non-plastics materials, which are
intended to be connected to pipes conforming to ISO 15875-2 for hot and cold water installations, whereby
the joints conform to the requirements of ISO 15875-5.
This document is applicable to fittings of the following types:
— mechanical fittings;
— electrofusion fittings;
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).
ISO 228-1, Pipe threads where pressure-tight joints are not made on the threads — Part 1: Dimensions, tolerances
and designation
ISO 527-2:2025, Plastics — Determination of tensile properties — Part 2: Test conditions for moulding and
extrusion plastics
ISO 1133-1, Plastics — Determination of the melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of
thermoplastics — Part 1: Standard method
ISO 1167-1, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination of the
resistance to internal pressure — Part 1: General method
ISO 1167-3, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination of the
resistance to internal pressure — Part 3: Preparation of components
ISO 1167-4, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination of the
resistance to internal pressure — Part 4: Preparation of assemblies
ISO 2768-1, General tolerances — Part 1: Tolerances for linear and angular dimensions without individual
tolerance indications
ISO 3126, Plastics piping systems — Plastics components — Determination of dimensions

ISO 15875-3:2025(en)
ISO 6259-1:2015, Thermoplastics pipes — Determination of tensile properties — Part 1: General test method
ISO 6509-1, Corrosion of metals and alloys — Determination of dezincification resistance of copper alloys with
zinc — Part 1: Test method
ISO 6957, Copper alloys — Ammonia test for stress corrosion resistance
ISO 7686, Plastics pipes and fittings — Determination of opacity
ISO 9080, Plastics piping and ducting systems — Determination of the long-term hydrostatic strength of
thermoplastics materials in pipe form by extrapolation
ISO 10147, Pipes and fittings made of crosslinked polyethylene (PE-X) — Estimation of the degree of crosslinking
by determination of the gel content
ISO 15875-1, Plastics piping system for hot and cold water installations — crosslinked polyethylene (PE-X) —
Part 1: General
ISO 15875-2, Plastics piping system for hot and cold water installations — crosslinked polyethylene (PE-X) —
Part 2: Pipes
ISO 15875-5, Plastics piping system for hot and cold water installations — crosslinked polyethylene (PE-X) —
Part 5: Fitness for purpose of the system
EN 681-1, Elastomeric seals — Materials requirements for pipe joint seals used in water and drainage
applications — Part 1: Vulcanized rubber
EN 681-2, Elastomeric seals — Materials requirements for pipe joint seals used in water and drainage
applications — Part 2: Thermoplastic elastomers
EN 10226-1, Pipe threads where pressure-tight joints are made on the threads — Part 1: Taper external threads
and parallel internal treads — Dimensions, tolerances and designation
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 15875-1 and the following apply.
ISO and IEC maintain terminological 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/
3.1.1 General
3.1.1.1
fitting
component of a piping system, which connects two or more pipes and/or fittings together, without any
further function
3.1.1.2
tolerance
permitted variation of the specified value of a quantity, expressed as the difference between the permitted
maximum and the permitted minimum value
3.1.1.3
control point
pressure test parameters to verify compliance with the predicted hydrostatic strength

