prEN ISO 15494

SLOVENSKI STANDARD
01-julij-2025
Cevni sistemi iz polimernih materialov za uporabo v industriji - Polibuten (PB),
polietilen (PE), polietilen s povišano temperaturno odpornostjo (PE-RT), zamreženi
polietilen (PE-X), polipropilen (PP) - Metrične serije za specifikacije delov
cevovoda in cevni sistem (ISO/DIS 15494:2025)
Plastics piping systems for industrial applications - Polybutene (PB), polyethylene (PE),
polyethylene of raised temperature resistance (PE-RT), crosslinked polyethylene (PE-X),
polypropylene (PP) - Metric series for specifications for components and the system
(ISO/DIS 15494:2025)
Kunststoff‑Rohrleitungssysteme für industrielle Anwendungen - Polybuten (PB),
Polyethylen (PE), Polyethylen erhöhter Temperaturbeständigkeit (PE‑RT), vernetztes
Polyethylen (PE‑X), Polypropylen (PP) - Metrische Reihen für Anforderungen an
Bauteile und das System (ISO/DIS 15494:2025)
Systèmes de canalisations en matières plastiques pour les applications industrielles -
Polybutène (PB), polyéthylène (PE), polyéthylène de meilleure résistance à la
température (PE-RT), polyéthylène réticulé (PE-X), polypropylène (PP) - Séries
métriques pour les spécifications pour les composants et le système (ISO/DIS
15494:2025)
Ta slovenski standard je istoveten z: prEN ISO 15494
ICS:
23.040.01 Deli cevovodov in cevovodi Pipeline components and
na splošno pipelines in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 15494
ISO/TC 138/SC 3
Plastics piping systems for
Secretariat: UNI
industrial applications —
Voting begins on:
Polybutene (PB), polyethylene
2025-05-27
(PE), polyethylene of raised
Voting terminates on:
temperature resistance (PE-RT),
2025-08-19
crosslinked polyethylene (PE-X),
polypropylene (PP) — Metric series
for specifications for components
and the system
Systèmes de canalisations en matières plastiques pour les
applications industrielles — Polybutène (PB), polyéthylène (PE),
polyéthylène de meilleure résistance à la température (PE-
RT), polyéthylène réticulé (PE-X), polypropylène (PP) — Séries
métriques pour les spécifications pour les composants et le
système
ICS: 23.040.01
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 15494:2025(en)
DRAFT
ISO/DIS 15494:2025(en)
International
Standard
ISO/DIS 15494
ISO/TC 138/SC 3
Plastics piping systems for
Secretariat: UNI
industrial applications —
Voting begins on:
Polybutene (PB), polyethylene
(PE), polyethylene of raised
Voting terminates on:
temperature resistance (PE-RT),
crosslinked polyethylene (PE-X),
polypropylene (PP) — Metric series
for specifications for components
and the system
Systèmes de canalisations en matières plastiques pour les
applications industrielles — Polybutène (PB), polyéthylène (PE),
polyéthylène de meilleure résistance à la température (PE-
RT), polyéthylène réticulé (PE-X), polypropylène (PP) — Séries
métriques pour les spécifications pour les composants et le
système
ICS: 23.040.01
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
or ISO’s member body in the country of the requester.
NATIONAL REGULATIONS.
