ISO 7186:2011

INTERNATIONAL ISO
STANDARD 7186
Third edition
2011-07-15
Ductile iron products for sewerage
applications
Produits en fonte ductile pour l'assainissement

Reference number
©
ISO 2011
©  ISO 2011
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2011 – All rights reserved

Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 Technical requirements .7
4.1 General .7
4.2 Pressure classification .9
4.3 Dimensional requirements .9
4.4 Material characteristics.13
4.5 Coatings and linings for pipes.14
4.6 Coatings for fittings and accessories .14
4.7 Systems design requirements .15
4.8 Leaktightness of pipeline components.15
4.9 Marking.15
5 Performance requirements.16
5.1 Leaktightness of joints .16
5.2 Diametral stiffness .17
5.3 Chemical resistance.18
5.4 Abrasion resistance .18
6 Test methods and test frequencies .18
6.1 Dimensions .18
6.2 Straightness of pipes .19
6.3 Tensile test.19
6.4 Brinell hardness .21
6.5 Works leaktightness test of pipes and fittings for pressure applications .21
6.6 Works leaktightness test of pipes and fittings for vacuum applications .22
7 Type tests.22
7.1 Leaktightness of gravity pipeline components.22
7.2 Leaktightness of joints to internal pressure.22
7.3 Leaktightness of joints to external pressure.23
7.4 Leaktightness of joints to negative internal pressure.24
7.5 Diametral stiffness of pipe.24
7.6 Chemical resistance to effluents .26
7.7 Abrasion resistance .27
8 Tables of dimensions.28
8.1 Socket and spigot pipes .28
8.2 Fittings for gravity applications.30
8.3 Fittings for pressure and vacuum applications .32
Annex A (informative) External protection .33
Annex B (informative) Internal protection .34
Annex C (normative) Allowable pressure for pressure sewers .35
Bibliography.36

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 7186 was prepared by Technical Committee ISO/TC 5, Ferrous metal pipes and metallic fittings,
Subcommittee SC 2, Cast iron pipes, fittings and their joints.
This third edition cancels and replaces the second edition (ISO 7186:1996), which has been technically
revised. A new classification system for pipes and fittings based on pressure is introduced with minimum wall
thickness determined by allowable operating pressure.

iv © ISO 2011 – All rights reserved

INTERNATIONAL STANDARD ISO 7186:2011(E)

Ductile iron products for sewerage applications
1 Scope
This International Standard specifies the requirements and test methods applicable to ductile iron pipes,
fittings, accessories and their joints for the construction of drains and sewers outside buildings:
⎯ to convey surface water (e.g. rainwater), domestic waste water and/or certain types of industrial effluents,
either in separate systems or in combined systems;
⎯ operating without pressure (gravity sewers) or with positive or negative pressure;
⎯ for installation below or above ground.
1)
NOTE In this International Standard, all pressures are relative pressures expressed in bar .
This International Standard contains specifications for materials, dimensions and tolerances, mechanical
properties and standard coatings of pipes, fittings and accessories. It also gives performance requirements for
all components including joints.
This International Standard is applicable to pipes, fittings and accessories cast by any type of foundry process
or manufactured by fabrication of cast components, as well as corresponding joints, in the size range DN 80 to
DN 2600 inclusive.
It is applicable to pipes, fittings and accessories which are
⎯ manufactured with socketed, flanged or spigot ends (joint design and gasket shape are outside the scope
of this International Standard), and
⎯ normally delivered internally and externally coated.
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 2531, Ductile iron pipes, fittings, accessories and their joints for water applications
ISO 4016, Hexagon head bolts — Product grade C
ISO 4034, Hexagon nuts — Product grade C
ISO 4633, Rubber seals — Joint rings for water supply, drainage and sewerage pipelines — Specification for
materials
ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method

