Plastics pipes and fittings — Butt fusion jointing procedures for polyethylene (PE) piping systems

ISO 21307:2017 establishes general principles regarding the procedure used in the construction and quality assessment of butt fusion jointing of polyethylene (PE) piping system components specified in accordance with relevant ISO standards. These components are installed in accordance with the relevant codes of practice, national regulations or industry guidance. Specifically, this document specifies three butt fusion jointing procedures for PE pipes and fittings. These are: - single low-pressure fusion jointing procedure; - dual low-pressure fusion jointing procedure; - single high-pressure fusion jointing procedure. ISO 21307:2017 takes into consideration the materials and components used, the fusion jointing procedure and equipment and the quality assessment of the completed joint. It can be applied in conjunction with appropriate national regulations and standards.

Tubes et raccords en matières plastiques — Modes opératoires d'assemblage par soudage bout à bout de tubes et raccords en polyéthylène (PE)

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Status
Published
Publication Date
29-Nov-2017
Current Stage
6060 - International Standard published
Start Date
30-Nov-2017
Completion Date
30-Nov-2017
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INTERNATIONAL ISO
STANDARD 21307
Third edition
2017-12
Plastics pipes and fittings — Butt
fusion jointing procedures for
polyethylene (PE) piping systems
Tubes et raccords en matières plastiques — Modes opératoires
d'assemblage par soudage bout à bout de tubes et raccords en
polyéthylène (PE)
Reference number
ISO 21307:2017(E)
ISO 2017
---------------------- Page: 1 ----------------------
ISO 21307:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

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ii © ISO 2017 – All rights reserved
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ISO 21307:2017(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Butt fusion jointing process ...................................................................................................................................................................... 4

4.1 General ........................................................................................................................................................................................................... 4

4.2 Principle ........................................................................................................................................................................................................ 4

4.3 Cleaning the pipe or fitting ends, planing unit and heater surfaces ......................................................... 5

4.4 Clamping the components ............................................................................................................................................................ 5

4.5 Planing the pipe or fitting ends ................................................................................................................................................ 5

4.6 Aligning the pipes or fittings ....................................................................................................................................................... 6

4.7 Calculation of the gauge pressure........................................................................................................................................... 6

4.8 Determination of the drag pressure ..................................................................................................................................... 6

4.9 Heating the pipe or fitting ends ................................................................................................................................................ 6

4.10 Jointing the pipe or fitting ends ................................................................................................................................................ 7

4.11 Cooling the pipe or fitting ends ................................................................................................................................................ 7

5 Butt fusion jointing procedures ............................................................................................................................................................ 7

5.1 General ........................................................................................................................................................................................................... 7

5.2 Single low-pressure fusion jointing procedure ........................................................................................................... 7

5.3 Dual low-pressure fusion jointing procedure .............................................................................................................. 9

5.4 Single high-pressure fusion jointing procedure ......................................................................................................10

6 Quality control .....................................................................................................................................................................................................12

6.1 General ........................................................................................................................................................................................................12

6.2 Destructive joint integrity testing........................................................................................................................................12

6.3 Non-destructive joint integrity testing ............................................................................................................................12

Annex A (informative) Examples of values of parameters for single low-pressure fusion

jointing procedure ...........................................................................................................................................................................................13

Annex B (informative) Examples of values of parameters for dual low-pressure fusion

jointing procedure ...........................................................................................................................................................................................14

Annex C (informative) Examples of values of parameters for single high-pressure fusion

jointing procedure ...........................................................................................................................................................................................15

Bibliography .............................................................................................................................................................................................................................16

© ISO 2017 – All rights reserved iii
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ISO 21307:2017(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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on 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 the following

URL: 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 21307:2011), which has been technically

revised.
The main changes compared to the previous edition are as follows:
— Added calculation of gauge pressure in 4.7;

— Included normative non-destructive joint integrity testing (visual examination with

requirements) in 6.3;
— Updated process parameters in Tables 1, 2, A.1, B.1 and C.1.
iv © ISO 2017 – All rights reserved
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ISO 21307:2017(E)
Introduction

With the increasing use of polyethylene (PE) pipes of larger diameters and wall thicknesses there is

a need for this document which provides details on three butt fusion procedures. This document is

developed for the benefit of countries without a national standard or technical specification for butt

fusion procedures of PE pipes. High quality butt fusion welds can be obtained with all three butt fusion

procedures mentioned in this document. The choice for one of these three procedures can depend on

experience, on the practical trials of the three butt fusion procedures and on availability of equipment.

