ISO 4427-3:2007

INTERNATIONAL ISO
STANDARD 4427-3
First edition
2007-08-01

Plastics piping systems — Polyethylene
(PE) pipes and fittings for water supply —
Part 3:
Fittings
Systèmes de canalisations en plastique — Tubes et raccords en
polyéthylène (PE) destinés à l'alimentation en eau
Partie 3: Raccords




Reference number
ISO 4427-3:2007(E)
©
ISO 2007

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ISO 4427-3:2007(E)
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ii © ISO 2007 – All rights reserved

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ISO 4427-3:2007(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 2
3 Terms, definitions, symbols and abbreviated terms. 3
4 Material . 4
4.1 PE compound. 4
4.2 Material for non-polyethylene parts. 4
5 General characteristics . 5
5.1 Appearance . 5
5.2 Design . 5
5.3 Colour . 5
5.4 Electrical characteristics for electrofusion fittings.5
5.5 Appearance of factory-made joints. 5
5.6 Effect on water quality. 5
6 Geometrical characteristics. 6
6.1 Measurement of dimensions . 6
6.2 Dimensions of electrofusion sockets. 6
6.3 Dimensions of spigot fittings . 8
6.4 Dimensions of socket fusion fittings. 8
6.5 Dimensions of fabricated fittings. 8
6.6 Dimensions of electrofusion saddle fittings. 10
6.7 Dimensions of mechanical fittings . 11
6.8 Dimensions of loose backing flanges and flange adapters . 11
7 Mechanical characteristics . 11
7.1 General. 11
7.2 Conditioning. 11
7.3 Requirements . 12
7.4 Retest in case of failure at 80 °C . 13
7.5 Performance requirements . 14
8 Physical characteristics. 14
8.1 Conditioning. 14
8.2 Requirements . 14
9 Chemical resistance of fittings in contact with chemicals. 15
10 Performance requirements . 15
11 Marking . 15
11.1 General. 15
11.2 Minimum required marking. 15
11.3 Fusion system recognition . 16
12 Packaging . 16
Annex A (normative) Socket fusion fittings . 17
Annex B (normative) Fabricated fittings. 19
Annex C (informative) Examples of typical terminal connections for electrofusion fittings . 26
Annex D (normative) Short-term pressure test method. 28
Annex E (normative) Tensile test for fitting/pipe assemblies. 30
Bibliography . 31
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ISO 4427-3:2007(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 4427-3 was prepared by Technical Committee ISO/TC 138, Plastics pipes, fittings and valves for the
transport of fluids, Subcommittee SC 2, Plastics pipes and fittings for water supplies.
ISO 4427 consists of the following parts, under the general title Plastics piping systems — Polyethylene (PE)
pipes and fittings for water supply:
⎯ Part 1: General
⎯ Part 2: Pipes
⎯ Part 3: Fittings
⎯ Part 5: Fitness for purpose of the system
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ISO 4427-3:2007(E)
Introduction
ISO 4427, the system standard, specifies the requirements for a piping system and its components when
made from polyethylene (PE). The piping system is intended to be used for water supply intended for human
consumption, including the conveyance of raw water prior to treatment and that of water for general purposes.
In respect of potential adverse effects on the quality of water intended for human consumption caused by the
products covered by ISO 4427:
a) ISO 4427 provides no information as to whether the products may be used without restriction;
b) existing national regulations concerning the use and/or the characteristics of these products are in force.
NOTE Guidance for assessment of conformity can be found in Bibliographical references [8] and [9].

