ISO 4437-2

• Abstract:

  This document specifies the characteristics of pipes made from polyethylene (PE) for piping systems in the field of the supply of gaseous fuels. It also specifies the test parameters for the test methods referred to in this document. In conjunction with ISO 4437-1, ISO 4437-3, ISO 4437-4 and ISO 4437-5, this document is applicable to PE pipes, fittings and valves, their joints, and joints with components of PE and other materials intended to be used under the following conditions: a) a maximum operating pressure (MOP), up to and including 10 bar[1], at a reference temperature of 20 °C for design purposes; b) an operating temperature between −20 °C and 40 °C. For operating temperatures between 20 °C and 40 °C, derating coefficients are defined in ISO 4437-5. The ISO 4437 series covers a range of MOPs and gives requirements concerning colours. This document is applicable to three types of pipes: — PE pipes (outside diameter, dn) including any identification stripes; — PE pipes with co-extruded layers on either or both the outside and/or inside of the pipe (total outside diameter, dn) as specified in Annex A, where all PE layers have the same MRS rating; — PE pipes (outside diameter, dn) with a peelable and contiguous thermoplastics additional layer on the outside of the pipe ("coated pipe") as specified in Annex B. It is the responsibility of the purchaser or specifier to make the appropriate selections from these aspects, taking into account their particular requirements and any relevant national regulations and installation practices or codes. [1] 1 bar = 0,1 MPa = 105 Pa; 1 MPa = 1 N/mm2.

• Status: Not Published
• ICS: 75.200 - Petroleum products and natural gas handling equipment
• ICS: 83.140.30 - Plastics pipes and fittings for non fluid use
• Technical Committee: ISO/TC 138/SC 4 - Plastics pipes and fittings for the supply of gaseous fuels
• Drafting Committee: ISO/TC 138/SC 4/WG 3 - PE Pipe Systems
• Current Stage: 6000 - International Standard under publication
• Start Date: 18-Aug-2026
• Completion Date: 26-Sep-2026

• Revises: ISO 4437-2:2024 - Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 2: Pipes
• Effective Date: 21-Sep-2024

Overview

ISO 4437-2:2026 is part of the ISO 4437 series covering plastics piping systems intended for the supply of gaseous fuels. Specifically, ISO 4437-2 addresses the characteristics and specifications for pipes made from polyethylene (PE), which are widely used for gas distribution networks. This international standard also defines test parameters to ensure product quality, performance, and safety under varying environmental and operating conditions.

By working in conjunction with related parts of the ISO 4437 series, this standard helps users ensure that all PE piping components - including pipes, fittings, and valves - are compatible, reliable, and suitable for gas transport applications.

Key Topics

• Product Scope: Applies to PE pipes, including pipes with identification stripes, co-extruded layers (on inside and/or outside), and pipes with peelable thermoplastic coatings.
• Performance Range:
  • Maximum Operating Pressure (MOP): Up to and including 10 bar, at a design reference temperature of 20 °C.
  • Temperature Range: Operating temperatures from -20 °C to +40 °C are supported, with derating factors for temperatures between 20 °C and 40 °C specified in ISO 4437-5.
• Material Requirements: Defines the types of PE compounds, purity, and acceptable additives to maintain high performance and durability.
• Geometric and Mechanical Characteristics: Specifies requirements for pipe dimensions, wall thickness, out-of-roundness, ovality, and length. Ensures consistency in physical properties such as tensile strength, ring stiffness, and resistance to rapid crack propagation.
• Marking and Identification: Establishes mandatory pipe markings for traceability, specification identification, and color coding, which help ensure proper installation and maintenance.
• Testing Parameters: Refers to standardized test methods for validating pipe strength, flexibility, and performance as outlined in referenced ISO standards.

Applications

Pipes manufactured according to ISO 4437-2 are essential for:

• Natural Gas and Hydrogen Distribution: Used in underground and above-ground gas supply systems, including those carrying blends of hydrogen with natural gas.
• Residential and Industrial Gas Networks: Provides safe, robust, and corrosion-resistant pipelines for utility companies and end-users.
• Infrastructure Upgrades and Expansion: Supports modernization of existing gas distribution systems and new installations demanding high reliability.
• Jointing with Fittings and Valves: Ensures compatibility and secure joining with PE fittings/valves as well as hybrid joints with components made from other materials.
• Compliance with Regulatory Frameworks: Enables designers and contractors to meet national and regional regulations governing gas pipeline infrastructure.

Related Standards

ISO 4437-2 is used in conjunction with other standards in the ISO 4437 series and key supporting documents to address all aspects of PE piping systems:

• ISO 4437-1: General requirements and overall framework for PE piping systems for gaseous fuels.
• ISO 4437-3: Specifications for fittings for PE gas pipes.
• ISO 4437-4: Requirements for the valves used with PE pipes for gaseous fuels.
• ISO 4437-5: Describes fitness-for-purpose testing, providing derating coefficients for applications above 20 °C.
• ISO/TS 4437-7: Guidance on conformity assessment.
• ISO/TS 10839: Recommended practice for design, handling, and installation of PE piping systems.
• Supporting Test Standards: Includes ISO 1133, ISO 1167, ISO 3126, and others referenced within ISO 4437-2.

