ISO 4437-1:2026

• Abstract:

  This document specifies materials and the general aspects of polyethylene (PE) piping systems in the field of the supply of gaseous fuels. NOTE For the purpose of this document, the term gaseous fuels includes, for example, natural gas, methane, butane, propane, hydrogen, manufactured gas, biogas, and mixtures of these gases. This document also specifies the test parameters for the test methods referred to in this document. In conjunction with ISO 4437-2, 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 maximum operating pressure (MOP) up to and including 10 bar1), at a design reference temperature of 20 °C; 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. The ISO 4437 series covers a range of MOPs and gives requirements concerning colours. 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 1)1 bar = 0,1 MPa = 105 Pa; 1 MPa = 1 N/mm2.

• Status: Published
• Publication Date: 13-Oct-2026
• 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: 6060 - International Standard published
• Start Date: 14-Oct-2026
• Completion Date: 14-Oct-2026

• Revises: ISO 4437-1:2024 - Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 1: General
• Effective Date: 21-Sep-2024

ISO 4437-1:2026 is an ISO International Standard for plastics piping systems for the supply of gaseous fuels, focused on polyethylene (PE) materials and the general requirements for the system. It specifies the materials, general system aspects, and test parameters used with the ISO 4437 series for PE pipes, fittings, valves, and their joints. It is written for compound manufacturers, pipe/fitting/valve makers, purchasers, specifiers, and others who need to qualify or select PE gas piping components.

What does ISO 4437-1:2026 specify?

ISO 4437-1:2026 specifies the material requirements and general rules for PE piping systems used with gaseous fuels. In practice, it sets the common framework for the rest of the ISO 4437 series, including the conditions under which the system is intended to be used.

The scope covers gaseous fuels such as natural gas, methane, butane, propane, hydrogen, manufactured gas, biogas, and mixtures of these gases. It applies, in conjunction with the companion parts, to PE pipes, fittings, valves, their joints, and joints between PE and other materials.

The document is organized into five clauses and four informative annexes.

Annex	What it covers
Annex A	Additional information related to the installation of PE 100-RC systems
Annex B	LPG and manufactured gas
Annex C	Resistance to rapid crack propagation (RCP)
Annex D	Additional information related to the suitability of PE pipe systems for 100% hydrogen and its admixtures with natural gas

The scope also sets the service window: maximum operating pressure (MOP) up to and including 10 bar at a design reference temperature of 20 °C, and operating temperatures between -20 °C and 40 °C. For 20 °C to 40 °C, derating coefficients are given in ISO 4437-5. The standard also notes that the ISO 4437 series covers a range of MOPs and colour requirements, so the purchaser or specifier must choose the appropriate combination for the local application.

What are the key requirements of ISO 4437-1:2026?

ISO 4437-1:2026 requires the PE compound, the fusion behaviour, and the material classification to be controlled and demonstrated by test. It is mainly a material and qualification standard, so the practical task is to prove that the chosen PE grade is suitable for gas service before it is used in pipes, fittings, or valves.

Material and compound requirements

Clause 5.1 requires pipes, fittings, and valves to be made from a PE compound that conforms to the document. The material is supplied as granules and must be suitable for producing components that meet ISO 4437-2, ISO 4437-3, or ISO 4437-4.

Clause 5.2 limits the additives and pigments to those needed for manufacture, fusibility, storage, and use. It also sets the compound colours: yellow for PE 80, orange for PE 100 and PE 100-RC, and black for all three grades. In practice, this helps buyers and manufacturers identify the intended material grade.

Compound test characteristics

Clause 5.2.3 and Tables 1 and 2 define the main property checks for compound in granule form and in pipe form. The listed checks cover density, oxidation induction time, melt mass-flow rate (MFR), volatile content, water content, carbon black content and dispersion, pigment dispersion, and resistance to slow crack growth (SCG) and other durability risks.

For pipe-form material, the document also uses tests for gas condensate resistance, weathering, resistance to rapid crack propagation (RCP), SCG for PE 80 and PE 100, accelerated SCG testing for PE 100-RC, and failure mode after a butt-fusion tensile test. In practice, these tests show whether the compound can survive handling, installation, pressure, and long-term service.

The compound manufacturer is responsible for proving conformity to these requirements.

Fusion compatibility

Clause 5.3 requires compounds meeting Table 1 to be fusible, and it requires the compound manufacturer to verify butt-fusion performance using the failure-mode test defined for fused joints. The document also treats conforming compounds as fusible to each other when requested and allows additional checks for special MFR ranges.

This matters because gas systems depend on sound joints, not just good pipe material. Fusion compatibility is therefore part of the material qualification, not an afterthought.

Classification and designation

Clause 5.4 classifies compounds by MRS (minimum required strength) as PE 80, PE 100, or PE 100-RC. The MRS is derived from long-term hydrostatic strength assessment using ISO 9080 and then classified in accordance with ISO 12162.

In practice, this is the link between material testing and the grade name used for procurement and design. If fittings or valves are made from the same compound as the pipes, they carry the same classification.

