ISO 6993-2:2006

INTERNATIONAL ISO
STANDARD 6993-2
First edition
2006-06-01
Buried, high-impact poly(vinyl chloride)
(PVC-HI) piping systems for the supply of
gaseous fuels —
Part 2:
Fittings for a maximum operating
pressure of 200 mbar (20 kPa)
Systèmes de canalisations enterrées en poly(chlorure de vinyle) à
résistance au choc améliorée (PVC-HI) pour réseaux de combustibles
gazeux —
Partie 2: Raccords pour une pression maximale de service de 200 mbar
(20 kPa)
Reference number
©
ISO 2006
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©  ISO 2006
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ii © ISO 2006 – All rights reserved

Contents Page
Foreword. iv
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms. 2
4 Material . 2
5 General characteristics of fittings. 3
6 Geometrical characteristics. 3
7 Physical characteristics. 7
8 Mechanical characteristics . 8
9 General requirements for fittings. 9
10 Performance requirements . 9
11 Test methods. 11
12 Marking . 11
Annex A (normative) Determination of resistance to gas constituents . 12
Annex B (normative) Determination of leaktightness of fitting joints by internal air pressure,
with and without mechanical loading. 14
Annex C (normative) Determination of leaktightness of fitting joints under negative pressure and
mechanical loading. 16
Bibliography . 18

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 6993-2 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 first edition of ISO 6993-2, together with ISO 6993-1, ISO 6993-3 and ISO 6993-4, cancels and replaces
ISO 6993:2001, of which it constitutes a technical revision.
ISO 6993 consists of the following parts, under the general title Buried, high-impact poly(vinyl chloride)
(PVC-HI) piping systems for the supply of gaseous fuels:
⎯ Part 1: Pipes for a maximum operating pressure of 1 bar (100 kPa)
⎯ Part 2: Fittings for a maximum operating pressure of 200 mbar (20 kPa)
⎯ Part 3: Fittings and saddles for a maximum operating pressure of 1 bar (100 kPa)
⎯ Part 4: Code of practice for design, handling and installation

iv © ISO 2006 – All rights reserved

INTERNATIONAL STANDARD ISO 6993-2:2006(E)

Buried, high-impact poly(vinyl chloride) (PVC-HI) piping
systems for the supply of gaseous fuels —
Part 2:
Fittings for a maximum operating pressure of 200 mbar (20 kPa)
1 Scope
This part of ISO 6993 gives the requirements for non-end load-bearing fittings made of high-impact poly(vinyl
chloride) (PVC-HI) intended to be used for the supply of gaseous fuels through buried pipelines having an
operating temperature range of 0 °C up to and including +30 °C and a maximum operating pressure of
1)
200 mbar (20 kPa) .
It is applicable only to fittings manufactured from the high-impact PVC materials PVC-A, PVC-CPE and
PVC-EPR and having joints with elastomeric sealing elements. The fittings are suitable for those gases not
containing potentially damaging components in such concentrations as to impair the properties of the fitting
material.
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 580:2005, Plastics piping and ducting systems — Injection-moulded thermoplastics fittings — Methods for
visually assessing the effects of heating
ISO 2507-1, Thermoplastics pipes and fittings — Vicat softening temperature — Part 1: General test method
ISO 2507-2, Thermoplastics pipes and fittings — Vicat softening temperature — Part 2: Test conditions for
unplasticized poly(vinyl chloride) (PVC-U) or chlorinated poly(vinyl chloride) (PVC-C) pipes and fittings and for
high impact resistance poly(vinyl chloride) (PVC-HI) pipes
ISO 3126, Plastics piping systems — Plastics components — Determination of dimensions
ISO 3127, Thermoplastics pipes — Determination of resistance to external blows — Round-the-clock method
ISO 6993-1, Buried, high-impact poly(vinyl chloride) (PVC-HI) piping systems for the supply of gaseous
fuels — Part 1: Pipes for a maximum operating pressure of 1 bar (100 kPa)
ISO 9080, Plastics piping and ducting systems — Determination of the long-term hydrostatic strength of
thermoplastics materials in pipe form by extrapolation
EN 682:2002, Elastomeric seals — Material requirements for seals used in pipes and fittings carrying gas and
hydrocarbon fluids
EN 922:1994, Plastics piping and ducting systems — Pipes and fittings of unplasticized poly(vinyl chloride)
(PVC-U) — Specimen preparation for determination of the viscosity number and calculation of the K-value

5 2
1) 1 bar = 0,1 MPa = 10 Pa; 1 MPa = 1 N/mm
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the terms, definitions, symbols and abbreviated terms given in ISO 6993-1
and the following terms, definitions and symbols apply.
3.1 Terms and definitions
3.1.1
fitting
component, other than a pipe, used in a pipeline
EXAMPLE Bend, tee, coupler, end cap.
3.1.2
joint
connection between the ends of two components (with smooth spigot-ends and/or sockets)
NOTE In this part of ISO 6993, only joints with elastomeric sealing elements are considered.
3.1.3
socket
end of the fitting in which the elastomeric sealing element is fixed and into which a smooth spigot-end can be
inserted
3.2 Symbols
d depth/total depth of cracks, delaminations, blisters, or open yield seam, as applicable
d mean inside diameter of socket-end
im
e , e , e , e minimum wall thicknesses of fitting
1 2 3 4
T depth of engagement
s
L crack/blister length
L maximum length of depth of engagement of socket
max
L minimum length of spigot-end
min
4 Material
4.1 Material for fittings
4.1.1 Composition
The fittings shall be made of high-impact PVC, to which only such additives are added that are necessary to
facilitate conformity of the components to this part of ISO 6993.
The impact-resistant modified PVC shall be one of the following compositions:
a) a mixture based on PVC;
b) a blend based on PVC;
c) a copolymer based on PVC;
d) a combination of these types.
The proportion of the impact modifier in the composition shall be at least 7 % by mass.
2 © ISO 2006 – All rights reserved

