SIST EN ISO 15875-2:2026

SLOVENSKI STANDARD
01-januar-2026
Cevni sistemi iz polimernih materialov za napeljave z vročo in hladno vodo -
Zamreženi polietilen (PE-X) - 2. del: Cevi (ISO 15875-2:2025)
Plastics piping systems for hot and cold water installations - Crosslinked polyethylene
(PE-X) - Part 2: Pipes (ISO 15875-2:2025)
Kunststoff-Rohrleitungssysteme für die Warm- und Kaltwasserinstallation – Vernetztes
Polyethylen (PE‑X) – Teil 2: Rohre (ISO 15875-2:2025)
Systèmes de canalisations en plastique pour les installations d'eau chaude et froide -
Polyéthylène réticulé (PE-X) - Partie 2: Tubes (ISO 15875-2:2025)
Ta slovenski standard je istoveten z: EN ISO 15875-2:2025
ICS:
23.040.20 Cevi iz polimernih materialov Plastics pipes
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 15875-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2025
EUROPÄISCHE NORM
ICS 23.040.20; 91.140.60 Supersedes EN ISO 15875-2:2003, EN ISO 15875-
2:2003/A1:2007, EN ISO 15875-2:2003/A2:2020
English Version
Plastics piping systems for hot and cold water installations
- Crosslinked polyethylene (PE-X) - Part 2: Pipes (ISO
15875-2:2025)
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 2: Tubes (ISO 15875-2:2025) - Teil 2: Rohre (ISO 15875-2:2025)
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 15875-2:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 15875-2:2025) 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 15875-2:2003, EN ISO 15875-2:2003/A1:2007, EN ISO 15875-
2:2003/A2:2020.
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 15875-2:2025 has been approved by CEN as EN ISO 15875-2:2025 without any
modification.
International
Standard
ISO 15875-2
Second edition
Plastics piping systems for hot
2025-10
and cold water installations —
Crosslinked polyethylene (PE-X) —
Part 2:
Pipes
Systèmes de canalisations en plastique pour les installations
d'eau chaude et froide — Polyéthylène réticulé (PE-X) —
Partie 2: Tubes
Reference number
ISO 15875-2:2025(en) © ISO 2025

ISO 15875-2:2025(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 15875-2:2025(en)
Contents Page
Foreword .v
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 2
3.1 Terms and definitions .2
3.2 Symbols .4
4 Generic requirements, instructions and explanations. 5
4.1 Designation PE-X .5
4.2 Application classes, design pressures and pipe dimension classes restrictions .5
4.3 Application classes — Responsibility of the purchaser or specifier .5
4.4 Use of the parts of the ISO 15875 series .5
4.5 PE-X pipes provided with a thin barrier layer .5
4.6 Completeness of tests .5
4.7 Test result interchangeability restriction .5
5 Material. 6
5.1 Pipe material .6
5.2 Evaluation of σ -curves .6
LPL
5.3 Reference lines . .7
5.4 Influence on water intended for human consumption .9
5.5 Barrier layer material .9
5.5.1 General .9
5.5.2 Thermal stability of the barrier layer material .9
5.5.3 Thermal stability of the adhesive layer material .9
5.5.4 Thermal stability of the outer layer material .9
6 General characteristics . 10
6.1 Pipe construction .10
6.2 Appearance .10
6.3 Opacity .10
6.4 Oxygen permeability .10
7 Geometrical characteristics . 10
7.1 Pipes without barrier layer(s) - General .10
7.2 Pipes without barrier layer - Dimensions of pipes .11
7.2.1 Outside diameters .11
7.2.2 Wall thicknesses and their tolerances .11
7.3 Pipes with barrier layer — Dimensions of pipes .14
7.3.1 General .14
7.3.2 Option I - Dimensional integration of the barrier layer .14
7.3.3 Option II - Barrier layer on top .14
8 Mechanical characteristics .15
9 Physical and chemical characteristics .16
10 Performance requirements . . 17
11 Marking . . 17
11.1 General requirements .17
11.2 Minimum required marking .17
Annex A (normative) Pipe construction .18
Annex B (normative) Derivation of S values .21
calc,max
Annex C (normative) Proof of the thermal stability of the barrier layer material resp. adhesive
layer material resp. outer layer material — Test procedure .23