© ISO 2017 – All rights reserved v
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INTERNATIONAL STANDARD ISO 21307:2017(E)
Plastics pipes and fittings — Butt fusion jointing
procedures for polyethylene (PE) piping systems
1 Scope

This document establishes general principles regarding the procedure used in the construction and

quality assessment of butt fusion jointing of polyethylene (PE) piping system components specified

in accordance with relevant ISO standards. These components are installed in accordance with the

relevant codes of practice, national regulations or industry guidance. Specifically, this document

specifies three butt fusion jointing procedures for PE pipes and fittings. These are:

— single low-pressure fusion jointing procedure;
— dual low-pressure fusion jointing procedure;
— single high-pressure fusion jointing procedure.

This document takes into consideration the materials and components used, the fusion jointing

procedure and equipment and the quality assessment of the completed joint. It can be applied in

conjunction with appropriate national regulations and standards.
[1][2][3][4][5][6]

NOTE 1 The references for these procedures are given in the Bibliography. Single low-

pressure fusion jointing procedure is derived from multiple procedures and agreed by experts, given in the

[1][2]
Bibliography .

NOTE 2 The three procedures detailed in this document are based on those most commonly used. It is not the

intention that one or more of these procedures be used to replace well established and verified industry based

procedures.
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 12176-1, Plastics pipes and fittings — Equipment for fusion jointing polyethylene systems — Part 1:

Butt fusion
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
heater plate temperature

measured temperature on the surface of the heater plate where the pipe or fitting wall cross-section

makes contact
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ISO 21307:2017(E)
3.2
nominal wall thickness

wall thickness tabulated in ISO 4065 , corresponding to the minimum wall thickness e at any

y,min
point e
3.3
nominal outside diameter

numerical designation of size which is common to all components in a thermoplastics piping system

other than flanges and components designated by thread size
3.4
standard dimension ratio
SDR

numerical designation of a pipe series, which is a convenient round number, approximately equal to the

dimension ratio of the nominal outside diameter, d , and the nominal wall thickness, e

n n
3.5
drag pressure

gauge pressure required to overcome, on a given machine, the sliding frictional drag force of the

machine and pipe
Note 1 to entry: Drag pressure, if present, can be a positive or negative value.
3.6
bead-up

initial melt under pressure around the circumference of the ends of the pipes or fittings which ensures

that complete pipe or fitting to heater plate contact is achieved
3.7
bead-up pressure

pressure exerted on the heater plate by the pipe or fitting ends during the bead-up phase of the

jointing cycle

Note 1 to entry: The value of the corresponding gauge pressure is calculated with Formulae (1) and (2).

3.8
bead-up size
bead size formed on the pipe or fitting ends during the bead-up phase
3.9
heat soak

portion of the heating cycle done at 0 to drag pressure so that the heat can melt the pipe or fitting to a

depth sufficient for proper mixing and fusion
3.10
heat soak pressure

pressure required to maintain the pipe or fitting in contact with the heater plate taking into account

the drag pressure
3.11
0 to drag pressure

lowest possible pressure during the heat soak that will allow the pipe or fitting to remain in contact

with the heater plate, up to a maximum of the current drag pressure

Note 1 to entry: The drag pressure required to move the pipe or fitting may be much higher than the pressure

required to maintain pipe or fitting/heater contact during heat soak.
1) To be published.
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ISO 21307:2017(E)
3.12
heating cycle

part of the welding process in which pipe or fitting ends are in contact with the heater plate composed

by bead up pressure and followed by heat soak pressure
3.13
heat soak time

time during which the heater plate is in contact with the pipe or fitting ends at the heat soak pressure

3.14
minimum bead size after heating
minimum value of bead size to be attained after completing the heat soak time
Note 1 to entry: Single high-pressure butt fusion procedure only.
3.15
heater plate removal time

time taken to separate the pipe or fitting ends from the heater plate, remove the heater plate and close

the carriage in order to bring the molten pipe or fitting ends together
3.16
fusion jointing pressure
interfacial pressure
actual pressure exerted on the pipe or fitting ends during jointing

Note 1 to entry: The value of the corresponding gauge pressure is calculated with Formulae (1) and (2).