Practical Value

Implementing ISO 4437-2 ensures the consistent performance and long-term reliability of PE piping systems for gaseous fuels, supporting utilities, engineers, and installers in delivering safe and sustainable gas infrastructure solutions. The standard's comprehensive requirements contribute to product quality, safety, regulatory compliance, and ease of maintenance, making it an essential reference in the gas distribution sector.

FINAL DRAFT
International
Standard
ISO/FDIS 4437-2
ISO/TC 138/SC 4
Plastics piping systems for
Secretariat: NEN
the supply of gaseous fuels —
Voting begins on:
Polyethylene (PE) —
2026-06-22
Part 2:
Voting terminates on:
2026-08-17
Pipes
Systèmes de canalisations en plastique pour la distribution de
combustibles gazeux — Polyéthylène (PE) —
Partie 2: Tubes
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 SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/FDIS 4437-2:2026(en) © ISO 2026

FINAL DRAFT
ISO/FDIS 4437-2:2026(en)
International
Standard
ISO/FDIS 4437-2
ISO/TC 138/SC 4
Plastics piping systems for
Secretariat: NEN
the supply of gaseous fuels —
Voting begins on:
Polyethylene (PE) —
Part 2:
Voting terminates on:
Pipes
Systèmes de canalisations en plastique pour la distribution de
combustibles gazeux — Polyéthylène (PE) —
Partie 2: Tubes
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 SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
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Published in Switzerland Reference number
ISO/FDIS 4437-2:2026(en) © ISO 2026

ii
ISO/FDIS 4437-2:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
3.1 Terms related to geometry .3
3.2 Terms related to material .4
3.3 Terms related to joints .5
4 Symbols and abbreviated terms. 5
4.1 Symbols .5
4.2 Abbreviated terms .6
5 Material. 6
5.1 Compound for pipes .6
5.2 Compound for identification stripes .7
5.3 External reworked material and recyclate .7
6 General characteristics . 7
6.1 Appearance .7
6.2 Colour .7
7 Geometrical characteristics . 7
7.1 Measurement of dimensions .7
7.2 Mean outside diameters, out-of-roundness (ovality) and tolerances .8
7.3 Wall thicknesses and related tolerances .9
7.3.1 Minimum wall thicknesses.9
7.3.2 Tolerance on the wall thicknesses .10
7.4 Coiled pipe .11
7.5 Lengths .11
8 Mechanical characteristics .11
8.1 Conditioning.11
8.2 Requirements .11
9 Physical characteristics .15
9.1 Conditioning. 15
9.2 Requirements . 15
9.3 Circumferential reversion of pipes with d ≥ 250 mm.16
n
10 Performance requirements . .16
11 Marking . .16
11.1 General .16
11.2 Minimum required marking .16
Annex A (normative) Pipes with co-extruded layers .18
Annex B (normative) Pipes with peelable layer .20
Annex C (normative) Squeeze-off technique .22
Bibliography .23

iii
ISO/FDIS 4437-2:2026(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 4, Plastics pipes and fittings for the supply of gaseous fuels.
This third edition cancels and replaces the second edition (ISO 4437-2:2024), which has been technically
revised.
The main changes are as follows:
— reference to information related to the suitability of PE pipe systems for 100 % hydrogen and its
admixtures with natural gas has been made;
— terms and definitions have been distributed over ISO 4437-1, ISO 4437-2 and ISO 4437-3;
— subclause 5.1, about the compound for pipes, has been restructured;
— the minimum wall thickness for DN 400, DN 500, DN 560 and DN 630 SDR 11 have been aligned with
ISO 4065;
— the circumferential reversion has been moved to subclause 9.3;
— a conversion and normalisation step has been included to the requirement for the CRB;
— the performance requirements for joints have been mentioned more explicitly by adding Table 7.
A list of all parts in the ISO 4437 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.

iv
ISO/FDIS 4437-2:2026(en)
Introduction
The ISO 4437 series specifies the requirements for a piping system and its components made from
polyethylene (PE) compounds, which is intended to be used for the supply of gaseous fuels.
This document covers the characteristics of pipes.
Requirements and test methods for materials and components, other than pipes, are specified in ISO 4437-1,
ISO 4437-3 and ISO 4437-4.
Characteristics for fitness for purpose of the system are covered in ISO 4437-5. ISO/TS 4437-7 gives guidance
for assessment of conformity.
Recommended practice for design, handling and installation is given in ISO/TS 10839.
The ISO 4437 series covers a range of MOPs and gives requirements concerning colours.