iii
ISO 15875-2:2025(en)
Bibliography .26

iv
ISO 15875-2:2025(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 15875-2:2003), which has been technically
revised. It also incorporates the Amendments ISO 15875-2:2003/Amd 1:2007 and ISO 15875-2:2003/
Amd 2:2020.
The main changes are as follows:
— the normative references have been updated;
— a new Clause 4 "Generic requirements, instructions and explanations" has been added and subsequent
clauses have been renumbered;
— pipe material has been specified more precisely;
— Formula (2) for the 110 °C reference curve has been added;
— a new subclause 5.3 "Reference lines" has been added;
— a new subclause 5.5 "Barrier layer material" has been added;
— a new subclause 5.5.1 "General" has been added;
— a new subclause 5.5.2 "Thermal stability of the barrier layer material" with requirements on the thermal
stability of the material has been added;
— a new subclause 5.5.3 "Thermal stability of the adhesive layer material" with requirements on the
thermal stability of the material has been added;

v
ISO 15875-2:2025(en)
— a new subclause 5.5.4 "Thermal stability of the outer layer material" with requirements on the thermal
stability of the material has been added;
— a new subclause 6.4 "Oxygen permeability" has been added;
— in subclause 7.2, the diameter range has been extended up to 250 mm;
— a new subclause 7.3 "Pipes with barrier layer - Dimensions of pipes" has been added;
— Clause 8, Table 12, mechanical characteristics of pipes, characteristic: resistance to internal pressure,
new test parameters have been added: 20 °C / 22 hours and 95 °C / 2 500 hours;
— in Clause 9, a requirement defining the point in time at which the minimum degree of crosslinking is to
be reached has been added;
— in Table 13, a new crosslinking method has been added: PE-Xe - UV light initiated crosslinking;
— a new Annex A "Pipe construction" has been added;
— Annex B (formerly Annex A) "Derivation of S values" has been changed from informative to
calc,max
normative;
— a new Annex C for the proof of the thermal stability of materials has been added;
— editorial modifications have been made to facilitate the readability of the document and to bring it in line
with the ISO/IEC Directives Part 2.
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.

vi
ISO 15875-2:2025(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 15875-3 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 ISO 15875 (all parts):
— ISO 15875 (all parts) 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 material and components, other than pipes, are specified in ISO 15875-1
and ISO 15875-3. 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 pipes.
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.
vii
International Standard ISO 15875-2:2025(en)
Plastics piping systems for hot and cold water installations —
Crosslinked polyethylene (PE-X) —
Part 2:
Pipes
1 Scope
This document specifies the characteristics of pipes 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 15875-1:2025, Table 1).
This document also specifies the test parameters for the test methods referred to in this document.
It is applicable to PE-X pipes with and without barrier layer.
This document is applicable to PE-X pipes for hot and cold water installations, which are intended to be
connected to fittings conforming to ISO 15875-3, whereby the joints conform to the requirements of
ISO 15875-5.
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 527-1:2019, Plastics — Determination of tensile properties — Part 1: General principles
ISO 527-2:2025, Plastics — Determination of tensile properties — Part 2: Test conditions for moulding and
extrusion plastics
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 1167-2, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination of the
resistance to internal pressure — Part 2: Preparation of pipe test pieces
ISO 2505, Thermoplastics pipes — Longitudinal reversion — Test method and parameters
ISO 2578:1993, Plastics — Determination of time-temperature limits after prolonged exposure to heat
ISO 3126, Plastics piping systems — Plastics components — Determination of dimensions
ISO 6259-1:2015, Thermoplastics pipes — Determination of tensile properties — Part 1: General test method
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 15875-2:2025(en)
ISO 11922-1, Thermoplastics pipes for the conveyance of fluids — Dimensions and tolerances — Part 1: Metric series
ISO 13760, Plastics pipes for the conveyance of fluids under pressure — Miner's rule — Calculation method for
cumulative damage
ISO 15875-1:2025, Plastics piping systems for hot and cold water installations — Crosslinked polyethylene (PE-
X) — Part 1: General
ISO 15876-2, Plastics piping systems for hot and cold water installations — Polybutene (PB) — Part 2: Pipes
ISO 15875-3, Plastics piping systems for hot and cold water installations - Crosslinked polyethylene (PE-X) - Part
3: Fittings
ISO 15875-5, Plastics piping systems for hot and cold water installations - Crosslinked polyethylene (PE-X) -Part
5: Fitness for purpose of the system
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
barrier layer material
functional layer material which provides the specific property as a barrier layer to reduce the permeation
of light or a specific medium or gas (e.g. oxygen) into the conveyed fluid and which is linked to the intended
application of the pipe
Note 1 to entry: Barrier layer materials are materials/layers which do not contribute to the stress bearing properties
of the pipe.
Note 2 to entry: PE-X pipes with a barrier layer embedded between two stress designed PE-X layers are not covered by
this document. For these pipes, the ISO 21003 series applies.
Note 3 to entry: In accordance with 7.3.1, the total layer thickness of the additional outer layers (including barrier
layer, adhesive layer, outer layer and other non-stress designed layers) shall not be larger than 0,40 mm. For pipes with
a total layer thickness of the additional outer layers greater than 0,40 mm, the ISO 21003 series applies.
3.1.2
adhesive layer material
functional embedded layer material which provides adhesion between two pipe layer materials
Note 1 to entry: Adhesive layer materials are materials/layers which do not contribute to the stress bearing properties
of the pipe.
Note 2 to entry: PE-X pipes with an adhesive layer embedded between two stress designed PE-X layers are not covered
by this document. For these pipes, the ISO 21003 series applies.
Note 3 to entry: In accordance with 7.3.1, the total layer thickness of the additional outer layers (including barrier
layer, adhesive layer, outer layer and other non-stress designed layers) shall not be larger than 0,40 mm. For pipes with
a total layer thickness of the additional outer layers larger than 0,40 mm the ISO 21003 series apply.

