ISO/TS 12512:2017

TECHNICAL ISO/TS
SPECIFICATION 12512
First edition
2017-07
Glass reinforced thermosetting
plastic (GRP) pipes — Determination
of initial specific ring stiffness using
segment test species cut from a pipe
Tubes en plastique thermodurcissables renforcés de verre (PRV) —
Détermination de la rigidité annulaire spécifique initiale et de la
résistance à la déflexion annulaire initiale en utilisant des éprouvettes
segmentaires découpées dans un tube
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
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ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 4
4.1 Overview . 4
4.2 Principle of test procedures to determine initial specific ring stiffness . 4
4.2.1 Method A . 4
4.2.2 Method B . 4
5 Apparatus . 4
5.2 Load application surface — General arrangement . 5
5.3 Dimension-measuring instruments . 5
5.4 Temperature-measuring instrument . 5
6 Test pieces . 6
6.1 Preparation . 6
6.2 Number . 6
6.3 Determination of dimensions . 6
6.3.1 Width . 6
6.3.2 Wall thickness . 7
6.3.3 Mean diameter . 7
7 Conditioning . 7
8 Procedure. 7
8.1 Test temperature . 7
8.2 Positioning of the test piece . 7
8.3 Determination of initial specific ring stiffness . 7
8.3.1 Method A: Using constant load . 8
8.3.2 Method B: Using constant deflection . .10
9 Calculations.11
10 Test report .12
Annex A (informative) Principles forming basis for use of segmental test pieces .13
Foreword
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This document was prepared by ISO/TC 138, Plastics pipes, fittings and valves for the transport of fluids,
SC 6, Reinforced plastics pipes and fittings for all applications.
iv © ISO 2017 – All rights reserved

Introduction
This document develops an alternative to the testing of full pipe rings to measure initial specific
ring stiffness (ISO 7685). The goal was to use ring segments which ideally would have led to the use
of smaller and more easily handled test specimens and standard testing machines. Much work was
done on developing equipment for testing ring segments and on the analysis of loading conditions and
calculation procedures and conducting testing programs.
There was neither sufficient nor uniform correlation of segment testing results to standard ring testing
results to allow the use of segment testing as an alternative stiffness test procedure. There were
indications that correlation was perhaps diameter (DN), stiffness class (SN) and pressure class (PN),
as well as specimen width, dependent. As initial ring stiffness (SN) is a key classification parameter for
GRP pipes this resulted in the segment test being not accepted as a viable alternative stiffness testing
procedure.
This document presents the last draft of the segment test method. It was agreed to issue this last
draft as a Technical Specification so that the work done would not be lost and perhaps will allow
interested parties to continue to develop the analysis of loading conditions, equipment development
and calculation procedures. It may also prove useful as a research tool.
TECHNICAL SPECIFICATION ISO/TS 12512:2017(E)
Glass reinforced thermosetting plastic (GRP) pipes —
Determination of initial specific ring stiffness using
segment test species cut from a pipe
1 Scope
This document specifies a method for determining the initial specific ring stiffness of pipes having a
nominal size of DN 2000 or larger, using segment test pieces cut from a glass-reinforced thermosetting
plastics (GRP) pipe.
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 7685, Plastics piping systems — Glass-reinforced thermosetting plastics (GRP) pipes — Determination
of initial specific ring stiffness
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 http:// www .iso .org/ obp
3.1
compressive load
F
load applied to a pipe to cause a diametric deflection
Note 1 to entry: Compressive load is expressed in newtons (N).
3.2
load applied to 79 ° segmental test piece
F
load applied to 79 ° segmental test piece to cause deflection
Note 1 to entry: Load applied to 79 ° segmental test piece is expressed in newtons (N).
3.3
deflection coefficient applied to 79 ° segmental test piece
ξ
coefficient given by Formula (1):
−5
ξ =+1860 2500× yd ×10 (1)
{}()
sm
where
y is the vertical deflection of the pipe ring derived from the 79 ° pipe segment (see 3.7);
s
d is the mean diameter of the pipe ring (see 3.8).
m
Note 1 to entry: Deflection coefficient applied to 79 ° segmental test piece is a dimensionless number.
3.4
vertical deflection
y
vertical change in diameter of a pipe in a horizontal position in response to a vertical compressive
load (3.1)
Note 1 to entry: Vertical deflection is expressed in metres (m).
3.5
relative vertical deflection
y/d
m
ratio of the vertical deflection (3.4) of a pipe, y, to its mean diameter, d (3.8)
m
Note 1 to entry: Relative vertical deflection when multiplied by 100 is expressed in percent (%). Otherwise it is a
dimensionless number.
3.6
derived vertical deflection of pipe segment
y
d
vertical deflection of the pipe segment, using Formula (2), which is derived by finite element analysis of
a pipe ring and which results in the same loading conditions as if the pipe segment were part of a pipe
ring deflected by the vertical deflection y
yy=×α (2)
d 79
where α is the conversion factor for 79 ° segment test piece determined by finite element analysis (see
Table 1).
Note 1 to entry: Derived vertical deflection is expressed in metres (m).
3.7
vertical deflection of pipe ring y derived from 79 ° pipe segment test
s
ratio of the vertical deflection of a pipe ring, to the derived vertical deflection of a 79 ° pipe segment
taken from the same pipe, when the same deflection force is applied to each unit is given by the
following formula:
yy=3,469 (3)
sd
where
y is the vertical deflection of pipe ring;
s
y is the derived vertical deflection of 79° segment.
d
3.8
mean diameter
d
m
diameter of the circle corresponding with the middle of the pipe wall cross-section
It is given by either Formula (4) or (5):
dd=+e (4)
mi
2 © ISO 2017 – All rights reserved

dd=−e (5)
me
where
...