ISO 22621-5:2010

INTERNATIONAL ISO
STANDARD 22621-5
First edition
2010-04-15


Plastics piping systems for the supply
of gaseous fuels for maximum
operating pressures up to and including
2 MPa (20 bar) — Polyamide (PA) —
Part 5:
Fitness for purpose of the system
Systèmes de canalisations en matières plastiques pour la distribution
de combustibles gazeux pour des pressions maximales de service
inférieures ou égales à 2 MPa (20 bar) — Polyamide (PA) —
Partie 5: Aptitude à l'emploi du système





Reference number
ISO 22621-5:2010(E)
©
ISO 2010

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ISO 22621-5:2010(E)
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ISO 22621-5:2010(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms, definitions, symbols and abbreviated terms .2
3.1 Terms and definitions — General .2
3.2 Terms and definitions for preparation of test assemblies by electrofusion .3
3.3 Symbols.3
4 Fitness for purpose .5
4.1 Method of preparation of assemblies for testing.5
4.2 Requirements for fitness for purpose.6
5 Overall service (design) coefficient.9
Annex A (normative) Preparation of test assemblies by butt fusion .10
Annex B (normative) Preparation of test assemblies by electrofusion .13
Annex C (normative) Test methods for the assessment of fitness for purpose of transition fittings.19
Annex D (normative) Derating coefficients for operating temperatures.21

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ISO 22621-5:2010(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 22621-5 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.
ISO 22621 consists of the following parts, under the general title Plastics piping systems for the supply of
gaseous fuels for maximum operating pressures up to and including 2 MPa (20 bar) — Polyamide (PA):
⎯ Part 1: General
⎯ Part 2: Pipes
⎯ Part 3: Fittings
⎯ Part 5: Fitness for purpose of the system
⎯ Part 6: Code of practice for design, handling and installation
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ISO 22621-5:2010(E)
Introduction
As polyamide material is used for piping systems for the supply of gaseous fuels both at low and high
pressure, ISO/TC 138/SC 4 experts decided to split the standardization programme into two series of
International Standards, with one series [ISO 15439 (all parts)] covering low pressures up to 0,4 MPa (4 bar),
and the other (ISO 22621) high pressures up to 2 MPa (20 bar).
Thin wall thickness pipes and solvent cement joints are used typically for pressures up to 0,4 MPa (4 bar),
while thicker wall thickness pipes and butt fusion, electrofusion and mechanical joints are typically used for
pressures up to 2 MPa (20 bar). For technical and safety reasons, it is not possible to mix the components of
the two types of piping system (thin wall thickness pipes cannot be jointed by butt fusion or mechanical joints
and vice versa). In particular, solvent cement joints must not be used for jointing for high-pressure piping
systems.

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INTERNATIONAL STANDARD ISO 22621-5:2010(E)

Plastics piping systems for the supply of gaseous fuels
for maximum operating pressures up to and including 2 MPa
(20 bar) — Polyamide (PA) —
Part 5:
Fitness for purpose of the system
1 Scope
This part of ISO 22621 specifies the requirements of fitness for purpose of the polyamide (PA) piping system,
intended to be buried and used for the supply of gaseous fuels at maximum operating pressures (MOP) up to
1)
and including 2 MPa (20 bar ).
It specifies the definitions of electrofusion and butt fusion joints.
It also specifies the method of preparation of test piece joints and the tests to be carried out on these joints for
assessing the fitness for purpose of the system under normal and extreme conditions.
In addition, it specifies the test parameters for the test methods to which it refers.
In conjunction with the other parts of ISO 22621, it is applicable to PA fittings, their joints and joints with
components of PA.
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 291, Plastics — Standard atmospheres for conditioning and testing
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 1167-4, Thermoplastics pipes, fittings and assemblies for the conveyance of fluids — Determination of
the resistance to internal pressure — Part 4: Preparation of assemblies
ISO 6259-1, Thermoplastics pipes — Determination of tensile properties — Part 1: General test method
ISO 13953, Polyethylene (PE) pipes and fittings — Determination of the tensile strength and failure mode of
test pieces from a butt-fused joint