3.17
gauge pressure

actual pressure (bead-up pressure or fusion jointing pressure with drag pressure) in the cylinders of

the butt fusion jointing machine read by the gauge
3.18
fusion jointing time
time period allotted for bead roll-over before cooling-cycle reduced pressure
Note 1 to entry: Dual low-pressure butt fusion procedure only.
3.19
cooling-cycle reduced pressure

pressure, exerted on the pipe or fitting ends during the cooling cycle of the dual low-pressure procedure

after fusion jointing time

Note 1 to entry: The value of the corresponding gauge pressure is calculated with Formulae (1) and (2).

3.20
cooling time in machine under pressure

time period during which the butt fusion joint remains under pressure when still clamped in the machine

3.21
cooling time in machine without pressure or out of machine

additional cooling period that may be required after the cooling time under pressure to ensure optimum

joint strength, particularly when working at high ambient temperatures and prior to rough handling or

pipe installation
3.22
operator

qualified person authorized to construct polyethylene (PE) systems from pipes and/or fittings, based

on a written procedure agreed by the pipeline operator according to ISO/TR 19480
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ISO 21307:2017(E)
3.23
pipeline operator

private or public organization authorized to design, construct and/or operate and maintain a pipeline

supply system
3.24
dummy joint

unfinished joint made prior to production welding to ensure cleanliness of the heater plate in which the

welding procedure is stopped after the heat soak time
3.25
jointing session
uninterrupted series of welds made with the same parameters and same equipment
3.26
rough handling

any action whereby stresses are applied to the fused joint, such as tensile and bending forces

Note 1 to entry: Some examples of rough handling are immediately after the cooling time in the machine under

pressure:
— the joint is removed from the machine by single point lifting at the joint;
— several lengths of joined pipe are pulled with the freshly made fusion joint;
— the joint is immediately subjected to a severe bending stress.
4 Butt fusion jointing process
4.1 General

Polyethylene (PE) pipes and fittings for the production of butt fusion joints in accordance with this

document should conform with the relevant ISO, local or national piping system standards.

PE components with fusion ends of different SDR/DR values shall not be jointed by butt fusion.

Ambient temperatures mentioned in this document shall be measured with a thermometer with an

accuracy of ± 1,0 °C.

To prevent potential contamination of welds it is recommended that welding is carried out in a shelter,

and the welding equipment is sited on a baseboard or ground sheet.

It is recommended to block off the PE pipe ends to prevent contamination and reduction of the

temperature of the heater plate.

It is recommended, before starting the welding procedure, to check the functioning of the fusion

equipment, particularly the temperature of the heating plate on both sides.

It is recommended to record the welding data in welding protocols or on data carriers.

4.2 Principle

The principle of butt fusion jointing is to heat two pipe or fitting ends for a specified time by means

of a heater plate maintained at a specified temperature. Following heater plate removal the pipe

ends are brought together by applying a specified pressure, and then cooled for a specified time. Butt

fusion joints shall be made by qualified operators using butt fusion jointing machines that conform to

ISO 12176-1. The training and level of skill of the operator shall be in accordance with the requirements

of the jointing procedure. A written jointing procedure, authorized by the pipeline operator, shall be

available prior to the construction of a pipeline. Any one of the three jointing procedures mentioned

in this document can be used as the basis. The jointing procedure shall include specification of the

4 © ISO 2017 – All rights reserved
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ISO 21307:2017(E)

jointing method, the fusion parameters, the fusion equipment, the jointing conditions, the level of skill

of the operator, and the quality control methods to be used. Guidelines for quality control are given in

Clause 6.
Key elements of the jointing process shall include:
a) cleaning the pipe or fitting ends, planing unit and heater surfaces;

b) clamping the components to be joined (pipe support with drag reducing rollers may be required to

ensure proper alignment);
c) planing the pipe or fitting ends;
d) aligning the pipes or fittings;
e) measuring the drag and compensating pressure accordingly;
f) melting the pipe or fitting ends;
g) jointing the pipe or fitting ends;

h) holding the pipe or fitting ends under pressure for the duration of the cooling time in the machine;

i) completing the cooling time in machine without pressure or out of machine if required.

