EN ISO 14692-3:2017

SLOVENSKI STANDARD
01-november-2017
1DGRPHãþD
SIST EN ISO 14692-3:2004
SIST EN ISO 14692-3:2004/AC:2007
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SROLPHUQLFHYRYRGL*53GHO1DþUWRYDQMHVLVWHPD,62
Petroleum and natural gas industries - Glass-reinforced plastics (GRP) piping - Part 3:
System design (ISO 14692-3:2017)
Erdöl- und Erdgasindustrie - Glasfaserverstärkte Kunststoffrohrleitungen (GFK) - Teil 3:
Systemauslegung (ISO 14692-3:2017)
Industries du pétrole et du gaz naturel - Canalisations en plastique renforcé de verre
(PRV) - Partie 3: Conception des systèmes (ISO 14692-3:2017)
Ta slovenski standard je istoveten z: EN ISO 14692-3:2017
ICS:
75.200 2SUHPD]DVNODGLãþHQMH Petroleum products and
QDIWHQDIWQLKSURL]YRGRYLQ natural gas handling
]HPHOMVNHJDSOLQD equipment
83.140.30 3ROLPHUQHFHYLLQILWLQJL]D Plastics pipes and fittings for
VQRYLNLQLVRWHNRþLQH non fluid use
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 14692-3
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2017
EUROPÄISCHE NORM
ICS 75.200; 83.140.30 Supersedes EN ISO 14692-3:2002
English Version
Petroleum and natural gas industries - Glass-reinforced
plastics (GRP) piping - Part 3: System design (ISO 14692-
3:2017)
Industries du pétrole et du gaz naturel - Canalisations Erdöl- und Erdgasindustrie - Glasfaserverstärkte
en plastique renforcé de verre (PRV) - Partie 3: Kunststoffrohrleitungen (GFK) - Teil 3:
Conception des systèmes (ISO 14692-3:2017) Systemauslegung (ISO 14692-3:2017)
This European Standard was approved by CEN on 22 June 2017.

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 CEN-CENELEC 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 CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14692-3:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 14692-3:2017) has been prepared by Technical Committee ISO/TC 67
"Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries"
in collaboration with Technical Committee CEN/TC 12 “Materials, equipment and offshore structures
for petroleum, petrochemical and natural gas industries” 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 March 2018 and conflicting national standards shall be
withdrawn at the latest by March 2018.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 14692-3:2002.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 14692-3:2017 has been approved by CEN as EN ISO 14692-3:2017 without any
modification.
INTERNATIONAL ISO
STANDARD 14692-3
Second edition
2017-08
Petroleum and natural gas
industries — Glass-reinforced plastics
(GRP) piping —
Part 3:
System design
Industries du pétrole et du gaz naturel — Canalisations en plastique
renforcé de verre (PRV) —
Partie 3: Conception des systèmes
Reference number
ISO 14692-3:2017(E)
©
ISO 2017
ISO 14692-3:2017(E)
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
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Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved