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INTERNATIONAL STANDARD ISO 4427-3:2007(E)

Plastics piping systems — Polyethylene (PE) pipes and fittings
for water supply —
Part 3:
Fittings
1 Scope
This part of ISO 4427 specifies the general aspects of fittings made from polyethylene (PE) for piping systems
intended for the conveyance of water for human consumption, including raw water prior to treatment and
water for general purposes.
It also specifies the test parameters for the test methods to which it refers.
In conjunction with the other parts of ISO 4427, it is applicable to PE fittings, their joints, to joints with
components of PE and to joints with mechanical fittings of other materials, intended to be used under the
following conditions:
1)
a) a maximum operating pressure (MOP) up to and including 25 bar ;
b) an operating temperature of 20 °C as the reference temperature.
NOTE 1 For applications operating at constant temperatures greater than 20 °C and up to 40 °C, see ISO 4427-1:2007,
Annex A.
NOTE 2 ISO 4427 covers a range of maximum operating pressures and gives requirements concerning colours and
additives. 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.
It is applicable to fittings of the following types:
⎯ fusion fittings — electrofusion fittings, butt fusion fittings and socket fusion fittings (see Annex A);
⎯ fabricated fittings (see Annex B);
⎯ mechanical fittings;
⎯ flanged fittings.

5 2

1) 1 bar = 0,1 MPa = 10 Pa; 1 MPa = 1 N/mm .
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ISO 4427-3:2007(E)
2 Normative references
The following referenced documents are indispensable for the application 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 1133:2005, Plastics — Determination of the melt mass-flow rate (MFR) and the melt volume-flow rate
2)
(MVR) of thermoplastics
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 1167-3, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination of
the resistance to internal pressure — Part 3: Preparation of components
ISO 3126, Plastics piping systems — Plastics components — Determination of dimensions
ISO 4427-1:2007, Plastics piping systems — Polyethylene (PE) pipes and fittings for water supply — Part 1:
General
ISO 4427-2:2007, Plastics piping systems — Polyethylene (PE) pipes and fittings for water supply — Part 2:
Pipes
ISO 4427-5, Plastics piping systems — Polyethylene (PE) pipes and fittings for water supply — Part 5: Fitness
for purpose of the system
ISO 4433-1, Thermoplastics pipes — Resistance to liquid chemicals — Classification — Part 1: Immersion
test method
ISO 4433-2, Thermoplastics pipes — Resistance to liquid chemicals — Classification — Part 2: Polyolefin
pipes
ISO 9624, Thermoplastics pipes for fluids under pressure — Mating dimensions of flange adapters and loose
backing flanges
ISO 11357-6, Plastics — Differential scanning calorimetry (DSC) — Part 6: Determination of oxidation
3)
induction time (isothermal OIT) and oxidation induction temperature (dynamic OIT)
ISO 12176-1, Plastics pipes and fittings — Equipment for fusion jointing polyethylene systems — Part 1: Butt
fusion
ISO 13951, Plastics piping systems — Test method for the resistance of polyolefin pipe/pipe or pipe/fitting
assemblies to tensile loading
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 13955, Plastics pipes and fittings — Crushing decohesion test for polyethylene (PE) electrofusion
assemblies
ISO 13957, Plastics pipes and fittings — Polyethylene (PE) tapping tees — Test method for impact resistance

