SIST ISO 4065:2018

Thermoplastics pipes -- Universal wall thickness table

This document specifies the relationship between the nominal wall thickness en and the nominal
outside diameter dn of thermoplastics pipes.
It is applicable to solid-wall thermoplastics pipes of constant circular cross-section along the whole
length of the pipe, whatever their method of manufacture, their composition or their intended
application.
NOTE Pipes with constant circular cross-section along the whole length of the pipe are commonly known as
pipes with smooth external and internal surfaces.

Tubes en matières thermoplastiques -- Tableau universel des épaisseurs de paroi

Plastomerne cevi - Preglednica univerzalne debeline stene

Ta dokument določa odnos med nominalno debelino stene (en) in nominalnim zunanjim premerom (dn) plastomernih cevi.
Uporablja se za plastomerne cevi s trdnimi stenami s stalnim krožnim prerezom po celotni dolžini cevi, ne glede na način njihove izdelave, njihovo sestavo ali predvideno uporabo.
OPOMBA: Cevi s stalnim krožnim prerezom po celotni dolžini cevi so splošno znane kot cevi z gladkimi zunanjimi in notranjimi površinami.

General Information

• Status: Published
• Public Enquiry End Date: 29-Jul-2018
• Publication Date: 23-Aug-2018
• ICS: 23.040.20 - Plastics pipes
• Technical Committee: PCV - Plastic pipes, fittings and valves
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 13-Aug-2018
• Due Date: 18-Oct-2018
• Completion Date: 24-Aug-2018
• Ref Project: ISO 4065:2018 - Thermoplastics pipes — Universal wall thickness table

Relations

• Replaces: SIST ISO 4065:2012 - Thermoplastics pipes -- Universal wall thickness table
• Effective Date: 01-Sep-2018

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 4065
Third edition
2018-01
Corrected version
2019-12
Thermoplastics pipes — Universal
wall thickness table
Tubes en matières thermoplastiques — Tableau universel des
épaisseurs de paroi
Reference number
ISO 4065:2018(E)
©
ISO 2018

---------------------- Page: 1 ----------------------
ISO 4065:2018(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 4065:2018(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Calculation of values . 2
4.1 Calculation of S values . 2
4.2 Calculation of wall thicknesses . 3
5 Wall thickness tables . 5
6 Deviations . 5
Bibliography .10
© ISO 2018 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 4065:2018(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.
This third edition cancels and replaces the second edition (ISO 4065:1996), which has been technically
revised.
The significant changes are:
— S-values and design stresses for 6,0 bar are deleted;
— Wall thickness values for pipes with diameters up to 3000 mm are included;
— The upper limit for tabled wall thicknesses increased to 150 mm;
— Additional pipe series S 10,5, S 13,3 and S 16,7 are left for use in non-pressure purposes only;
— Definitions are updated to follow modern plastics piping terminology.
This corrected version of ISO 4065:2018 incorporates the following corrections:
The missing decimal separators in Tables 1 and 2 have been reinserted.
iv © ISO 2018 – All rights reserved

---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 4065:2018(E)
Thermoplastics pipes — Universal wall thickness table
1 Scope
This document specifies the relationship between the nominal wall thickness e and the nominal
n
outside diameter d of thermoplastics pipes.
n
It is applicable to solid-wall thermoplastics pipes of constant circular cross-section along the whole
length of the pipe, whatever their method of manufacture, their composition or their intended
application.
NOTE Pipes with constant circular cross-section along the whole length of the pipe are commonly known as
pipes with smooth external and internal surfaces.
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 3, Preferred numbers — Series of preferred numbers
ISO 497:1973, Guide to the choice of series of preferred numbers and of series containing more rounded
values of preferred numbers
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 https:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1
nominal outside diameter
d
n
specified outside diameter, assigned to a nominal size DN
Note 1 to entry: Nominal outside diameter is expressed in millimetres.
Note 2 to entry: For metric pipes conforming to this document, the nominal outside diameter, expressed in
millimetres, is the minimum mean outside diameter dem.min specified in the applicable pipe standard.
3.2
mean outside diameter
d
em
value of the measurement of the outer circumference of the pipe in any cross-section divided by π,
rounded up to the nearest 0,1 mm
Note 1 to entry: The value of π is taken to be 3,142.
© ISO 2018 – All rights reserved 1

