SIST EN ISO 9080:2003
(Main)Plastics piping and ducting systems - Determination of the long-term hydrostatic strength of thermoplastics materials in pipe form by extrapolation (ISO 9080:2003)
Plastics piping and ducting systems - Determination of the long-term hydrostatic strength of thermoplastics materials in pipe form by extrapolation (ISO 9080:2003)
This European Standard specifies methods for estimation of the long-term hydrostatic strength of thermoplastics materials. The methods are applicable to all known types of thermoplastics and cross-linked thermoplastics pipes at any temperature and to any practible test medium. The methods were developed on the basis of test data from pipes of relative small sizes. The pipe sizes to be tested are specified in the relevant product standard.
Kunststoff-Rohrleitungs- und Schutzrohrsysteme - Bestimmung des Zeitstand-Innendruckverhaltens von thermoplastischen Rohrwerkstoffen durch Extrapolation (ISO 9080:2003)
Diese Internationale Norm beschreibt ein Verfahren zur Ermittlung der Zeitstand-Innendruckfestigkeit von thermoplastischen Werkstoffen durch statistische Extrapolation.
Dieses Verfahren gilt bei den vorgesehenen Temperaturen für sämtliche Arten thermoplastischer Rohre. Es wurde auf der Grundlage von Prüfergebnissen für Rohrsysteme entwickelt. Die Maße der zu prüfenden Rohre können in den entsprechenden Produkt-/Systemnormen festgelegt sein; sie sind in den Prüfbericht aufzunehmen.
Systemes de canalisations et de gaines en matieres plastiques - Détermination de la résistance hydrostatique a long terme des matieres thermoplastiques sous forme de tubes par extrapolation (ISO 9080:2003)
L'ISO 9080:2003 décrit une méthode d'estimation de la résistance hydrostatique à long terme des matières thermoplastiques à l'aide d'une extrapolation par les statistiques.
La présente méthode peut être utilisée pour tous les types de tubes thermoplastiques aux températures appropriées. Elle a été développée sur la base de données d'essai provenant de systèmes de canalisations.
Cevni in kanalski sistemi iz polimernih materialov - Določanje dolgotrajne hidrostatične trdnosti termoplastičnih materialov za cevi z metodo ekstrapolacije (ISO 9080:2003)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 9080:2003
01-oktober-2003
&HYQLLQNDQDOVNLVLVWHPLL]SROLPHUQLKPDWHULDORY'RORþDQMHGROJRWUDMQH
KLGURVWDWLþQHWUGQRVWLWHUPRSODVWLþQLKPDWHULDORY]DFHYL]PHWRGRHNVWUDSRODFLMH
,62
Plastics piping and ducting systems - Determination of the long-term hydrostatic strength
of thermoplastics materials in pipe form by extrapolation (ISO 9080:2003)
Kunststoff-Rohrleitungs- und Schutzrohrsysteme - Bestimmung des Zeitstand-
Innendruckverhaltens von thermoplastischen Rohrwerkstoffen durch Extrapolation (ISO
9080:2003)
Systemes de canalisations et de gaines en matieres plastiques - Détermination de la
résistance hydrostatique a long terme des matieres thermoplastiques sous forme de
tubes par extrapolation (ISO 9080:2003)
Ta slovenski standard je istoveten z: EN ISO 9080:2003
ICS:
23.040.20 Cevi iz polimernih materialov Plastics pipes
SIST EN ISO 9080:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 9080:2003
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SIST EN ISO 9080:2003
EUROPEAN STANDARD
EN ISO 9080
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2003
ICS 23.040.20
English version
Plastics piping and ducting systems - Determination of the long-
term hydrostatic strength of thermoplastics materials in pipe
form by extrapolation (ISO 9080:2003)
Systèmes de canalisations et de gaines en matières Kunststoff-Rohrleitungs- und Schutzrohrsysteme -
plastiques - Détermination de la résistance hydrostatique à Bestimmung des Zeitstand-Innendruckverhaltens von
long terme des matières thermoplastiques sous forme de thermoplastischen Rohrwerkstoffen durch Extrapolation
tubes par extrapolation (ISO 9080:2003) (ISO 9080:2003)
This European Standard was approved by CEN on 28 February 2003.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2003 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9080:2003 E
worldwide for CEN national Members.