ISO 15875-2:2025(en)
3.1.3
outer layer material
pipe layer material exposed to the outer environment intended for protection, identification by colour or
coverage of other pipe layers
Note 1 to entry: Outer layer materials are materials/layers which do not contribute to the stress bearing properties of
the pipe.
Note 2 to entry: Multiple outer layers can be applied to the pipes on the outer diameter side of the pipe wall (with or
without barrier or adhesive layers). The total thickness of all combined additional outer layers shall be not more than
0,40 mm.
Note 3 to entry: PE-X pipes with embedded between two stress designed PE-X layers are not covered by this document,
for these the ISO 21003 series apply
Note 4 to entry: In accordance with 7.3.1, the total layer thickness of the additional outer layers (including barrier
layer, adhesive layer, outer layer and other non-stress designed layers) shall not be larger than 0,40 mm. For pipes with
a total layer thickness of the additional outer layers greater than 0,40 mm, the ISO 21003 series applies.
3.1.4
pipes with barrier layer
plastics pipes provided with a thin additional outer barrier layer (e.g. to prevent or greatly diminish the
diffusion of gases and the transmission of light through the pipe wall), where the PE-X base pipe exclusive of
any addition of additional (outer) layers meets the design stress requirements of this document.
Note 1 to entry: Such pipes typically have an outside (barrier) layer of maximum 0,40 mm thickness, including any
adhesive. Pipes with an outer layer greater than 0,40 mm are considered as multilayer pipes (see ISO 23001-1), with
the outer layer then being the first of multiple layers rather than having only barrier function.
3.1.5
tolerance
permitted variation of the specified value of a quantity, expressed as the difference between the permitted
maximum and the permitted minimum value
3.1.6
minimum mean outside diameter
d
em,min
minimum value for the mean outside diameter as specified for a given nominal size
3.1.7
maximum mean outside diameter
d
em,max
maximum value for the mean outside diameter as specified for a given nominal size
3.1.8
out-of-roundness
ovality
difference between the measured maximum outside diameter and the measured minimum outside diameter
in the same cross–sectional plane of a pipe or spigot end of a fitting, or the difference between the measured
maximum inside diameter and the measured minimum inside diameter in the same cross–sectional plane of
a socket end of a fitting
3.1.9
wall thickness (at any point)
e
measured thickness of the pipe/fitting wall at any point around the circumference of a component, rounded
up to the nearest 0,1 mm
ISO 15875-2:2025(en)
3.1.10
minimum wall thickness (at any point)
e
min
minimum thickness of the pipe/fitting wall at any point around the circumference of a component, as
specified
3.1.11
maximum wall thickness (at any point)
e
max
maximum thickness of the pipe/fitting wall at any point around the circumference of a component, as
specified
3.1.12
design stress for cold water application
σ
cold
stress value for the intended use of a 20 °C / 50 years lifetime (cold water) application
3.1.13
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
3.2 Symbols
C overall service (design) coefficient
d mean outside diameter
em
d minimum mean outside diameter
em,min
d maximum mean outside diameter
em,max
d nominal outside diameter
n
e wall thickness at any point
e maximum wall thickness at any point
max
e minimum wall thickness at any point
min
e nominal wall thickness
n
p internal hydrostatic pressure
p design pressure
D
S calculated pipe value
calc
S maximum calculated pipe value
calc,max
T temperature
T cold water temperature
cold
T design temperature
D
T malfunction temperature
mal
T maximum design temperature
max
ISO 15875-2:2025(en)
t time
σ hydrostatic stress
σ design stress at 20 °C
cold
σ design stress
D
σ design stress of plastics pipe material
DP
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. This
document does not apply to values of design temperature (T ), maximum temperature (T ) and
D max
malfunction temperature (T ) and service times in excess of those defined in ISO 15875-1.
mal
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 particular requirements and any relevant national regulations
and installation practices or codes.
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 This document is applicable to PE-X pipes for hot and cold water installations, which are intended to be
connected to fittings conforming to ISO 15875-3, whereby the joints conform to the requirements of ISO 15875-5.
4.5 PE-X pipes provided with a thin barrier layer
In the case of PE-X pipes provided with a thin barrier layer, e.g. to prevent or greatly diminish the diffusion
of gases and the transmission of light through the pipe wall, the design stress requirements are totally met
by the base PE-X pipe.
4.6 Completeness of tests
In order to conform with this document, all requirements of this document shall be met.
4.7 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.