v
FINAL DRAFT International Standard ISO/FDIS 4437-2:2026(en)
Plastics piping systems for the supply of gaseous fuels —
Polyethylene (PE) —
Part 2:
Pipes
1 Scope
This document specifies the characteristics of pipes made from polyethylene (PE) for piping systems in the
field of the supply of gaseous fuels.
NOTE 1 Additional information related to the installation of PE 100-RC systems is given in ISO 4437-1:2026,
Annex A.
NOTE 2 Additional information about the suitability of PE pipe systems for hydrogen and its admixtures is given in
ISO 4437-1:2026, Annex D.
It also specifies the test parameters for the test methods referred to in this document.
In conjunction with ISO 4437-1, ISO 4437-3, ISO 4437-4 and ISO 4437-5, this document is applicable to PE
pipes, fittings and valves, their joints, and joints with components of PE and other materials intended to be
used under the following conditions:
1)
a) a maximum operating pressure, MOP, up to and including 10 bar , at a design reference temperature of
20 °C;
b) an operating temperature between −20 °C and 40 °C.
For operating temperatures between 20 °C and 40 °C, derating coefficients are specified in ISO 4437-5.
This document is applicable to three types of pipe:
— PE pipes (outside diameter, d ) including any identification stripes;
n
— PE pipes with co-extruded layers on either or both the outside and/or inside of the pipe (total outside
diameter, d ) as specified in Annex A, where all PE layers have the same MRS rating;
n
— PE pipes (outside diameter, d ) with a peelable and contiguous thermoplastics additional layer on the
n
outside of the pipe ("coated pipe") as specified in Annex B.
It is the responsibility of the purchaser or specifier to make the appropriate selections from these aspects,
taking into account their particular requirements and any relevant national guidance or regulations and
installation practices or codes.
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 1133-1, Plastics — Determination of the melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of
thermoplastics — Part 1: Standard method
5 2
1) 1 bar = 0,1 MPa = 10 Pa; 1 MPa = 1 N/mm .

ISO/FDIS 4437-2:2026(en)
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, 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 3126, Plastics piping systems — Plastics components — Determination of dimensions
ISO 4437-1, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 1: General
ISO 4437-5, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 5: Fitness for
purpose of the system
ISO 6259-1, Thermoplastics pipes — Determination of tensile properties — Part 1: General test method
ISO 6259-3, Thermoplastics pipes — Determination of tensile properties — Part 3: Polyolefin pipes
ISO 9969, Thermoplastics pipes — Determination of ring stiffness
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 13477, Thermoplastics pipes for the conveyance of fluids — Determination of resistance to rapid crack
propagation (RCP) — Small-scale steady-state test (S4 test)
ISO 13478, Thermoplastics pipes for the conveyance of fluids — Determination of resistance to rapid crack
propagation (RCP) — Full-scale test (FST)
ISO 13479, Polyolefin pipes for the conveyance of fluids — Determination of resistance to crack propagation —
Test method for slow crack growth on notched pipes
ISO 13968, Plastics piping and ducting systems — Thermoplastics pipes — Determination of ring flexibility
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
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4437-1 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/

ISO/FDIS 4437-2:2026(en)
3.1 Terms related to geometry
3.1.1
nominal size
DN/OD
numerical designation of the size of a component related to the outside diameter
Note 1 to entry: It is a convenient round number approximately equal to the manufacturing dimension in millimetres
(mm). It is not applicable to components designated by thread size.
3.1.2
nominal outside diameter
d
n
specified outside diameter assigned to a nominal size (3.1.1)
Note 1 to entry: It is expressed in millimetres (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
minimum mean outside diameter
d
em,min
minimum value for the mean outside diameter (3.1.3) as specified for a given nominal size (3.1.1)
3.1.5
maximum mean outside diameter
d
em,max
maximum value for the mean outside diameter (3.1.3) as specified for a given nominal size (3.1.1)
3.1.6
out-of-roundness
ovality
difference between the measured maximum and the measured minimum outside diameter in the same
cross-section of a component
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 ISO 4437 series, the value of the nominal wall
thickness, e , is identical to the specified minimum wall thickness at any point (3.1.9), 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
Note 1 to entry: The symbol for the wall thickness of a fitting and valve body at any point is E.
3.1.9
minimum wall thickness at any point
e
min
minimum value for the wall thickness at any point (3.1.8) around the circumference of a component

ISO/FDIS 4437-2:2026(en)
3.1.10
tolerance
permitted variation of the specified value of a quantity, expressed as the difference between the permitted
maximum and the permitted minimum values
3.1.11
wall thickness tolerance
T
y
permitted difference between the wall thickness at any point (3.1.8) and the nominal wall thickness (3.1.7)
Note 1 to entry: e ≤ e ≤ e + T .
n n y
3.1.12
standard dimension ratio
SDR
numerical designation of a pipe series (3.1.13), which is a convenient round number, approximately equal to
the dimension ratio of the nominal outside diameter (3.1.2) and the nominal wall thickness (3.1.7)
3.1.13
pipe series
S
number for pipe designation
Note 1 to entry: The relationship between the pipe series, S, and the standard dimension ratio, SDR, (3.1.12) is given by
the following formula, as specified in ISO 4065.
SDR−1
S=
3.2 Terms related to material
3.2.1
compound
clearly defined homogenous extruded mixture of base polymer (3.2.4) (polyethylene) 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
3.2.2
virgin material
plastics material in the form of pellets or granules that has not been subjected to use or processing other
than that required for its initial manufacture
Note 1 to entry: Does not contain any reworked plastics material and/or plastics recyclate.
Note 2 to entry: Ethylene used for the polymerisation of the virgin material come from fossil sources (naphtha, oil, gas,
etc.), renewable sources or from chemical recycling process.
[11]
[SOURCE: EN 14541-1:2022 , 3.1, modified – powder, floc, etc. removed, Note 2 to entry removed, Note 3 to
entry removed and new Note 2 to entry added]
3.2.3
reworked material
plastics material from rejected unused products or trimmings capable of being reclaimed within the same
process that generated it
Note 1 to entry: Restrictions for use of reworked material for pipes are specified in ISO 4437-2, fittings in ISO 4437-3
and for valves in ISO 4437-4.
Note 2 to entry: Previously referred to as “own reprocessed material”.
[11]
[SOURCE: EN 14541-1:2022 , 3.2 –Note 1 to entry removed, Note 2 to entry changed]