---------------------- Page: 5 ----------------------
ISO 4065:2018(E)

3.3
wall thickness at any point
e
measured wall thickness at any point around the circumference of the pipe, rounded to the next
higher 0,1 mm
3.4
nominal wall thickness
e
n
wall thickness tabulated in this document, and identical to the minimum permissible wall thickness at
any point, e
min
3.5
standard dimension ratio
SDR
numerical designation of a pipe series, which is a convenient round number, approximately equal to the
ratio of the nominal outside diameter d of а pipe to its nominal wall thickness e
n n
Note 1 to entry: This value may also be derived from the formula given in 3.6.
3.6
pipe series
S
dimensionless number related to the nominal outside diameter d and nominal wall thickness e given
n n
by the following formula:
SDR−1
S=
2
4 Calculation of values
4.1 Calculation of S values
For pressure pipes the relationship is expressed as follows:
σ
S= (1)
p
where
pd()−e
e
σ =
2e
where
р is the internal pressure;
σ is the induced stress;
 р and σ being expressed in the same units.
[1]
For the selection of р and σ, refer to ISO 161-1 .
S-values are selected from the R 10 series of preferred numbers given in ISO 3, except for S 11,2 and S 14
which are selected from the R 20 series (see Tables 2 and 3).
2 © ISO 2018 – All rights reserved

---------------------- Page: 6 ----------------------
ISO 4065:2018(E)

4.2 Calculation of wall thicknesses
According to ISO 161-1, wall thicknesses for pressure pipes are calculated from either of the following
formulae:
1
e = ×d (2)
nn
σ
21+
p
and
1
ed= × (3)
nn
21S+
where
e is the nominal wall thickness;
n
d is the nominal outside diameter;
n
 e and d being expressed in the same units;
n n
σ is the induced stress;
р is the internal pressure;
 σ and р being expressed in the same units;
S is the series number.
The general formulae are also applicable to the relationship between the nominal pressure PN and the
design stress σ , as follows:
s
1
ed= × (4)
n n
σ
s
21+
PN
where σ is the design stress.
s
Values for PN are selected from the R 10 series of preferred numbers given in ISO 3.
Values for σ equal to or less than 10 МРа are selected from the R 10 series of preferred numbers given
s
in ISO 3, while those greater than 10 МРа are selected from the R 20 series.
S may therefore be defined as the quotient of the design stress and the maximum allowable operating
pressure as follows:
σ
s
S= (5)
PN
For nominal pressures between 2,5 bar and 25 bar and design stresses between 2,5 МРа and 36 МРа,
the corresponding S values are given in Table 1.
© ISO 2018 – All rights reserved 3

---------------------- Page: 7 ----------------------
ISO 4065:2018(E)

Table 1 — Individual S-values calculated from selected values of design stress, σ ,
s
and nominal pressure, PN
PN
Design
bar
stress
σ
...

SLOVENSKI STANDARD
oSIST ISO 4065:2018
01-julij-2018
Plastomerne cevi - Preglednica univerzalne debeline stene
Thermoplastics pipes -- Universal wall thickness table
Tubes en matières thermoplastiques -- Tableau universel des épaisseurs de paroi
Ta slovenski standard je istoveten z: ISO 4065:2018
ICS:
23.040.20 Cevi iz polimernih materialov Plastics pipes
oSIST ISO 4065:2018 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

oSIST ISO 4065:2018

---------------------- Page: 2 ----------------------

oSIST ISO 4065:2018
INTERNATIONAL ISO
STANDARD 4065
Third edition
2018-01
Thermoplastics pipes — Universal
wall thickness table
Tubes en matières thermoplastiques — Tableau universel des
épaisseurs de paroi
Reference number
ISO 4065:2018(E)
©
ISO 2018