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SIST EN ISO 9080:2003
EN ISO 9080:2003 (E)
CORRECTED 2003-07-16
Foreword
This document (EN ISO 9080:2003) has been prepared by Technical Committee ISO/TC 138
"Plastics pipes, fittings and valves for the transport of fluids" in collaboration with Technical
Committee CEN/TC 155 "Plastics piping systems and ducting systems", the secretariat of which
is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by September 2003, and conflicting national
standards shall be withdrawn at the latest by September 2003.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium, Czech
Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and
the United Kingdom.
Endorsement notice
The text of ISO 9080:2003 has been approved by CEN as EN ISO 9080:2003 without any
modifications.
NOTE Normative references to International Standards are listed in Annex ZA (normative).
2
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SIST EN ISO 9080:2003
EN ISO 9080:2003 (E)
Annex ZA
(normative)
Normative references to international publications
with their relevant European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of
any of these publications apply to this European Standard only when incorporated in it by
amendment or revision. For undated references the latest edition of the publication referred to
applies (including amendments).
NOTE Where an International Publication has been modified by common modifications, indicated
by (mod.), the relevant EN/HD applies.
Publication Year Title EN Year
ISO 3146 2000 Plastics - Determination of melting EN ISO 3146 2000
behaviour (melting temperature or
melting range) of semi-crystalline
polymers by capillary tube and
polarizing-microscope methods
3
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SIST EN ISO 9080:2003
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SIST EN ISO 9080:2003
INTERNATIONAL ISO
STANDARD 9080
First edition
2003-03-15
Plastics piping and ducting systems —
Determination of the long-term
hydrostatic strength of thermoplastics
materials in pipe form by extrapolation
Systèmes de canalisations et de gaines en matières plastiques —
Détermination de la résistance hydrostatique à long terme des matières
thermoplastiques sous forme de tubes par extrapolation
Reference number
ISO 9080:2003(E)
©
ISO 2003
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SIST EN ISO 9080:2003
ISO 9080:2003(E)
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ii © ISO 2003 — All rights reserved
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SIST EN ISO 9080:2003
ISO 9080:2003(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 1
4 Acquisition of test data . 3
5 Procedure . 3
6 Example of calculation for a semi-crystalline polymer, software validation. 7
7 Test report . 7
Annex A (normative) Methods of data gathering and analysis . 9
Annex B (normative) Automatic knee detection . 13
Annex C (informative) Example of application of SEM to stress rupture data. 15
Annex D (informative) SEM software. 23
Bibliography . 24
© ISO 2003 — All rights reserved iii
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SIST EN ISO 9080:2003
ISO 9080:2003(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.
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 9080 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.
It cancels and replaces ISO/TR 9080:1992, which has been technically revised.
iv © ISO 2003 — All rights reserved
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SIST EN ISO 9080:2003
ISO 9080:2003(E)
Introduction
General
ISO/TR 9080, upon which this International Standard is based, is the result of considerable discussion within
working group 10 of subcommittee 5 of technical committee 138 of the International Organization for
Standardization (ISO) (referred to hereafter as ISO/TC 138/SC 5/WG 10), which was entrusted with the
development of the standard, which represents an agreed compromise incorporating features of several
accepted national procedures.
Furthermore, it is emphasized that the standard extrapolation method (SEM) described is not intended to be
used to disqualify existing procedures for arriving at design stresses or allowable pressures for pipelines made
of plastics materials, or to disqualify pipelines made of materials proven by such procedures, which long years
of experience have shown to be satisfactory. This SEM is meant to be used to qualify a material in pipe form
prior to the introduction of such a material on the market.
A software package has been developed for the SEM analysis as described in Annex A and Annex B. A
Windows-based programme is available on diskette (see Annex D).
NOTE Use of this software package is recommended.
Principles
The suitability for use of a plastics pressure pipe is first of all determined by the performance under stress of
its material of construction, taking into account the envisaged service conditions (e.g. temperature). It is
conventional to express this by means of the hydrostatic (hoop) stress which a plastics pipe made of the
material under consideration is expected to be able to withstand for 50 years at an ambient temperature of
20 °C using water as the internal test medium. The outside environment can be water or air.