1) 100 kPa = 1 bar = 0,1 MPa; 1 MPa = 1 N/mm .
ISO 7005-2, Metallic flanges — Part 2: Cast iron flanges
ISO 7091, Plain washers — Normal series — Product grade C
ISO 10804, Restrained joint systems for ductile iron pipelines — Design rules and type testing
EN 1092-2, Flanges and their joints — Circular flanges for pipes, valves, fittings and accessories,
PN designated — Part 2: Cast iron flanges
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
ductile iron
type of cast iron used for pipes, fittings and accessories in which graphite is present primarily in spheroidal
form
[ISO 2531:2009, definition 3.8]
3.2
pipe
casting of uniform bore, with straight axis, having either socket, spigot or flanged ends
NOTE This does not apply to flanged sockets, flanged spigots and collars, which are classified as fittings.
[ISO 2531:2009, definition 3.22]
3.3
fitting
casting other than a pipe, which allows pipeline deviation, change of direction or bore
NOTE Flanged sockets, flanged spigots and collars are also classified as fittings.
[ISO 2531:2009, definition 3.9]
3.4
accessory
any casting other than a pipe or fitting, which is used in a pipeline
EXAMPLE 1 Glands and bolts for mechanical flexible joints.
EXAMPLE 2 Glands, bolts and locking rings or segments for restrained joints.
[ISO 2531:2009, definition 3.1]
3.5
inspection chamber
component of a discharge system, of a drain or of a sewer providing access from the ground surface for
inspection and maintenance equipment
3.6
manhole
component of a sewer of sufficient size to provide access from the ground surface for inspection and
maintenance operations by personnel and equipment
2 © ISO 2011 – All rights reserved

3.7
flange
end of a pipe or fitting, extending perpendicular to its axis, with bolt holes equally spaced on a circle
NOTE A flange can be fixed (e.g. integrally cast, screwed-on or welded-on) or adjustable. An adjustable flange
comprises a ring, in one or several parts bolted together, which bears on an end joint hub and can be freely rotated around
the barrel axis before jointing.
[ISO 2531:2009, definition 3.10]
3.8
spigot
male end of a pipe or fitting
[ISO 2531:2009, definition 3.26]
3.9
spigot end
maximum insertion depth of the spigot, L , plus 50 mm
i
[ISO 2531:2009, definition 3.27]
See Figure 5.
3.10
socket
female end of a pipe or fitting to make the connection with the spigot of the next component
[ISO 2531:2009, definition 3.25]
3.11
gasket
sealing component of a joint
[ISO 2531:2009, definition 3.13]
3.12
joint
connection between the ends of pipes and/or fittings in which a gasket is used to effect a seal
[ISO 2531:2009, definition 3.15]
3.13
flexible joint
joint providing significant angular deflection and movement parallel and/or perpendicular to the pipe axis
[ISO 2531:2009, definition 3.12]
3.14
push-in flexible joint
flexible joint assembled by pushing the spigot through the gasket into the socket of the mating component
[ISO 2531:2009, definition 3.23]
3.15
mechanical flexible joint
flexible joint in which sealing is obtained by applying pressure to the gasket by mechanical means, e.g. a
gland
[ISO 2531:2009, definition 3.18]
3.16
restrained joint
joint in which a means is provided to prevent separation of the assembled joint
[ISO 2531:2009, definition 3.24]
3.17
flanged joint
joint between two flanged ends
[ISO 2531:2009, definition 3.11]
3.18
nominal size
DN
alphanumeric designation of size for components of a pipework system, which is used for reference purposes
NOTE 1 It comprises the letters DN followed by a dimensionless whole number, which is indirectly related to the
physical size, in millimetres, of the bore or outside diameter of the end connections.
NOTE 2 Adapted from ISO 6708:1995, definition 2.1.
3.19
nominal pressure
PN
numerical designation, which is a convenient rounded number, used for reference purposes
NOTE 1 All components of the same nominal size, DN, designated by the same PN number have compatible mating
dimensions.
NOTE 2 Adapted from ISO 7268.
3.20
leaktightness test pressure
pressure applied to a component during manufacturing in order to ensure its leaktightness
3.21
allowable operating pressure
PFA
maximum internal pressure, excluding surge, that a component can safely withstand in permanent service
[ISO 2531:2009, definition 3.2]
3.22
allowable maximum operating pressure
PMA
maximum internal pressure, including surge, which a component can safely withstand in service
NOTE Adapted from ISO 2531:2009, definition 3.17.
4 © ISO 2011 – All rights reserved