---------------------- Page: 3 ----------------------

oSIST ISO 4065:2018
ISO 4065:2018(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2018, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2018 – All rights reserved

---------------------- Page: 4 ----------------------

oSIST ISO 4065:2018
ISO 4065:2018(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Calculation of values . 2
4.1 Calculation of S values . 2
4.2 Calculation of wall thicknesses . 3
5 Wall thickness tables . 5
6 Deviations . 5
Bibliography .10
© ISO 2018 – All rights reserved iii

---------------------- Page: 5 ----------------------

oSIST ISO 4065:2018
ISO 4065:2018(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.
This third edition cancels and replaces the second edition (ISO 4065:1996), which has been technically
revised.
The significant changes are:
— S-values and design stresses for 6,0 bar are deleted;
— Wall thickness values for pipes with diameters up to 3000 mm are included;
— The upper limit for tabled wall thicknesses increased to 150 mm;
— Additional pipe series S 10,5, S 13,3 and S 16,7 are left for use in non-pressure purposes only;
— Definitions are updated to follow modern plastics piping terminology.
iv © ISO 2018 – All rights reserved

---------------------- Page: 6 ----------------------

oSIST ISO 4065:2018
INTERNATIONAL STANDARD ISO 4065:2018(E)
Thermoplastics pipes — Universal wall thickness table
1 Scope
This document specifies the relationship between the nominal wall thickness e and the nominal
n
outside diameter d of thermoplastics pipes.
n
It is applicable to solid-wall thermoplastics pipes of constant circular cross-section along the whole
length of the pipe, whatever their method of manufacture, their composition or their intended
application.
NOTE Pipes with constant circular cross-section along the whole length of the pipe are commonly known as
pipes with smooth external and internal surfaces.
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 3, Preferred numbers — Series of preferred numbers
ISO 497:1973, Guide to the choice of series of preferred numbers and of series containing more rounded
values of preferred numbers
3 Terms a nd definiti ons
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 https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
nominal outside diameter
d
n
specified outside diameter, assigned to a nominal size DN
Note 1 to entry: Nominal outside diameter is expressed in millimetres.
Note 2 to entry: For metric pipes conforming to this document, the nominal outside diameter, expressed in
millimetres, is the minimum mean outside diameter dem.min specified in the applicable pipe standard.
3.2
mean outside diameter
d
em
value of the measurement of the outer circumference of the pipe in any cross-section divided by π,
rounded up to the nearest 0,1 mm
Note 1 to entry: The value of π is taken to be 3,142.
© ISO 2018 – All rights reserved 1

---------------------- Page: 7 ----------------------

oSIST ISO 4065:2018
ISO 4065:2018(E)

3.3
wall thickness at any point
e
measured wall thickness at any point around the circumference of the pipe, rounded to the next
higher 0,1 mm
3.4
nominal wall thickness
e
n
wall thickness tabulated in this document, and identical to the minimum permissible wall thickness at
any point, e
min
3.5
standard dimension ratio
SDR
numerical designation of a pipe series, which is a convenient round number, approximately equal to the
ratio of the nominal outside diameter d of а pipe to its nominal wall thickness e
n n
Note 1 to entry: This value may also be derived from the formula given in 3.6.
3.6
pipe series
S
dimensionless number related to the nominal outside diameter d and nominal wall thickness e given
n n
by the following formula:
SDR−1
S=
2
4 Calculation of values
4.1 Calculation of S values
For pressure pipes the relationship is expressed as follows:
σ
S= (1)
p
where
pd()−e
e
σ =
2e
where
р is the internal pressure;
σ is the induced stress;
 р and σ being expressed in the same units.
[1]
For the selection of р and σ, refer to ISO 161-1 .
S-values are selected from the R 10 series of preferred numbers given in ISO 3, except for S 11,2 and S 14
which are selected from the R 20 series (see Tables 2 and 3).
2 © ISO 2018 – All rights reserved