ISO copyright office
RECIPIENTS OF THIS DRAFT ARE INVITED
CP 401 • Ch. de Blandonnet 8
TO SUBMIT, WITH THEIR COMMENTS,
CH-1214 Vernier, Geneva
NOTIFICATION OF ANY RELEVANT PATENT
Phone: +41 22 749 01 11
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 15494:2025(en)
ii
ISO/DIS 15494:2025(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 4
3.1 Geometrical definitions .4
3.2 Material definitions .5
3.3 Definitions related to material characteristics .6
3.4 Definitions related to service conditions .7
4 Symbols and abbreviated terms. 8
4.1 Symbols .8
4.2 Abbreviated terms .8
5 Material. 9
5.1 General .9
5.2 Hydrostatic strength properties .9
5.3 Material characteristics .10
5.3.1 General .10
5.3.2 Use of reworked and recyclate material .10
5.3.3 Resistance to rapid crack propagation, RCP .10
5.4 Materials for components not made from PB, PE, PE-RT, PE-X, or PP .10
5.4.1 General .10
5.4.2 Metallic materials .10
5.4.3 Sealing materials .11
5.4.4 Other materials .11
6 General characteristics .11
6.1 Appearance .11
6.2 Colour .11
6.3 Influence of UV radiation .11
6.4 Resistance to rapid crack propagation, RCP .11
7 Geometrical characteristics .12
7.1 General . 12
7.2 Mean outside diameters, out-of-roundness (ovality), and tolerances . 12
7.3 Wall thicknesses and related tolerances . 12
7.4 Angles . 12
7.5 Laying lengths . 12
7.6 Threads . 12
7.7 Mechanical fittings . 12
7.8 Joint dimensions of valves . 13
8 Mechanical characteristics .13
8.1 Resistance to internal pressure of components . 13
8.2 Calculation of the test pressure for components . 13
8.2.1 Pipes . 13
8.2.2 Fittings . 13
8.2.3 Valves . 13
9 Physical characteristics .13
10 Chemical characteristics .13
10.1 Effects on the component material(s) . 13
10.2 Effects on the fluids .14
11 Electrical characteristics . 14
12 Performance requirements . . 14

iii
ISO/DIS 15494:2025(en)
12.1 General .14
12.2 Fusion compatibility .14
13 Classification of components . 14
14 Design and installation .15
15 Declaration of conformity .15
16 Marking . .15
16.1 General . 15
16.2 Minimum required marking of pipes . 15
16.3 Minimum required marking of fittings .16
16.4 Minimum required marking of valves .16
Annex A (normative) Specific characteristics and requirements for industrial piping systems
made from polybutene (PB) . 17
Annex B (normative) Specific characteristics and requirements for industrial piping systems
made from polyethylene (PE) .31
Annex C (normative) Specific characteristics and requirements for industrial piping systems
made from polyethylene of raised temperature resistance (PE-RT) .63
Annex D (normative) Specific characteristics and requirements for industrial piping systems
made from crosslinked polyethylene (PE-X) .71
Annex E (normative) Specific characteristics and requirements for industrial piping systems
made from polypropylene (PP) .80
Annex F (informative) Design and installation .112
Annex ZA (informative) Relationship between this European Standard and the essential
requirements of Directive 2014/68/EU for pressure equipment aimed to be covered .113
Bibliography .118

iv
ISO/DIS 15494:2025(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 documents 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 03, Plastics pipes and fittings for industrial applications.
This third edition cancels and replaces the second edition (ISO 15494:#), which has been technically revised.
The main changes are as follows:
— in the text PE 63 has been deleted with the reference graphs and PE–100 RC has been added,
— in Annex E the impact resistance of pipes and test parameters for round the clock method has been added
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/DIS 15494:2025(en)
Introduction
This International Standard specifies the characteristics and requirements for a piping system and its
components made from polybutene (PB), polyethylene (PE), polyethylene of raised temperature resistance
(PE-RT), crosslinked polyethylene (PE-X), or polypropylene (PP), as applicable, intended to be used for
industrial applications above ground or below ground by authorities, design engineers, certification bodies,
inspection bodies, testing laboratories, manufacturers, and users.
At the date of publication of this International Standard, standards for piping systems of other plastics used
for industrial applications are the following:
ISO 10931, Plastics piping systems for industrial applications — Poly(vinylidene fluoride) (PVDF) —
Specifications for components and the system
ISO 15493, Plastics piping systems for industrial applications — Acrylonitrile-butadiene-styrene (ABS),
unplasticized poly(vinyl chloride) (PVC-U), chlorinated poly(vinyl chloride) (PVC-C) — Specifications for
components and the system — Metric series

vi
DRAFT International Standard ISO/DIS 15494:2025(en)
Plastics piping systems for industrial applications —
Polybutene (PB), polyethylene (PE), polyethylene of raised
temperature resistance (PE-RT), crosslinked polyethylene
(PE-X), polypropylene (PP) — Metric series for specifications
for components and the system
1 Scope
This International Standard specifies the characteristics and requirements for components such as pipes,
fittings, and valves made from one of the following materials intended to be used for thermoplastics piping
systems under pressure or vacuum conditions in the field of industrial applications above and below ground:
— polybutene (PB);
— polyethylene (PE);
— polyethylene of raised temperature resistance (PE-RT);
— crosslinked polyethylene (PE-X);
— polypropylene (PP).