2) Under revision.
3) To be published. (Revision of ISO 11357-6:2002)
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ISO 4427-3:2007(E)
ISO 14236, Plastics pipes and fittings — Mechanical-joint compression fittings for use with polyethylene
pressure pipes in water supply systems
EN 681-1:1996, Elastomeric seals — Materials requirements for pipe joint seals used in water and drainage
applications — Part 1: Vulcanized rubber
EN 681-2:2000, Elastomeric seals — Materials requirements for pipe joint seals used in water and drainage
applications — Part 2: Thermoplastic elastomers
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the terms, definitions, symbols and abbreviated terms given in ISO 4427-1
and the following terms and definitions apply.
3.1
electrofusion socket fitting
polyethylene (PE) fitting which contains one or more integral heating elements that are capable of
transforming electrical energy into heat to realize a fusion joint with a spigot end or pipe
3.2
electrofusion saddle fitting
polyethylene (PE) fitting which contains one or more integral heating elements that are capable of
transforming electrical energy into heat to produce a fusion onto a pipe
3.2.1
tapping tee
electrofusion saddle fitting (top-loading or wraparound) which contains an integral cutter used for cutting
through the wall of the main pipe, which remains in the body of the tapping tee after installation
3.2.2
branch saddle
electrofusion saddle fitting (top-loading or wraparound) which requires an ancillary cutting tool for drilling the
hole in the adjoining main pipe
3.3
spigot end fitting
polyethylene (PE) fitting where the outside diameter of the spigot length is equal to the nominal outside
diameter, d , of the corresponding pipe
n
3.4
socket fusion fitting
polyethylene (PE) fitting where the socket mouth is designed to be fusion-jointed with a spigot end or a pipe
using heated tools
3.5
fabricated fitting
fitting produced from pipe conforming to ISO 4427-2 and/or from injection-moulded fittings in accordance with
this part of ISO 4427
3.6
mechanical fitting
fitting used for assembling a polyethylene (PE) pipe to another PE pipe or any other element of the piping
system
NOTE 1 The mechanical fitting can be supplied for field assembly or pre-assembled by the manufacturer and generally
includes a compression part to provide pressure integrity, leaktightness and resistance to end loads. A support sleeve
inserted into the pipe bore provides a permanent support for the PE pipe to prevent creep in the pipe wall under radial
compressive forces.
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ISO 4427-3:2007(E)
NOTE 2 The metallic parts of the fitting can be assembled to metallic pipes by using screw threads, compression joints,
welded or flanged connections including PE flanges. The fitting can allow either a dismountable or permanently assembled
joint. In some cases, the supporting ring can also act as a grip ring.
3.7
voltage regulation
control of energy supplied during the fusion process of an electrofusion fitting by means of the voltage
parameter
3.8
intensity regulation
control of energy supplied during the fusion process of an electrofusion fitting by means of the current
parameter
4 Material
4.1 PE compound
The PE compound from which the fittings are made shall be in accordance with ISO 4427-1.
4.2 Material for non-polyethylene parts
4.2.1 General
The materials and constituent elements used in making the fitting (including elastomers, greases and any
metal parts) shall be as resistant to the external and internal environments as the other elements of the piping
system and shall have a life expectancy under the following conditions at least equal to that of the PE pipe
conforming to ISO 4427-2 with which they are intended to be used:
a) during storage;
b) under the effect of the fluids being conveyed;
c) taking account of the service environment and operating conditions.
The requirements for the level of material performance for non-polyethylene parts shall be at least as stringent
as that of the PE compound for the piping system.
Other materials used in fittings and in contact with the PE pipe shall not adversely affect the pipe performance
or initiate stress cracking.
4.2.2 Metal parts
All parts susceptible to corrosion shall be adequately protected.
When dissimilar metallic materials are used which may be in contact with moisture, steps shall be taken to
avoid galvanic corrosion.
4.2.3 Elastomers
Elastomeric materials used for the manufacture of seals shall conform to EN 681-1 or EN 681-2, as applicable.
4.2.4 Other materials
Greases or lubricants shall not exude on to the fusion areas and shall not affect the long-term performance of
the fitting nor have any adverse effect on the quality of the water.
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ISO 4427-3:2007(E)
5 General characteristics
5.1 Appearance
When viewed without magnification, the internal and external surfaces of the fitting shall be smooth, clean and
free from scoring, cavities and other surface defects such as would prevent conformity of the fitting to this part
of ISO 4427.
5.2 Design
The design of the fitting shall be such that, when assembling the fitting onto the pipe or other components in
accordance with the manufacturer's recommendations, the electrical coils and/or seals are not displaced.
5.3 Colour
The fitting shall be either black or blue. For fabricated fittings, the colour characteristics of pipes shall be in
accordance with ISO 4427-2.
For above-ground installations, all blue components should be protected from direct UV light.
5.4 Electrical characteristics for electrofusion fittings
The electrical protection to be provided by the system depends on the voltage and the current strength used
and on the characteristics of the electricity power.
For voltages greater than 25 V, direct human contact with the energised parts shall not be possible when the
fitting is in the fusion cycle during assembly in accordance with the instructions of the manufacturer of the
fittings and assembly equipment, as applicable.
NOTE 1 This type of fitting is a part of an electrical system as defined in IEC 60335-1, IEC 60364-1 and IEC 60449.
Protection against direct contacts with active parts (live conductors) is required for conformity with IEC 60529. This
protection is a function of the work site conditions.
NOTE 2 See Annex C for examples of typical electrofusion terminal connectors.
The surface finish of the terminal pins shall allow a minimum contact resistance in order to satisfy the
resistance tolerance requirements (nominal value ± 10 %).
5.5 Appearance of factory-made joints
The following requirements apply only to joints and fittings made or assembled in the factory.
The internal and external surfaces of the pipe and fitting after fusion jointing, examined visually without
magnification, shall be free from melt exudation outside the confines of the fitting apart from that which may be
declared acceptable by the fitting manufacturer or used as a fusion marker.
Any melt exudation shall not cause wire movement in electrofusion fittings leading to short circuiting when
jointed in accordance with the manufacturer’s instructions. There shall be no excessive creasing of the internal
surfaces of the adjoining pipes or spigots.
5.6 Effect on water quality
Attention is drawn to the requirements of national regulations (see also the Introduction). See
ISO 4427-1:2007, Clause 5.
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ISO 4427-3:2007(E)
6 Geometrical characteristics
6.1 Measurement of dimensions
The dimensions of the fittings shall be measured in accordance with ISO 3126. In case of dispute, the
measurement of dimensions shall be made not less than 24 h after manufacture and after conditioning for at
least 4 h at (23 ± 2) °C.
6.2 Dimensions of electrofusion sockets
6.2.1 Diameters and lengths of electrofusion sockets
When measured in accordance with 6.1, the diameters and lengths of electrofusion sockets (see Figure 1)
shall be in accordance with Table 1.
The mean inside diameter of the fitting in the middle of the fusion zone, D , shown in Figure 1, shall not be
1
less than d . The manufacturer shall declare the actual maximum and minimum values of D and L for