These key elements are explained in more detail in 4.3 to 4.11.
4.3 Cleaning the pipe or fitting ends, planing unit and heater surfaces

Before placing them in the machine, clean the inside and outside of the pipe or fittings to be joined by

wiping the joint area with a clean lint-free cloth, using a suitable solvent (e.g. ethanol, isopropanol)

only if necessary or if specified in codes of practice or national regulations. All foreign matter shall be

removed from the jointing area.

If the pipe has a protective outer layer, it shall be peeled back far enough so that the pipe can be properly

clamped in the fusion machine, unless otherwise specified by the pipe manufacturer.

Cleaning the planing unit and the heater plate surfaces shall be done using a clean lint-free cloth, a

clean lint-free cloth with a suitable solvent or by making dummy joints at the start of each jointing

session whenever the heater plate has been allowed to cool below 180 °C and for a change of pipe size

or SDR/DR prior to commencement of production welding. The number of dummy joints to be made

shall be included in the written jointing procedure and/or as specified in codes of practice or national

regulations.
4.4 Clamping the components

Clamp the components in the butt fusion jointing machine and adjust as necessary to achieve proper

alignment. Pipe support may be needed to achieve proper alignment and reduce drag. It is recommended

to support the pipe(s) to ensure the uniformity of the drag pressure.

NOTE Pipe support can be achieved by using rollers or appropriate low friction alignment blocks, etc.

It is good practice to ensure that the pipe details printed along the two pipes are aligned and placed at

the top of the machine when possible.
4.5 Planing the pipe or fitting ends

Plane the pipe or fitting ends to establish clean, parallel mating surfaces that are perpendicular to the

centreline of the machine guide rods.
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ISO 21307:2017(E)
4.6 Aligning the pipes or fittings

Remove any shavings from the pipe or fitting ends being careful not to touch the planed surfaces. If the

planed surface becomes contaminated, the surface shall be replaned.

Inspect the pipe or fitting ends for incomplete planing, voids or other imperfections, and then bring them

together to check for proper alignment and gap. The pipe or fitting ends shall be rounded and aligned to

ensure compliance with relevant codes of practice, national regulations or industry guidelines.

4.7 Calculation of the gauge pressure
The gauge pressure can be calculated from the following formula:
 A 
GP = IP××10 +DP (1)
 
 c 
where
GP is the gauge pressure (bar);
IP is the interfacial pressure (MPa);

A is the total piston area, given by the manufacturer of the butt fusion jointing equipment (mm );

A is the interfacial surface area (mm );
DP is the drag pressure (bar).

NOTE The interfacial pressure is the amount of force per unit of pipe area required to butt fuse the pipe or

fitting ends
The interfacial surface area can be calculated from the following formula:
A = π × (d − e ) × e (2)
s n n n
where
d is the nominal outside diameter of the pipe (mm);
e is the nominal wall thickness of the pipe (mm).
4.8 Determination of the drag pressure

Determine the drag pressure after clamping and aligning. The drag pressure shall be added to the bead

up and fusion jointing pressure.
4.9 Heating the pipe or fitting ends

The surface of the heater plate that comes into contact with the pipe or fitting ends shall be clean, oil-

free and coated with a non-stick coating to prevent molten plastic from adhering to the heater plate

surface. Refer to the specific fusion jointing procedure for the correct heater temperatures.

