EN ISO 13760:1998

SLOVENSKI STANDARD
01-julij-1999
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Plastics pipes for the conveyance of fluids under pressure - Miner's rule - Calculation
method for cumulative damage (ISO 13760:1998)
Kunststoffrohre für den Transport von Fluiden unter Druck - Minersche Regel -
Berechnungsverfahren für kumultative Schädingungen (ISO 13760:1998)
Tubes en matieres plastiques pour le transport des fluides sous pression - Regle de
Miner - Méthode de calcul du cumul des dommages (ISO 13760:1998)
Ta slovenski standard je istoveten z: EN ISO 13760:1998
ICS:
23.040.20 Cevi iz polimernih materialov Plastics pipes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 13760
First edition
1998-05-15
Plastics pipes for the conveyance of fluids
under pressure — Miner's rule —
Calculation method for cumulative damage
Tubes en matières plastiques pour le transport des fluides sous pression —
Règle de Miner — Méthode de calcul du cumul des dommages
A
Reference number
ISO 13760:1998(E)
ISO 13760:1998(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.
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.
International Standard ISO 13760 was prepared by Technical Committee
ISO/TC 138, Plastics pipes, fittings and valves for the transport of fluids,
Subcommittee SC 5, General properties of pipes, fittings and valves of
plastic materials and their accessories — Test methods and basic
specifications.
Annexes A, B and C of this International Standard are for information only.
©  ISO 1998
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 the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
ii
©
INTERNATIONAL STANDARD  ISO ISO 13760:1998(E)
Plastics pipes for the conveyance of fluids under pressure —
Miner's rule — Calculation method for cumulative damage
1 Scope
This International Standard specifies a method for calculating the maximum allowable hoop stress applicable to
pipes exposed to varying internal pressures and/or temperatures during their expected lifetime. This method is
generally known as Miner's rule.
It is necessary to apply Miner's rule to each failure mechanism separately. Thus, for mechanical failure due to
internal pressure, other failure mechanisms, such as oxidative or dehydrochlorinative degradative failure
mechanisms, are to be neglected (assuming, of course, no interaction). A material may be used only when it is
proven to conform to all failure mechanism criteria.
NOTE — Miner's rule is an empirically based procedure, and is only a first approximation to reality.
2 Normative reference
The following standard contains provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of the publication, the edition indicated was valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
ISO 10508:1995, Thermoplastics pipes and fittings for hot and cold water systems.
3 Symbols and abbreviated terms
For the purposes of this International Standard, the following symbols and abbreviations apply:
a fraction of a year, expressed as a percentage, when referring to set of conditions “i”;
i
t lifetime under a specified set of conditions “i” (i = 1, 2, 3, etc.) expressed in years;
i
t lifetime at malfunction temperature T as defined in ISO 10508;
m
m
t lifetime at maximum operating temperature T as defined in ISO 10508;
max max
t lifetime at operating temperature T as defined in ISO 10508;
o o
t maximum permissible time of use under varying conditions, expressed in years;
x
TYD total yearly damage, expressed as a percentage.
©
ISO
ISO 13760:1998(E)
4 Principle
Miner's rule is based on the following assumptions:
a) The total damage a material or product is allowed to suffer from a certain type of attack is constant (100 %).
b) Under constant conditions, the damage done is proportional to the duration of the attack. The material or product
will last till the 100 % damage level has been reached. The time needed for this is called t , in this context expressed
i
in years. Per year, the amount of damage done is % .
t
i
This is the proportionality rule.
NOTE — The amount of damage is not necessarily visible or measurable; it may, e.g., also be the passing of an induction time.
c) If a material is exposed to attack for only part of a year (say a % of the year, instead of 100 % of the year), the
i
100 a
yearly damage is not % but %. This follows from the proportionality rule.
t t
i i
d) In the case of damage of the same type but under varyious sets of conditions (differing severity, temperature,
pressure, stress, etc.), one after the other, the total damage per year will be the combined effect of the various sets
of conditions. The additivity rule states that the separate amounts of damage may be added. The result is the
cumulative damage under varying conditions.
5 Procedure
Calculate the total yearly damage (TYD) using the following equation:
a
i
TYD = (1)
�
t
i
expressed as a percentage of the total permissible damage.
Calculate the maximum permissible time of use t , in years, using the following equation:
x
t = (2)
x
TYD
NOTE — See annex A for example calculations and annex B for the assessment of oxidative stability.
©
ISO
ISO 13760:1998(E)
Annex A
(informative)
Examples of the use of Miner's rule
A.1 Example of varying conditions
An illustrative exa
...