ISO 14692-3:2017(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 3
4 Layout requirements . 3
4.1 General . 3
4.2 Space requirements . 4
4.3 System supports. 4
4.3.1 General. 4
4.3.2 Pipe-support contact surface . 5
4.4 Isolation and access for cleaning . 5
4.5 Vulnerability . 5
4.5.1 Point loads . 5
4.5.2 Abuse. 5
4.5.3 Dynamic excitation and interaction with adjacent equipment and piping . 6
4.5.4 Exposure to light and ultraviolet radiation . 6
4.5.5 Low temperatures and requirements for insulation . 6
4.6 Fire and blast . 6
5 Hydraulic design . 7
5.1 General . 7
5.2 Flow characteristics . 7
5.3 General velocity limitations . 7
5.4 Erosion . 8
5.4.1 General. 8
5.4.2 Particulate content . 8
5.4.3 Piping configuration . 8
5.4.4 Cavitation . 8
5.5 Water hammer . 8
6 Generation of design envelopes . 9
6.1 Partial factors . 9
6.1.1 Design life . 9
6.1.2 Chemical degradation . 9
6.1.3 Fatigue and cyclic loading . 9
6.2 Part factor, f .
2 10
6.3 Combinations of part factor and partial factors .11
6.4 Design envelope .11
7 Stress analysis .13
7.1 Analysis methods .13
7.2 Pipe stress analysis software .14
7.3 Analysis requirements .14
7.4 Flexibility factors . .14
7.5 Stress intensification factors .14
7.6 Modelling fittings .15
7.7 Allowable deflections .15
7.7.1 Vertical deflection in aboveground piping systems .15
7.7.2 Vertical deflection in buried piping systems .15
7.8 Allowable stresses .16
7.9 External pressure .19
7.10 Axial compressive loading (buckling) .20
7.10.1 Shell buckling .20
7.10.2 Euler buckling .20
ISO 14692-3:2017(E)
7.10.3 Buckling pressure — Buried piping .21
7.10.4 Upheaval buckling pressure .22
7.11 Longitudinal pressure expansion .23
8 Other design aspects .23
8.1 Fire . .23
8.1.1 General.23
8.1.2 Fire endurance .24
8.1.3 Fire reaction .24
8.1.4 Fire-protective coatings .25
8.2 Static electricity .25
9 Installer and operator documentation.26
Annex A (normative) Cyclic de-rating factor — A .27
Annex B (normative) Flexibility factors and stress intensification factors .29
Bibliography .36
iv © ISO 2017 – All rights reserved

ISO 14692-3:2017(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.
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
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www.iso.org/iso/foreword.html.
This second edition cancels and replaces the first edition (ISO 14692-3:2002), which has been
technically revised. It also incorporates the Technical Corrigendum ISO 14692-3:2002/Cor 1:2005.
This document was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore
structures for petroleum, petrochemical and natural gas industries, Subcommittee SC 6, Processing
equipment and systems.
A list of all the parts of ISO 14692 can be found on the ISO website.
ISO 14692-3:2017(E)
Introduction
The objective of this document is to ensure that piping systems, when designed using the components
qualified in ISO 14692-2, will meet the specified performance requirements. These piping systems are
designed for use in oil and natural gas industry processing and utility service applications. The main
users of the document will be the principal, design contractors, suppliers contracted to do the design,
certifying authorities and government agencies.
vi © ISO 2017 – All rights reserved

INTERNATIONAL STANDARD ISO 14692-3:2017(E)
Petroleum and natural gas industries — Glass-reinforced
plastics (GRP) piping —
Part 3:
System design
1 Scope
This document gives guidelines for the design of GRP piping systems. The requirements and
recommendations apply to layout dimensions, hydraulic design, structural design, detailing, fire
endurance, spread of fire and emissions and control of electrostatic discharge.
This document is intended to be read in conjunction with ISO 14692-1.
Guidance on the use of this document can be found in Figure 1, which is a more detailed flowchart of
steps 5 and 6 in ISO 14692-1:2017, Figure 1.
ISO 14692-3:2017(E)
Figure 1 — Guidance on the use of this document
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 14692-1:2017, Petroleum and natural gas industries — Glass-reinforced plastics (GRP) piping — Part 1:
Vocabulary, symbols, applications and materials
2 © ISO 2017 – All rights reserved

ISO 14692-3:2017(E)
ISO 14692-2:2017, Petroleum and natural gas industries — Glass-reinforced plastics (GRP) piping — Part 2:
Qualification and manufacture
ASTM D2992, Standard Practice for Obtaining Hydrostatic or Pressure Design Basis for Fiberglass (Glass-
Fiber-Reinforced Thermosetting-Resin) Pipe and Fittings
ASTM D2412, Standard Test Method for Determination of External Loading Characteristics of Plastic Pipe
by Parallel-Plate Loading
AWWA Manual M45, Fiberglass pipe design
3 Terms and definitions
For the purposes of this document, the terms, definitions, symbols and abbreviated terms given in
ISO 14692-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
4 Layout requirements
4.1 General
GRP products are proprietary and the choice of component sizes, fittings and material types can be
limited depending on the supplier. Potential vendors should be identified early in design to determine
possible limitations of component availability. The level of engineering support that can be provided by
the supplier should also be a key consideration during vendor selection.