NOTE 1 Requirements for industrial valves are given in this International Standard and/or in other standards.
Valves are to be used with components conforming to this International Standard provided that they conform
additionally to the relevant requirements of this International Standard.
This International Standard is applicable to either PB, PE, PE-RT, PE-X, or PP pipes, fittings, valves, and
their joints and to joints with components of other plastics and non-plastic materials, depending on their
suitability, intended to be used for the conveyance of liquid and gaseous media as well as solid matter in
fluids for industrial applications under pressure or vacuum conditions, such as the following examples:
— chemical plants;
— industrial sewerage engineering;
— power engineering (e.g. cooling and general purpose water);
— mining;
— electroplating and pickling plants;
— semiconductor industry;
— agricultural production plants;
— fire fighting;
— water treatment;
— geothermal;
— compressed air applications.
NOTE 2 Where relevant, national regulations (e.g. water treatment) are applicable, other application areas are
permitted if the requirements of this International Standard and/or applicable national requirements are fulfilled.
National regulations in respect of fire behaviour and explosion risk are applicable.

ISO/DIS 15494:2025(en)
Characteristics and requirements which are applicable for all materials (PB, PE, PE-RT, PE-X, or PP) are
covered by the relevant clauses of this International Standard. Those characteristics and requirements
which are dependent on the material are given in the relevant normative annex for each material (see
Table 1).
Table 1 — Material-specific annexes
Material Annex
Polybutene (PB) A
Polyethylene (PE) B
Polyethylene of raised temperature resistance (PE-RT) C
Crosslinked polyethylene (PE-X) D
Polypropylene (PP) E
Components conforming to any of the product standards listed in the bibliography or with national standards,
as applicable, may be used with components conforming to this International Standard, provided that they
conform to the requirements for joint dimensions and to the relevant requirements of this International
Standard.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 7-1, Pipe threads where pressure-tight joints are made on the threads — Part 1: Dimensions, tolerances and
designation
ISO 179-1, Plastics — Determination of Charpy impact properties — Part 1: Non-instrumented impact test
ISO 228-1, Pipe threads where pressure-tight joints are not made on the threads — Part 1: Dimensions, tolerances
and designation
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 1167-1:2006, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination of
the resistance to internal pressure — Part 1: General method
ISO 1167-2:2006, 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 1167-3:2007, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination of
the resistance to internal pressure — Part 3: Preparation of components
ISO 1167-4:2007, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination of
the resistance to internal pressure — Part 4: Preparation of assemblies
ISO 1183-1, Plastics — Methods for determining the density of non-cellular plastics — Part 1: Immersion method,
liquid pyknometer method and titration method
ISO 1183-2, Plastics — Methods for determining the density of non-cellular plastics — Part 2: Density gradient
column method
ISO 17885, Plastics piping systems — Mechanical fittings for pressure piping systems — Specifications
ISO 2505, Thermoplastics pipes — Longitudinal reversion — Test method and parameters
ISO 3126, Plastics piping systems — Plastics components — Determination of dimensions

ISO/DIS 15494:2025(en)
ISO 3127, Thermoplastics pipes — Determination of resistance to external blows — Round-the-clock method
ISO 3501, Plastics piping systems — Mechanical joints between fittings and pressure pipes — Test method for
resistance to pull-out under constant longitudinal force
ISO 4065, Thermoplastics pipes — Universal wall thickness table
ISO 4427-1:2007, Plastics piping systems — Polyethylene (PE) pipes and fittings for water supply — Part 1: General
ISO 6964, Polyolefin pipes and fittings — Determination of carbon black content by calcination and pyrolysis —
Test method
ISO/TR 7620, Rubber materials — Chemical resistance
ISO 9080:2012, Plastics piping and ducting systems — Determination of the long-term hydrostatic strength of
thermoplastics materials in pipe form by extrapolation
ISO 9854-1, Thermoplastics pipes for the transport of fluids — Determination of Charpy impact properties —