ISO/FDIS 4437-2:2026(en)
3.2.4
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 in the ISO 4437 series is physical or mechanical
[11]
[SOURCE: EN 14541-1:2022 , 3.5 — Note 2 to entry changed]
3.2.5
base polymer
polymer produced by the material supplier for the manufacture of the compound (3.2.1)
3.3 Terms related to joints
3.3.1
squeeze-off
restriction of the gas flow to an acceptable rate through mechanical compression of the pipe
Note 1 to entry: See Annex C.
4 Symbols and abbreviated terms
4.1 Symbols
For the purpose of this document, the following symbols apply.
C design coefficient
d mean outside diameter
em
d maximum mean outside diameter
em,max
d minimum mean outside diameter
em,min
d nominal outside diameter
n
e wall thickness (at any point) around the circumference of a component
e minimum wall thickness (at any point)
min
e nominal wall thickness
n
strain hardening modulus
p
p critical pressure
c
p critical pressure obtained in full-scale test
c,full-scale
p critical pressure obtained in S4-test
cS4
S pipe series
T wall thickness tolerance
y
t time
θ temperature
σ lower confidence limit of the predicted hydrostatic strength
LPL
ISO/FDIS 4437-2:2026(en)
4.2 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
ANPT accelerated notched pipe test
CRB cracked round bar (test)
DN/OD nominal size, outside diameter-related
LPL lower predicted limit
MFR melt mass-flow rate
MOP maximum operating pressure
MRS minimum required strength
NPT notched pipe test
PE polyethylene
RC raised crack resistance
RCP rapid crack propagation
SCG slow crack growth
SDR standard dimension ratio
SHT strain hardening test
5 Material
5.1 Compound for pipes
The PE compound from which the pipes are made shall conform to ISO 4437-1.
The pipes shall be made from:
— virgin material, or
— reworked material from the extrusion process from the same PE compound from any of the manufacturer’s
own plants, or
— reworked material from the injection moulding process from the same PE compound from any of the
manufacturer’s own plants, or
— a mixture of two or more of the above, all from the same PE compound.
Reworked material may be used from:
— the base pipe of peelable layer pipe (coated pipe), and
— pipes with or without identification stripes.
For co-extruded pipes, see Annex A.
Reworked material from co-extruded pipes or from pipes reworked with the peelable layer attached shall
not be used.
ISO/FDIS 4437-2:2026(en)
A pipe can only be designated as a PE 100-RC pipe if it is produced from PE 100-RC materials, which fulfil
the requirements of ISO 4437-1:2026, Table 1 and 2, and is declared as PE 100-RC by the raw material
manufacturer, and fulfils the requirements of Table 3 and 5 of this document for PE 100-RC. A co-extruded
pipe made of a combination of PE 100 and PE 100-RC layers shall be regarded as PE 100 and marked
accordingly.
5.2 Compound for identification stripes
The stripe compound (see 6.2) shall be manufactured from a PE base polymer in accordance with ISO 4437-1,
which is used for a pipe compound for which fusion compatibility has been proven.
The compound used for identification stripes in the form of a pipe shall conform to the decohesion test
requirement of resistance to weathering as described in ISO 4437-1:2026, Table 2.
The OIT of the stripe compound shall be ≥ 20 min at 210 °C, measured by the compound supplier in
b
accordance with ISO 11357-6 (table footnote of Table 6 applies).
5.3 External reworked material and recyclate
Reworked material obtained from external sources and recyclate (pre-consumer and post-consumer
material) shall not be used.
6 General characteristics
6.1 Appearance
When viewed without magnification, the internal and external surfaces of pipes shall be smooth and clean
and shall have no scoring, cavities and other surface defects to an extent that would prevent conformity to
this document.
The ends of the pipe shall be cut cleanly and square to the axis of the pipe.
6.2 Colour
Pipes shall be black (PE 80, PE 100 and PE 100-RC), yellow (PE 80) or orange (PE 100 and PE 100-RC). In
addition, black PE 80 pipes may be identified by yellow stripes and black PE 100 and PE 100-RC pipes may be
identified by yellow or orange stripes, according to national preference.
The outer co-extruded layer of co-extruded pipes (see Annex A) or the outer peelable layer of peelable-layer
pipes (see Annex B) shall be either black, yellow or orange. In addition, identification stripes may be used
according to national preference.
National preference for colour can be stated in the National Foreword.
7 Geometrical characteristics
7.1 Measurement of dimensions
The dimensions of the pipe shall be measured in accordance with ISO 3126 and rounded to the next 0,1 mm.
In case of dispute, the measurements of dimensions shall be made directly after conditioning for at least 4 h
at (23 ± 2) °C and at least 24 h after manufacture.
Indirect measurement at the stage of production is allowed at shorter time periods, provided that evidence
is shown of correlation.
ISO/FDIS 4437-2:2026(en)
7.2 Mean outside diameters, out-of-roundness (ovality) and tolerances
The mean outside diameters of the pipe, d , shall conform to Table 1.
em
For straight pipes, the maximum out-of-roundness shall conform to Table 1. For coiled pipes, the maximum
out-of-roundness shall be specified by agreement between the manufacturer and the end user.
Care should be taken that packaging and storage does not lead to an increased out-of-roundness and
flattening of the pipe. Additional information is given in ISO/TS 10839.
Table 1 — Mean outside diameters and out-of-roundness
Dimensions in millimetres
Nominal outside Mean outside diameter Maximum out-