5 2
1) 1 bar = 0,1 MPa = 10 Pa; 1 MPa = 1 N/mm .
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ISO 22621-5:2010(E)
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 22621-1, Plastics piping systems for the supply of gaseous fuels for maximum operating pressures up to
and including 2 MPa (20 bar) — Polyamide (PA) — Part 1: General
ISO 22621-2, Plastics piping systems for the supply of gaseous fuels for maximum operating pressures up to
and including 2 MPa (20 bar) — Polyamide (PA) — Part 2: Pipes
ISO 22621-3, Plastics piping systems for the supply of gaseous fuels for maximum operating pressures up to
and including 2 MPa (20 bar) — Polyamide (PA) — Part 3: Fittings
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the terms, definitions, symbols and abbreviated terms given in ISO 22621-1
and the following apply.
3.1 Terms and definitions — General
3.1.1
electrofusion joint
joint between a PA electrofusion socket or saddle fitting and a pipe or a spigot end fitting
NOTE The electrofusion fittings are heated 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.
3.1.2
butt fusion joint (using heated tool)
joint made by heating the planed ends the surfaces of which match by holding them against a flat heating
plate until the PA material reaches fusion temperature, removing the heating plate quickly and pushing the two
softened ends against one another
3.1.3
fusion compatibility
ability of two similar or dissimilar polyamide materials to be fused together to form a joint which conforms to
the performance requirements of this standard
3.1.4
transition fitting
fitting that makes a transition joint between a polyamide (PA) piping and a metallic pipe
3.1.5
transition joint
joint at which two different piping materials (the PA and metal piping) are connected
3.1.6
anodeless riser
type of transition fitting which is designed to transport gas from an underground polyamide (PA) service line to
above-ground steel piping
NOTE In an anodeless riser, the PA pipe is always the gas carrier, at least, in the below ground section.
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ISO 22621-5:2010(E)
3.2 Terms and definitions for preparation of test assemblies by electrofusion
3.2.1
reference time
t
R
theoretical fusion time indicated by the fitting manufacturer for the reference ambient temperature
See Annex B.
3.2.2
fusion energy
electrical energy supplied during the fusion-jointing cycle as measured at the terminals of the fitting at a given
ambient temperature, T , and for electrical parameters whose values lie within the tolerance ranges declared
a
by the manufacturer
NOTE 1 The fitting manufacturer is generally required to state in the technical file any variations in fusion energy input
required as a function of the ambient temperature in the range T to T .
min max
NOTE 2 Where applicable, energy measurement should exclude the effect of terminal contact resistance.
3.2.3
reference energy
energy supplied to a fitting having a nominal electrical resistance and using the nominal fusion parameters
defined by the manufacturer at the reference ambient temperature, T
R
See Annex B.
3.2.4
maximum energy
maximum value of the fusion energy supplied for jointing at a given ambient temperature, T
a
See Annex B.
3.2.5
minimum energy
minimum value of the fusion energy supplied for jointing at a given ambient temperature, T
a
See Annex B.
3.2.6
nominal energy
nominal energy supplied for jointing at a given ambient temperature, T
a
See Annex B.
3.3 Symbols
Application Symbol Description Unit
Symbols used in more than one e nominal pipe wall thickness mm
n
a
phase of the fusion-jointing cycle
d nominal external diameter of the pipe
n
p pressure applied to the butt fusion joint interface
t duration of each phase in the fusion cycle
T nominal temperature (23 ± 2) °C °C
nom
T maximum permissible ambient temperature °C
max
T minimum permissible ambient temperature °C
min

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ISO 22621-5:2010(E)
Application Symbol Description Unit
a
Symbols for joint geometry ∆a misalignment between the pipes or fittings to be mm
butt-fused, expressed in terms of the difference between
the external diameters
∆w clearance between the fusion faces, expressed in terms mm
of the gap between the prepared faces
Symbols for ambient T ambient temperature at which the joint is made °C
a
ab
temperature
Symbols for butt fusion cycle T heater-plate temperature, measured in the zone of the °C
a
parameters : heater-plate surface in contact with the pipe or spigot
ends to be butt-fused
⎯ General
⎯ Phase 1: heating p interface pressure during the heating phase, i.e. the MPa
1
pressure applied in the contact zone
B initial bead width taken as the bead width at the end of mm
1
the heating phase
t heating time, taken as the time necessary to obtain a s
1
bead of width B in the joint region during the heating
1
phase
⎯ Phase 2: heat soak
p pressure between the heater plate and the pipe or spigot MPa
2
ends during the heat soak phase
t duration of internal heating during the heat soak phase s
2
⎯ Phase 3: withdrawal of
t time between the moment when the heater plate is s
3
heater plate
removed from the pipe and/or spigot ends and the
moment when the pipe and/or spigot ends are placed in
contact with each other
⎯ Phase 4: pressure
t time required to establish the butt fusion pressure s
4
increase
⎯ Phase 5: butt fusion
p pressure applied to the contact zone during the butt MPa
5
fusion phase
t time during which the assembly remains under the butt min
5
fusion pressure in the machine
⎯ Phase 6: cooling
t cooling time during which the butt-fused assembly is not min
6
subjected to any rough handling; this cooling can take
place outside the machine
B bead width obtained at the end of the cooling phase mm
2
Symbols for the preparation of test D mean inside diameter of the fusion zone of a fitting in the
im
c
assemblies by electrofusion radial plane located a distance L + 0,5L from the face
3 2
of the fitting socket
D maximum theoretical value of D as declared by the
im,max im
fitting manufacturer
D maximum inside diameter of the fusion zone of the fitting
i,max
D minimum inside diameter of the fusion zone of the fitting
i,min
d outside diameter of a pipe or fitting spigot
e
d mean outside diameter of a pipe or fitting spigot in
em
conformance with ISO 22621-2 and ISO 22621-3, as
applicable, and calculated from the measured
circumference