ISO 15875-3:2025(en)
3.1.1.4
service coefficient
overall service (design) coefficient
C
overall coefficient with a value greater than one, which takes into consideration service conditions as well
as properties of the components of a piping system other than those represented in the lower confidence
limit of the predicted hydrostatic strength, σ
LPL
3.1.2 Mechanical fittings
3.1.2.1
compression fitting
fitting with internal support in which the joint is made by screwing a union nut along a thread to compress a
ring on the outside wall of the pipe and finally to cause a clamping of the pipe between the ring and the inner
support of the fitting
Note 1 to entry: The fitting may be with or without elastomeric sealing element.
3.1.2.2
radial press fitting
fitting, with internal support in which the joint is made by a radial compression of a ring with a pressing tool on
the outside wall of the pipe to cause a clamping of the pipe between the ring and the inner support of the fitting
Note 1 to entry: The fitting may be with or without sealing element.
3.1.2.3
axial press fitting
fitting with internal support in which the joint is made by an axial movement of a sleeve with a pressing tool
to cause a clamping of the pipe between the sleeve and the inner support of the fitting
Note 1 to entry: The fitting may be with or without sealing element.
3.1.2.4
push-fit fitting
fitting, which incorporates a sealing element, a gripping device and uses optionally an internal support
Note 1 to entry: The joint is made by pushing the pipe into the fitting and a seal is achieved without the use of heat or tools.
Note 2 to entry: In some designs, this type of joint can be disconnected and re-connected or disconnected and the
fitting re-used elsewhere.
Note 3 to entry: The internal support can be an integrated part of the fitting or a separate part (supporting sleeve).
3.1.2.5
radial shrink fitting
fitting, with internal support in which the joint is made by a radial shrinking of the PE-X pipe and a previously
expanded visco-elastic polymeric ring on the outside wall of the pipe to cause a clamping of the pipe between
the ring and the inner support of the fitting
Note 1 to entry: The fitting may be with or without a sealing element.
Note 2 to entry: The internal support can be an integrated part of the fitting or a separate part (supporting sleeve).
3.1.2.6
plastic transition fitting
plastic fitting with a metal end, where a metallic part is embedded in the plastic fitting body
Note 1 to entry: The metal end could be e. g. a metallic thread or a soldering end.

ISO 15875-3:2025(en)
3.1.2.7
electrofusion fitting
fitting in which the joint with the pipe is made by melting together the outer part of the pipe and the inner
part of the fitting by means of heat induced by current flowing in an appropriate resistor inserted in the
fitting body
3.2 Symbols
C overall service (design) coefficient
d outside diameter (at any point)
e
d nominal outside diameter
n
d mean inside diameter of socket
sm
p internal hydrostatic pressure
p design pressure
D
T temperature
T design temperature
D
T malfunction temperature
mal
T maximum design temperature
max
t time
σ hydrostatic stress
σ design stress
D
σ design stress of plastics fitting material
DF
σ hydrostatic stress values of plastics fitting material taken from the reference line for the appli-
F
cable time and temperature
σ lower confidence limit of the predicted hydrostatic strength
LPL
4 Generic requirements, instructions and explanations
4.1 Designation PE-X
The designation crosslinked polyethylene is used together with the abbreviation PE-X throughout this
document.
4.2 Application classes, design pressures and pipe dimension classes restrictions
ISO 15875-1 covers a range of application classes, design pressures and pipe dimension classes. For values
of design temperature (T ), maximum temperature (T ) and malfunction temperature (T ) and service
D max mal
times in excess of those defined in ISO 15875-1, this document does not apply.
4.3 Application classes — Responsibility of the purchaser or specifier
It is the responsibility of the purchaser or specifier to make the appropriate selections from these application
classes (see ISO 15875-1), taking into account their particular requirements and any relevant national
regulations and installation practices or codes.

ISO 15875-3:2025(en)
4.4 Use of the parts of the ISO 15875 series
This document is intended to be used only in conjunction with all the other parts of the ISO 15875 series.
NOTE According to the scope, this document is applicable to fittings made from PE-X or other plastics or non-
plastics materials, which are intended to be connected to pipes conforming to ISO 15875-2 for hot and cold water
installations, whereby the joints conform to the requirements of ISO 15875-5.
4.5 Completeness of tests
In order to conform with this document, all requirements of this document shall be met.
4.6 Test result interchangeability restriction
The test results for a specific combination of a pipe and a fitting, obtained from a piping system test according
to ISO 15875-5, cannot be transferred to other combinations of pipes and fittings.
5 Material characteristics
5.1 Plastics fitting body material subjected to hydrostatic stress
5.1.1 General
The material from which the fittings bodies subjected to hydrostatic stress are made shall be a plastics
compound.
The stabilisers and additives (e.g. pigments, lubricants) added by the manufacturer are part of the compound
and shall be specified by the manufacturer in their quality plan.
Compounds with fillers or reinforcements (e.g. chalk or fibre) shall not be used.
NOTE The use of reworked material and recyclate is specified in ISO 15875-1:2024, 6.4
5.1.2 PE-X Fitting body material
The PE-X compound shall conform to material requirements specified in ISO 15875-1 and ISO 15875-2.
The compound shall be tested in the form of tubular test pieces, made by injection moulding or extrusion.
The test pieces made of the compound shall be tested in accordance with the test methods specified in
Table 1, using the indicated parameters. The test pieces shall withstand the hydrostatic hoop stress without
bursting or leakage.
NOTE 1 In case the PE-X fitting material is identical with the PE-X pipe material, the requirement according to this
clause is already covered by testing according ISO 15875-2.
NOTE 2 Straight couplers can be also used when tested according to Table 1. In this case, the most critical position
(smallest wall thickness) of the base body of the coupler is the basis for the calculation of the hydrostatic hoop stress.
The area of the stiffener is not relevant in this context.