Design limits and formulation changes

Clause 5.5 sets the design coefficient, C, for gaseous-fuel piping systems at not less than 2 and ties design stress to the PE grade. It also notes that a higher design coefficient should be considered for LPG or manufactured gas.

Clause 5.6 says that changes in dosage levels or manufacturing process that affect performance can require a new qualification of the compound. For users, this is the quality-control trigger that matters when a supplier changes formulation or process.

Annex A adds installation-oriented information for PE 100-RC systems, including where the material is especially useful. Annex B gives extra caution for LPG and manufactured gas. Annex C explains the basis of RCP testing. Annex D gives hydrogen-related information and permeation guidance.

What terms does ISO 4437-1:2026 define?

• Lower confidence limit of the predicted hydrostatic strength (LPL) - the 97.5 % lower confidence limit for predicted hydrostatic strength at a given temperature and time.
• Minimum required strength (MRS) - the rounded-down LPL at 20 °C and 50 years; the document specifies only 8 MPa or 10 MPa values.
• Maximum operating pressure (MOP) - the highest continuous effective pressure allowed in the piping system.
• Design coefficient (C) - a factor greater than 1 that accounts for service conditions and component properties not captured by LPL alone.
• Design stress (σs) - the allowable stress at 20 °C, derived from MRS divided by C.
• Fusion compatibility - the ability of similar or dissimilar PE compounds to be fused into a joint.
• Electrofusion joint - a joint between an electrofusion fitting and a pipe or spigot end fitting made by heating the joint surfaces with the fitting’s embedded element.

Who uses ISO 4437-1:2026?

ISO 4437-1:2026 is used by compound manufacturers, pipe manufacturers, fitting and valve manufacturers, and laboratories that perform material qualification tests. These users need the document to prove compound properties, classify the material, and check fusion compatibility.

It is also relevant to purchasers and specifiers, network owners, installation companies, and conformity assessment teams. They use it when selecting PE grades, setting procurement requirements, deciding on installation methods, and checking whether a material is suitable for a specific gas service or local installation practice.

What changed in ISO 4437-1:2026 from the previous edition?

ISO 4437-1:2026 cancels and replaces ISO 4437-1:2024, and the foreword states that it has been technically revised. The changes named in the document are:

• terms and definitions were redistributed across ISO 4437-1, ISO 4437-2, and ISO 4437-3;
• a conversion and normalisation step was added to the cracked round bar (CRB) test requirement;
• recommended stress ranges for the CRB test and stress levels for the accelerated full notch creep test (AFNCT) were added;
• the strip-bend test and the crush test were added as alternatives to tests in ISO 13954;
• a requirement for electrofusion compatibility was added;
• information on suitability for 100% hydrogen and admixtures with natural gas was added.

Which standards are used with ISO 4437-1:2026?

ISO 4437-1:2026 relies on a set of companion parts and test standards.

• ISO 4437-2, ISO 4437-3, ISO 4437-4, ISO 4437-5 - the companion parts for pipes, fittings, valves, and fitness for purpose of the system.
• ISO 11295 - gives the rehabilitation-related terminology used in Annex A.
• ISO 12162 and ISO 9080 - support MRS classification and long-term strength assessment.
• ISO 11413 and ISO 11414 - give the preparation of electrofusion and butt-fusion test assemblies.
• ISO 1167-1 and ISO 1167-2 - cover resistance to internal pressure.
• ISO 6259-1 and ISO 6259-3 - cover tensile properties of pipes.
• ISO 13477, ISO 13478, and ISO 13479 - cover rapid crack propagation and crack propagation testing.
• ISO 13953, ISO 13954, ISO 13955, and ISO 21751 - cover joint decohesion or failure-mode testing for fused assemblies.
• ISO 1133-1, ISO 1183-1, ISO 1183-2, ISO 11357-6, ISO 15512, ISO 6964, ISO 18553, and EN 12099 - support the granule property checks in Table 1.
• ISO 16770, ISO 16871, ISO 18488, and ISO 18489 - support the SCG, weathering, and crack-growth-related tests used for PE 100-RC and other durability checks.

What does the ISO 4437-1:2026 document contain?

ISO 4437-1:2026 contains the system scope, the normative references, terms and definitions, symbols and abbreviated terms, and the material requirements for PE gas piping compounds. It also contains the main qualification framework for granules and pipe-form material, including the test methods used to prove density, thermal stability, flow, cleanliness, dispersion, fusion behaviour, and crack-growth resistance.

The document includes Table 1 for compound characteristics in granule form, Table 2 for characteristics in pipe form, and Table 3 for classification and designation. Annex A compares PE 100 and PE 100-RC behaviour and gives installation-related guidance, Annex B discusses LPG and manufactured gas, Annex C explains RCP and the test methods behind it, and Annex D gives hydrogen suitability discussion, permeation formulas, and a worked permeation example.