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ISO 22621-5:2010(E)
Application Symbol Description Unit
d mean outside diameter of a pipe or fitting spigot after
emp
preparation for assembly with the outer layer, removed
by scraping or peeling and calculated from the
circumference measured in a radial plane coincident with
the centre of the fusion zone at a distance L + 0,5L
3 2
from the face of the fitting socket after assembly
e nominal wall thickness of the pipe mm
n
e depth of scraping or the thickness of material removed mm
s
from the pipe surface by peeling
L nominal length of the fusion zone as indicated by the
2
fitting manufacturer
L nominal distance from the face of the fitting socket to the
3
leading edge of the fusion zone
a
See Annex A.
b
The ambient temperature may vary from the minimum temperature, T , to the maximum temperature, T , defined by
min max
agreement between the manufacturer and purchaser.
c
See Figure B.1; see Annex B.

4 Fitness for purpose
4.1 Method of preparation of assemblies for testing
4.1.1 General
The joints shall be made by using pipes conforming to ISO 22621-2 or fittings conforming to ISO 22621-3.
Test pieces for pressure test shall be closed with pressure-tight, end-load-bearing end caps, plugs or flanges,
which shall be provided with connections for the entry of water and release of air.
4.1.2 Butt fusion joints
PA pipes and spigot end fittings intended to be used for jointing by butt fusion shall be prepared and
assembled in accordance with Annex A.
4.1.3 Electrofusion jointing
PA pipes and fittings intended to be used for jointing by electrofusion shall be prepared and assembled in
accordance with Annex B.
For joints with electrofusion socket fittings and joints with electrofusion saddle fittings, test joints shall be
prepared to check the fitness for purpose of the fittings under extreme jointing conditions.
For joints with electrofusion saddle fittings, the electrofusion saddle fitting shall be fused to the pipe, while it is
pneumatically pressurized to the allowable maximum operating pressure. The pipe shall be cut immediately
after the manufacturer-prescribed cooling time has elapsed.
These joints with electrofusion saddle fitting should be prepared taking national safety regulations into
consideration.
For straight equal electrofusion socket fittings (couplers), test joints on selected diameters out of the product
range shall be prepared with a gap of 0,05d between the pipe end and the maximum theoretical depth of
n
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ISO 22621-5:2010(E)
penetration of the fitting, where for diameters greater than 225 mm, the adjoining pipes shall be arranged to
provide the maximum angular deflection possible for the fitting, limited to 1,5°.
4.2 Requirements for fitness for purpose
4.2.1 Fitness for purpose for butt fusion joints
4.2.1.1 Under normal conditions — Ambient temperature 23 °C
For the assessment of fitness for purpose under normal conditions, butt fusion joints shall have the
characteristic of tensile strength conforming to the requirement given in Table 5, using the parameters as
specified in Annex A, Table A.2 and Table A.3, at an ambient temperature of (23 ± 2) °C and the scheme
listed in Table 1.
Table 1 — Scheme for butt fusion joints
Pipe
Pipe/spigot end fitting
PA 11 160 PA 11 180 PA 12 160 PA 12 180
a
PA 11 160 X X Jointing not allowed Jointing not allowed
a
PA 11 180 X X Jointing not allowed Jointing not allowed
a
PA 12 160 Jointing not allowed Jointing not allowed X X
a
PA 12 180 Jointing not allowed Jointing not allowed X X
This table should be interpreted as follows: as an example, for a pipe or a spigot end fitting made from a PA 11 160 compound, a joint
should be tested with a pipe made from PA 11 160 compound. When requested by the purchaser or end user, for mixed compound
joints, test pieces should be used incorporating PA 11 160 and PA 11 180 compounds.
a
Only when requested by the purchaser or end user.