3.23
allowable site test pressure
PEA
maximum hydrostatic pressure that a newly installed component can withstand for a relatively short duration,
when either fixed above ground level or laid and backfilled underground, in order to measure the integrity and
tightness of the pipeline
NOTE This test pressure is different from the system test pressure which is related to the design pressure of the
pipeline.
[ISO 2531:2009, definition 3.3]
3.24
diametral stiffness of a pipe
characteristic of a pipe allowing it to resist diametral deflection under loading
[ISO 2531:2009, definition 3.7]
3.25
discharge system
system of pipes, fittings, accessories and joints used to collect and drain waste water and rainwater from a
building
NOTE It comprises discharge pipes, stack ventilation pipes and rainwater downpipes, installed within the limits of a
building or attached to the building.
3.26
drain
system of pipes, fittings, accessories and joints installed outside the limits of a building in order to connect the
discharge system of the building to a sewer or a septic tank
3.27
sewer
pipeline designed to collect waste water and rainwater from buildings and surface water and to convey them
to the point of disposal or treatment
3.28
gravity sewer
sewer operating normally under free flowing conditions
3.29
pumping sewer
pressure sewer
sewer (or section of a sewer) operating under positive pressure
3.30
vacuum sewer
sewer operating under negative pressure
3.31
combined sewer
sewer collecting together rainwater, surface water and waste water
3.32
separate sewer system
sewerage system which collects waste water separately from surface water
3.33
batch
quantity of castings from which a sample may be taken for testing purposes during manufacture
[ISO 2531:2009, definition 3.4]
3.34
type test
proof-of-design test, which is done once and is repeated only after change of design
[ISO 2531:2009, definition 3.29]
3.35
laying length
L
e
length by which a pipeline progresses when an additional pipe is installed
NOTE 1 For socket and spigot pipes, it is equal to the total length of the pipe, L , minus the maximum spigot insertion
tot
depth, L , as given by the manufacturer and as shown in Figure 5. For flanged pipes, it is equal to the total length of the
i
pipe.
NOTE 2 It is expressed in metres.
NOTE 3 Adapted from ISO 2531:2009, definition 3.16.
3.36
standardized length
length of pipe barrel and fitting body or branch
NOTE 1 For socket and spigot pipes, it is designated L (l for branches). For flanged pipes, and fittings, it is
u u
designated L (l for branches). See Figure 5 and ISO 2531.
NOTE 2 For flanged pipes and fittings, the standardized length L (l for branches) is equal to the total length. For
socketed pipes and fittings, the standardized length L (l for branches) is equal to the total length minus the depth of
u u
socket, as indicated in the manufacturer's handbooks.
NOTE 3 Adapted from ISO 2531:2009, definition 3.28
3.37
ovality
out-of-roundness of a pipe section, equal to Equation (1):
A − A
()
100 (1)
A + A
()
where
A is the maximum axis, in millimetres;
A is the minimum axis, in millimetres.
[ISO 2531:2009, definition 3.21]
6 © ISO 2011 – All rights reserved