International
Standard
ISO 4437-1
Third edition
Plastics piping systems for
2026-10
the supply of gaseous fuels —
Polyethylene (PE) —
Part 1:
General
Systèmes de canalisations en plastique pour la distribution de
combustibles gazeux — Polyéthylène (PE) —
Partie 1: Généralités
Reference number
© ISO 2026
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 3
3.1 Terms related to material characteristics .3
3.2 Terms related to service conditions .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. 7
5.1 Material of the components .7
5.2 Compound .7
5.2.1 Additives and pigments .7
5.2.2 Colour .7
5.2.3 Characteristics .7
5.3 Fusion compatibility .11
5.4 Classification and designation . . 12
5.5 Design coefficient and design stress . 12
5.6 Change of compound formulation . 12
Annex A (informative) Additional information related to the installation of PE 100-RC systems .13
Annex B (informative) LPG and manufactured gas .15
Annex C (informative) Resistance to rapid crack propagation (RCP) .16
Annex D (informative) Additional information related to the suitability of PE pipe systems for
100 % hydrogen and its admixtures with natural gas .18
Bibliography .22

iii
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 4437-1:2024), which has been technically
revised.
The main changes are as follows:
— terms and definitions have been distributed over ISO 4437-1, ISO 4437-2 and ISO 4437-3;
— a conversion and normalisation step has been included in the requirements for the cracked round bar
(CRB) test;
— recommended stress ranges for the CRB and stress levels for the accelerated full notch creep test (AFNCT)
have been added;
— the strip-bend test (ISO 21751) and the crush test (ISO 13955) have been added as alternatives to tests
outlined in ISO 13954;
— a requirement for the electrofusion compatibility has been added;
— information related to the suitability of polyethylene (PE) pipe systems for 100 % hydrogen and its
admixtures with natural gas has been added.
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
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 materials and the general aspects of the plastics piping system.
Requirements and test methods for components of the piping system are specified in ISO 4437-2, 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.

v
International Standard ISO 4437-1:2026(en)
Plastics piping systems for the supply of gaseous fuels —
Polyethylene (PE) —
Part 1:
General
1 Scope
This document specifies materials and the general aspects of polyethylene (PE) piping systems in the field of
the supply of gaseous fuels.
NOTE For the purpose of this document, the term gaseous fuels includes, for example, natural gas, methane,
butane, propane, hydrogen, manufactured gas, biogas, and mixtures of these gases.
This document also specifies the test parameters for the test methods referred to in this document.
In conjunction with ISO 4437-2, 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.
The ISO 4437 series covers a range of MOPs and gives requirements concerning colours.
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
ISO 1167-1, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination of the
resistance to internal pressure — Part 1: General method
ISO 1167-2, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination of the
resistance to internal pressure — Part 2: Preparation of pipe test pieces
ISO 1183-1, Plastics — Methods for determining the density of non-cellular plastics — Part 1: Immersion method,
liquid pycnometer method and titration method
5 2
1) 1 bar = 0,1 MPa = 10 Pa; 1 MPa = 1 N/mm .

ISO 1183-2, Plastics — Methods for determining the density of non-cellular plastics — Part 2: Density gradient
column method
ISO 4437-2:2026, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 2: Pipes
ISO 4437-3, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 3: Fittings
ISO 4437-4, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 4: Valves
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 6964, Polyolefin pipes and fittings — Determination of carbon black content by calcination and pyrolysis —
Test method
ISO 9080, Plastics piping and ducting systems — Determination of the long-term hydrostatic strength of
thermoplastics materials in pipe form by extrapolation
ISO 11295, Plastics piping systems used for the rehabilitation of pipelines — Classification and overview of
strategic, tactical and operational activities
ISO 11357-6, Plastics — Differential scanning calorimetry (DSC) — Part 6: Determination of oxidation induction
time (isothermal OIT) and oxidation induction temperature (dynamic OIT)
ISO 11413:2019, Plastics pipes and fittings — Preparation of test piece assemblies between a polyethylene (PE)
pipe and an electrofusion fitting
ISO 11414:2009, Plastics pipes and fittings — Preparation of polyethylene (PE) pipe/pipe or pipe/fitting test
piece assemblies by butt fusion
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 13478, Thermoplastics pipes for the conveyance of fluids — Determination of resistance to rapid crack
propagation (RCP) — Full-scale test (FST)
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 13954, Plastics pipes and fittings — Peel decohesion test for polyethylene (PE) electrofusion assemblies of
nominal outside diameter greater than or equal to 90 mm
ISO 15512, Plastics — Determination of water content
ISO 16770, Plastics — Determination of environmental stress cracking (ESC) of polyethylene — Full-notch creep
test (FNCT)
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
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 terms and definitions given in ISO 4437-2, ISO 4437-3, ISO 11295 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/
3.1 Terms related to material characteristics
3.1.1
lower confidence limit of the predicted hydrostatic strength
σ
LPL
quantity that represents the 97,5 % lower confidence limit of the predicted hydrostatic strength at
temperature θ and time t
Note 1 to entry: It is expressed in megapascals (MPa).
3.1.2
minimum required strength
MRS
value of the lower confidence limit of the predicted hydrostatic strength (3.1.1) at 20 °C and 50 years, rounded
down to the next smaller value of the R10 series or the R20 series
Note 1 to entry: Only compounds with an MRS of 8 MPa or 10 MPa are specified in this document.
Note 2 to entry: The R10 series and the R20 series conform to ISO 3.
Note 3 to entry: It is expressed in megapascals (MPa).
[SOURCE: ISO 12162:2009, 3.3, modified — Note 1 to entry has been removed and replaced with new Notes
1 to 3 to entry.]
3.1.3
design coefficient
C
coefficient with a value greater than 1 which takes into consideration service conditions as well as
properties of the components of a piping system other than those represented in the lower confidence limit of
the predicted hydrostatic strength (3.1.1)
3.1.4
design stress
σ
s
allowable stress for a given application at 20 °C that is derived from the minimum required strength, MRS
(3.1.2), by dividing it by the design coefficient, C (3.1.3)
Note 1 to entry: This is demonstrated in the following formula:

