ISO 10803:2011

Design method for ductile iron pipes

ISO 10803:2011 specifies the design of ductile iron pipes used for conveying water, sewerage and other fluids, with or without internal pressure and with or without earth and traffic loading.

Méthode de calcul des tuyaux en fonte ductile

General Information

• Status: Published
• Publication Date: 01-Dec-2011
• ICS: 23.040.10 - Iron and steel pipes
• Technical Committee: ISO/TC 5/SC 2 - Cast iron pipes, fittings and their joints
• Drafting Committee: ISO/TC 5/SC 2 - Cast iron pipes, fittings and their joints
• Current Stage: 9599 - Withdrawal of International Standard
• Due Date: 20-Nov-2024
• Completion Date: 20-Nov-2024

Relations

• Revised: ISO 10803:2024 - Design method for ductile iron pipes
• Effective Date: 06-Jun-2022
• Revises: ISO 10803:1999 - Design method for ductile iron pipes
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 10803
Second edition
2011-12-01
Design method for ductile iron pipes
Méthode de calcul des tuyaux en fonte ductile

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,
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Published in Switzerland
ii © ISO 2011 – All rights reserved

Contents Page
Foreword . iv
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
4  Design procedure . 2
5  Design for internal pressure . 3
6  Design for external loads. 3
Annex A (informative) Dimensions of preferred and other class pipes . 9
Annex B (informative) Allowable depths of cover for pipes conforming to ISO 2531 . 12
Annex C (informative) Allowable depths of cover for pipes conforming to ISO 7186 . 54
Annex D (informative) Trench types . 58
Annex E (informative) Soil classification . 59
Bibliography . 60

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 10803 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 second edition cancels and replaces the first edition (ISO 10803:1999), which has been technically
revised.
iv © ISO 2011 – All rights reserved

INTERNATIONAL STANDARD ISO 10803:2011(E)

Design method for ductile iron pipes
1 Scope
This International Standard specifies the design of ductile iron pipes used for conveying water, sewerage and
other fluids
 with or without internal pressure, and
 with or without earth and traffic loading.
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 7186, Ductile iron products for sewerage applications
ISO 7268, Pipe components — Definition of nominal pressure
ISO 10802, Ductile iron pipelines — Hydrostatic testing after installation
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7268 and the following apply.
3.1
allowable operating pressure
PFA
maximum internal pressure, excluding surge, which a component can safely withstand in permanent service
3.2
allowable maximum operating pressure
PMA
maximum internal pressure, including surge, which a component can safely withstand in service
3.3
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 ensure the integrity and
leaktightness of the pipeline
NOTE This test pressure is different from the system test pressure, which is related to the design pressure of the
pipeline.
3.4
embedment
arrangement and type(s) of material around a buried pipeline, which contribute to its structural performance
See Figure D.1.
3.5
bedding
lower part of the embedment, composed of the lower bedding (if necessary) and the upper bedding
See Figure D.1.
3.6
bedding reaction angle
conventional angle used in the calculation model to account for the actual soil pressure distribution at pipe
invert
3.7
compaction
deliberate densification of soil during the installation process
3.8
standard Proctor density
degree of soil compaction, as defined in AASHTO T99 using a 2,5 kg rammer and a 305 mm drop
4 Design procedure
4.1 The pipe wall thickness shall provide adequate strength against the internal pressure of the fluid and
against the effects of external loads due to backfill and surcharge, i.e. traffic loadings.
Ductile iron pipes in compliance with ISO 2531 are classified according to their allowable operating pressure
for use in water applications. Ductile iron pipes in compliance with ISO 7186 are for sewerage applications
either under pressure or under gravity. Using the equations given in Clauses 5 and 6, the design of buried
pipes is performed by determining
a) the minimum pipe wall thickness for the allowable operating pressure (PFA), and
b) the depths of cover as given in Annexes B and C.
4.2 The design procedure for the pipes is the following:
a) from the allowable operating pressure of the pipeline, select the class of pipe as appropriate from
ISO 2531 or ISO 7186 [the minimum pipe wall thickness of these pipes has been calculated from
Equation (1)];
b) calculate the allowable depth of cover in accordance with Clause 6;
c) if the allowable depth of cover is not adequate, select higher a pressure class of pipe and repeat
steps 4.2 a) and b) until the allowable depth of cover is acceptable.
NOTE 1 In practice, in most cases, the pressure class and the allowable depth of cover for the pipes can be selected
from the appropriate tables in Annexes B or C without carrying out the detailed calculations as explained above.
NOTE 2 When installed and operated under the conditions for which they are designed, ductile iron pipes, fittings,
accessories and their joints maintain all their functional characteristics over their operating life, due to constant material
properties, to the stability of their cross-section and to their design with high safety factors.
NOTE 3 In certain countries, national standards or regulations can specify other design procedures.
2 © ISO 2011 – All rights reserved