ISO 15875-2:2025(en)
5 Material
5.1 Pipe material
The material from which the pipes are made shall be polyethylene (PE) which is crosslinked during or after
the manufacturing of the pipe.
The PE material shall be crosslinked by peroxide, silane, electron beam, azo or UV light in order to change
the chemical structure in such a way that the polymer chains are connected with each other to a three-
dimensional net by chemical bonds.
NOTE 1 The new structure makes it no longer possible to melt or dissolve the polymer unless first destroying its
structure. It is therefore possible to assess the level of crosslinking by measurement of the degree of gelation.
The choice of stabilisers and additives (e. g. pigments, lubricants) is part of the formulation and shall be
specified by the manufacturer. The use of filled or reinforced compounds (e.g. chalk filled or fibre reinforced
compounds) is not permitted. Unspecified formulations shall not be used. This limitation shall also apply to
barrier layer material, adhesive layer material and outer layer material.
NOTE 2 The use of reworked material and recyclate is specified in ISO 15875-1:2025, 6.4
5.2 Evaluation of σ -curves
LPL
The pipe material shall be evaluated in accordance with ISO 9080 or an equivalent document in which
internal pressure tests are made in accordance with ISO 1167-1 and ISO 1167-2 to find the σ -values. The
LPL
test temperatures for the ISO 9080 testing are 20 °C, 60 °C or 70 °C, 95 °C and 110 °C. The σ -value thus
LPL
determined shall be on or above the corresponding reference line (see 5.3) up to the extrapolation time
limited to a maximum of 50 years as shown in Table 1. The requirement “on or above reference line” has to
be fulfilled only within the extrapolation time limit given in Table 1.
Table 1 — Extrapolation time limit
a)
Test temperature (°C) Extrapolation time according to ISO 9080
(years)
20 50
60 50
70 50
95 4
110 °C 1 y
a)
based on testing at 110 °C/1 year and limited to a maximum of 50 years
NOTE One equivalent way of evaluation is to calculate the σ -value for each temperature (e.g. 20 °C, 60 °C to
LPL
70 °C, 95 °C and 110 °C) individually.
The reference curves in Figure 1 in the temperature range of 10 °C to 95 °C for PE-X are derived from
Formula (1):
lg(t) = -105,861 8 - (18 506,15/T) x lg(σ) + 57 895,49/T - 24,799 7 x lg(σ) (1)
The reference curve in Figure 1 for the temperature of 110 °C for PE-X is derived from Formula (2):
lg(t) = 37,495 8 - (84,033 6 x lg(σ)) (2)
Alternatively, conformance with the reference lines should be demonstrated by plotting the individual
experimental results of the internal pressure tests on the graph. At least 97,5 % of these experimental
results shall lie on or above the reference lines.

ISO 15875-2:2025(en)
5.3 Reference lines
Figure 1 contains the reference lines (hoop stress over time to fracture) for expected strength of crosslinked
polyethylene (PE-X). The data represented by the reference lines is required in order to calculate typical
material related values, e.g. the design stress.

