EN 1555-2:2025

SLOVENSKI STANDARD
01-december-2025
Cevni sistemi iz polimernih materialov za oskrbo s plinastimi gorivi - Polietilen
(PE) - 2. del: Cevi
Plastics piping systems for the supply of gaseous fuels - Polyethylene (PE) - Part 2:
Pipes
Kunststoff-Rohrleitungssysteme für die Gasversorgung - Polyethylen (PE) - Teil 2: Rohre
Systèmes de canalisations en plastique pour la distribution de combustibles gazeux -
Polyéthylène (PE) - Partie 2 : Tubes
Ta slovenski standard je istoveten z: EN 1555-2:2025
ICS:
83.140.30 Polimerne cevi in fitingi za Plastics pipes and fittings for
snovi, ki niso tekočine non fluid use
91.140.40 Sistemi za oskrbo s plinom Gas supply systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 1555-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2025
EUROPÄISCHE NORM
ICS 23.040.20 Supersedes EN 1555-2:2021
English Version
Plastics piping systems for the supply of gaseous fuels -
Polyethylene (PE) - Part 2: Pipes
Systèmes de canalisations en plastique pour la Kunststoff-Rohrleitungssysteme für die Gasversorgung
distribution de combustibles gazeux - Polyéthylène - Polyethylen (PE) - Teil 2: Rohre
(PE) - Partie 2 : Tubes
This European Standard was approved by CEN on 11 August 2025.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 1555-2:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
3.1 Terms related to geometry . 9
3.2 Terms related to material . 10
3.3 Terms related to joints . 11
4 Symbols and abbreviated terms . 11
4.1 Symbols. 11
4.2 Abbreviated terms . 12
5 Material . 12
5.1 Compound for pipes . 12
5.2 Compound for identification stripes . 13
5.3 External reworked material and recyclate . 13
6 General characteristics . 13
6.1 Appearance . 13
6.2 Colour . 13
7 Geometrical characteristics . 14
7.1 Measurement of dimensions. 14
7.2 Mean outside diameters, out-of-roundness (ovality) and tolerances . 14
7.3 Wall thicknesses and related tolerances . 15
7.3.1 Minimum wall thicknesses . 15
7.3.2 Tolerance on the wall thicknesses . 17
7.4 Coiled pipe . 18
7.5 Lengths . 18
8 Mechanical characteristics . 19
8.1 Conditioning . 19
8.2 Requirements . 19
9 Physical characteristics . 24
9.1 Conditioning . 24
9.2 Requirements . 24
9.3 Circumferential reversion of pipes with d ≥ 250 mm . 25
n
10 Performance requirements . 26
11 Marking . 26
11.1 General . 26
11.2 Minimum required marking . 26
11.3 Additional marking . 27
Annex A (normative) Pipes with co-extruded layers . 28
A.1 General . 28
A.2 Material . 28
A.3 Geometrical characteristics . 28
A.4 Mechanical characteristics . 28
A.5 Physical characteristics . 28
A.6 Marking . 28
A.7 Delamination . 29
A.8 Integrity of the structure . 29
Annex B (normative) Pipes with peelable layer . 30
B.1 General . 30
B.2 Geometrical characteristics . 30
B.3 Mechanical characteristics . 30
B.4 Physical characteristics . 30
B.5 Peelable layer adhesion . 30
B.6 Marking . 30
Annex C (normative) Squeeze-off technique . 32
Bibliography . 33

European foreword
This document (EN 1555-2:2025) has been prepared by Technical Committee CEN/TC 155 “Plastics
piping systems and ducting systems”, the secretariat of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2026, and conflicting national standards shall be
withdrawn at the latest by April 2026.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 1555-2:2021.
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 EN 1555-1, EN 1555-2 and EN 1555-3;
— subclause 5.1 about the compound for pipes has been restructured;
— the requirement for the compound used for identification stripes has been updated;
— 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;
— the mechanical characteristics of pipes with peelable layer have been updated;
— the requirement for the squeeze-off has been adjusted.
System Standards are based on the results of the work being undertaken in ISO/TC 138 “Plastics pipes,
fittings and valves for the transport of fluids”, which is a Technical Committee of the International
Organization for Standardization (ISO).
They are supported by separate standards on test methods to which references are made throughout the
System Standard.
The System Standards are consistent with general standards on functional requirements and on
recommended practice for installation.
EN 1555 consists of the following parts:
— EN 1555-1, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 1:
General;
— EN 1555-2, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 2: Pipes
(this document);
— EN 1555-3, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 3:
Fittings;
— EN 1555-4, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 4: Valves;
— EN 1555-5, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 5: Fitness
for purpose of the system;
In addition, the following document provides guidance on the assessment of conformity:
— CEN/TS 1555-7, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 7:
Guidance for assessment of conformity.
NOTE EN 12007-2 prepared by CEN/TC 234 “Gas infrastructure” deals with the recommended practice for
installation of plastics pipes system in accordance with EN 1555 (all parts).
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United
Kingdom.
Introduction
The EN 1555 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
EN 1555-1, EN 1555-3 and EN 1555-4.
Characteristics for fitness for purpose of the system are covered in EN 1555-5. CEN/TS 1555-7 gives
guidance for assessment of conformity.
Recommended practice for design, handling and installation is given in EN 12007-2.