MRS
 
s
C
Note 2 to entry: It is expressed in megapascals (MPa).
3.1.5
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 minutes (g/10 min).
3.2 Terms related to service conditions
3.2.1
gaseous fuel
substance that reacts exothermically with oxygen, which is in gaseous state at a temperature of 15 °C and at
atmospheric pressure
Note 1 to entry: The energy contained in the fuel is released when it burns.
Note 2 to entry: Typical gaseous fuels are for example natural gas, methane, butane, propane, hydrogen, manufactured
gas, biogas, . , and mixtures of these gases.
Note 3 to entry: Additional information about the suitability of PE pipe systems for hydrogen and its admixtures can
be found in Annex D.
3.2.2
maximum operating pressure
MOP
maximum effective pressure of the fluid in the piping system, which is allowed in continuous use
Note 1 to entry: It is expressed in bar. It takes into account the physical and the mechanical characteristics of the
components of a piping system. It is calculated using the following formula:
20MRS
MOP 
CSDR 1

Note 2 to entry: Research on long-term performance prediction of polyethylene gas distribution systems shows a
possible service life of at least 100 years; see References [18], [19] and [20].
3.2.3
design reference temperature
temperature for which the piping system is designed
Note 1 to entry: It is used as the base for further calculation when designing a piping system or parts of a piping
system for operating temperatures different from the design reference temperature (see ISO 4437-5).
3.2.4
manufactured gas
synthetic gas
gas which has been treated and can contain components that are not typical of natural gas
Note 1 to entry: Manufactured (synthetic) gases can contain substantial amounts of chemical species that are not
typical of natural gases or common species found in atypical proportions as in the case of wet and sour gases.
Note 2 to entry: Manufactured gases fall into two distinct categories, as follows:
a) those that are intended as synthetic or substitute natural gases, and that closely match true natural gases in both
composition and properties;
b) those that, whether or not intended to replace or enhance natural gas in service, do not closely match natural
gases in composition.
Case b) includes gases such as town gas, coke oven gas (undiluted), and LPG/air mixtures. None of which is
compositionally similar to a true natural gas (even though, in the latter case, it can be operationally interchangeable
with natural gas).
[SOURCE: ISO 14532:2014, 2.1.1.4]
3.3 Terms related to joints
3.3.1
butt fusion joint
joint made by heating the planed ends of pipes or spigot end fittings, the surfaces of which are fused together
by holding them against a flat heating plate until the polyethylene material reaches fusion temperature,
removing the heating plate quickly and pushing the two softened ends against one another
3.3.2
electrofusion joint
joint between a polyethylene electrofusion socket fitting or electrofusion saddle fitting and a pipe or spigot
end fitting, made by heating the electrofusion fitting by the Joule effect of the heating element incorporated
at their jointing surfaces, causing the material adjacent to them to melt, and the pipe and fitting surfaces to
fuse
3.3.3
fusion compatibility
ability of two similar or dissimilar polyethylene compounds to be fused together to form a joint
4 Symbols and abbreviated terms
4.1 Symbols
For the purposes of this document, the following symbols apply.
A surface area
C design coefficient
d nominal outside diameter
n
E wall thickness (at any point) of a fitting and valve body
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
L length of a pipe
Δp difference in partial pressure
p critical pressure
c
p critical pressure obtained in full-scale test
c,full-scale
p critical pressure obtained in S4-test
cS4
P permeation coefficient
coef
Q mass flow rate
m
Q permeated volume per time unit
V
S pipe series
T wall thickness tolerance
y
t time
θ temperature
ρ density
Δσ stress range
σ design stress
s
σ lower confidence limit of the predicted hydrostatic strength
LPL
4.2 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
AFNCT accelerated full notch creep test
ANPT accelerated notched pipe test
CRB cracked round bar (test)
DN/OD nominal size
FNCT full notch creep test
LPL lower predicted limit
LPG liquefied petroleum gas
MFR melt mass-flow rate
MOP maximum operating pressure
MRS minimum required strength
NPT notched pipe test
OIT oxidation induction time
PE polyethylene
PLT point load test
RC raised crack resistance
RCP rapid crack propagation
SCG slow crack growth
SDR standard dimension ratio
SHT strain hardening test
5 Material
5.1 Material of the components
The pipes, fittings and valves shall be made of a PE compound conforming to this document.
This document includes materials classified as PE 80 and PE 100.
Another type of PE 100, designated as PE 100-RC with enhanced resistance to SCG, is also included in this
document; see Annex A for additional information.
The material described in this document is a compound, which shall be supplied in the form of granules,
suitable for the production of pipes conforming to ISO 4437-2, fittings conforming to ISO 4437-3 or valves
conforming to ISO 4437-4.
5.2 Compound
5.2.1 Additives and pigments
The compound shall be made by adding to the PE base polymer only those additives and pigments (e.g. carbon
black) necessary for the manufacture of pipes, fittings and valves conforming to ISO 4437-2, ISO 4437-3 and
ISO 4437-4, as applicable, and for their fusibility, storage and use.
The carbon black used in the production of black compound shall have an average (primary) particle size of
10 nm to 25 nm. The particle size shall be declared by the carbon black supplier.
All additives and pigments shall be uniformly dispersed.
5.2.2 Colour
The colour of the compound shall be yellow (PE 80), orange (PE 100 and PE 100-RC) or black (PE 80, PE 100
and PE 100-RC).
5.2.3 Characteristics
5.2.3.1 Characteristics of the compound in the form of granules
The compound in the form of granules used for the manufacture of pipes, fittings and valves shall have
characteristics conforming to the requirements given in Table 1.
Table 1 — Characteristics of the compound in the form of granules
Test parameters
a
Characteristic Requirement Test method
Parameter Value
Compound density ≥ 930 kg/m Test temperature 23 °C ISO 1183-1 or
c
ISO 1183-2
b
Number of test pieces Shall conform to
ISO 1183-1 or ISO 1183-
c
d
Oxidation induction time (OIT) ≥ 20 min Test temperature 210 °C ISO 11357-6
(thermal stability)
Test atmosphere Oxygen
Sample mass (15 ± 2) mg
b
Number of test pieces 3
TTabablele 1 1 ((ccoonnttiinnueuedd))
Test parameters
a
Characteristic Requirement Test method
Parameter Value
Melt mass-flow rate (MFR) (0,20 ≤ MFR ≤ 1,40) g/10 min Loading mass 5 kg ISO 1133-1