Part 1: General test method
ISO 9854-2, Thermoplastics pipes for the transport of fluids — Determination of Charpy impact properties —
Part 2: Test conditions for pipes of various materials
ISO 10147, Pipes and fittings made of crosslinked polyethylene (PE-X) — Estimation of the degree of crosslinking
by determination of the gel content
ISO 11414, Plastics pipes and fittings — Preparation of polyethylene (PE) pipe/pipe or pipe/fitting test piece
assemblies by butt fusion
ISO 11922-1:2018, Thermoplastics pipes for the conveyance of fluids — Dimensions and tolerances — Part 1:
Metric series
ISO 11357-6, Plastics — Differential scanning calorimetry (DSC) — Part 6: Determination of oxidation induction
time (isothermal OIT) and oxidation induction temperature (dynamic OIT)
ISO 12162, Thermoplastics materials for pipes and fittings for pressure applications — Classification, designation
and design coefficient
ISO 13477, Thermoplastics pipes for the conveyance of fluids — Determination of resistance to rapid crack
propagation (RCP) — Small-scale steady-state test (S4 test)
ISO 13479:2022, Polyolefin pipes for the conveyance of fluids — Determination of resistance to crack propagation
— Test method for slow crack growth on notched pipes
ISO 13953, Polyethylene (PE) pipes and fittings — Determination of the tensile strength and failure mode of test
pieces from a butt-fused joint
ISO 14531-1, Plastics pipes and fittings — Crosslinked polyethylene (PE-X) pipe systems for the conveyance of
gaseous fuels — Metric series — Specifications — Part 1: Pipes
ISO 15512, Plastics — Determination of water content
ISO 16135, Industrial valves — Ball valves of thermoplastics materials
ISO 16136, Industrial valves — Butterfly valves of thermoplastics materials
ISO 16137, Industrial valves — Check valves of thermoplastics materials
ISO 16138, Industrial valves — Diaphragm valves of thermoplastics materials
ISO 16139, Industrial valves — Gate valves of thermoplastics materials
ISO 16770, Plastics — Determination of environmental stress cracking (ESC) of polyethylene — Full-notch creep
test (FNCT)
ISO/DIS 15494:2025(en)
ISO 16871, Plastics piping and ducting systems — Plastics pipes and fittings — Method for exposure to direct
(natural) weathering
ISO 18488, Polyethylene (PE) materials for piping systems — Determination of Strain Hardening Modulus in
relation to slow crack growth — Test method
ISO 18489:2015, Polyethylene (PE) materials for piping systems — Determination of resistance to slow crack
growth under cyclic loading — Cracked Round Bar test method
ISO 18553, Method for the assessment of the degree of pigment or carbon black dispersion in polyolefin pipes,
fittings and compounds
ISO 21787, Industrial valves — Globe valves of thermoplastics materials
EN 12099, Plastics piping systems — Polyethylene piping materials and components — Determination of
volatile content
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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/
3.1 Geometrical definitions
NOTE The symbols d and e correspond to d and e , given in other International Standards such as ISO 11922-1.
e ey y
3.1.1
nominal outside diameter
d
n
specified outside diameter assigned to a nominal size DN/OD
Note 1 to entry: The nominal inside diameter of a socket is equal to the nominal outside diameter of the corresponding pipe.
Note 2 to entry: It is expressed in millimetres.
3.1.2
outside diameter at any point
d
e
value of the measurement of the outside diameter through its cross-section at any point of the pipe, rounded
to the next greater 0,1 mm
3.1.3
mean outside diameter
d
em
value of the measurement of the outer circumference of the pipe or spigot end of a fitting in any cross-section
divided by π (= 3,142), rounded to the next greater 0,1 mm
3.1.4
mean inside diameter of a socket
arithmetical mean of two measured inside diameters perpendicular to each other
3.1.5
nominal size of flange
DN
numerical designation of the size of a flange for reference purposes and related to the manufacturing
dimension in millimetres
ISO/DIS 15494:2025(en)
3.1.6
out-of-roundness
ovality
difference between the maximum and the minimum outside diameter in the same cross-section of a pipe
or spigot
3.1.7
nominal wall thickness
e
n
numerical designation of the wall thickness of a component, which is a convenient round number,
approximately equal to the manufacturing dimension in millimetres (mm)
Note 1 to entry: For thermoplastics components conforming to the different annexes of ISO 15494, the value of the
nominal wall thickness, e , is identical to the specified minimum wall thickness at any point, e .