---------------------- Page: 8 ----------------------

oSIST ISO 4065:2018
ISO 4065:2018(E)

4.2 Calculation of wall thicknesses
According to ISO 161-1, wall thicknesses for pressure pipes are calculated from either of the following
formulae:
1
e = ×d (2)
nn
σ
21+
p
and
1
ed= × (3)
nn
21S+
where
e is the nominal wall thickness;
n
d is the nominal outside diameter;
n
 e and d being expressed in the same units;
n n
σ is the induced stress;
р is the internal pressure;
 σ and р being expressed in the same units;
S is the series number.
The general formulae are also applicable to the relationship between the nominal pressure PN and the
design stress σ , as follows:
s
1
ed= × (4)
n n
σ
s
21+
PN
where σ is the design stress.
s
Values for PN are selected from the R 10 series of preferred numbers given in ISO 3.
Values for σ equal to or less than 10 МРа are selected from the R 10 series of preferred numbers given
s
in ISO 3, while those greater than 10 МРа are selected from the R 20 series.
S may therefore be defined as the quotient of the design stress and the maximum allowable operating
pressure as follows:
σ
s
S= (5)
PN
For nominal pressures between 2,5 bar and 25 bar and design stresses between 2,5 МРа and 36 МРа,
the corresponding S values are given in Table 1.
© ISO 2018 – All right
...

SLOVENSKI STANDARD
SIST ISO 4065:2018
01-september-2018
1DGRPHãþD
SIST ISO 4065:2012
Plastomerne cevi - Preglednica univerzalne debeline stene
Thermoplastics pipes -- Universal wall thickness table
Tubes en matières thermoplastiques -- Tableau universel des épaisseurs de paroi
Ta slovenski standard je istoveten z: ISO 4065:2018
ICS:
23.040.20 Cevi iz polimernih materialov Plastics pipes
SIST ISO 4065:2018 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST ISO 4065:2018

---------------------- Page: 2 ----------------------

SIST ISO 4065:2018
INTERNATIONAL ISO
STANDARD 4065
Third edition
2018-01
Thermoplastics pipes — Universal
wall thickness table
Tubes en matières thermoplastiques — Tableau universel des
épaisseurs de paroi
Reference number
ISO 4065:2018(E)
©
ISO 2018

---------------------- Page: 3 ----------------------

SIST ISO 4065:2018
ISO 4065:2018(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2018, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2018 – All rights reserved

---------------------- Page: 4 ----------------------

SIST ISO 4065:2018
ISO 4065:2018(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Calculation of values . 2
4.1 Calculation of S values . 2
4.2 Calculation of wall thicknesses . 3
5 Wall thickness tables . 5
6 Deviations . 5
Bibliography .10
© ISO 2018 – All rights reserved iii

---------------------- Page: 5 ----------------------

SIST ISO 4065:2018
ISO 4065:2018(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.
This third edition cancels and replaces the second edition (ISO 4065:1996), which has been technically
revised.
The significant changes are:
— S-values and design stresses for 6,0 bar are deleted;
— Wall thickness values for pipes with diameters up to 3000 mm are included;
— The upper limit for tabled wall thicknesses increased to 150 mm;
— Additional pipe series S 10,5, S 13,3 and S 16,7 are left for use in non-pressure purposes only;
— Definitions are updated to follow modern plastics piping terminology.
iv © ISO 2018 – All rights reserved