Maximum deviation of ±20 % of the
Test temperature 190 °C
e, f
nominal value
Time 10 min
b
Number of test pieces Shall conform to
ISO 1133-1
b
Volatile content ≤ 350 mg/kg Number of test pieces 1 EN 12099
(equivalent to ≤ 0,035 % by mass)
g b
Water content ≤ 300 mg/kg Number of test pieces 1 ISO 15512
(equivalent to ≤ 0,03 % by mass)
h b
Carbon black content (2,0 to 2,5) % (mass fraction) Number of test pieces Shall conform to ISO 6964
i
ISO 6964
h j
Carbon black dispersion Grade ≤ 3 Preparation of test pieces Free ISO 18553
Rating of appearance A1, A2, A3 or B b
Number of test pieces Shall conform to
ISO 18553
k j
Pigment dispersion Grade ≤ 3 Preparation of test pieces Free ISO 18553
Rating of appearance A1, A2, A3 or B
b
Number of test pieces Shall conform to
ISO 18553
Resistance to SCG for PE 100- ≥ 53,0 MPa Test temperature 80 °C ISO 18488
p
RC
Thickness 300 µm
l
Strain hardening test (SHT)
Test speed Shall conform to
ISO 18488
b
Number of test pieces Shall conform to
ISO 18488
Resistance to SCG for PE 100- ≥ 1,5 × 10 cycles at an interpolated Test temperature 23 °C ISO 18489
RC stress range (Δσ ) of 12,5 MPa and
Type of test In air
l converted and normalised to a di-
Cracked round bar (CRB) test
ameter of 14 mm and an initial crack
Diameter of test piece 14 mm
m
length of 1,40 mm
Reference stress range 12,5 MPa
Target initial crack length Shall conform to
a * ISO 18489
ini
Waveform/frequency Sinusoid/10 Hz
b
Number of test pieces Shall conform to
ISO 18489
TTabablele 1 1 ((ccoonnttiinnueuedd))
Test parameters
a
Characteristic Requirement Test method
Parameter Value
Resistance to SCG for PE 100- ≥ 550 h at an interpolated reference Test temperature 90 °C ISO 16770
RC tensile stress of
p
Environment Lauramine oxide
n, o
4 MPa
Accelerated FNCT
l
Concentration 2 % (mass fraction)
(AFNCT) or
≥ 300 h at an interpolated reference
Test piece dimension 10 mm square
tensile stress of
q
n, o
Failure mode Brittle
5 MPa
b
Number of test pieces Shall conform to
ISO 16770
NOTE 1 Chemical Abstracts Service (CAS) Registry Number® is a trademark of the American Chemical Society (ACS). This information is given
for the convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products can be
used if they can be shown to lead to the same results.
NOTE 2 Arkopal® N100 is an example of a suitable product available commercially. This information is given for the convenience of users of
this document and does not constitute an endorsement by ISO of this product.
NOTE 3 Dehyton® PL is an example of a suitable product available commercially. This information is given for the convenience of users of this
document and does not constitute an endorsement by ISO of this product.
NOTE 4 The requirement for CRB of 1,5 × 10 cycles is under revision based on the analysis of current round robin performances.
a
Conformity to these requirements shall be proven by the compound manufacturer.
b
The number of test pieces given indicates the number required to establish a value for the characteristic described in this table. The number
of test pieces required for batch release testing and product verification testing should be listed in the manufacturer’s quality plan. Guidance
on assessment of conformity can be found in ISO/TS 4437-7.
c
ISO 1183-3 may be used as alternative. In case of dispute, ISO 1183-1 or ISO 1183-2 shall apply.
d
Test may be carried out at 200 °C or 220 °C provided that a clear correlation has been established. In case of dispute, the reference tempera-
ture shall be 210 °C. The test may be carried out on melt flow extrudate or pellet. In case of dispute, the test shall be carried out on pellet. The
sample thickness is free and not in accordance with ISO 11357-6.
e
Nominal value given by the compound manufacturer.
f
Materials with a nominal value of (0,15 ≤ MFR < 0,20) g/10 min may be introduced. In such case 5.3.1 applies. The lowest MFR value resulting
from the maximum lower deviation of the nominal value is to be not less than 0,15 g/10 min.
g
Volatile or water content shall be measured. In case of dispute, the requirement for water content shall be used, using method B.2 of
ISO 15512. As an alternative method, ISO 760 may be used. The requirement applies to the compound manufacturer at the stage of manufactur-
ing and to the compound user at the stage of processing (if the water content exceeds the limit, drying is required prior to use).
h
Only for black compounds.
i
In case of dispute, Method A “Electric Tube Furnace” shall be used.
j
In case of dispute, the test pieces shall be prepared by the microtome method.
k
Only for non-black compounds.
l
These tests are only performed on PE 100-RC material.
m
For interpolation, CRB test target stress ranges should be chosen between 11,5 MPa and 13,5 MPa. Target stress ranges of 11,5 MPa,
12,2 MPa, 12,8 MPa and 13,5 MPa are recommended. After the test the stress range is to be converted and normalised to a diameter of 14 mm
and an initial crack length of 1,4 mm, in accordance with ISO 18489:2015, Annex A.
n
This requirement correlates to a test in accordance with ISO 16770, with a stress of 4 MPa at 80 °C in nonylphenol ethoxylate with no failure
[21]
for a period of 8 760 h and may be used as an alternative . Nonylphenol ethoxylate (CAS Registry Number® 9016-45-9) with a trade name of
Arkopal® N100 is used for this test with a concentration for testing of 2 % (mass fraction). In case of dispute, the AFNCT applies.
o
AFNCT test stress levels should be chosen close to the nominal stress in order to avoid long testing times. Test stress levels of 3,7 MPa,
3,9 MPa, 4,2 MPa, 4,5 MPa for the 4 MPa reference stress, and 4,7 MPa, 4,9 MPa and 5,2 MPa and 5,5 MPa for the 5 MPa reference stress are
recommended.
p
Lauramine oxide (CAS Registry Number® 85408-49-7) is commercially available as Dehyton® PL. The dilution of the lauramine oxide in the
product shall be taken into account when calculating the concentration of 2 % (mass fraction). For example, when Dehyton® PL is used, it is
already diluted to 30 % (mass fraction). Therefore, 6,67 % (mass fraction) of Dehyton® PL is needed to obtain 2 % (mass fraction) lauramine
oxide.
q
Test specimens tested at a tensile stress of ≥ 4 MPa (or ≥ 5 MPa) may be terminated once the minimum failure time of 550 h (or 300 h) has
been achieved, in which case there is no failure mode. Test specimens tested at a tensile stress of < 4 MPa (or < 5 MPa) may be terminated once
the interpolated failure time of 550 h (at the reference tensile stress of 4 MPa) or 300 h (at the reference tensile stress of 5 MPa) is achieved,
taking possible scatter in the actual tensile stress into account.
5.2.3.2 Characteristics of the compound in the form of pipe
Unless otherwise specified by the applicable test method, the test pieces shall be conditioned at (23 ± 2) °C
before testing in accordance with Table 2.

