ISO 10468:2018

INTERNATIONAL ISO
STANDARD 10468
Second edition
2018-05
Glass-reinforced thermosetting
plastics (GRP) pipes — Determination
of the ring creep properties under wet
or dry conditions
Tubes en plastiques thermodurcissables renforcés de verre (PRV) —
Détermination de la rigidité annulaire spécifique à long terme en
fluage en conditions mouillées et calcul du facteur de fluage mouillé
Reference number
ISO 10468:2018(E)
©
ISO 2018

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ISO 10468:2018(E)

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© ISO 2018
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ISO 10468:2018(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 4
5 Apparatus . 4
6 Test piece . 6
7 Number of test pieces . 6
8 Determination of the dimensions of the test pieces . 7
9 Conditioning . 7
10 Procedure. 7
11 Calculation . 7
11.1 Extrapolation of the deflection data . 7
11.2 Calculation of the long-term specific ring creep stiffness for position 1 . 8
11.3 Calculation of the creep factor . 8
12 Test report . 8
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ISO 10468:2018(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
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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
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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, Subcommittee SC 6, Reinforced plastics pipes and fittings for all applications.
This second edition cancels and replaces the first edition (ISO 10468:2003), which has been technically
revised. It also incorporates the Amendment ISO 10468:2003/Amd1: 2010.
The main changes compared to the previous edition are as follows:
— modified the title;
— clarified accuracy statements;
— combined wet and dry creep testing (ISO 7684) into a single document;
— referenced ISO 3126 for dimension determination.
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ISO 10468:2018(E)

Introduction
This edition of ISO 10468 includes both wet and dry creep testing. The basic procedures and calculations
are the same for wet or dry creep testing with the only difference whether or not the test piece is
immersed in water. This allows better maintenance of the test procedures and calculation methods
and collects all material relating to creep testing of GRP pipe products into a single document. Upon
publication of this edition of ISO 10468, it is intended to withdraw ISO 7684.
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INTERNATIONAL STANDARD ISO 10468:2018(E)
Glass-reinforced thermosetting plastics (GRP) pipes —
Determination of the ring creep properties under wet or
dry conditions
1 Scope
This document specifies methods for determining the ring creep properties for glass-reinforced
thermosetting plastics (GRP) pipes. Properties include the creep factor and the long-term specific creep
stiffness. Testing is performed under either wet (total immersion in water) or dry conditions.
Dry creep testing is typically performed for the assessment and control of raw material consistency.
Wet creep testing is typically undertaken to determine the long-term creep performance in simulated
use conditions.
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 3126, Plastics piping systems — Plastics components — Determination of dimensions
ISO 7685, Plastics piping systems — Glass-reinforced thermosetting plastics (GRP) pipes — Determination
of initial specific ring stiffness
ISO 10928, Plastics piping systems — Glass-reinforced thermosetting plastics (GRP) pipes and fittings —
Methods for regression analysis and their use
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 http: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp
3.1
vertical compressive force
F
vertical force, applied to a horizontal pipe to cause a vertical deflection
Note 1 to entry: Vertical compressive force is expressed in newtons.
3.2
specific ring stiffness
S
measure of the resistance of a pipe to ring deflection, per metre of length, under external load as defined
by Formula (1):
EI×
S = (1)
3
d
m
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ISO 10468:2018(E)

where
E is the apparent modulus of elasticity as determined in a ring stiffness test, in newtons per
square metre;
I is the second moment of area in the longitudinal direction per metre length, in metres to the
4
fourth power per metre (m /m), i.e.
3
e
I= (2)
12
where
e is the wall thickness of the pipe, in metres;
d is the mean diameter (3.3) of the pipe, in metres.
m
Note 1 to entry: Specific ring stiffness is expressed in newtons per square meter.
3.3
mean diameter
d
m
diameter, of the circle corresponding with the middle of the pipe wall cross-section and given by either
Formula (3) or (4)
dd=+e (3)
mi
dd=−e (4)
me
where
d is the internal diameter, in metres;
i
d is the external diameter, in metres;
e
e is the wall thickness of the pipe, in metres.
Note 1 to entry: Mean diameter is expressed in metres.
3.4
initial specific ring stiffness
S
0
value of S determined by testing using constant load in accordance with ISO 7685
Note 1 to entry: Initial specific ring stiffness is expressed in newtons per square metre.
3.5
long-term specific ring creep stiffness at position 1
S
x,1
value of S at a reference position, position 1 (see 10.2), at x years, obtained by extrapolation of long-term
stiffness measurements at a constant force (see 3.2 and 10.2)
Note 1 to entry: Long-term specific ring creep stiffness at position 1 is expressed in newtons per square metre.
3.6
calculated long-term specific ring creep stiffness
S
x,creep
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ISO 10468:2018(E)

calculated value of S at x years obtained using Formula (5):
SS=×α (5)
xx,creep 0 ,creep
where
x is the elapsed time, in years (or hours), specified in the referring standard;
α is the creep factor (3.7);
x,creep
S is the initial specific ring stiffness, in newtons per square metre.
0
Note 1 to entry: Calculated long-term specific ring creep stiffness is expressed in newtons per square metre.
3.7
creep factor
α
x,creep
ratio of the long-term specific ring creep stiffness to the initial specific ring stiffness, both at a reference
position, position 1 (see 10.2), and given by Formula (6):
S
x,,1 creep
α = (6)
x,creep
S
01,
where
S is the ring stiffness at position 1, in newtons per square metre at 0,1 h;
0,1
S is the long-term specific ring creep stiffness at position 1 at time x, in newtons per
x,1,creep
square metre.
3.8
vertical deflection
y
vertical change in diameter of a pipe in a horizontal position, in response to a vertical compressive
force (3.1)
Note 1 to entry: Vertical deflection is expressed in metres.
3.9
long-term vertical deflection
y
x,1
value of the vertical deflection y, at the reference p
...