In certain cases, it is necessary to determine the value of the hydrostatic strength at either shorter lifetimes or
higher temperatures, or on occasion both. The method given in this International Standard is designed to meet
the need for both types of estimate. The result obtained will indicate the lower prediction limit (LPL), which is
the lower confidence limit of the prediction of the value of the stress that can cause failure in the stated time at
a stated temperature (the ultimate stress).
NOTE The MRS value (at 20 °C) is usually based on data obtained using water as the internal and external test
medium. It is obvious that indeed all data are used for validation of regression curves at higher temperatures (e.g. 70 °C),
including the data obtained with air as the external medium (e.g. at 110 °C).
This International Standard provides a definitive procedure incorporating an extrapolation using test data at
different temperatures analysed by multiple linear regression analysis. The results permit the determination of
material-specific design values in accordance with the procedures described in the relevant system standards.
This multiple linear regression analysis is based on the rate processes most accurately described by
log (stress) versus log (time) models.
10 10
In order to assess the predictive value of the model used, it has been considered necessary to make use of
the estimated 97,5 % lower prediction limit (LPL). The 97,5 % lower prediction limit is equivalent to the lower
confidence limit of the 95 % confidence interval of the predicted value. This convention is used in the
mathematical calculations to be consistent with the literature. This aspect necessitates the use of statistical
techniques.
The method can provide a systematic basis for the interpolation and extrapolation of stress rupture
characteristics at operating conditions different from the conventional 50 years at 20 °C. Taking into account
the extrapolation factors (see 5.1.4), the extrapolation time limit can go up to 100 years.
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SIST EN ISO 9080:2003
ISO 9080:2003(E)
It is essential that the medium used for pressurizing the pipe does not have an adverse effect on the pipe. In
general, water is considered to be such a medium.
Long consideration was given to deciding which variable should be taken as the independent variable to
calculate the long-term hydrostatic strength. The choice was between time and stress.
The basic question the method has to answer can be formulated in two ways as follows.
a) What is the maximum stress (or pressure) that a given pipe system can withstand at a given temperature
for a defined time?
b) How long will a pipe system last when subjected to a defined stress (or pressure) at a given temperature?
Both questions are relevant.
If the test data for the pipe under study does not show any scatter and if the pipe material can be described
perfectly by the chosen empirical model, the regression with either time independence or stress independence
will be identical. This is never the case because the circumstances of testing are never ideal nor will the
material be 100 % homogeneous. The observations will therefore always show scatter. The regressions
calculated using the two optional independent variables will not be identical and the difference will increase
with increasing scatter.
The variable that is assumed to be most affected by the largest variability (scatter) is the time variable and it
has to be considered as a dependent variable (random variable) in order to allow a correct statistical treatment
of the data set in accordance with this method. However, for practical reasons, the industry prefers to present
stress as a function of time as an independent variable.
Use of the methods
This extrapolation method is designed to meet the following two requirements:
1)
a) To estimate the lower prediction limit (at 97,5 % probability level) of the stress which a pipe made of the
material under consideration is able to withstand for 50 years at an ambient temperature of 20 °C using
water or air as the test environment.
b) To estimate the value of the lower prediction limit (at 97,5 % probability level) of the stress, either at
different lifetimes or at different temperatures, or on occasion both.
There are several extrapolation models in existence, which have different numbers of terms. This SEM will
use only models with two, three or four parameters.
Adding more terms could improve the fit but would also increase the uncertainty of the predictions.
The SEM describes a procedure for estimating the lower prediction limit (at 97,5 % probability level) whether a
knee (which demonstrates the transition between type A and type B crack behaviour) is found or not (see
Annex B).
The materials have to be tested in pipe form for the method to be applicable.
The final result of the SEM for a specific material is the lower prediction limit (at 97,5 % probability level) of the
hydrostatic strength, expressed in terms of the hoop stress, at a given time and a given temperature.
1) In various ISO documents, the lower prediction limit (LPL) is referred to as the lower confidence limit (LCL), where
LCL is the 97,5 % lower confidence limit for the mean hydrostatic strength.
vi © ISO 2003 — All rights reserved
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SIST EN ISO 9080:2003
INTERNATIONAL STANDARD ISO 9080:2003(E)
Plastics piping and ducting systems — Determination of the
long-term hydrostatic strength of thermoplastics materials in
pipe form by extrapolation
1 Scope
This International Standard describes a method for estimating the long-term hydrostatic strength of
thermoplastics materials by statistical extrapolation.
