ISO 7685:1998

Plastics piping systems — Glass-reinforced thermosetting plastics (GRP) pipes — Determination of initial specific ring stiffness

Systèmes de canalisation en matières plastiques — Tubes en plastiques thermodurcissables renforcés de verre (PRV) — Détermination de la rigidité annulaire spécifique initiale

General Information

• Status: Withdrawn
• Publication Date: 15-Jul-1998
• Withdrawal Date: 15-Jul-1998
• ICS: 23.040.20 - Plastics pipes
• Technical Committee: ISO/TC 138/SC 6 - Reinforced plastics pipes and fittings for all applications
• Drafting Committee: ISO/TC 138/SC 6 - Reinforced plastics pipes and fittings for all applications
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 11-Jul-2019

Relations

• Revised: ISO 7685:2019 - Glass-reinforced thermosetting plastics (GRP) pipes — Determination of initial ring stiffness
• Effective Date: 23-Apr-2016
• Consolidated By: ISO 11199-2:1999 - Walking aids manipulated by both arms — Requirements and test methods — Part 2: Rollators
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 7685
First edition
1998-07-15
Plastics piping systems — Glass-reinforced
thermosetting plastics (GRP) pipes —
Determination of initial specific ring
stiffness
Systèmes de canalisation en matières plastiques — Tubes en plastiques
thermodurcissables renforcés de verre (PRV) — Détermination de la rigidité
annulaire spécifique initiale
A
Reference number
ISO 7685:1998(E)

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ISO 7685:1998(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 collab-
orates 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 7685 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 CEN/TC 155, Plastics piping systems
and ducting systems.
This International Standard is one of a series of standards on test methods
for plastics piping systems and ducting systems.
©  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 [e-mail]
Printed in Switzerland
ii

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©
INTERNATIONAL STANDARD  ISO ISO 7685:1998(E)
Plastics piping systems — Glass-reinforced thermosetting plastics
(GRP) pipes — Determination of initial specific ring stiffness
1  Scope
This International Standard specifies methods for determining the initial specific ring stiffness of glass-reinforced
thermosetting plastics (GRP) pipes. Two methods are given, and within the specified deflection limits each is
equally valid and may be used for any diameter.
2  Definitions
For the purposes of this International Standard, the following definitions apply:
2.1
compressive load (F)
load applied to a pipe to cause a diametric deflection
It is expressed in newtons.
2.2
( )
vertical deflection y
vertical change in diameter of a pipe in a horizontal position in response to a vertical compressive load (see 2.1)
It is expressed in metres.
2.3
relative vertical deflection (y/d )
m
ratio of the vertical deflection y (see 2.2) to the mean diameter of the pipe d (see 2.4)
m
2.4
mean diameter (d )
m
diameter of the circle corresponding with the middle of the pipe wall cross-section
It is given, in metres, by either of the following equations:
d = d + e
m i
d = d - e
m e
where
d is the average of the measured internal diameters (see 5.3.3), in metres;
i
d is the average of the measured external diameters (see 5.3.3), in metres;
e
e is the average of the measured wall thicknesses of the pipe (see 5.3.2), in metres.
1

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ISO
ISO 7685:1998(E)
2.5
specific ring stiffness (S)
a physical characteristic of the pipe, which is a measure of the resistance to ring deflection under external load
This characteristic is determined by testing and is defined, in newtons per square metre, by the equation
EI×
S=
3
d
m
where
E is the apparent modulus of elasticity as determined in the ring stiffness test, in newtons per square metre;
I is the second moment of area in the longitudinal direction per metre length, expressed in metres to the
fourth power per metre, i.e.
3
e
I =
12
where
e is the wall thickness of the test piece, in metres;
d is the mean diameter (see 2.4) of the test piece, in metres.
m
2.6
initial specific ring stiffness (S )
0
initial value of S obtained by testing in accordance with this International Standard
It is expressed in newtons per square metre.
3  Principle
A length of pipe is loaded throughout its length to compress it diametrically. Two ways are given for doing this,
method A (constant load) and method B (constant deflection), either of which can be used:
Method A: After applying the load necessary to give a relative deflection of (3 – 0,5) %, the load is kept constant for
a specified period of time and the final deflection is determined at the end of this period.
Method B: After applying the load necessary to give the initial relative deflection specified in the referring standard,
the deflection is kept constant for a specified period of time and at the end of this period the final load being applied
is determined.
NOTE — It is assumed that the following test parameters are set by the standard making reference to this International
Standard:
a) the method to be used (A or B);
b) the length of the test pieces (see 5.1);
c) the number of test pieces (see 5.2);
d) if applicable, the details of conditioning of the test pieces (see clause 6);
e) for method B, the relative deflection to be applied (see 7.3.3).
4  Apparatus
4.1  Compressive-loading machine, comprising a system capable of applying, without shock, a compressive
force (suitable for method A or B) at a controlled rate through two parallel load application surfaces conforming to
4.2 so that a horizontally orientated pipe test piece conforming to clause 5 can be compressed vertically. The
accuracy of loading shall be – 1 % of the maximum indicated load.
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ISO
ISO 7685:1998(E)
4.2  Load application surfaces
4.2.1  General arrangement
The surfaces shall be provided by a pair of plates (see 4.2.2), or a pair of beam bars (see 4.2.3), or a combination
of one such plate and one such bar, with their major axes perpendicular to and centred on the direction of
application of the load F by the compressive-loading machine, as shown in figure 1. The surfaces in contact with the
test piece shall be flat, smooth, clean and parallel.
Plates and beam bars shall have a length at least equal to that of the test piece (see cl
...