Where possible, piping systems should maximize the use of prefabricated spoolpieces to minimize
the amount of site work. Overall spool dimensions should be sized taking into account the following
considerations:
— limitations of site transport and handling equipment;
— installation and erection limitations;
— limitations caused by the necessity to allow a fitting tolerance for installation (“cut to fit”
requirements).
The designer shall evaluate system layout requirements in relation to the properties of proprietary
piping systems available from manufacturers, including but not limited to the following:
a) axial thermal expansion requirements;
b) ultraviolet radiation and weathering resistance requirements;
c) component dimensions;
d) jointing system requirements;
e) support requirements;
f) provision for isolation for maintenance purposes;
g) connections between modules and decks;
h) flexing during lifting of modules;
ISO 14692-3:2017(E)
i) ease of possible future repair and tie-ins;
j) vulnerability to risk of damage during installation and service;
k) fire performance;
l) control of electrostatic charge.
The hydrotest provides the most reliable means of assessing system integrity. Whenever possible, the
system should be designed to enable pressure testing to be performed on limited parts of the system
as soon as installation of those parts is complete. This is to avoid a final pressure test late in the
construction work of a large GRP piping system, when problems discovered at a late stage would have a
negative effect on the overall project schedule.
4.2 Space requirements
The designer shall take account of the larger space envelope of some GRP components compared to
steel. Some GRP fittings have longer lay lengths and are proportionally more bulky than the equivalent
metal component and may be difficult to accommodate within confined spaces. If appropriate, the
problem can be reduced by fabricating the pipework or piping as an integral spoolpiece in the factory
rather than assembling it from the individual pipe fittings.
If space is limited, consideration should be given to designing the system to optimize the attributes of
both GRP and metal components.
4.3 System supports
4.3.1 General
GRP piping systems can be supported using the same principles as those for metallic piping systems.
However, due to the proprietary nature of piping systems, standard-size supports will not necessarily
match the pipe outside diameters.
The following requirements and recommendations apply to the use of system supports.
a) Supports shall be spaced to avoid sag (excessive displacement over time) and/or excessive vibration
for the design life of the piping system.
b) In all cases, support design shall be in accordance with the manufacturer’s guidelines.
c) Where there are long runs, it is possible to use the low modulus of the material to accommodate
axial expansion and eliminate the need for expansion joints, provided the system is well anchored
and guided. In this case, the designer shall recognize that the axial expansion due to internal
pressure is now restrained and the corresponding thrust loads are partly transferred to the
anchors.
d) Valves or other heavy attached equipment shall be adequately and, if necessary, independently
supported. When evaluating valve weight, valve actuation torque shall also be considered.
NOTE Some valves are equipped with heavy control mechanisms located far from the pipe centreline
and can cause large bending and torsional loads.
e) GRP piping shall not be used to support other piping, unless agreed with the principal.
f) GRP piping shall be adequately supported to ensure that the attachment of hoses at locations such
as utility or loading stations does not result in the pipework being pulled in a manner that can
overstress the material.
Pipe supports can be categorized into those that permit movement and those that anchor the pipe.