The pipe manufacturer shall declare, according to 4.2.1.1, which pipes from his own product range conforming
to ISO 22621-2 are compatible with each other for butt fusion.
The fitting manufacturer shall declare, according to 4.2.1.1, the SDR range and MRS values of pipes
conforming to ISO 22621-2, to which his fittings conforming to ISO 22621-3 can be fused by using the same
procedures (e.g. times, temperatures, fusion pressures) to conform to this part of ISO 22621. If there is a need
for deviation in fusion procedures, the fitting manufacturer shall state this clearly.
4.2.1.2 Under extreme conditions
For butt fusion joints, the characteristics to be examined for fitness for purpose under extreme conditions shall
conform to Table 2.
Table 2 — Relationship between the joints and fitness for purpose characteristics
Butt fusion joint Associated characteristic
Both components of the joint: same MRS and same SDR Hydrostatic strength
a
(80 °C, 165 h)
Joint: minimum and maximum condition
Both components of the joint: same MRS and same SDR Tensile strength for butt fusion joint
Joint: minimum and maximum condition
a
As specified in Annex A concerning misalignment [A.5 a)] and the limit values of fusion parameters (Table A.4).

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ISO 22621-5:2010(E)
When tested in accordance with the test methods as specified in Table 5 using the indicated parameters, the
joints shall have characteristics conforming to the requirements given in Table 5.
The fitting manufacturer shall declare, according to Table 2, as applicable, the fitness for purpose under
extreme conditions of his fittings.
The pipe manufacturer shall declare, according to Table 2, the fitness for purpose under extreme conditions of
his pipes.
4.2.2 Fitness for purpose for electrofusion joints
4.2.2.1 Under normal conditions — Ambient temperature 23 °C
For the assessment of fitness for purpose under normal conditions, electrofusion joints shall have the
characteristic of decohesive resistance or cohesive strength, as applicable, conforming to the requirement
given in Table 5, using assembly condition 1 as specified in Annex B, Table B.3, at an ambient temperature of
(23 ± 2) °C and the scheme listed in Table 3.
Table 3 — Scheme for electrofusion joints
Electrofusion fitting
Pipe
with electrofusion
socket
PA 11 160 PA 11 180 PA 12 160 PA 12 180
SDR maximum SDR minimum SDR maximum SDR minimum
a
PA 11 160 X X Jointing not allowed Jointing not allowed
a
PA 11 180 X X Jointing not allowed Jointing not allowed
a
PA 12 160 Jointing not allowed Jointing not allowed X X
a
PA 12 180 Jointing not allowed Jointing not allowed X X
This table should be interpreted as follows: as an example, for an electrofusion fitting made from a PA 11 160 compound, a joint should
be tested with a pipe made from PA 11 160 compound and an SDR maximum and another joint should be tested with a pipe made from
PA 11 160 compound and an SDR minimum.
a
Only when requested by the purchaser.

The fitting manufacturer shall declare, according to 4.2.2.1, the SDR range and MRS values of pipes
conforming to ISO 22621-2, to which his fittings conforming to ISO 22621-3 can be fused by using the same
procedures (e.g. times, temperatures, fusion pressures) to conform to this part of ISO 22621. If there is a need
for deviation in fusion procedures, the fitting or valve manufacturer shall state this clearly.
4.2.2.2 Under extreme conditions
For electrofusion joints, the characteristics to be examined for fitness for purpose under extreme conditions
shall conform to Table 4.
When tested in accordance with the test methods as specified in Table 5 using the indicated parameters, the
joints shall have characteristics conforming to the requirements given in Table 5.
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ISO 22621-5:2010(E)
Table 4 — Relationship between the joints and fitness for purpose characteristics
Electrofusion joint, Electrofusion joint,
Associated characteristic
a a
including socket fitting including saddle fitting
b
Decohesive resistance
Pipe: MRS maximum
b
SDR minimum
Joint: conditions 2.2 and 3.2 of
c
Table B.3
b
Cohesive strength
Pipe: MRS maximum
b
SDR minimum
Joint: conditions 2.2 and 3.2 of
c
Table B.3
a
If accepted by the purchaser, the minimum and maximum energy conditions 2.2 and 3.2 may be replaced by a nominal energy at a
given ambient temperature, T , defined by the fitting manufacturer (see 3.2.6).
a
b
As declared by the fitting manufacturer according to 4.2.2.1.
c
As specified in Table B.3 with T and T as stated in the fitting manufacturer's technical specification.
min max