Table 2 — Characteristics of compound in the form of pipe
Test parameters
a
Characteristic Requirement Test method
Parameter Value
Resistance to gas No failure during the Conditioning period (pipe 1 500 h in air at 23 °C ISO 1167-1 and ISO 1167-2
condensate test period of any test filled with condensate)
piece
End caps Type A
Test temperature 80 °C
Orientation Free
b
Number of test pieces 3
Circumferential (hoop) stress 2,0 MPa
Pipe dimensions:
d 32 mm
n
e 3 mm
n
c
Type of test Synthetic condensate inter-
nal and water external to the
test piece (“liquid-in-water”)
Test period ≥ 20 h
Resistance to The weathered test Preconditioning (weathering): ≥ 3,5 GJ/m ISO 16871
d, e
weathering pieces shall fulfil the cumulative radiant exposure
requirements of the fol-
b
Number of test pieces See below
lowing characteristics,
a), b) and c) below:
f
a)  Decohesion of an elec- a)  Sample prepared in accordance with ISO 11413:2019, Jointing condition 1: a) ISO 13954
trofusion joint 23 °C; ≤ 33 % brittle failure
d : 110 mm SDR 11
n
b)  Hydrostatic strength b)  Shall conform to ISO 4437-2:2026, Table 4 b) ISO 1167-1 and
(1 000 h at 80 °C) d : 32 mm SDR 11 (preferred) or 110 mm SDR 11 ISO 1167-2
n
c)  Elongation at break c)  Shall conform to ISO 4437-2:2026, Table 4 c) ISO 6259-1 and
d : 32 mm SDR 11 (preferred) or 110 mm SDR 11 ISO 6259-3
n
h
Resistance to rapid crack p ≥ 1,5 MOP Pipe dimension d : 250 mm SDR 11 ISO 13477
c n
propagation (RCP) with
Test temperature 0 °C
g
p = 3,6 p + 2,6
(Critical pressure, p ) c cS4
c
Pressurizing fluid air
b
Number of test pieces Shall conform to
ISO 13477
Resistance to SCG for No failure during the Pipe dimension d : 110 mm SDR 11 ISO 13479
n
PE 80 and PE 100 test period of any test
Test temperature 80 °C
i piece
Notched pipe test (NPT)
Internal test pressure for:
PE 80, SDR 11 8,0 bar
PE 100, SDR 11 9,2 bar
Test period ≥ 500 h
Type of test Water internal and water
external to the test piece
(“water-in-water”)
b
Number of test pieces Shall conform to
ISO 13479
Resistance to SCG for No failure during the Pipe dimension d : 110 mm SDR 11 ISO 13479
n
PE 100-RC test period of any test
Test temperature 80 °C
piece
Accelerated notched pipe
j
Internal test pressure for:
test (ANPT)
PE 100-RC, SDR 11 9,2 bar
k
Test period ≥ 300 h
Type of test Water internal and detergent
solution external to the test
l
piece (“water-in-liquid”)
b
Number of test pieces Shall conform to ISO 13479