4 © ISO 2017 – All rights reserved

ISO 14692-3:2017(E)
4.3.2 Pipe-support contact surface
The following requirements and recommendations apply to GRP piping support.
a) In all cases supports shall have sufficient length to support the piping without causing damage and
shall be lined with an elastomer or other suitable soft material.
b) Point loads shall be avoided. This can be accomplished by using supports with at least 60° of
contact.
c) Clamping forces, where applied, shall be such that crushing of the pipe does not occur. Local
crushing can result from a poor fit and all-round crushing can result from over-tightening.
d) Supports should be preferably located on plain-pipe sections rather than at fittings or joints. One
exception to this is the use of a "dummy leg" support directly on an elbow or tee (or piece of pipe).
Consideration shall be given to the support conditions of fire-protected GRP piping. Supports placed on
the outside of fire protection can result in loads irregularly transmitted through the coating, which can
result in shear/crushing damage and consequent loss of support integrity. Supports in direct contact
with intumescent coatings can also alter the performance of the coating (i.e. prevent expansion of the
coating under fire). This may require application of intumescent coatings to the pipe support itself in
order to protect the pipe at the hanger or pipe support.
Pipe resting in fixed supports that permit pipe movement shall have abrasion protection in the form of
saddles, elastomeric materials or sheet metal.
Anchor supports shall be capable of transferring the required axial loads to the pipe without causing
overstress of the GRP pipe material. Anchor clamps are recommended to be placed between either a
thrust collar laminated to the outer surface of the pipe or two double 180° saddles, adhesive-bonded
to the outer surface of the pipe. The manufacturer’s standard saddles are recommended and shall be
bonded using standard procedures.
4.4 Isolation and access for cleaning
The designer should make provision for isolation and easy access for maintenance purposes, for
example, for removal of scale and blockages in drains. The joint to be used for isolation or access should
be shown at the design stage and should be located in a position where the flanges can in practice be
jacked apart, e.g. it should not be in a short run of pipe between two anchors.
4.5 Vulnerability
4.5.1 Point loads
Point loads shall be minimized and the GRP piping locally reinforced where necessary.
4.5.2 Abuse
The designer shall give consideration to the risk of abuse to GRP piping during installation and service
and the need for permanent impact shielding.
Sources of possible abuse include the following:
a) any area where the piping can be stepped on or used for personnel support;
b) impact from dropped objects;
c) any area where piping can be damaged by adjacent crane activity, e.g. booms, loads, cables, ropes
or chains;
d) weld splatter from nearby or overhead welding activities.
ISO 14692-3:2017(E)
Small pipe branches (e.g. instrument and venting lines), which are susceptible to shear damage, should
be designed with reinforcing gussets to reduce vulnerability. Impact shielding, if required, should be
designed to protect the piping together with any fire-protective coating.
4.5.3 Dynamic excitation and interaction with adjacent equipment and piping
The designer shall give consideration to the relative movement of fittings, which can cause the GRP
piping to become overstressed. Where required, consideration shall be given to the use of flexible
fittings.
The designer should ensure that vibration due to the different dynamic response of GRP (as compared
with carbon steel piping systems) does not cause wear at supports or overstress in branch lines. The
designer should ensure that the GRP piping is adequately supported to resist shock loads that can
be caused by transient pressure pulses, e.g. operation of pressure safety valves, valve closure etc.
Reference [8] provides further guidance.
4.5.4 Exposure to light and ultraviolet radiation
Where GRP piping is exposed to the sun, the designer shall consider whether additional ultra violet
radiation (UV) protection is required to prevent surface degradation of the resin. If the GRP is a
translucent material, the designer should consider the need to paint the outside to prevent possible
algae growth in slow-moving water within the pipe.
4.5.5 Low temperatures and requirements for insulation
The designer shall consider the effects of low temperatures on the properties of the pipe material, for
example, the effect of freeze/thaw. For liquid service, the designer should particular pay attention to
the freezing point of the internal liquid. For completely filled lines, solidification of the internal fluid
can cause an expansion of the liquid volume, which can cause the GRP piping to crack or fail. For water
service, the volumetric expansion during solidification or freezing is more than sufficient to cause the
GRP piping to fail.