3.38
deviation
amount by which the design length may differ from the standardized length of a pipe or a fitting
NOTE 1 Pipes and fittings are designed to a length selected in the range of standard length plus or minus the deviation
(see Table 3); they are manufactured to this length plus or minus the tolerance given in Table 4.
NOTE 2 Adapted from ISO 2531:2009, definition 3.6.
3.39
component
any product defined as an element of a pipeline, such as a pipe, fitting or accessory
[ISO 2531:2009, definition 3.5]
See 3.2, 3.3 and 3.4.
3.40
hoop stress
σ
stress in a pipe or fitting under pressure, acting tangentially to the perimeter of a transverse section
[ISO 2531:2009, definition 3.14]
4 Technical requirements
4.1 General
4.1.1 Pipes, fittings and accessories
Thicknesses, lengths and coatings are specified in 4.3.2, 4.3.3, and 4.5 and 4.6, respectively. Where, by
agreement between the manufacturer and the purchaser, pipes and fittings with different lengths, thicknesses
and/or coatings, and other types of fittings than those given in 8.2 and 8.3, are supplied in accordance with
this International Standard, they shall comply with all the other requirements of this International Standard.
This includes pipes and fittings manufactured to national standards and regulations.
The standard nominal sizes DN of pipes and fittings are the following:
80, 100, 125, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1400, 1500,
1600, 1800, 2000, 2200, 2400, 2600.
The stiffness and allowable diametral deflection of ductile iron pipes are those given in Table 11.
The pressures PFA, PMA and PEA (see 3.21, 3.22 and 3.23) for pressure sewers are those indicated in
Annex C.
NOTE Where designed, installed, operated and maintained with due regard to the factors described in Annexes A
and B, ductile iron pipes, fittings, accessories and their joints maintain their functional characteristics over their service life,
due to time-independent material properties and high factors of safety.
4.1.2 Surface condition and repairs
Pipes, fittings and accessories shall be free from defects and surface imperfections which can impair their
compliance with the requirements of Clauses 4 and 5.
Where necessary, pipes and fittings may be repaired by the manufacturer, for example by welding, to remove
surface imperfections and localized defects, which do not affect the entire wall thickness, provided the
repaired pipes and fittings comply with all the requirements of Clauses 4 and 5.
4.1.3 Types of joints and interconnection
4.1.3.1 General
Joint design and gasket shapes are beyond the scope of this International Standard.
Rubber gasket materials shall conform to the requirements of ISO 4633 for sewerage applications. Where
materials other than rubber are necessary (e.g. high-temperature flanged joints), they shall conform to the
appropriate International Standards.
4.1.3.2 Flanged joints
Flanged joints shall be designed such that they can be attached to flanges whose dimensions and tolerances
comply with ISO 7005-2 or EN 1092-2. This ensures interconnection between all flanged components (pipes,
fittings, valves, etc.) of the same DN and PN and adequate joint performance. Bolts and nuts shall comply, as
a minimum, with the requirements of ISO 4016 and ISO 4034, property class 4.6. Where washers are required
they shall comply with ISO 7091.
In addition, each type of flanged joint shall be designed to meet the performance requirements as specified in
ISO 2531.
Although it does not affect interconnection, the manufacturer's handbook shall indicate whether products
contained therein are normally delivered with fixed or loose flanges.
4.1.3.3 Flexible joints
Pipes and fittings with flexible joints shall be in accordance with 4.3.1.1 for their spigot external diameters, DE,
and their tolerances. This provides the possibility of interconnection between components equipped with
different types of flexible joints. In addition, each type of flexible joint shall be designed to meet the
performance requirements of 5.1.
For interconnection with certain types of joints operating within a tighter tolerance range on DE, the
manufacturer's guidance should be followed as to the means of ensuring adequate joint performance up to the
highest pressures (e.g. measurement and selection of external diameter).
For interconnection with existing pipelines, which can have external diameters not in accordance with 4.3.1.1,
the manufacturer's guidance should be followed as to the appropriate means of interconnection (e.g.
adaptors).
4.1.3.4 Restrained joints
Restrained joints for ductile iron pipelines shall be designed in accordance with ISO 10804. Their spigot
external diameters, DE, and their tolerances shall comply with 4.3.1.1.
4.1.4 Colour identification
Pipes and fittings for sewers and drains shall be identified externally by a specific colour (see national
standard). Identification is possible by various means, e.g. external paint, polyethylene sleeving or a warning
tape.
NOTE This is to allow easy identification of installed sewers and drains and to avoid mistaking with pipelines for
water and gas supply.
8 © ISO 2011 – All rights reserved