Nominal size
diameter of-roundness for
a
d d
DN/OD
em,min em,max
b
d straight pipes
n
16 16 16,0 16,3 1,2
20 20 20,0 20,3 1,2
25 25 25,0 25,3 1,2
32 32 32,0 32,3 1,3
40 40 40,0 40,4 1,4
50 50 50,0 50,4 1,4
63 63 63,0 63,4 1,5
75 75 75,0 75,5 1,6
90 90 90,0 90,6 1,8
110 110 110,0 110,7 2,2
125 125 125,0 125,8 2,5
140 140 140,0 140,9 2,8
160 160 160,0 161,0 3,2
180 180 180,0 181,1 3,6
200 200 200,0 201,2 4,0
225 225 225,0 226,4 4,5
250 250 250,0 251,5 5,0
280 280 280,0 281,7 9,8
315 315 315,0 316,9 11,1
355 355 355,0 357,2 12
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ISO/FDIS 4437-2:2026(en)
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ISO/TC 138/SC 4
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Secretariat: NEN
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Date: 2026-0306-05
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Plastics piping systems for the supply of gaseous fuels —
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Polyethylene (PE) — —
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Part 2: Style Definition
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Systèmes de canalisations en plastique pour la distribution de combustibles gazeux — Polyéthylène (PE) — —
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St l D fi iti
ISO/DISFDIS 4437-2:20252026(en)
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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, Formatted: Default Paragraph Font, French (France)
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
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at the address below or ISO’s member body in the country of the requester.
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ISO copyright office
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CP 401 • Ch. de Blandonnet 8
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CH-1214 Vernier, Geneva
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Phone: + 41 22 749 01 11
E-mail: [e-mail]
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Website: www.iso.org
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Published in Switzerland
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ii
ISO/FDIS 4437-2:2026(en)
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Contents
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Foreword . vi
Introduction . viii
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 3
3.1 Terms related to geometry . 3
3.2 Terms related to material . 5
3.3 Terms related to joints . 5
4 Symbols and abbreviated terms . 6
4.1 Symbols . 6
4.2 Abbreviated terms . 6
5 Material . 7
5.1 Compound for pipes . 7
5.2 Compound for identification stripes . 7
5.3 External reworked material and recyclate. 8
6 General characteristics . 8
6.1 Appearance . 8
6.2 Colour . 8
7 Geometrical characteristics . 8
7.1 Measurement of dimensions . 8
7.2 Mean outside diameters, out-of-roundness (ovality) and tolerances . 8
7.3 Wall thicknesses and related tolerances . 10
7.4 Coiled pipe . 14
7.5 Lengths. 14
8 Mechanical characteristics . 14
8.1 Conditioning . 14
8.2 Requirements . 14
9 Physical characteristics . 19
9.1 Conditioning . 19
9.2 Requirements . 19
9.3 Circumferential reversion of pipes with d ≥ 250 mm . 20
n
10 Performance requirements . 20
11 Marking . 21
11.1 General . 21
11.2 Minimum required marking . 21
Annex A (normative) Pipes with co-extruded layers . 23
Annex B (normative) Pipes with peelable layer . 25
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Annex C (normative) Squeeze-off technique . 27
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Bibliography . 28
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Foreword . v
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Introduction . vii
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1 Scope . 1
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© ISO 2026 – All rights reserved
iii
ISO/DISFDIS 4437-2:20252026(en)
2 Normative references . 1
3 Terms and definitions . 2
3.1 Terms related to geometry . 3
3.2 Terms related to material . 4
3.3 Terms related to joints . 5
4 Symbols and abbreviated terms . 5
4.1 Symbols . 5
4.2 Abbreviated terms . 6
5 Material . 6
5.1 Compound for pipes . 6
5.2 Compound for identification stripes . 7
5.3 External reworked and recycled material . 7
6 General characteristics . 7
6.1 Appearance . 7
6.2 Colour . 7
7 Geometrical characteristics . 8
7.1 Measurement of dimensions . 8
7.2 Mean outside diameters, out-of-roundness (ovality) and tolerances . 8
7.3 Wall thicknesses and related tolerances . 9
7.3.1 Minimum wall thicknesses . 9
7.3.2 Tolerance on the wall thicknesses . 10
7.4 Coiled pipe . 11
7.5 Lengths . 12
8 Mechanical characteristics . 12
8.1 Conditioning . 12
8.2 Requirements . 12
9 Physical characteristics . 16
9.1 Conditioning . 16
9.2 Requirements . 16
9.3 Circumferential reversion of pipes with d ≥ 250 mm . 17
n
10 Performance requirements . 17
11 Marking . 18
11.1 General . 18
11.2 Minimum required marking . 18
Annex A (normative) Pipes with co-extruded layers . 20
A.1 General . 20
A.2 Material . 20
A.3 Geometrical characteristics . 20
A.4 Mechanical characteristics . 20
A.5 Physical characteristics . 20
A.6 Marking . 20
A.7 Delamination . 20
A.8 Integrity of the structure . 21
Annex B (normative) Pipes with peelable layer . 22
B.1 General . 22
B.2 Geometrical characteristics . 22
B.3 Mechanical characteristics . 22
B.4 Physical characteristics . 22
iv
ISO/FDIS 4437-2:2026(en)
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B.5 Peelable layer adhesion . 22
B.6 Marking . 22
Annex C (normative) Squeeze-off technique . 24
Bibliography . 25

