ISO 161-1:2018

Thermoplastics pipes for the conveyance of fluids - Nominal outside diameters and nominal pressures - Part 1: Metric series

ISO 161-1:2018 specifies the nominal outside diameters for metric thermoplastics pipes for the conveyance of fluids in pressure and non-pressure applications. It also specifies nominal pressure ratings and minimum required strengths for pressure applications. ISO 161-1:2018 is applicable to smooth thermoplastics pipes of constant circular cross-section along the whole length of the pipe, whatever their method of manufacture or material of construction. ISO 161-1:2018 is not applicable to pipes designated according to the nominal inside diameter DN/ID. ISO 161-1:2018 is a basis for standards writers for the selection of nominal diameters and nominal pressures in the drafting of product standards.

Tubes en matières thermoplastiques pour le transport des fluides — Diamètres extérieurs nominaux et pressions nominales — Partie 1: Série métrique

General Information

• Status: Published
• Publication Date: 07-Jan-2018
• ICS: 23.040.20 - Plastics pipes
• Technical Committee: ISO/TC 138 - Plastics pipes, fittings and valves for the transport of fluids
• Drafting Committee: ISO/TC 138 - Plastics pipes, fittings and valves for the transport of fluids
• Current Stage: 9093 - International Standard confirmed
• Start Date: 06-Oct-2023
• Completion Date: 13-Dec-2025

Relations

• Amended By: ISO 161-1:2018/Amd 1:2023 - Thermoplastics pipes for the conveyance of fluids - Nominal outside diameters and nominal pressures - Part 1: Metric series - Amendment 1
• Effective Date: 06-Jun-2022
• Revises: ISO 161-1:1996 - Thermoplastics pipes for the conveyance of fluids - Nominal outside diameters and nominal pressures - Part 1: Metric series
• Effective Date: 16-Nov-2013

Overview

ISO 161-1:2018 - Thermoplastics pipes for the conveyance of fluids - Part 1: Metric series - defines the nominal outside diameters (dn), nominal pressure ratings (PN) and minimum required strengths (MRS) for metric thermoplastics pipes used to convey fluids. The standard applies to smooth thermoplastics pipes with a constant circular cross-section (regardless of material or manufacturing method) and serves as a reference basis for product standard writers. It does not apply to pipes designated by nominal inside diameter (DN/ID).

Key topics and requirements

• Nominal outside diameter (dn): Values are specified in a metric table covering nominal sizes up to 3 000 mm (DN 3000 uses the R 40 series in ISO 3). For metric pipes conforming to ISO 161-1, dn equals the minimum mean outside diameter dem.min specified in the applicable pipe standard.
• Nominal pressure rating (PN): PN values are selected from the R 10 preferred-number series (ISO 3). ISO 161-1:2018 extends PN choices (including PN 25) and clarifies that PN 6 must be designed using 6.3 bar from the R 10 series.
• Minimum required strength (MRS): MRS is defined as the lower confidence limit (LPL) of long-term hydrostatic strength at 20 °C for 50 years, rounded to preferred-number series values. MRS steps from 1 to 20 MPa use R 10 increments; MRS values above 20 MPa use R 20 increments.
• Design stress and hydrostatic stress: Design stress σS = MRS / C, where C is the design coefficient (see ISO 12162). Hydrostatic stress for internal pressure p is given by σ = p·d / (2·e) (with d = outside diameter, e = wall thickness).
• Terminology and measurement rules: Definitions for outside diameter at any point, mean outside diameter, minimum mean outside diameter and other terms are provided to ensure consistency in product standards.

Applications and who uses it

ISO 161-1:2018 is essential for:

• Standards writers drafting thermoplastics pipe product standards and specifications
• Pipe manufacturers and material suppliers specifying nominal sizes and pressure ratings
• Pipeline designers, civil and mechanical engineers selecting pipe systems for pressure and non-pressure fluid conveyance
• Test laboratories and certification bodies assessing long-term pressure performance
• Procurement and regulatory authorities harmonizing technical requirements across projects

Related standards

• ISO 3 - Preferred numbers (R series used for dn, PN, MRS rounding)
• ISO 12162 - Thermoplastics materials for pipes and fittings for pressure applications (classification and design coefficient)
• ISO 497 - Guide to choice of preferred-number series

Keywords: ISO 161-1:2018, thermoplastics pipes, nominal outside diameter, nominal pressure, MRS, metric series, pipe standards, conveyance of fluids.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 161-1
Fourth edition
2018-01
Thermoplastics pipes for the
conveyance of fluids — Nominal
outside diameters and nominal
pressures —
Part 1:
Metric series
Tubes en matières thermoplastiques pour le transport des fluides —
Diamètres extérieurs nominaux et pressions nominales —
Partie 1: Série métrique
Reference number
©
ISO 2018
© 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
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Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Nominal outside diameter, d . 3
n
5 Nominal pressure rating (PN). 4
6 Minimum required strength (MRS) . 4
Bibliography . 5
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 fourth edition cancels and replaces the third edition (ISO 161-1:1996), which has been technically
revised.
The significant changes are:
— Nominal diameters are extended up to 3 000 mm;
— Nominal pressure PN 25 bar is added;
— Nominal pressure PN 6 shall be designed using 6,3 bar; designation based on 6,0 bar is deleted;
— MRS values up to 20 are based on R 10 increments. MRS values above 20 are based on R 20 increments;
— Definitions are updated to follow modern plastics piping terminology.
A list of all the parts in the ISO 161 series, can be found on the ISO website.
iv © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 161-1:2018(E)
Thermoplastics pipes for the conveyance of fluids —
Nominal outside diameters and nominal pressures —
Part 1:
Metric series
1 Scope
This document specifies the nominal outside diameters for metric thermoplastics pipes for the
conveyance of fluids in pressure and non-pressure applications. It also specifies nominal pressure
ratings and minimum required strengths for pressure applications.
It is applicable to smooth thermoplastics pipes of constant circular cross-section along the whole length
of the pipe, whatever their method of manufacture or material of construction.
It is not applicable to pipes designated according to the nominal inside diameter DN/ID.
This document is a basis for standards writers for the sele
...