ISO 15875-3:2025(en)
Table 1 — Control points of PE-X material identical to PE-X pipe compound
Characteristic Requirement Test parameters for the individual tests Test method
Resistance to No bursting or Hydrostatic Test Test Number of ISO 1167-1,
internal leakage during (hoop) stress temperature period test pieces ISO 1167-2
pressure the test period and
MPa °C h
ISO 1167-3
12,0 20 1 3
4,6 95 165 3
4,4 95 1 000 3
b
4,3 95 2 500 3
Test parameters for all tests
a
Sampling procedure
Type of end cap Type a)
Orientation of test piece Not specified
Type of test Water-in-water
a
The sampling procedure is not specified. For guidance, see ISO/TS 15875-7.
NOTE Hydrostatic (hoop) stress values given in Table 1 were agreed upon by experts. Calculated values derived from the PE-X
reference lines can differ.
b
2 500 h test is only a confirmation test according to ISO/TS 15875-7 and not needed in type testing.
The nominal diameter of the tubular test pieces shall be in the range of the nominal diameters of fittings
normally produced by the manufacturer.
5.1.3 Plastics fitting body material not identical to PE-X, but specified by an ISO standard according
to Annex B
The fitting compound shall conform to the material requirements specified in the relevant ISO document
listed in Annex B.
The compound shall be tested in form of tubular test pieces, made by injection moulding or extrusion.
The test pieces made of the compound shall be tested in accordance with the test methods specified in
Table 2, using the indicated parameters. The test pieces shall withstand the hydrostatic hoop stress without
bursting or leakage.
NOTE Straight couplers can be also used when tested according to Table 1. In this case, the most critical position
(smallest wall thickness) of the base body of the coupler is the basis for the calculation of the hydrostatic hoop stress.
The area of the stiffener is not relevant in this context.

ISO 15875-3:2025(en)
Table 2 — Control points of a fitting material not identical to PE-X pipe compound specified by an
ISO standard according to Annex B
Characteristic Requirement Test parameters for the individual tests Test method
Resistance to No bursting or Hydrostatic Test Test Number of ISO 1167-1,
internal leakage during (hoop) stress temperature period test pieces ISO 1167-2,
pressure the test period ISO 1167-3
MPa °C h
According to the 20 1 3
reference lines
95 165 3
defined in the
95 1 000 3
applicable ISO
standard accord-
b
95 2 500 3
ing to Annex B
Test parameters for all tests
a
Sampling procedure
Type of end cap Type a)
Orientation of test piece Not specified
Type of test Water-in-water
a
The sampling procedure is not specified. For guidance, see ISO/TS 15875-7.
b
2 500 h test is only a confirmation test according to ISO/TS 15875-7 and not needed in type testing.
The nominal diameter of the tubular test pieces shall be in the range of the nominal diameters of fittings
normally produced by the manufacturer.
5.1.4 Plastics fitting body material not specified by an ISO standard according to Annex B
The fitting material in the form of injection moulded or extruded tubular test pieces shall be evaluated by
using the method given in ISO 9080 or equivalent where internal pressure tests are made in accordance
with ISO 1167-1 and ISO 1167-3 to find the σ -values.
LPL
The σ -values and its corresponding σ -curve thus determined shall be used to determine the values of
LPL LPL
hydrostatic stress of the control points at the temperature and time given in Table 3.
The test pieces made of the compound shall be tested in accordance with the test methods specified in
Table 3, using the indicated parameters. The test pieces shall withstand the hydrostatic hoop stress without
bursting or leakage.
NOTE One equivalent way of evaluation is to calculate the σ -value for each temperature (for example, 20 °C,
LPL
70 °C and 95 °C) individually.