n min
3.1.8
wall thickness at any point
e
wall thickness at any point around the circumference of a component rounded to the next greater 0,1 mm
3.1.9
pipe series
S
dimensionless number for pipe designation conforming to ISO 4065
Note 1 to entry: The relationship between the pipe series, S, and the standard dimension ratio, SDR, is given by the
following formula as specified in ISO 4065:
SDR1−
S =
Note 2 to entry: Flanges are designated on the basis of PN.
3.1.10
standard dimension ratio
SDR
numerical designation of a pipe series, which is a convenient round number, approximately equal to the
dimension ratio of the nominal outside diameter, d , and the nominal wall thickness, e
n n
3.1.11
bend
Fitting curved in shape which the relative bending radius is ≥1 x d
n
Note 1 to entry: Bend fittings are manufactured in different ways e.g. injection moulded, prefabricated or swept bends etc.
3.2 Material definitions
3.2.1
Compound
homogenous extruded mixture of base polymer and additives, i.e. anti-oxidants, pigments, carbon black, UV-
stabilizers and others, at a dosage level necessary for the processing and use of components conforming to
the requirements of this document
3.2.2
Virgin material
material in a form such as granules or powder that has not been subjected to use or processing other than
that required for its manufacture, and to which no reworked or recyclable materials have been added

ISO/DIS 15494:2025(en)
3.2.3
Reworked material
plastics materials from rejected unused products or trimmings that have been manufactured and retained
within plants owned and operated by the same legal entity
3.2.4
Base polymer
Polymer produced by the material supplier for the manufacture of the compound according to this document.
3.2.5
Recyclate
plastics material resulting from the recycling of pre-consumer and post-consumer plastics products
Note 1 to entry: Also referred to as “secondary raw material” or “recycled plastics” or “regenerate”.
Note 2 to entry: Recycling can be chemical, physical or mechanical
3.2.6
melt mass-flow rate
MFR
value relating to the viscosity of the molten material at a specified temperature and load
Note 1 to entry: It is expressed in grams per 10 min (g/10 min).
3.3 Definitions related to material characteristics
3.3.1
lower confidence limit of the predicted hydrostatic strength
σ
LPL
quantity with the dimensions of stress, which represents the 97,5 % lower confidence limit of the predicted
hydrostatic strength at a temperature, θ, and time, t
Note 1 to entry: It is expressed in megapascals.
3.3.2
minimum required strength
MRS
value of σ at 20 °C and 50 years, rounded down to the next smaller value of the R10 series or the R20 series
LPL
[1] [2]
Note 1 to entry: The R10 series conforming to ISO 3 and the R20 series to ISO 497 .
3.3.3
design stress
σ
s
allowable stress for a given application at 20 °C that is derived from the MRS by dividing it by the coefficient C
Note 1 to entry: Design stress can be calculated using the following formula:
MRS
σ =
s
C
Note 2 to entry: It is expressed in megapascals.
3.3.4
design coefficient
C
coefficient with a value greater than one which takes into consideration service conditions as well as the
properties of the components of a piping system other than those represented in the lower confidence limit
Note 1 to entry: Minimum design coefficients are defined in ISO 12162.

ISO/DIS 15494:2025(en)
Note 2 to entry: There might be a need of additional service factors depending on the service conditions as described
in annex F to calculate the overall design coefficient.
3.4 Definitions related to service conditions
3.4.1
nominal pressure
PN
numerical designation used for reference purposes related to the mechanical characteristics of the
components of a piping system.
Note 1 to entry: A pressure, in bar, with the numerical value of PN is identical with the pressure, PS, as defined by
Reference [3] if both pressures are taken at 20 °C.