4.2 Pressure classification
4.2.1 General
Depending on the manner by which the surface water or sewerage is transported, the sewerage system can
be classified as a pressure sewer or a gravity sewer and, accordingly, flexibly jointed pipeline systems can be
classified as pressure pipes/fittings or gravity pipes/fittings.
The allowable pressures within a pipeline system shall be limited to the lowest pressure classification
component within the system.
Components with flanged joints shall be classified by the PN number of the flange.
Pressure pipes can be used in gravity pipeline systems.
4.2.2 Gravity pipes
Gravity pipes are designed for gravity sewer applications. Their normal service, internal and external
pressures are defined in Table 6.
4.2.3 Pressure pipes
Pressure pipes are designed for pressure sewer applications and are classified by the allowable operating
pressure (PFA), prefixed by a letter C.
Allowable pipeline pressures relationships are as follows:
a) allowable operating pressure  (PFA) = (C), in bar;
b) maximum allowable operating pressure (PMA) = 1,20 × (PFA), in bar;
c) allowable site test pressure  (PEA) = (1,20 × PFA) + 5, in bar.
The pressure pipes shall be selected from the preferred pressure classes C25, C30 and C40 as defined in
ISO 2531. Their normal service internal and external pressures are defined in Table 6.
Other pressure classes, specified in ISO 2531, may be used if applicable.
The allowable pressures within a pipeline system shall be limited to the lowest pressure classification
component within the system.
4.3 Dimensional requirements
4.3.1 Diameter
4.3.1.1 External diameter
Table 12 gives the values of the external diameter DE of the spigot end of pipes and fittings, when measured
circumferentially using a circumferential tape in accordance with 6.1.1. The positive tolerance is +1 mm and
applies to all pressure classes of pipes and also to flanged spigot fittings.
The negative tolerance depends on the design of each type of joint and can be as specified in national
standards, or, when not so specified, in the manufacturer's handbook, for the type of joint and the nominal
size considered.
In addition, the ovality (see 3.37) of the spigot end of pipes and fittings shall
⎯ remain within the tolerances on DE for DN 80 to DN 200, and
⎯ not exceed 1 % of DE for DN 250 to DN 600 or 2 % for DN > 600.
The manufacturer's recommendations should be followed with respect to the necessity and means of ovality
correction; certain types of flexible joints can accept the maximum ovality without the need for spigot re-
rounding prior to jointing.
4.3.1.2 Internal diameter
The nominal values of the internal diameters of centrifugally cast pipes, expressed in millimetres, are
approximately equal to the numbers indicating their nominal size, DN.
4.3.2 Wall thickness
4.3.2.1 Pipes with flexible joints
4.3.2.1.1 Gravity pipes
The minimum wall thickness for gravity pipes shall be as given in Table 12.
The minimum wall thickness, e , is equal to the nominal wall thickness, e , minus 1 mm for DN 80 to
min nom
DN 300 and minus 1,2 mm for DN 350.
4.3.2.1.2 Pressure pipes
The minimum wall thickness, e , and shall be not less than 3 mm and shall be determined using
min
Equation (2):
PFA××SF DE
e = (2)
min
20R+×PFA SF
()
m
where:
e is the minimum pipe wall thickness, in millimetres;
min
PFA is the allowable operating pressure, in bar;
SF is the safety factor for PFA (= 3);
DE is the nominal pipe external diameter (see Table 12), in millimetres;
R is the minimum tensile strength of ductile iron, in megapascals (R = 420 MPa; see Table 5).
m m
NOTE Equation (2) is derived from Barlow's equation, i.e. hoop stress, σ = PD/2t (see 3.40).
For pressure pipes centrifugally cast, the minimum wall thickness, e , shall not be less than 3 mm. The
min
nominal wall thickness, e , is equal to the minimum wall thickness, e , plus (1,3 + 0,001 DN).
nom min
For pressure pipes not centrifugally cast, the minimum wall thickness, e , shall not be less than 4,7 mm. The
min
nominal wall thickness, e , is equal to the minimum wall thickness, e , plus (2,3 + 0,001 DN).
nom min
10 © ISO 2011 – All rights reserved