---------------------- Page: 6 ----------------------

SIST ISO 4065:2018
INTERNATIONAL STANDARD ISO 4065:2018(E)
Thermoplastics pipes — Universal wall thickness table
1 Scope
This document specifies the relationship between the nominal wall thickness e and the nominal
n
outside diameter d of thermoplastics pipes.
n
It is applicable to solid-wall thermoplastics pipes of constant circular cross-section along the whole
length of the pipe, whatever their method of manufacture, their composition or their intended
application.
NOTE Pipes with constant circular cross-section along the whole length of the pipe are commonly known as
pipes with smooth external and internal surfaces.
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 3, Preferred numbers — Series of preferred numbers
ISO 497:1973, Guide to the choice of series of preferred numbers and of series containing more rounded
values of preferred numbers
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 https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
nominal outside diameter
d
n
specified outside diameter, assigned to a nominal size DN
Note 1 to entry: Nominal outside diameter is expressed in millimetres.
Note 2 to entry: For metric pipes conforming to this document, the nominal outside diameter, expressed in
millimetres, is the minimum mean outside diameter dem.min specified in the applicable pipe standard.
3.2
mean outside diameter
d
em
value of the measurement of the outer circumference of the pipe in any cross-section divided by π,
rounded up to the nearest 0,1 mm
Note 1 to entry: The value of π is taken to be 3,142.
© ISO 2018 – All rights reserved 1

---------------------- Page: 7 ----------------------

SIST ISO 4065:2018
ISO 4065:2018(E)

3.3
wall thickness at any point
e
measured wall thickness at any point around the circumference of the pipe, rounded to the next
higher 0,1 mm
3.4
nominal wall thickness
e
n
wall thickness tabulated in this document, and identical to the minimum permissible wall thickness at
any point, e
min
3.5
standard dimension ratio
SDR
numerical designation of a pipe series, which is a convenient round number, approximately equal to the
ratio of the nominal outside diameter d of а pipe to its nominal wall thickness e
n n
Note 1 to entry: This value may also be derived from the formula given in 3.6.
3.6
pipe series
S
dimensionless number related to the nominal outside diameter d and nominal wall thickness e given
n n
by the following formula:
SDR−1
S=
2
4 Calculation of values
4.1 Calculation of S values
For pressure pipes the relationship is expressed as follows:
σ
S= (1)
p
where
pd()−e
e
σ =
2e
where
р is the internal pressure;
σ is the induced stress;
 р and σ being expressed in the same units.
[1]
For the selection of р and σ, refer to ISO 161-1 .
S-values are selected from the R 10 series of preferred numbers given in ISO 3, except for S 11,2 and S 14
which are selected from the R 20 series (see Tables 2 and 3).
2 © ISO 2018 – All rights reserved

---------------------- Page: 8 ----------------------

SIST ISO 4065:2018
ISO 4065:2018(E)

4.2 Calculation of wall thicknesses
According to ISO 161-1, wall thicknesses for pressure pipes are calculated from either of the following
formulae:
1
e = ×d (2)
nn
σ
21+
p
and
1
ed= × (3)
nn
21S+
where
e is the nominal wall thickness;
n
d is the nominal outside diameter;
n
 e and d being expressed in the same units;
n n
σ is the induced stress;
р is the internal pressure;
 σ and р being expressed in the same units;
S is the series number.
The general formulae are also applicable to the relationship between the nominal pressure PN and the
design stress σ , as follows:
s
1
ed= × (4)
n n
σ
s
21+
PN
where σ is the design stress.
s
Values for PN are selected from the R 10 series of preferred numbers given in ISO 3.
Values for σ equal to or less than 10 МРа are selected from the R 10 series of preferred numbers given
s
in ISO 3, while those greater than 10 МРа are selected from the R 20 series.
S may therefore be defined as the quotient of the design stress and the maximum allowable operating
pressure as follows:
σ
s
S= (5)
PN
For nominal pressures between 2,5 bar and 25 bar and design stresses between 2,5 МРа and 36 МРа,
the corresponding S values are given in Table 1.
© ISO 2018
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