5 Design for internal pressure
5.1 Design equation for wall thickness
The minimum wall thickness of pipes, e , shall be not less than 3 mm (as specified in ISO 2531) or 2,4 mm
min
(ISO 7186) and shall be determined using Equation (1):
PFASF DE
e  (1)
min
20R(PFA SF)
m
where
e is the minimum pipe wall thickness to resist hoop stress due to internal pressure, in millimetres;
min
1)
is the allowable operating pressure, in bar (see 5.2);
PFA
SF is the design safety factor (see 5.2);
DE is the nominal pipe external diameter, in millimetres (see Annex A);
R is the minimum ultimate tensile strength of the ductile iron, in megapascals (R  420 MPa in
m m
ISO 2531 and ISO 7186).
Nominal wall thickness, e , of the pipe is calculated as given by Equation (2):
nom
ee  1,3 0,001DN (2)
 
nom min
where DN is the nominal diameter of pipe as defined in ISO 2531 and ISO 7186, in millimetres.
Nominal pipe wall thicknesses for various classes in accordance with ISO 2531 are given in Table A.1 and
nominal pipe wall thicknesses for pressure and gravity pipe classes in accordance with ISO 7186 are given in
Table A.2.
5.2 Design safety factors
The minimum pipe wall thickness, e , shall be calculated with a design safety factor of 2,5 for the maximum
min
allowable operating pressure (i.e. PMA as indicated in ISO 2531 and ISO 7186) and a design safety factor
of 3 for the allowable operating pressure (i.e. PFA as indicated in ISO 2531 and ISO 7186).
NOTE This allows field testing of installed ductile iron pipelines in compliance with ISO 10802 by application of test
pressures up to the allowable test pressures given in ISO 2531 and ISO 7186.
6 Design for external loads
6.1 Design equation
Kq
x
 100 (3)

80SE,061
or
1) 100 kPa = 1 bar = 0,1 MPa; 1 MPa = 1 N/mm .

 8SE 0,061

q (3)
K 100
x
where
 is the pipe diametral deflection, in percent of external diameter, D;
K is the deflection coefficient depending on bedding reaction angle;
x
q is the vertical pressure at pipe crown due to all external loads, in megapascals;
S is the pipe diametral stiffness, in megapascals,
EI
S
()D
where
E is the modulus of elasticity of the pipe wall material, in megapascals (170 000 MPa for
ductile iron);

e
stiff
I   is the second moment of area of the pipe wall per unit length, in millimetres to the
 

third power;
D is the mean diameter of pipe DE e , in millimetres;
 
stiff
DE is the nominal pipe external diameter as specified in ISO 2531 and ISO 7186, in millimetres;
e is the average of the minimum pipe wall thickness of the pipe and nominal wall thickness of
stiff
pipe, in millimetres;
E is the modulus of soil reaction, in megapascals.
Pipe material stiffness values, S, may be taken from the relevant annexes of ISO 2531 and ISO 7186.
The values of E and K are given in Table 1 for each trench type and soil group.
x
NOTE The design equation is based on the Spangler model (see Figure 1), where the vertical pressure, q, is acting
downward and:
 is uniformly distributed at the pipe crown over a diameter;
 is in equilibrium with a pressure, acting upward at the pipe invert, uniformly distributed over the bedding reaction
angle 2;
 causes a pipe deflection, which gives rise to a horizontal reaction pressure at pipe sides, parabolically distributed
over an angle of 100°.
4 © ISO 2011 – All rights reserved

Key
1 vertical pressure, q
2 lateral reaction pressure = 0,01 E
3 vertical reaction pressure = q/sin
Figure 1 — Spangler model
6.2 Loads applied to the pipe and calculation for the allowable depth of cover
6.2.1 General
The total vertical pressure, q, acting at pipe crown is the sum of the following components:
qq q (4)
where
q is the pressure from earth loads;
q is the pressure from traffic loads;
NOTE The pressure from traffic loads, q , is greater than that from normal static loads applied to the ground surface;
however, any abnormal surface loading can require special consideration.
The value of q obtained from Equation (4) is basically a function of H (allowable depth of cover), i.e.
qf ()H (5)
Equating this to Equation (3) (see 6.1):
 (8SE 0,061 )

fH() (6)
()K (100)
x
The value of allowable depth of cover, H, may be determined after calculating the value of q as given in 6.2.2
and 6.2.3 and other parameters as defined.
6.2.2 Pressure from earth loads
Equation (7) shall be used to calculate q from the weight of the earth prism immediately above the pipe:
qH 0,001
(7)
where
q is the pressure at pipe crown, in megapascals;
 is the unit weight of the backfill, in kilonewtons per cubic metre;
H is the height of cover (distance from pipe crown to ground surface), in metres.
In the absence of other data, the unit weight of the soil is taken as being equal to 20 kN/m in order to cover
the vast majority of cases. If a preliminary geotechnical survey determines that the actual unit weight of the
backfill is less than 20 kN/m , the actual value may be used for determining q .
If, however, it appears that the actual value is more than 20 kN/m , the actual value should be used.
6.2.3 Pressure from traffic loads
The value of q shall be calculated using Equation (8), based on wheel load taken from national and/or local
applicable standards and regulations.

4
q0,04 (1 210 DN) (8)
H
where
q is the pressure at pipe crown, in megapascals;
 is a traffic load factor; the following are th
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