4.3.2.2 Flanged pipe
Flanged pipe shall be classified by PN number. The pressure class of the barrel of the flanged pipes shall be
equal to or greater than a value, in bar, equal to the PN of the flanges. The pressure class of the flanged pipe
barrel to be used for fabricated flanged pipe shall be as indicated in 8.2 for weld-on flanges, screwed-on
flanges and integrally cast flanges.
NOTE Pipe threads are regarded as loss of wall thickness.
4.3.2.3 Fittings
4.3.2.3.1 Fittings for gravity applications
The iron wall thickness of fittings for gravity applications is defined by the manufacturer. The thickness shall
be equal to or greater than those of pipes of the same DN.
4.3.2.3.2 Fittings for pressure applications
Fittings for pressure application shall be in accordance with 8.3.
4.3.3 Length
4.3.3.1 Socket and spigot pipes
The standardized lengths of socket and spigot pipes shall be as given in Table 1.
Table 1 — Standardized lengths of socket and spigot pipes
Dimensions in metres
a
DN Standardized lengths, L
u
80 to 600 4 or 5 or 5,5 or 6 or 9
700 and 800 4 or 5,5 or 6 or 7 or 9
900 to 2600 4 or 5 or 5,5 or 6 or 7 or 8,15 or 9
NOTE Not all the standardized lengths are available in all countries.
a
See 3.36.
The manufacturer's design lengths, L (see 3.36), shall be within a deviation of ±250 mm of the lengths given
u
in Table 1 and shall be given in their handbook. The actual length, L , shall be measured in accordance
u
with 6.1.3 and shall not differ from the manufacturer's design length by more than the tolerance given in
Table 4. Of the total number of socket and spigot pipes being supplied in each diameter, the percentage of
shorter pipes shall not exceed 10 %.
NOTE 1 Pipes cut for test purposes can be excluded from the 10 % limitation and treated as full length pipes.
NOTE 2 When pipes are ordered on a meterage basis, the manufacturer can determine the required quantity of pipes
to be supplied by the summation of the measured individual pipe laying lengths.
4.3.3.2 Flanged pipes
The lengths of flanged pipes shall be as given in Table 2. Other lengths are available by agreement between
the manufacturer and the purchaser.
Table 2 — Standardized lengths of flanged pipes
Dimensions in metres
a
Type of pipe DN Standardized lengths, L
With cast-on flanges 80 to 2600 0,5 or 1 or 2 or 3
80 to 500 2 or 3 or 4 or 5
With screwed-on or welded-on flanges 600 to 1000 2 or 3 or 4 or 5 or 6
1100 to 2600 4 or 5 or 6 or 7
a
See 3.36.
4.3.3.3 Fittings
Fittings for gravity applications shall be in conformity with 8.2.
Fittings for pressure applications shall be supplied in conformity with ISO 2531.
Table 3 — Permissible deviations on lengths of fittings
Dimensions in metres
Type of fitting DN Deviation
Flanged sockets
80 to 1200 ±25
Flanged spigots
1400 to 2600 ±35
Collars, tapers
+50
80 to 1200
−25
Tees
+75
1400 to 2600
−35
Bends 90° (1/4) 80 to 2600 ±(15 + 0,03 DN)
Bends 45° (1/8) 80 to 2600 ±(10 + 0,025 DN)
80 to 1200 ±(10 + 0,02 DN)
Bends 22°30' (1/16) and 11°15' (1/32)
1400 to 2600 ±(10 + 0,025 DN)
Fittings for gravity applications 80 to 2600 ±(15 + 0,03 DN)

4.3.3.4 Tolerances on lengths
The tolerances on lengths shall be as given in Table 4.
Table 4 — Tolerances on lengths
Dimensions in metres
Type of casting Tolerance
−30
Socket and spigot pipes (full length or shortened)
+70
Fittings for socketed joints ±20
a
Pipes and fittings for flanged joints ±10
a
By agreement between the manufacturer and the purchaser, smaller tolerances are possible, but not less than ±3 mm for DN ≤ 600
and ±4 mm for DN > 600.
12 © ISO 2011 – All rights reserved