ISO 15875-2:2025(en)
Key
X time, t , to fracture, in hours
1 1
X time, t , to fracture, in years
2 2
Y hoop stress, σ, in megapascal
Figure 1 — Reference lines for expected strength of crosslinked polyethylene (PE-X)

ISO 15875-2:2025(en)
5.4 Influence on water intended for human consumption
The material shall conform to ISO 15875-1:2025, 6.2.
5.5 Barrier layer material
5.5.1 General
Only plastics materials shall be used for the barrier layer, the adhesive layer and the outer layer.
5.5.2 Thermal stability of the barrier layer material
If the pipe contains a barrier layer, the thermal stability of the barrier layer material shall be proven.
The thermal stability of the barrier layer material shall be tested using the test methods indicated in Table 2.
The barrier layer material shall conform to the requirements given in this Table 2.
Table 2 — Physical and chemical characteristics of the barrier layer material
Characteristic Requirement Test method
Thermal stability of the barrier layer T ≥ 70 °C See Annex C
50y
material
5.5.3 Thermal stability of the adhesive layer material
If the pipe contains an adhesive layer, the thermal stability of the adhesive layer material shall be proven.
The thermal stability of the adhesive layer material shall be tested using the test methods indicated in
Table 3.
The adhesive layer material shall conform to the requirements given in this Table 3.
Table 3 — Physical and chemical characteristics of the adhesive layer material
Characteristic Requirement Test method
Thermal stability of the adhesive layer T ≥ 70 °C See Annex C
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5.5.4 Thermal stability of the outer layer material
If the pipe contains an outer layer, the thermal stability of the outer layer material shall be proven.
If the outer layer is made of a material defined in ISO 15874-2, ISO 15875-2, ISO 15876-2 or ISO 22391-2,
the thermal stability of the outer layer material shall be tested on a pipe samples made of the outer layer
material according to the relevant clauses "Physical and chemical characteristics of pipes" and "Thermal
stability of the pipe by hydrostatic pressure testing", in the related part 2 of the standards mentioned.
If the outer layer material is different from the above mentioned materials, the following procedure shall occur.
The thermal stability of the outer layer material shall be tested using the test methods indicated in Table 4.
The outer layer material shall conform to the requirements given in this Table 4.
Table 4 — Physical and chemical characteristics of the outer layer material
Characteristic Requirement Test method
Thermal stability of the outer layer T ≥ 70 °C See Annex C
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ISO 15875-2:2025(en)
6 General characteristics
6.1 Pipe construction
The pipe construction shall conform to the requirements of Annex A.
The positioning of the barrier layer within the pipe construction shall conform to the requirements of
Annex A.
6.2 Appearance
When viewed without magnification, the internal and external surfaces of pipes shall be smooth, clean and
free from scoring, cavities and other surface defects to an extent that would prevent conformity to this
document. The material shall not contain visible impurities. Slight variations in the appearance of the colour
shall be permitted. The ends of the pipe shall be cut cleanly and square to the axis of the pipe.
6.3 Opacity
Crosslinked polyethylene (PE-X) pipes 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 specified in ISO 7686 shall not be used.
6.4 Oxygen permeability
Crosslinked polyethylene (PE-X) pipes that are declared to be oxygen tight, shall be tested according to the
methods and parameters given in Table 5 in order to meet the requirements given for application classes 4 and 5.
Depending on the application class, tests shall be carried out at 40 °C and/or 80 °C.
Results determined at a temperature of 80 °C do not allow any conclusions regarding the test at a test
temperature of 40 °C and vice versa.
Table 5 — Oxygen permeability of pipes
Characteristic Requirement Test parameters Test method
Parameter Value
Oxygen permeability of Application class 4 Test temperature 40 °C ISO 17455
the PE-X pipe including Measuring procedure Method I
an oxygen barrier layer (Dynamic test meth-
F
ox, day
od)
≤ 0,32 mg/m day
Application class 5 Test temperature 80 °C
Measuring procedure Method I
(Dynamic test meth-
F
ox, day
od)
≤ 3,60 mg/m day
7 Geometrical characteristics
7.1 Pipes without barrier layer(s) - General
Dimensions shall be measured in accordance with ISO 3126.
The maximum calculated pipe value, S , for the applicable application class and design pressure, p , is
calc,max D
given in Table 6.
ISO 15875-2:2025(en)
Table 6 — S -values for PE-X
calc,max
p Application class
D
Class 1
...