Note 2 to entry: For plastics piping systems conveying water, it corresponds to the maximum continuous operating
pressure in bar, which can be sustained for water at 20 °C for 50 years, based on the following minimum design
coefficient:
10σσ20
ss
PN= =
S SDR−1
[]
where
σ is expressed in MPa;
s
PN is expressed in bar.
5 2
Note 3 to entry: 1 bar = 0,1 MPa = 10 Pa; 1 MPa= 1 N/mm .
3.4.2
hydrostatic stress
σ
stress induced in the wall of a pipe when an internal hydrostatic pressure is applied
Note 1 to entry: The hydrostatic stress is related to the applied internal hydrostatic pressure, in bar p, the wall
thickness, e, at any point and the mean outside diameter, d , of a pipe and calculated using the following formula:
em
de−
em min
σ =p
20 e
min
Note 2 to entry: Formula is applicable for pipes only.
Note 3 to entry: It is expressed in megapascals.
3.4.3
long-term hydrostatic stress
σ
LTHS
quantity with the dimensions of stress, which represents the predicted mean strength at a temperature T
and time t
Note 1 to entry: It is expressed in megapascals.
[SOURCE: ISO 9080:2012, 3.9]
ISO/DIS 15494:2025(en)
4 Symbols and abbreviated terms
4.1 Symbols
C design coefficient
d outside diameter (at any point)
e
d mean outside diameter
em
d nominal outside diameter
n
DN nominal size of flange
e wall thickness (at any point)
e nominal wall thickness
n
h height of the flange adaptor shoulder
f
l free length
P internal hydrostatic pressure
p Highest crack-arrest pressure below the lowest crack-propagation pressure
c
p maximum allowable pressure
s
r radius of shoulder of flange adapter
f
T temperature
t time
ρ material density
σ hydrostatic stress
σ lower confidence limit of the predicted hydrostatic strength
LPL
σ long-term hydrostatic strength
LTHS
σ design stress
s
4.2 Abbreviated terms
MFR melt mass-flow rate
MOP maximum operating pressure
MRS minimum required strength
OIT oxidation induction time
PB polybutene
PE polyethylene
PE 80 polyethylene designated on the basis of the minimum required strength
PE 100 polyethylene designated on the basis of the minimum required strength

ISO/DIS 15494:2025(en)
PE 100-RC polyethylene designated on the basis of the minimum required strength and having raised crack
resistance
PE-RT polyethylene of raised temperature resistance
PE-X crosslinked polyethylene
PP polypropylene
PP-H polypropylene homopolymer
PP-B polypropylene block-copolymer
PP-R polypropylene random-copolymer
PP-RCT polypropylene random-copolymer with modified crystallinity
PN nominal pressure
S pipe series S
SDR standard dimension ratio
TIR true impact rate
5 Material
5.1 General
The material from which the components are made shall either be PB, PE, PE-RT, PE-X, or PP, as applicable, to
which are added those additives that are needed to facilitate the manufacture of pipes, fittings, and valves
conforming to this International Standard.
Note For PEX, the material is only existing in form of a component (crosslinked pipe)
The additives used shall be uniformly dispersed.
The additives shall not be dosed separately or together in quantities sufficient to impair the fabrication or
fusion characteristics of the component or to impair the chemical, physical, or mechanical characteristics as
specified in this International Standard.
5.2 Hydrostatic strength properties
The material shall be evaluated according to ISO 9080 by analysis of sustained pressure tests carried out in
accordance with ISO 1167-1 and ISO 1167-2 to classify the material in accordance with ISO 12162.
Conformity of the relevant material to the reference curves given for PB (see Annex A), PE (see Annex B),
PE-RT (see Annex C), PE-X (see Annex D), and PP (see Annex E) shall be proven according to the applicable
Annex of this International Standard.
For design, these reference curves shall be used as a basis.
Classification and verification of conformity to reference curves of the material shall be done by the
compound manufacturer.
NOTE In some cases, the component manufacturer can be regarded as the raw compound manufacturer.
Where fittings and valves are manufactured from the same material as pipes, the material classification and
verification of conformity to reference curves shall be the same as for pipes.

ISO/DIS 15494:2025(en)
For the classification and verification of conformity to reference curves of a material intended only for the
manufacture of fittings and valves, the test piece can be an injection-
...