TTabablele 2 2 ((ccoonnttiinnueuedd))
Test parameters
a
Characteristic Requirement Test method
Parameter Value
Determination of the fail- Test to failure: Pipe dimension d : 110 mm SDR 11 ISO 13953
n
ure mode in a tensile test Ductile – pass
Test temperature 23 °C
on a butt-fusion weld Brittle – fail
b
Number of test pieces Shall conform to ISO 13953
NOTE 1 Chemical Abstracts Service (CAS) Registry Number® is a trademark of the American Chemical Society (ACS). This information is given
for the convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products may be
used if they can be shown to lead to the same results.
NOTE 2 Arkopal® N100 is an example of a suitable product available commercially. This information is given for the convenience of users of
this document and does not constitute an endorsement by ISO of this product.
NOTE 3 Dehyton® PL is an example of a suitable product available commercially. This information is given for the convenience of users of this
document and does not constitute an endorsement by ISO of this product.
a
Conformity to these requirements shall be proven by the compound manufacturer.
b
The number of test pieces given indicates the number required to establish a value for the characteristic described in this table. The number
of test pieces required for batch release testing and product verification testing should be listed in the manufacturer’s quality plan. Guidance
on assessment of conformity can be found in ISO/TS 4437-7.
c
50 % n-decane and 50 % (mass fraction) 1-3-5 trimethylbenzene.
d
Only for non-black compounds.
e 2
For outdoor storage for one year a cumulative radiant exposure of up to 7 GJ/m is valid based on current measurements. Information on
regional levels of UV radiation can be found on web pages of national authorities e.g. meteorological institutes.
f
Alternatively, the strip-bend test according to ISO 21751 or the crush test according to ISO 13955 may be used.
g
If the requirement is not met or S4 test equipment is not available, then (re)testing by using the full-scale test shall be performed in accord-
ance with ISO 13478. In this case: p = p . Further information is given in Annex C.
c c,full-scale
h
For PE 80 materials, smaller pipe diameters may be used for the RCP test. RCP performance is dependent on wall thickness. Pipe of nominal
wall thickness e ≥ 15 mm shall be tested for RCP performance.
n
i
This test is not performed on PE 100-RC materials.
j
The ANPT is specifically for testing PE 100-RC materials.
k
This requirement correlates to a test on 110 mm diameter SDR 11 PE 100-RC pipe in accordance with ISO 13479, at a pressure level of 9,2 bar
[22][23][24]
at 80 °C, water-in-water, with no failure in a test period of 8 760 h, and may be used as an alternative . In case of dispute, the ANPT
applies, see ISO 13479:2022, Annex D.
l
Nonylphenol ethoxylate (CAS Registry Number® 9016-45-9) with a trade name of Arkopal® N100 is used for this test with a concentration for
testing using a 2 % (mass fraction) aqueous solution. This detergent will be replaced by lauramine oxide (CAS Registry Number® 85408–49– ®
7), which is commercially available as Dehyton PL. The requirement for the ANPT using lauramine oxide is under development at the time of
publication of this document.
5.3 Fusion compatibility
5.3.1 The compounds conforming to Table 1 shall be fusible. The compound manufacturer shall check that
the requirement for the failure mode in a tensile test given in Table 2 is fulfilled for a butt fusion joint. The
test sample shall be prepared by using the parameters specified in ISO 11414:2009, Annex A, at an ambient
temperature of (23 ± 2) °C, from pipes both manufactured from that compound.
Fusion compatibility shall be demonstrated by the compound manufacturer for each compound of their own
product range.
For nominal (0,15 ≤ MFR < 0,20) g/10 min pipe compounds, butt fusion compatibility shall be tested in
accordance with ISO 13953 on pipes d ≥ 200 mm and e ≥ 20 mm instead of the tensile test on d 110 mm
n n n
pipes as specified in Table 2.
For nominal (0,15 ≤ MFR < 0,20) g/10 min pipe compounds, electrofusion compatibility shall be tested using
the normal conditions in accordance with ISO 4437-5 on pipes d ≥ 250 mm, SDR 11, with fittings made from
n
PE 100 or PE 100-RC.
5.3.2 Compounds conforming to Table 1 are considered fusible to each other. If requested, the compound
manufacturer shall demonstrate this by checking that the requirement for the failure mode in a tensile
test given in Table 2 is fulfilled for a butt fusion joint prepared by using the parameters as specified in
ISO 11414:2009, Annex A, at an ambient temperature of (23 ± 2) °C from two pipes manufactured from the
compounds from their own range covered by this request.