The method is applicable to all types of thermoplastics pipe at applicable temperatures. It was developed on
the basis of test data from pipe systems. The dimensions of the pipes to be tested may be specified in the
relevant product/system standards and, if so, are included in the test report.
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 1167, Thermoplastics pipes for the conveyance of fluids — Resistance to internal pressure — Test
method
ISO 2507-1:1995, Thermoplastics pipes and fittings — Vicat softening temperature — Part 1: General test
method
2)
ISO 3126:— , Plastics piping systems — Plastics piping components — Measurement and determination of
dimensions
ISO 3146:2000, Plastics — Determination of melting behaviour (melting temperature or melting range) of
semi-crystalline polymers by capillary tube and polarizing-microscope methods
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
internal pressure
p
force per unit area, in bars, exerted by the medium in the pipe
2) To be published. (Revision of ISO 3126:1974)
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SIST EN ISO 9080:2003
ISO 9080:2003(E)
3.2
stress
σ
force per unit area, in megapascals, in the wall of the pipe in the hoop (circumferential) direction due to
internal pressure
NOTE It is derived from the internal pressure using the following simplified equation:
pd()−e
em y,min
σ =
20e
y,min
where
p is the internal pressure, in bars;
d is the mean outside diameter of the pipe, in millimetres;
em
e is the minimum measured wall thickness of the pipe, in millimetres.
y,min
3.3
test temperature
T
t
temperature, in degrees Celsius, at which stress rupture data have been determined
3.4
maximum test temperature
T
t,max
maximum temperature, in degrees Celsius, at which stress rupture data have been determined
3.5
service temperature
T
s
temperature, in degrees Celsius, at which the pipe will be used
3.6
failure time
t
time, in hours, to occurrence of a leak in the pipe
3.7
long-term hydrostatic strength
σ
LTHS
quantity, in megapascals, with the dimensions of stress, which represents the predicted mean strength at a
temperature T and time t
3.8
lower confidence limit of the predicted hydrostatic strength
σ
LPL
quantity, in megapascals, with the dimensions of stress, which represents the 97,5 % lower confidence limit of
the predicted hydrostatic strength at a temperature T and time t
NOTE It is given by
σ = σ
LPL (T, t, 0,975)
3.9
knee
transition point between two modes of failure, which can be represented by a change in slope of a
log (stress) versus log (time) plot of hydrostatic stress rupture data
10 10
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SIST EN ISO 9080:2003
ISO 9080:2003(E)
3.10
branch
line of constant slope in the log (stress) versus log (time) plot representing the same failure mode
10 10
3.11
extrapolation time factor
k
e
factor for calculation of the extrapolation time limits
4 Acquisition of test data
4.1 Test conditions
The pipe stress rupture data shall be determined in accordance with ISO 1167. The determination of the
resistance to internal pressure shall be carried out using straight pipes.
The mean outside diameter and minimum wall thickness of each pipe test piece shall be determined in
accordance with ISO 3126.
In cases of dispute, pipes of one diameter selected from the range 25 mm to 63 mm shall be tested. The pipes
tested shall be made from the same batch of material and come from the same extrusion run.
4.2 Distribution of internal pressure levels and time ranges
4.2.1 For each temperature selected, a minimum of 30 observations shall be obtained, regularly spread
over at least five internal pressure levels. For statistical reasons, it is required that more than one observation
be recorded at each internal pressure level. Internal pressure levels shall be selected such that at least four
observations will occur above 7 000 h and at least one above 9 000 h (see also 5.1.4). In the event of the
presence of a knee, a statistically adequate number of observations shall be collected for both branches, in
order to ensure sufficient precision of the result.
4.2.2 For all temperatures, failure times up to 10 h shall be neglected.
4.2.3 At temperatures u 40 °C, failure times up to 1 000 h may be neglected, provided that the number of
remaining observations conforms to 4.2.1. In that case, all points under the selected time and temperature
shall be discarded.
4.2.4 Test pieces which have not failed at the lowest internal pressure levels may be used as observations
in the multiple regression computations and for the determination of the presence of a knee. Otherwise, they
may be disregarded.