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 EN 1555-1:2025,
Annex A.
NOTE 2 Additional information about the suitability of PE pipe systems for hydrogen and its admixtures is given
in EN 1555-1:2025, Annex B.
It also specifies the test parameters for the test methods referred to in this document.
In conjunction with EN 1555-1, EN 1555-3, EN 1555-4 and EN 1555-5, 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 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 EN 1555-5.
The EN 1555 series covers a range of MOPs and gives requirements concerning colours.
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
n
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 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.
EN 1555-1:2025, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 1:
General
EN 1555-5, Plastics piping systems for the supply of gaseous fuels — Polyethylene (PE) — Part 5: Fitness for
purpose of the system
EN 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 1133-1)

1 5 2
bar = 0,1 MPa. = 10 Pa; 1 MPa = 1 N/mm .
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 1167-1:2006)
EN 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 1167-2)
EN ISO 2505, Thermoplastics pipes — Longitudinal reversion — Test method and parameters (ISO 2505)
EN ISO 3126, Plastics piping systems — Plastics components — Determination of dimensions (ISO 3126)
EN ISO 6259-1, Thermoplastics pipes — Determination of tensile properties — Part 1: General test method
(ISO 6259-1)
EN ISO 6259-3, Thermoplastics pipes — Determination of tensile properties — Part 3: Polyolefin pipes
(ISO 6259-3)
EN ISO 9969, Thermoplastics pipes — Determination of ring stiffness (ISO 9969)
EN ISO 11357-6, Plastics — Differential scanning calorimetry (DSC) — Part 6: Determination of oxidation
induction time (isothermal OIT) and oxidation induction temperature (dynamic OIT) (ISO 11357-6)
EN 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 13477)
EN ISO 13478, Thermoplastics pipes for the conveyance of fluids — Determination of resistance to rapid
crack propagation (RCP) — Full-scale test (FST) (ISO 13478)
EN 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 13479:2022)
EN ISO 13968, Plastics piping and ducting systems — Thermoplastics pipes — Determination of ring
flexibility (ISO 13968)
ISO 11922-1:2018, Thermoplastics pipes for the conveyance of fluids — Dimensions and tolerances — Part
1: Metric series
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
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1555-1 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/
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 EN 1555 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
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 ≤≤ee + T
n ny
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 [8]:
SDR− 1
S=
3.2 Terms related to material
3.2.1
compound
clearly defined homogenous extruded mixture of base polymer (3.2.5) (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.
[SOURCE: EN 14541-1:2022, 3.1, modified – powder, floc, etc. removed, Note 2 to entry removed and
Note 3 to entry removed]
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 EN 1555-2, fittings in
EN 1555-3 and for valves in EN 1555-4.
Note 2 to entry: Previously referred to as “own reprocessed material”.
[SOURCE: EN 14541-1:2022, 3.2 –Note 1 to entry removed, Note 2 to entry changed]
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 can be chemical, physical or mechanical.
[SOURCE: EN 14541-1:2022, 3.5]
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
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 EN 1555-1.
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.
A pipe can only be designated as an PE 100-RC pipe if it is produced from PE 100-RC materials, which
fulfil the requirements of EN 1555-1:2025, Table 1 and Table 2, and is declared as PE 100-RC by the raw
material manufacturer, and fulfils the requirements of Table 3 and Table 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
EN 1555-1, 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 EN 1555-1:2025, Table 2.
The OIT of the stripe compound shall be ≥ 20 min at 210 °C, measured by the compound supplier in
b
accordance with EN 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 EN 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.
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 p
...