4.1.2 Long-term strength
The MRS value of the injection-moulding material shall be at least 14 MPa. Conformity to this requirement
shall be proven using a long-term evaluation in accordance with ISO 9080. Testing is to be carried out at
20 °C, 40 °C and 60 °C, for periods up to 10 000 h. At 60 °C no knee shall occur before 5 000 h.
For injection-moulding compounds, this test shall be carried out on test pieces in the form of an injection
moulded or extruded sample in solid wall pipe form made from the relevant injection-moulding material.
NOTE The MRS evaluation is used for a material qualification and is not intended to be used for a pressure rating.
4.1.3 Vicat softening temperature
The Vicat softening temperature of the injection-moulding material shall be not less than 74 °C when
determined in accordance with ISO 2507-1 and ISO 2507-2.
4.1.4 K-value
The K-value of the unplasticized polyvinyl chloride (PVC-U) resin in the injection-moulding material shall
exceed 57, when measured in accordance with EN 922.
4.2 Material for elastomeric sealing elements
The material of the elastomeric sealing elements shall conform to EN 682:2002, type G.
The elastomeric sealing element shall have no detrimental effects on the properties of the components.
5 General characteristics of fittings
5.1 Contaminants
The material of the fitting shall not be shown to contain any contaminants, such as inorganic particles or
agglomerations thereof, exceeding 50 µm in size, when measured in accordance with 11.1 and 11.2.
5.2 Appearance and finish
The appearance and finish of the fittings shall be examined visually without magnification.
Internal and external surfaces shall be free from grooves, pits, blisters, indications of burning, an unacceptable
form of cold-flow and other irregularities that could have a detrimental effect on the mechanical properties of
the material and/or on the functional quality of the component.
Transitions in the form shall be smooth, in order to avoid notch influence. The corners in the grooves, in
particular for the fixing of the elastomeric sealing elements, shall be rounded.
6 Geometrical characteristics
6.1 Measurements
All dimensions shall be measured in accordance with ISO 3126.
6.2 Fittings
6.2.1 Fittings with socket-ends
6.2.1.1 Mean inside diameter of socket-end
The mean inside diameter of the socket-end, d , shall be in accordance with Table 1.
im
Table 1 — Minimum values of mean inside diameter of socket-end
Mean inside diameter of socket-end
Nominal outside diameter of
d
connecting pipe im
d
n
Minimum
mm
50 50,4
63 63,4
75,5
90 90,5
110 110,6
125 125,6
140,7
160 160,7
180 180,8
200 200,8
225,9
250 251,0
280 281,1
315 316,3
356,3
400 401,3
6.2.1.2 Out-of-roundness of socket-end
The difference between the greatest and the smallest measured inside diameter in the socket-end shall be, in
any cross-section, not greater than 0,007 × d , where d is the nominal outside diameter of the connecting
n n
pipe, expressed in millimetres. The calculated value shall be rounded off to the next higher 0,1 mm.
6.2.1.3 Height of stop shoulder or dead stop
At installation or at maximum allowable angular deflection, fittings with a stop shoulder or dead stop shall not
allow any further pushing of the connecting pipe.
The minimum and maximum inside diameter of the socket at the stop shoulder or dead stop shall not be less
than the values according to Table 2.
4 © ISO 2006 – All rights reserved

Table 2 — Mean inside diameter of socket at stop shoulder or dead stop
Dimensions in millimetres
Nominal outside diameter of
Mean inside diameter of socket at stop shoulder or dead stop
connecting pipe
d
n
Minimum Maximum
50 45,2 47,2
63 56,9 60,2
67,8 72,3
90 81,3 87,0
110 99,4 106,3
125 112,9 120,7
126,4 135,3
160 144,5 154,5
200 180,6 193,2
225 203,2 217,4
225,8 241,5
280 252,7 270,5
315 284,5 304,4
355 320,5 342,9
361,0 386,3
6.2.1.4 Wall thickness and depth of engagement
The minimum wall thickness, and the depth of engagement, T , as shown in Figure 1, shall be in accordance
s
with Table 3.
The lengths, L and L , as shown in Figure 1, shall be less than or equal to the values according to
min max
Table 3.
6.2.2 Fittings with smooth spigot-ends
The lengths, L and L , as shown in Figure 1, shall be greater than or equal to the values according to
min max
Table 3.
The minimum wall thicknesses, e , e , e and e , of a fitting fabricated from pipe or of an injection moulded
1 2 3 4
fitting shall be in accordance with Table 3.
The dimensions of fittings with a spigot-end shall be in accordance with the requirements of 6.2 for connecting
pipes, over a length L (see Table 3 and Figure 1).
min
Figure 1 — Dimensions of fittings (see Table 3)
Table 3 — Wall thickness and depth of engagement of fittings
Dimensions in millimetres
Fittings fabricated from pipes Injection moulded fittings T L
s max
d
n
Minimum wall thickness
Minimum L
min
e , e , e e e , e , e e
1 2 3 4 1 2 3 4
50 2,0 1,5 2,5 2,0 38 89
63 2,0 1,5 2,5 2,0 40 96
2,0 1,5 2,9 2,3 42 102
90 2,2 1,7 3,5 2,8 44 108
110 2,7 2,1 4,3 3,4 47 115
125 3,1 2,4 4,9 3,9 49 123
3,5 2,6 5,4 4,3 52 127
160 3,9 3,0 6,2 4,9 54 131
180 4,4 3,3 6,9 5,5 57 136
200 4,9 3,7 7,8 6,2 60 143
5,5 4,
...