n 1 1
determining suitability for clamping and joint assembly.
In the case of a fitting having sockets of differing sizes, each socket shall conform to the requirements for the
corresponding nominal diameter.

Key
a
D mean inside diameter in fusion zone
1
b
D bore that is minimum diameter of flow channel through body of fitting
2
c
L depth of penetration of pipe or male end of spigot fitting
1
d
L heated length within socket
2
e
L distance between mouth of fitting and start of fusion zone
3
a
D is measured in a plane parallel to the plane of the mouth at a distance of L + 0,5L .
1 3 2
b
D W (d − 2e ).
2 n min
c
In the case of a coupling without a stop, it is not greater than half the total length of the fitting.
d
As declared by the manufacturer to be the nominal length of the fusion zone.
e
As declared by the manufacturer to be the nominal unheated entrance length of the fitting. L shall be W 5 mm.
3
Figure 1 — Dimensions of electrofusion sockets
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ISO 4427-3:2007(E)
Table 1 — Electrofusion socket dimensions
Dimensions in millimetres
Depth of penetration
Nominal diameter Fusion zone
L L
1,min 1,max
L
of the fitting
2,min
d
n Intensity regulation Voltage regulation
20 20 25 41 10
25 20 25 41 10
32 20 25 44 10
40 20 25 49 10

50 20 28 55 10
63 23 31 63 11
75 25 35 70 12
90 28 40 79 13
110 32 53 82 15

125 35 58 87 16
140 38 62 92 18
160 42 68 98 20
180 46 74 105 21
200 50 80 112 23

225 55 88 120 26
250 73 95 129 33
280 81 104 139 35
315 89 115 150 39
355 99 127 164 42