Install the heater plate in the butt fusion jointing machine and bring both pipe or fitting ends

simultaneously into full contact with the heater plate to produce molten surfaces for fusion jointing. To

ensure that full contact is made between the pipe or fitting ends and the heater plate, the initial contact

shall be made under bead-up pressure. After holding the pressure until a specified bead-up size has

formed all around the pipe(s) and or fitting end(s) circumference(s), the pressure shall be adjusted to

the heat soak pressure without breaking contact between the heater plate and the pipe or fitting ends

for a period equal to the heat soak time.
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ISO 21307:2017(E)
4.10 Jointing the pipe or fitting ends

On completion of the heat soak time, move the pipe or fitting ends from the heater plate. Then remove

the heater plate and bring the heated pipe or fitting ends together within the maximum specified time

limit in a controlled manner to apply the fusion jointing pressure which takes into account the drag

pressure.
4.11 Cooling the pipe or fitting ends

The joint shall be held immobile under pressure in the butt fusion jointing machine for the period of time

defined as the cooling time in the machine under pressure. The fusion jointing pressure (and in case of

the dual low-pressure jointing procedure the cooling-cycle reduced pressure) shall be maintained in

accordance with the procedure used.

Allowing appropriate time for cooling under pressure prior to removal from the machine clamps is

important in order to develop strength and achieve joint integrity.

Further cooling may take place in the machine without pressure or out of the machine, particularly if

working at higher temperatures than (23 ± 2) °C or when the joint is subjected to rough handling.

5 Butt fusion jointing procedures
5.1 General

The following three butt fusion jointing procedures are described in detail in 5.2 to 5.4:

— single low-pressure fusion jointing procedure;
— dual low-pressure fusion jointing procedure;
— single high-pressure fusion jointing procedure.

The dual low-pressure fusion jointing procedure is only applicable for pipes and spigot end fittings with

a wall thickness greater than 22 mm.

NOTE For the purpose of this document the minimum cooling time under pressure, for all three butt fusion

jointing procedures, is based on cooling to a mid-wall temperature of 80 °C (at an ambient temperature of

(23 ± 2) °C).
5.2 Single low-pressure fusion jointing procedure

Butt fusion jointing conforming to the single low-pressure procedure shall be performed as specified

in Table 1. Examples of values of parameters for the single low-pressure fusion jointing procedure are

given in Annex A.
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ISO 21307:2017(E)

Table 1 — Phases, parameters and values for single low-pressure fusion jointing procedure

Phase Parameter Unit Value
(see Figure 1)
1 and 2 Heater plate temperature °C 225 ± 10
0,17 ± 0,02
Bead-up pressure MPa
1 + drag pressure
Minimum bead-up size mm 0,5 + 0,1 × e
Minimum heat soak time s (13,5 ± 1,5) × e
Heat soak pressure MPa 0 to drag pressure
3 Maximum heater plate removal time s See ISO 12176-1
Maximum time to achieve fusion jointing pressure s 3 + 0,03 × d
4 0,17 ± 0,02
Fusion jointing pressure MPa
+ drag pressure
Minimum cooling time in the machine under pressure, for
5 min e + 3
wall thickness < 18 mm
Minimum cooling time in the machine under pressure, for
2 c
min 0,015 × e − 0,47 × e + 20
n n
wall thickness ≥ 18 mm
6 Minimum cooling time out of the machine min
See definition 3.5.

Use the lowest possible pressure during the heat soak that will allow the pipe to remain in contact with the heater plate, up to a maximum of the

current drag pressure.
c 2

The minimum cooling time in the machine under pressure is e + 3 or 0,015 × e − 0,47 × e + 20 (depending on the wall thickness) at an ambient

n n n

temperature of (23 ± 2) °C. This is the cooling time for the butt joint when still in the machine and under pressure. Cooling times may be shortened and

should be lengthened depending on ambient temperatures (approximately 1 % per 1 °C).

A cooling time out of the machine and before rough handling may be recommended.

Figure 1 illustrates the single low-pressure fusion jointing cycle, with an explanation of the individual

elements of the fusion jointing cycle.
Key
X time t bead-up time
Y pressure t heat soak time
p bead-up pressure t heater plate removal time
1 3
p heat soak pressure t time to achieve fusion jointing press
...

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