4.3.4 Straightness of pipes
Pipes shall be straight, with a maximum deviation of 0,125 % of their length.
The verification of this requirement is normally carried out by visual inspection, but in case of doubt or in
dispute, the deviation shall be measured in accordance with 6.2.
4.3.5 Inspection chambers
Inspection chambers shall be manufactured either as an integral item or by site assembly of a bottom part and
a vertical part.
Normal access sizes shall be the following: 250, 300, 400, 600 mm.
The leaktightness of inspection chambers shall be in conformity with 4.8.
4.3.6 Manholes
Manholes are composed of a vertical part of DN ≥ 800, a bottom plate, a top plate capable of receiving a
frame and a manhole cover, and 2 or more inlets/outlets fixed to the vertical part.
The number and location of the inlets/outlets shall preserve the hydraulic continuity inside the manhole.
The leaktightness of manholes shall be in conformity with 4.8.
4.4 Material characteristics
4.4.1 Tensile properties
Pipes, fittings and accessories made of ductile iron shall have the tensile properties shown in Table 5.
During the manufacturing process, the manufacturer shall carry out suitable tests to verify these tensile
properties; such tests may be either
a) a batch sampling system whereby samples are obtained from the pipe spigot or, for fittings, from samples
cast separately or integrally with the casting concerned (test bars shall be machined from these samples
and tensile tested according to 6.3), or
b) a system of process control testing (e.g. non-destructive), by which a positive correlation can be
demonstrated with the tensile properties specified in Table 5; testing verification procedures shall be
based on the use of comparator samples having known and verifiable properties. This system of testing
shall be supported by tensile testing in accordance with 6.3.
Table 5 — Tensile properties
Minimum tensile strength
Minimum percent elongation after fracture
R
A
m
Type of casting
MPa %
DN 80 to DN 2600 DN 80 to DN 1000 DN 1100 to DN 2600
Pipes centrifugally cast 420 10 7
Pipes not centrifugally cast,
420 5 5
fittings and accessories
By agreement between the manufacturer and the purchaser, the 0,2 % proof stress (R ) may be measured. It shall be
p02
not less than: 270 MPa when A ≥ 12 % for DN 80 to DN 1000 or A ≥ 10 % for DN > 1000; 300 MPa in other cases.
For centrifugally cast pipes of DN 80 to DN 1000 and having a design minimum wall thickness of 10 mm or greater, the
minimum elongation after fracture shall be 7 %.
4.4.2 Brinell hardness
The hardness of the various components shall be such that they can be cut, tapped, drilled and/or machined
with standard tools. In case of dispute, the hardness shall be measured according to 6.4.
The Brinell hardness shall not exceed 230 HBW for centrifugally cast pipes and 250 HBW for non-centrifugally
cast pipes, fittings and accessories. For components manufactured by welding, a higher Brinell hardness is
allowed in the heat-affected zone of the weld.
4.5 Coatings and linings for pipes
4.5.1 General
Pipes shall be normally delivered internally and externally coated.
4.5.2 External coatings
Ductile iron pipeline systems can be installed in a wide range of external operating environments. These
environments can be characterized according to their aggressivity. For relevant factors, see A.1.
Coatings specified by relevant International Standards are available as specified in A.2. Other coatings are
also available.
Except for the pipes intended only for the transportation of rainwater, domestic waste water in pressure
applications, or non-septic domestic sewerage, the surfaces which can come into contact with the effluents
(internal surface of the socket and external surface of the spigot end) shall be coated with a special coating,
whose chemical resistance should be in conformity with 5.3.
4.5.3 Internal linings
Ductile iron pipeline systems can be used to convey surface water, domestic waste water and/or certain types
of industrial effluents. These internal effluents can be characterized according to their aggressivity. Relevant
factors to be considered are given in B.1.
Linings specified by relevant International Standards are available as specified in B.2. Other linings are also
available.
Except for the pipes intended only for the transportation of rainwater, domestic waste water in pressure
applications, or non-septic domestic sewerage, the chemical resistance should be in conformity with 5.3, and
the abrasion resistance should be in conformity with 5.4.
4.6 Coatings for fittings and accessories
4.6.1 General
Fittings and accessories shall be normally delivered internally and externally coated.
4.6.2 External coatings
Ductile iron pipeline systems can be installed in a wide range of external operating environments. These
environments can be characterized according to their aggressivity. For relevant factors, see A.1.
Coatings specified by relevant International Standards are available as specified in A.3. Other coatings are
available.
14 © ISO 2011 – All rights reserved