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© ISO 2026 – All rights reserved
v
ISO/DISFDIS 4437-2:20252026(en)
Foreword Formatted: Adjust space between Latin and Asian text,
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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.
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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
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Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
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This document was prepared by Technical Committee ISO/TC 138, Plastics pipes, fittings and valves for the
transport of fluids, Subcommittee SC 4, Plastics pipes and fittings for the supply of gaseous fuels.
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This third edition cancels and replaces the second edition (ISO 4437-2:2024), which has been technically
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
revised.
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
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The main changes are as follows:
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— — reference to information related to the suitability of PE pipe systems for 100 % hydrogen and its
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admixtures with natural gas has been made;
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— — terms and definitions have been distributed over ISO 4437-1, ISO 4437-2 and ISO 4437-3; Formatted: Default Paragraph Font
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— — subclause 5.1subclause 5.1, about the compound for pipes, has been restructured;
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— — the minimum wall thickness for DN 400, DN 500, DN 560 and DN 630 SDR 11 have been aligned with
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ISO 4065;
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— — the circumferential reversion has been moved to subclause 9.3;subclause 9.3;
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— — a conversion and normalisation step has been included to the requirement for the CRB;
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— — the performance requirements for joints have been mentioned more explicitly by adding
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Table 7.Table 7.
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A list of all parts in the ISO 4437 series can be found on the ISO website.
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vi
ISO/FDIS 4437-2:2026(en)
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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.
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© ISO 2026 – All rights reserved
vii
ISO/DISFDIS 4437-2:20252026(en)
Introduction
The ISO 4437 series specifies the requirements for a piping system and its components made from
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polyethylene (PE) compounds, which is intended to be used for the supply of gaseous fuels.
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This document covers the characteristics of pipes.
Requirements and test methods for materials and components, other than pipes, are specified in ISO 4437-1,
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ISO 4437-3 and ISO 4437-4.
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Characteristics for fitness for purpose of the system are covered in ISO 4437-5. ISO/TS 4437-7 gives guidance
for assessment of conformity.
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Recommended practice for design, handling and installation is given in ISO/TS 10839.
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The ISO 4437 series covers a range of MOPs and gives requirements concerning colours.
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viii
FINAL DRAFT International Standard ISO/FDIS 4437-2:2026(en)