The pipe may need to be insulated and/or fitted with electrical surface heating to prevent freezing in
cold weather or to maintain the flow of viscous fluids. The designer shall give consideration to:
a) additional loading due to mass and increased cross-sectional area of the insulation;
b) ensuring that electrical surface heating does not raise the pipe temperature above its rated
temperature.
Heat tracing should be spirally wound onto GRP piping in order to distribute the heat evenly round the
pipe wall. Heat distribution can be improved if aluminium foil is first wrapped around the pipe.
4.6 Fire and blast
The effect of a fire event (including blast) on the layout requirements shall be considered. The possible
events to be considered in the layout design of a GRP piping system intended to function in a fire include
the following:
a) blast overpressure, drag forces and projectile impacts;
b) fire protection of joints and supports;
c) interface with metal fixtures;
d) formation of steam traps in piping containing stagnant water, which would reduce the conduction
of heat away by water;
e) jet fire;
6 © ISO 2017 – All rights reserved

ISO 14692-3:2017(E)
f) heat release and spread of fire for piping in manned spaces, escape routes or areas where personnel
are at risk;
g) smoke emission, visibility and toxicity for piping in manned spaces, escape routes or areas where
personnel are at risk.
Penetrations (wall, bulkhead, deck) shall not weaken the division that they penetrate. The main
requirements are to prevent passage of smoke and flames, to maintain structural integrity and to
limit the temperature rise on the unexposed side. Penetrations shall therefore comply with the same
requirements that apply to the relevant hazardous divisions. This requires the penetration to have
been fire-tested and approved for use with the specific type of GRP piping under consideration.
5 Hydraulic design
5.1 General
The aim of hydraulic design is to ensure that GRP piping systems are capable of transporting the
specified fluid at the specified rate, pressure and temperature throughout their intended service
life. The selection of nominal pipe diameter depends on the internal diameter required to attain the
necessary fluid flow consistent with the fluid and hydraulic characteristics of the system.
5.2 Flow characteristics
Fluid velocity, density of fluid, interior surface roughness of pipes and fittings, length of pipes,
inside diameter of pipes, as well as resistance from valves and fittings shall be taken into account
when estimating pressure losses. The smooth surface of the GRP can result in lower pressure losses
compared to metal pipe. Conversely, the presence of excessive protruding adhesive beads will increase
pressure losses.
5.3 General velocity limitations
When selecting the flow velocity for the GRP piping system, the designer shall take into account the
following concerns that can limit velocities in piping systems:
a) unacceptable pressure losses;
b) prevention of cavitation at pumps and valves;
c) prevention of transient overloads (water hammer);
d) reduction of erosion;
e) reduction of noise;
f) reduction of wear in components such as valves;
g) pipe diameter and geometry (inertia loading).
For typical GRP installations, the mean linear velocity for continuous service of liquids is between 1 m/s
and 5 m/s with intermittent excursions up to 10 m/s. For gas, the mean linear velocity for continuous
service is between 1 m/s and 10 m/s with intermittent excursions up to 20 m/s. Higher velocities are
acceptable if factors that limit velocities are eliminated or controlled, e.g. vent systems that discharge
into the atmosphere.
ISO 14692-3:2017(E)
5.4 Erosion
5.4.1 General
The following factors influence the susceptibility of GRP piping to erosion damage:
a) fluid velocity;
b) piping configuration;
c) particle size, density and shape;
d) particulate/fluid ratio;
e) onset of cavitation.
The designer shall refer to the manufacturer and consider reducing the velocity if doubts exist on
erosion performance.
5.4.2 Particulate content
The erosion properties of GRP are sensitive to the particulate content. The designer shall take into
account the likely particulate content in the fluid and reduce the maximum mean velocity accordingly.
For GRP, the maximum erosion damage typically occurs at a hard-particle impingement angle of
between 45° and 90°, i.e. at bends and tees. At low impingement angles (<15°), i.e. at relatively straight
sections, erosion damage is minimal. Further information on erosion can be found in DNV RP 0501.