ISO 15875-3:2025(en)
Table 3 — Control points of a fitting material not specified by an ISO standard according to Annex B
Characteristic Requirement Test parameters for the individual tests Test method
Resistance to No bursting or Hydrostatic Test Test Number of ISO 1167-1
internal leakage during (hoop) stress temperature period test pieces and
pressure the test period ISO 1167-3
MPa °C h
20 1 3
95 165 3
According to the
σ curve
95 1 000 3
LPL
b
95 2 500 3
Test parameters for all tests
a
Sampling procedure
Type of end cap Type a)
Orientation of test piece Not specified
Type of test Water-in-water
a
The sampling procedure is not specified. For guidance, see ISO/TS 15875-7.
b
2 500 h test is only a confirmation test according to ISO/TS 15875-7 and not needed in type testing.
The nominal diameter of the tubular test pieces shall be in the range of the nominal diameters of fittings
normally produced by the manufacturer.
5.2 Plastics material of auxiliary fittings parts subjected to mechanical stress
For plastics material of auxiliary fitting parts such as plastics screw nuts or plastics clamping rings, which
are not in contact with the media (water) during the application, but are subjected to mechanical stress and
temperature, the following shall apply.
— Thermal stability requirements shall be met according to Annex C. Alternatively, the material shall
conform to the requirements given in 5.1 including to the thermal stability requirements given in 9.1.1.
Compounds with fillers or reinforcements (e.g. chalk or fibre) can be used.
5.3 Metallic fitting body material
Metallic materials for fittings intended to be used with components conforming to the ISO 15875 series
shall be either copper alloys or stainless steel alloys. The alloys shall be defined according to a standard or
regulatory document.
NOTE Examples for such standards and regulatory documents are listed in the bibliography.
For copper alloys, the fittings made thereof shall conform to 9.2.
5.4 Influence on water intended for human consumption
The material shall conform to ISO 15875-1:2025, 6.2.
6 General characteristics
6.1 Appearance
6.1.1 Appearance of plastic fittings
When viewed without magnification, the internal and external surfaces of fittings shall be smooth, clean and
free from scoring, cavities and other surface defects to an extent that would prevent conformance with this
document. The material shall not contain visible impurities. Slight variations in appearance of the colour
shall be permitted. Each end of a fitting shall be perpendicular to its axis.

ISO 15875-3:2025(en)
6.1.2 Appearance of metal fittings
When viewed without magnification, the internal and external surfaces of fittings shall be clean, free from
any residues from the production (e. g. free from cast sand, grease or release agent) and shall have no sharp
edges or cracks.
6.2 Opacity
Plastic fittings that are declared to be opaque shall not transmit more than 0,2 % of visible light when tested
in accordance with ISO 7686. In case of dispute the integrated sphere mentioned in ISO 7686 shall not be used.
7 Geometrical characteristics
7.1 General
7.1.1 Overview
The manufacturer shall state the dimension and tolerances of the fittings in their internal quality plan.
Dimensions of plastic fittings shall be measured in accordance with ISO 3126.
Dimensions of metal fittings shall be measured in accordance with ISO 2768-1.
7.1.2 Nominal diameter(s)
The nominal diameter(s), d , of a fitting shall correspond to and be designated by the nominal outside
n
diameter(s) of the pipe(s) conforming to ISO 15875-2, for which they are designed.
7.1.3 Angles
The preferred nominal angles of non-straight fittings are 45° and 90°.
7.1.4 Threads
Threads used for jointing shall conform to EN 10226-1. Where a thread is used as a fastening thread for
jointing an assembly (e.g. union nuts), it shall conform to ISO 228-1, except that these requirements need not
apply to the threads used by the manufacturer to join component parts of a fitting together.
7.2 Dimensions of sockets for electro-fusion fittings
The dimensions of sockets for electrofusion fittings are shown in Figure 1.
The values of lengths L and L (see Figure 1) shall be in accordance with Table 4. The manufacturer shall
1 2
declare the actual length.
The values for D , D , D as well as for L and L may be given by the manufacturer for additional information.
1 2 3 3 4
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