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Plastics piping systems for the supply of gaseous fuels — Polyethylene
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(PE) — —
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Part 2:
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Pipes
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1 Scope
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This document specifies the characteristics of pipes made from polyethylene (PE) for piping systems in the
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field of the supply of gaseous fuels.
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NOTE 1 Additional information related to the installation of PE 100-RC systems is given in ISO 4437-1:2026, Annex A.
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NOTE 2 Additional information about the suitability of PE pipe systems for hydrogen and its admixtures is given in
ISO 4437-1:2026, Annex D.
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It also specifies the test parameters for the test methods referred to in this document.
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In conjunction with ISO 4437-1, ISO 4437-3, ISO 4437-4 and ISO 4437-5, this document is applicable to PE
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pipes, fittings and valves, their joints, and joints with components of PE and other materials intended to be
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used under the following conditions:
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1 1)
a) a) a maximum operating pressure, MOP, up to and including 10 bar , , at a design reference
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temperature of 20 °C;
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b) b) an operating temperature between −20 °C and 40 °C.
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For operating temperatures between 20 °C and 40 °C, derating coefficients are specified in ISO 4437-5.
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The ISO 4437 series covers a range of MOPs and gives requirements concerning colours.
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This document is applicable to three types of pipe: .
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— — PE pipes (outside diameter, d ) including any identification stripes;
n
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— — PE pipes with co-extruded layers on either or both the outside and/or inside of the pipe (total outside Formatted
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diameter, d ) as specified in Annex A,Annex A, where all PE layers have the same MRS rating;
n
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— — PE pipes (outside diameter, d ) with a peelable and contiguous thermoplastics additional layer on the .
n
outside of the pipe ("coated pipe") as specified in Annex B.Annex B.
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It is the responsibility of the purchaser or specifier to make the appropriate selections from these aspects,
taking into account their particular requirements and any relevant national guidance or regulations and Formatted
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installation practices or codes.
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1 5 2
1 bar = 0,1 MPa = 10 Pa; 1 MPa = 1 N/mm .
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1) 5 2 .
1 bar = 0,1 MPa = 10 Pa; 1 MPa = 1 N/mm .
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ISO/DISFDIS 4437-2:20252026(en)
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 1133--1, Plastics — Determination of the melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of
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thermoplastics — Part 1: Standard method
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ISO 1167--1:2006, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination
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of the resistance to internal pressure — Part 1: General method
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
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
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ISO 2505, Thermoplastics pipes — Longitudinal reversion — Test method and parameters
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ISO 3126, Plastics piping systems — Plastics components — Determination of dimensions
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ISO 4437--1, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 1: General
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ISO 4437--5, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 5: Fitness for
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purpose of the system
ISO 6259--1, Thermoplastics pipes — Determination of tensile properties — Part 1: General test method
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ISO 6259--3, Thermoplastics pipes — Determination of tensile properties — Part 3: Polyolefin pipes
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ISO 9969, Thermoplastics pipes — Determination of ring stiffness
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ISO 11922--1:2018, Thermoplastics pipes for the conveyance of fluids — Dimensions and tolerances — Part
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1: Metric series
ISO 11357--6, Plastics — Differential scanning calorimetry (DSC) — Part 6: Determination of oxidation
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induction time (isothermal OIT) and oxidation induction temperature (dynamic OIT)
ISO 13477, Thermoplastics pipes for the conveyance of fluids — Determination of resistance to rapid crack
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propagation (RCP) — Small-scale steady-state test (S4 test)
ISO 13478, Thermoplastics pipes for the conveyance of fluids — Determination of resistance to rapid crack
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propagation (RCP) — Full-scale test (FST)
ISO 13479, Polyolefin pipes for the conveyance of fluids — Determination of resistance to crack propagation
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— Test method for slow crack growth on notched pipes
ISO 13968, Plastics piping and ducting systems — Thermoplastics pipes — Determination of ring flexibility
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ISO 18488, Polyethylene (PE) materials for piping systems — Determination of Strain Hardening
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Modulusstrain 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
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growth under cyclic loading — Cracked Round Bar test method
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ISO 18553, Method for the assessment of the degree of pigment or carbon black dispersion in polyolefin pipes,
fittings and compounds
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ISO/FDIS 4437-2:2026(en)
3 Terms and definitions
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For the purposes of this document, the terms and definitions given in ISO 4437-1 and the following apply.
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ISO and IEC maintain terminology databases for use in standardization at the following addresses:
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— — ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
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— — IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
3.1 Terms related to geometry
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3.1.1 3.1.1 Adjust space between Asian text and numbers, Tab
stops: Not at 0.71 cm
nominal size
DN/OD
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numerical designation of the size of a component related to the outside diameter
and Asian text, Adjust space between Asian text and
numbers
Note 1 to entry: It is a convenient round number approximately equal to the manufacturing dimension in millimetres
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(mm). It is not applicable to components designated by thread size.
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3.1.2 3.1.2
nominal outside diameter Formatted: Regular Italic, Font: Bold, Not Italic
d
n
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...
specified outside diameter assigned to a nominal size (3.1.1)(3.1.1)
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Note 1 to entry: It is expressed in millimetres (mm).
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3.1.3 3.1.3
mean outside diameter
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d
em
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value of the measurement of the outer circumference of the pipe or spigot end of a fitting in any cross-section
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divided by π (= 3,142), rounded to the next greater 0,1 mm
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3.1.4 3.1.4
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minimum mean outside diameter
d Formatted: Font: Bold
em,min
minimum value for the mean outside diameter (3.1.3)(3.1.3) as specified for a given nominal size (3.1.1)(3.1.1)
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3.1.5 3.1.5 .
maximum mean outside diameter
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d
em,max
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maximum value for the mean outside diameter (3.1.3)(3.1.3) as specified for a given nominal size (3.1.1)(3.1.1)
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3.1.6 3.1.6
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out-of-roundness
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ovality
difference between the measured maximum and the measured minimum outside diameter in the same cross-
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section of a component
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3.1.7 3.1.7
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nominal wall thickness
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e
n
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numerical designation of the wall thickness of a component, which is a convenient round number,
approximately equal to the manufacturing dimension in millimetres (mm) Formatted: Font: 10 pt
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Note 1 to entry: For thermoplastics components conforming to the ISO 4437 series, the value of the nominal wall
thickness, en, is identical to the specified minimum wall thickness at any point (3.1.9),(3.1.9), emin. Formatted
...
© ISO 2026 – All rights reserved
ISO/DISFDIS 4437-2:20252026(en)