5 Procedure
5.1 Data gathering and analysis
NOTE The method is based on linear regression and calculation details given in Annex A. It requires testing at one or
more temperatures and times of one year or longer and is applicable whether or not indications are found for the presence
of a knee.
5.1.1 Required test data
Obtain test data in accordance with clause 4 and the following conditions, using two or more temperatures T ,
1
T , … , T :
2 n
a) Each pair of adjacent temperatures shall be separated by at least 10 °C.
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SIST EN ISO 9080:2003
ISO 9080:2003(E)
b) The highest test temperature T shall not exceed the Vicat softening temperature VST determined
t,max B.50
in accordance with ISO 2507-1:1995 minus 15 °C for amorphous or predominantly amorphous polymers,
or the melting temperature determined in accordance with ISO 3146:2000 minus 15 °C for crystalline or
semi-crystalline polymers.
c) The number of observations and the distribution of internal pressure levels at each temperature shall
conform to 4.2.
d) To obtain an optimum estimate of σ , the range of test temperatures shall be selected such that it
LPL
includes the service temperature or range of service temperatures.
e) The data obtained at the lowest test temperature may be used down to 20 °C below this temperature,
provided that there is no change of state of the material.
Any failures resulting from contamination shall be disregarded.
5.1.2 Detection of a knee and validation of data and model
Use the procedure given in Annex B to detect the presence of any knee.
After detecting a knee at any particular temperature, split the data set into two groups, one belonging to the
first branch, the other belonging to the second branch.
Fit the multiple linear regression as described in Annex A independently, using all first-branch failures for all
temperatures and all second-branch failures for all temperatures.
When only using one temperature, the problem is reduced to simple linear regression analysis. In that case,
the use of the extrapolation factor k (see 5.1.4) is not applicable.
e
NOTE When studying the data for the occurrence of a knee, attention should be paid to the occurrence of a
degradative failure. Such data (usually characterized by a nearly stress-independent line and visually recognizable) should
be discarded for the calculation of the creep rupture branch.
5.1.3 Visual verification
Plot the observed failure points, the σ linear regression lines and the σ curves as a graph on a
LTHS LPL
log σ /log (time) scale.
10 10
5.1.4 Extrapolation time limits and extrapolation time factor k
e
Determine the extrapolation time limits using the following information and procedures.
The time limits t for which extrapolation is allowed, are bound to temperature-dependent values. The
e
extrapolation time factor k as a function of ∆T is based on the following equation:
e
DT = T − T
t
where
T is the test temperature to which the extrapolation time factor k is applied, T u T , in degrees
t e t t,max
Celsius;
T is the maximum test temperature, in degrees Celsius;
t,max
T is the temperature for which the extrapolation time limit is calculated, T u T, in degrees Celsius;
s
T is the service temperature, in degrees Celsius;.
s
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SIST EN ISO 9080:2003
ISO 9080:2003(E)
Calculate the extrapolation time t , in hours, using the following equation:
e
t = k t
e e max
When t is equal to 8 760 h (1 year), k represents the maximum extrapolation time t in years, to be used
max e e
only for extrapolation downwards in the temperature range. Obtain the maximum test time t , in hours, by
max
averaging the logarithms of the five longest failure times, which are not necessarily at the same stress level,
but at the same temperature. Test pieces that have not yet failed may be considered as “failures” for this
purpose. All those points shall belong to the population with which all calculations are performed.
Examples of the application of the extrapolation time limits are presented in Figures 1 to 3. Figure 2
represents the case that a knee has been detected only at the highest temperature. Figure 3 refers specifically
to the case that a knee has been detected at higher temperatures. Values of the extrapolation factor k are
e
assigned in 5.2 and 5.3.
Figure 1 — Extrapolation time limits in the case of extrapolation
without a knee at the highest test temperature
Figure 2 — Extrapolation time limits in the case of extrapolation
with a knee only at the highest test temperature
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SIST EN ISO 9080:2003
ISO 9080:2003(E)
Figure 3 — Extrapolation time limits in the case of extrapolation
with knees at different test temperatures
5.2 Extrapolation factors for polyolefins (crystalline or semi-crystalline polymers)
For extrapolation of creep rupture data of polyolefins, the extrapolation time limits are based on an
experimentally determined lifetime at the relevant maximum test temperature and an Arrhenius equation for
the temperature dependence using the apparent activation energy calculated from the
...
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