Except for the fittings and accessories intended only for the transportation of rainwater, domestic waste water
in pressure applications, or non-septic domestic sewerage, the surfaces which can come into contact with the
effluents (internal surfaces of the socket and external surface of the spigot end) shall be coated with a special
coating, whose chemical resistance should be in conformity with 5.3.
4.6.3 Internal linings
Ductile iron pipeline systems can be used to convey surface water, domestic waste water and/or certain types
of industrial effluents. These internal effluents can be characterized according to their aggressivity. Relevant
factors for consideration are given in B.1.
Linings specified by relevant International Standards are available as specified in B.4. Other linings are also
available.
Except for the fittings and accessories intended only for the transportation of rainwater, domestic waste water
in pressure applications, or non-septic domestic sewerage, the chemical resistance should be in conformity
with 5.3, and the abrasion resistance should be in conformity with 5.4.
4.7 Systems design requirements
Installed sewer systems constructed with ductile iron components in conformity with this International
Standard shall be leaktight to the pressures given in Table 6, depending on the way in which they are normally
operated.
Table 6 — Operating pressure of sewer system
Internal pressure External pressure
Type of operation
bar bar
Continuous Occasional Continuous
Gravity sewer 0 to 0,5 2 1
Pressure sewer See PFA in Annex C See PMA in Annex C 1
Vacuum sewer −0,5 −0,8 1
This applies under all normal service conditions, including foreseeable external loads and joint movements
(both angular and radial).
4.8 Leaktightness of pipeline components
Ductile iron pipes, fittings, inspection chambers and manholes shall be leaktight when used under the
conditions for which they are designed (see 4.7).
When tested according to 6.5, pipes and fittings for positive pressure applications shall exhibit no visible
leakage, sweating or any other sign of failure.
When tested according to 7.1, pipes and fittings for gravity applications shall exhibit no visible leakage,
sweating or any other sign of failure.
When tested according to 6.6, pipes and fittings for vacuum applications shall exhibit no visible leakage,
sweating or any other sign of failure.
4.9 Marking
All pipes and fittings shall be durably and legibly marked and shall bear at least the following indications:
a) a reference to this International Standard, i.e. ISO 7186;
b) the manufacturer's name or mark;
c) identification of the year of manufacture;
d) identification as ductile iron;
e) the DN;
f) the PN rating of flanges, if applicable;
g) identification of the application (gravity or pressure).
List items b) to f) shall be cast-on or cold stamped. List items a) and g) can be applied by any method, e.g.
painted on the castings.
5 Performance requirements
5.1 Leaktightness of joints
5.1.1 General
All flexible joints for ductile iron pipes and components shall be designed in compliance with the requirements
of 5.1. If the design has been tested and documented by the manufacturer and successfully used for a
minimum of 10 years, the performance of a type test as specified in 5.1.2 for internal pressure, as specified
in 5.1.3 for external pressure and as specified in 5.1.4 for negative internal pressure is only required for
significant changes in design, which could adversely affect the performance of the joint.
Joint designs shall be type tested to demonstrate leaktightness to both internal and external pressure under
the most unfavourable conditions of casting tolerances and joint movements.
There shall be a type test for at least one DN for each of the groupings given in Table 7. One DN is
representative of a grouping when the performances are based on the same design parameters throughout
the size range.
Table 7 — DN groupings for type tests
DN groupings 80 to 250 300 to 600 700 to 1000 1100 to 2000 2200 to 2600
Preferred DN in each grouping 200 400 800 1600 2400

If a grouping covers products of different designs and/or manufactured by different processes, the grouping
shall be subdivided.
If, for a manufacturer, a grouping contains only one DN, this DN may be considered as part of the adjacent
grouping provided that it is of identical design and manufactured by the same process.
The type tests shall be carried out in the configuration of maximum design radial gap between the
components to be jointed (smallest spigot together with largest socket).
In the type test, the maximum gap shall be equal to the maximum design radial gap with a tolerance of % .
−5
The internal socket diameter may be machined to achieve this, even if the resulting diameter is slightly outside
the normal manufacturing tolerance.
All joints shall be performance tested with a spigot having an average iron wall thickness (over a distance of
two times DN, in millimetres, from the spigot face) equal to the specified minimum value for the pipe for which
+10
the joint is designed, % . It is permissible to machine the spigot of the pipe bore to achieve the required
thickness.
Restrained flexible joints shall be designed and tested in accordance with ISO 10804.
16 © ISO 2011 – All rights reserved

5.1.2 Positive internal pressure
The leaktightness of joints to positive internal pressure shall be tested as specified in 7.2; the joints shall
exhibit no visible leakage during 2 h, in the two following positions:
a) joint aligned and subjected to a shear: the shear force across the joint, expressed in newtons, shall not be
less than 30 times DN;
b) joint deflected: the test angular deflection shall be the maximum allowable deflection indicated in the
manufacturer's handbook, but not less than 3°30' for DN 80 to DN 300
...