3.1.8 3.1.8
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wall thickness at any point
and Asian text, Adjust space between Asian text and
e
numbers
wall thickness at any point around the circumference of a component rounded to the next greater 0,1 mm
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Note 1 to entry: The symbol for the wall thickness of a fitting and valve body at any point is E.
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3.1.9 3.1.9
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
minimum wall thickness at any point
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
e
min
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minimum value for the wall thickness at any point (3.1.8)(3.1.8) around the circumference of a component
and Asian text, Adjust space between Asian text and
numbers
3.1.10 3.1.10
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tolerance
permitted variation of the specified value of a quantity, expressed as the difference between the permitted
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maximum and the permitted minimum values
Subscript
3.1.11 3.1.11
wall thickness tolerance
Ty
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permitted difference between the wall thickness at any point (3.1.8)(3.1.8) and the nominal wall thickness
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(3.1.7)(3.1.7)
Subscript
Note 1 to entry: en ≤ e ≤ en + Ty.
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3.1.12 3.1.12
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
standard dimension ratio
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
SDR
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numerical designation of a pipe series (3.1.13),(3.1.13), which is a convenient round number, approximately
and Asian text, Adjust space between Asian text and
equal to the dimension ratio of the nominal outside diameter (3.1.2)(3.1.2) and the nominal wall thickness
numbers
(3.1.7)(3.1.7)
3.1.13 3.1.13
pipe series
S
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number for pipe designation
Note 1 to entry: The relationship between the pipe series, S, and the standard dimension ratio, SDR, (3.1.12)(3.1.12) is
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given by the following formula, as specified in ISO 4065.
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stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
SDR−1
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
S =
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𝑆𝑆𝑆𝑆𝑆𝑆 −  1
𝑆𝑆=
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ISO/FDIS 4437-2:2026(en)
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3.2 Terms related to material
...
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3.2.1 3.2.1
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compound
clearly defined homogenous extruded mixture of base polymer (3.2.4)(3.2.4) (polyethylene) and additives (i.e.
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anti-oxidants, pigments, carbon black, UV-stabilizers and others) at a dosage level necessary for the processing
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and use of components
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3.2.2
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...
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...
3.2.2
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virgin material .
plastics material in the form of pellets or granules that has not been subjected to use or processing other than
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...
that required for its initial manufacture
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Note 1 to entry: Does not contain any reworked plastics material and/or plastics recyclate.
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Note 2 to entry: Ethylene used for the polymerisation of the virgin material come from fossil sources (naphtha, oil, gas,
etc.), renewable sources or from chemical recycling process. Formatted
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[11][11]
[SOURCE: EN 14541--1:2022, , 3.1, modified – powder, floc, etc. removed, Note 2 to entry removed, Note 3
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to entry removed and new Note 2 to entry added] .
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3.2.3 3.2.3
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reworked material
plastics material from rejected unused products or trimmings capable of being reclaimed within the same Formatted
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process that generated it
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Note 1 to entry: Restrictions for use of reworked material for pipes are specified in ISO 4437-2, fittings in ISO 4437-3 .
and for valves in ISO 4437-4.
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Note 2 to entry: Previously referred to as “own reprocessed material”. .
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[11][11]
[SOURCE: EN 14541--1:2022, , 3.2 –Note 1 to entry removed, Note 2 to entry changed]
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3.2.4 3.2.4 Formatted
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recyclate
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plastics material resulting from the recycling of pre-consumer and post-consumer plastics products
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Note 1 to entry: Also referred to as “secondary raw material” or “recycled plastics” or “regenerate”.
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Note 2 to entry: Recycling in the ISO 4437 series is physical or mechanical .
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[11][11]
[SOURCE: EN 14541--1:2022, , 3.5 — Note 2 to entry changed]
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3.2.5 3.2.5
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base polymer
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polymer produced by the material supplier for the manufacture of the compound (3.2.1)(3.2.1)
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3.3 Terms related to joints
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3.3.1 3.3.1
squeeze-off
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restriction of the gas flow to an acceptable rate through mechanical compression of the pipe
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© ISO 2026 – All rights reserved
ISO/DISFDIS 4437-2:20252026(en)
Note 1 to entry: See Annex C. See Annex C.
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4 Symbols and abbreviated terms
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4.1 Symbols
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For the purpose of this document, the following symbols apply.
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C design coefficient
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d mean outside diameter
em
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d maximum mean outside diameter
em,max
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d minimum mean outside diameter
em,min
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dn nominal outside diameter
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e wall thickness (at any point) around the circumference of a component
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e minimum wall thickness (at any point)
min
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en nominal wall thickness
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strain hardening modulus
p
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p critical pressure
c Formatted
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p critical pressure obtained in full-scale test Formatted
c,full-scale
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pcS4 critical pressure obtained in S4-test .
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S pipe series
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T wall thickness tolerance
y
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t time
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θ temperature
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σ lower confidence limit of the predicted hydrostatic strength
LPL
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4.2 Abbreviated terms
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For the purposes of this document, the following abbreviated terms apply.
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ANPT accelerated notched pipe test
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CRB cracked round bar (test)
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DN/OD nominal size, outside diameter-related
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LPL lower predicted limit
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MFR melt mass-flow rate
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MOP maximum operating pressure
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MRS minimum required strength
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NPT notched pipe test
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PE polyethylene
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ISO/FDIS 4437-2:2026(en)
RC raised crack resistance Formatted: Table body (+), Adjust space between Latin
and Asian text, Adjust space between Asian text and
RCP rapid crack propagation
numbers
SCG slow crack growth
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and Asian text, Adjust space between Asian text and
SDR standard dimension ratio
numbers
SHT strain hardening test
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5 Material
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5.1 Compound for pipes
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The PE compound from which the pipes are made shall conform to ISO 4437-1.
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The pipes shall be made from:
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— — virgin material, or
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— — reworked material from the extrusion process from the same PE compound from any of the
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manufacturer’s own plants, or .
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— — reworked material from the injection moulding process from the same PE compound from any of the
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manufacturer’s own plants, or
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— — a mixture of two or more of the above, all from the same PE compound.
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Reworked material may be
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