5.4 Classification and designation
Compounds shall be designated by the type of PE material. The minimum required strength (MRS) shall
conform to Table 3 when tested in the form of pipe.
Table 3 — Classification and designation of compounds
Classification by MRS
Designation
MPa
8 PE 80
PE 100
PE 100-RC
The compound shall be evaluated in accordance with ISO 9080 on pipes at least at three temperatures, where
the first temperature is either 20 °C or 23 °C, and the second temperature is 80 °C or alternatively 95 °C, and
the third temperature is free between 30 °C and 70 °C, to find the σ . The MRS value shall be derived from
LPL
the σ and the compound shall be classified by the compound manufacturer in accordance with ISO 12162.
LPL
At the highest tested temperature of 80 °C or 95 °C, there shall be no knee detected in the regression curve
at a time t < 5 000 h.
The conformity of the designation of the compound to the classification given in Table 3 shall be demonstrated
by the compound manufacturer.
Where fittings or valves are manufactured from the same compound as pipes, then the material classification
shall be the same as for pipes.
For the classification of a compound intended only for the manufacture of fittings or valves, test pieces in the
form of extruded pipe made from the compound shall be used.
5.5 Design coefficient and design stress
The design coefficient, C, for pipes, fittings and valves for the supply of gaseous fuels shall be greater than or
equal to 2. The maximum value for the design stress, σ , shall be 4,0 MPa for PE 80 and 5,0 MPa for PE 100
s
and PE 100-RC materials.
A higher design coefficient, C, should be considered for the use of liquefied petroleum gas (LPG) or
manufactured gas (see Annex B).
5.6 Change of compound formulation
Any change in the dosage levels or manufacturing process of the compound affecting its performance can
require a new qualification of the compound.
[15]
NOTE Guidance can be found in ISO/TS 4437-7 and PPI TR-3 .

Annex A
(informative)
Additional information related to the installation of PE 100-RC
systems
A.1 Pipe material
Polyethylene materials have been used for the manufacture of piping systems for gas supply since the
1960s, offering a corrosion resistant system. Since this time, the materials used for these systems have been
developed and improved in terms of performance, potential pressure rating, and above all, durability and
resistance to RCP.
While initial improvements increased the material’s pressure resistance (PE 63, PE 80 and PE 100),
[25]
considerable progress has been made in recent years in increasing the resistance to SCG.
The main technical advantage of PE 100-RC is that it is even more resistant to SCG. PE 100-RC materials for
piping systems require a separate number of tests to assess SCG performance. Piping systems made from
such materials are expected to exhibit greater durability in alternative trenchless installation methods
where more surface damage could be encountered or wh
...