The fitting manufacturer shall declare according to Table 4, as applicable, the fitness for purpose under
extreme conditions of his fittings.
Table 5 — Characteristics for fitness for purpose of the system
Test parameters
Characteristic Requirement Test method
Parameter Value
Hydrostatic strength No failure during the End caps Type A ISO 1167-1
(80 °C, 165 h) test period of any test
Orientation Free ISO 1167-4
piece
Conditioning time 6 h
Type of test Water-in-water
Circumferential (hoop) stress
PA 11 160 and PA 12 160 10,0 MPa
PA 11 180 and PA 12 180 11,5 MPa
Test period 165 h
Test temperature 80 °C
Cohesive resistance for Length of initiation Test temperature 23 °C ISO 13954 or
electrofusion socket rupture u L /3 in brittle ISO 13955
2
fittings failure
Cohesive resistance for Surface rupture: Test temperature 23 °C ISO 22621-3
electrofusion saddle Annex D
u 25 %, brittle failure
fittings
Test temperature 23 °C ISO 13953
Tensile strength for Test to failure:
— butt fusion fittings — ductile: pass
— spigot end fittings — brittle: fail

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ISO 22621-5:2010(E)
4.2.3 Fitness for purpose for transition fittings
4.2.3.1 Leaktightness test
The transition joint shall be leak-free when leak tested at 0,5 bar and at a minimum of 1,5 MOP at both
(23 ± 2) °C and (−29 ± 2) °C in accordance with C.3.
4.2.3.2 Leaktightness with temperature cycling
The transition joint shall be leak-free after 10 temperature cycles as tested at 0,5 bar and a minimum of
1,5 MOP in accordance with C.5.
4.2.3.3 Leaktightness after tensile pull test
4.2.3.3.1 Transition joints in transition fittings and anodeless risers in PA sizes less than 110 mm shall be
qualified under this requirement if the pipe is pulled to a minimum of 25 % elongation, as indicated by when
the length of the unrestrained PA piping has been elongated to 125 % of its original length, when tested in
accordance with C.4, and is bubble tight in accordance with 4.2.3.3.3. No leakage or pullout is permitted.
4.2.3.3.2 For PA sizes 110 mm and greater, the joint shall be qualified by pull testing to tensile stress equal
to, or greater than, the maximum tensile stress that would be produced by a temperature change of 38 °C
when tested in accordance with C.4. No leakage or pullout is permitted in accordance with 4.2.3.3.3. Failure of
one sample constitutes failure of this test.
4.2.3.3.3 The transition joint shall be leak tested at 0,5 bar and a minimum of 1,5 MOP, prior to and at the
end of the test, while still under tensile load and immediately following the tensile test. No leakage shall be
permitted when tested in accordance with C.4.
4.2.3.3.4 Each nominal size transition design, in PA, shall be tested, except testing of the heaviest wall PA
piping shall qualify all thinner wall PA pipe joints of the same outside diameter.
4.2.3.4 Leaktightness after constant tensile load joint test
The transition joint shall be leak tested at 0,5 bar and a minimum of 1,5 MOP, prior to, at the end of the test
while still under tensile load, and immediately following the constant tensile load (CTL) joint test according to
C.6. No leakage shall be permitted when tested in accordance with C.3.
5 Overall service (design) coefficient
The minimum value of the overall service (design) coefficient, C, for pipes and fittings for the supply of
gaseous fuels shall be 2, or higher values according to national regulations.
To this value other coefficients may be applied, taking into account different aspects, such as:
a) operating temperature range;
b) specific material aspects;
c) storage and laying conditions.
NOTE For information about derating coefficients for other operating temperatures, see Annex D.
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ISO 22621-5:2010(E)
Annex A
(normative)

Preparation of test assemblies by butt fusion
A.1 General
This annex specifies a method for preparing butt fusion jointed test piece assemblies between PA pipes and
spigot-ended fittings.
A.2 Pipes used for test assemblies
The pipes used for test assemblies shall be taken from straight lengths.
A.3 Conditioning
Condition the pipes used
...