ISO 10468:2023

INTERNATIONAL ISO
STANDARD 10468
Third edition
2023-07
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 des propriétés de fluage annulaires en conditions
humides ou sèches
Reference number
© ISO 2023
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Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 4
5 Apparatus . 4
5.1 Compressive loading machine . 4
5.2 Force application surfaces. 4
5.2.1 General arrangement. 4
5.2.2 Plates . 5
5.2.3 Beam bars . 5
5.3 Water container . 5
5.4 Measuring devices . 5
6 Test piece . 5
7 Number of test pieces .6
8 Determination of the dimensions of the test pieces . 6
9 Conditioning . 7
10 Procedure .7
11 Calculation . 7
11.1 Extrapolation of the deflection data . 7
11.2 Calculation of the long-term ring creep stiffness for position 1 . 8
11.3 Calculation of the creep factor . 8
12 Test report . 8
iii
Foreword
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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,
in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/
TC 155, Plastics piping systems and ducting systems, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 10468:2018), which has been technically
revised.
The main changes are as follows:
— the Introduction has been deleted as the information is no longer relevant to this edition of the
document;
— in the test report, the “plot of measured deflection versus time” has been changed from an obligation
into an option of plotting deflection versus time or stiffness versus time;
— initial ring stiffness according to ISO 7685 can now be measured by constant load or constant
deflection.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
INTERNATIONAL STANDARD ISO 10468:2023(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 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, Glass-reinforced thermosetting plastics (GRP) pipes — Determination of initial ring stiffness
ISO 10928:2016, 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 terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
vertical compressive force
F
vertical force, applied to a horizontal pipe to cause a vertical deflection (3.7)
Note 1 to entry: Vertical compressive force is expressed in Newtons.
3.2
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)
d
m
where
d is the mean diameter (3.3) of the pipe, in metres;
m
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
fourth power per metre (m /m), as shown in Formula (2):
e
I= (2)
where e is the wall thickness of the pipe, in metres.
Note 1 to entry: Ring stiffness is expressed in Newtons per square metre.
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 Formula (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 ring stiffness
S
value of ring stiffness, S (3.2), determined by testing in accordance with ISO 7685
Note 1 to entry: Initial ring stiffness is expressed in Newtons per square metre.
3.5
long-term ring creep stiffness at position 1
S
x,1,creep
value of ring stiffness, S (3.2), at a reference position, position 1, at x years, obtained by extrapolation of
long-term stiffness measurements at a constant force ()
Note 1 to entry: See 10.2.
Note 2 to entry: Long-term ring creep stiffness at position 1 is expressed in Newtons per square metre.
3.6
creep factor
α
x,creep
ratio of the long-term ring creep stiffness to the initial ring stiffness (3.4), both at a reference position,
position 1 (see 10.2), and given by Formula (5):
S
x,,1 creep
α = (5)
x,creep
S
01,
...