400 110 140 179 47
450 122 155 195 51
500 135 170 212 56
560 147 188 235 61
630 161 209 255 67
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ISO 4427-3:2007(E)
6.2.2 Wall thickness
In order to prevent stress concentrations, any changes in wall thickness of the fitting body shall be gradual.
a) The wall thickness of the body of the fitting at any point, E, shall be greater than or equal to e for the
min
corresponding pipe at any part of the fitting located at a distance beyond a maximum of 2L /3 from all
1
entrance faces if the fitting and the corresponding pipe are made from a polyethylene having the same
MRS.
If the fitting is produced from a polyethylene having an MRS that is different from that of the
corresponding pipe, the relationship between the wall thickness of the fitting, E, and the pipe, e , shall
min
be in accordance with Table 2.
b) In the case of a wall thickness design different from that according to a), fittings and associated fusion
joints shall additionally meet the performance requirements given in 7.5.
Table 2 — Relationship between pipe and fitting wall thickness
Material
Relationship between fitting wall thickness, E,
and pipe wall thickness, e
min
Pipe Fitting
PE 80 PE 100 E W 0,8e
min
PE 100 PE 80 E W 1,25e
min
6.2.3 Out-of-roundness of bore of a fitting (at any point)
When a fitting leaves the site of the manufacturer, the out-of-roundness of the bore of a fitting at any point
shall not exceed 0,015d .
n
6.2.4 Spigots
For fittings that contain spigot outlets (e.g. electrofusion equal tee with spigotted branch), the dimensions of
the spigot shall be according to 6.3.
6.3 Dimensions of spigot fittings
When measured according to 6.1, the spigot dimensions shall be in accordance with Table 3 (see Figure 2).
6.4 Dimensions of socket fusion fittings
Where the description and dimensions of fittings of this type is required, Annex A applies.
6.5 Dimensions of fabricated fittings
Where the description and dimensions of fittings of this type is required, Annex B applies.
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ISO 4427-3:2007(E)
Table 3 — Spigot dimensions
Dimensions in millimetres
Mean outside
Socket
e
diameter
Electrofusion Butt fusion
Nominal
fusion
a
of fusion end
outside
diameter
Tubular
Out-of- Out-of-
Tubular
Grade Grade Min. Cut-back Tubular Cut-back
of spigot
length
round- round-
b
A B bore length length length
length

L
ness ness
2,min
c d
d D D D max. D L L L max. L
Normal Special
n 1,min 1,max 1,max 2 1,min 2,min 2,min 1,min
20 20,0 — 20,3 0,3 13 25 41 11 — — — —
25 25,0 — 25,3 0,4 18 25 41 12,5 — — — —
32 32,0 — 32,3 0,5 25 25 44 14,6 — — — —
40 40,0 — 40,4 0,6 31 25 49 17 — — — —
50 50,0 — 50,4 0,8 39 25 55 20 — — — —
63 63,0 — 63,4 0,9 49 25 63 24 1,5 5 16 5
75 75,0 — 75,5 1,2 59 25 70 25 1,6 6 19 6
90 90,0 — 90,6 1,4 71 28 79 28 1,8 6 22 6
110 110,0 — 110,7 1,7 87 32 82 32 2,2 8 28 8
125 125,0 — 125,8 1,9 99 35 87 35 2,5 8 32 8
140 140,0 — 140,9 2,1 111 38 92 — 2,8 8 35 8
160 160,0 — 161,0 2,4 127 42 98 — 3,2 8 40 8
180 180,0 — 181,1 2,7 143 46 105 — 3,6 8 45 8
200 200,0 — 201,2 3,0 159 50 112 — 4,0 8 50 8
225 225,0 — 226,4 3,4 179 55 120 — 4,5 10 55 10
250 250,0 — 251,5 3,8 199 60 129 — 5,0 10 60 10
280 280,0 282,6 281,7 4,2 223 75 139 — 9,8 10 70 10
315 315,0 317,9 316,9 4,8 251 75 150 — 11,1 10 80 10
355 355,0 358,2 357,2 5,4 283 75 164 — 12,5 10 90 12
400 400,0 403,6 402,4 6,0 319 75 179 — 14,0 10 95 12
450 450,0 454,1 4
...