5.4.3 Piping configuration
The presence of turbulence generators can have a significant influence on the erosion rate of GRP
piping, depending on fluid velocity and particulate content. The designer shall consider the degree of
turbulence and risk of possible erosion when deciding the piping configuration. To minimize potential
erosion damage in GRP piping systems, the following shall be avoided:
a) sudden changes in flow direction;
b) local flow restrictions or initiators of flow turbulence, e.g. excessive adhesive (adhesive beads) on
the inside of adhesive-bonded connections.
5.4.4 Cavitation
GRP piping is susceptible to rapid damage by cavitation. Cavitation conditions are created in piping
systems more easily than is generally realized, and the general tendency for systems to be designed
for high velocities exacerbates the situation further. Potential locations of cavitation include angles at
segmented elbows, tees and reducers, flanges where the gasket has been installed eccentrically and
joints where excessive adhesive has been applied.
The designer shall use standard methods to predict the onset of cavitation at likely sites, such as
control valves, and apply the necessary techniques to ensure that cavitation cannot occur under normal
operating conditions.
5.5 Water hammer
The susceptibility of GRP piping to pressure transients and out-of-balance forces caused by water
hammer depends on the magnitude of pressure and frequency of occurrence. A full hydraulic transient
analysis shall be carried out, if pressure transients are expected to occur, to establish whether the GRP
piping is susceptible to water hammer. The analysis shall cover all anticipated operating conditions
including priming, actuated valves, pump testing, wash-down hoses, etc.
8 © ISO 2017 – All rights reserved

ISO 14692-3:2017(E)
If there is a significant risk of water hammer, the designer shall employ standard techniques to ensure
that pressure transients do not exceed the hydrotest pressure.
A typical cause of water hammer is the fast closing of valves. The longer the pipeline or piping section
and the higher the liquid velocity, the greater the shock load will be. Shock loading generally induces
oscillation in the piping system. Since GRP pipe has a lower axial modulus of elasticity than the
equivalent steel pipe, longitudinal oscillations are generally more significant.
A hydraulic transient analysis can identify the potential requirement for vacuum breakers to prevent
vacuum conditions and vapour cavity formation. The proper selection and sizing of vacuum breakers
(also known as air-vacuum valves) can prevent water-column separation and reduce water hammer
effects. The sizing and the location of the vacuum breakers are critical. The air shall be admitted
quickly to be effective and shall be sized to account for the substantial pressure that can occur due
to the compression of the air during resurge. Air removal is often accomplished with a combined
air-release/air-vacuum valve.
6 Generation of design envelopes
6.1 Partial factors
6.1.1 Design life
A shall be used to scale the long term envelopes to the design envelopes at design lives other than
20 years. A shall be defined by Formula (1):
A = (1)
((logltG)(−×og 175 200))
xx
where
t is the time expressed in h;
G is the gradient of regression line at xx °C;
xx
A shall not be greater than 1,0.
6.1.2 Chemical degradation
A shall be used to scale the long term envelopes to the design envelopes to account for the effect of
chemical degradation. See ISO 14692-2:2017, 4.5.2.
6.1.3 Fatigue and cyclic loading
A shall be used to scale the long term envelopes to the design envelopes and shall be calculated taking
into account Figure 2 and Annex A.
ISO 14692-3:2017(E)
Key
1 fully static loading
2 fully cyclic loading
R cyclic loading ratio, =σ /σ
c min max
f cyclic long term strength factor (default value of 4,0), =σ /σ
c 100 000 (static) 150 000 000 (cyclic)
Figure 2 — A as a function of the number of cycles and the loading ratio
6.2 Part factor, f
The part factor for sustained loading, f , to be used in the assessment of sustained loads, shall be
determined taking into account operating conditions and risk associated with the piping system. The
value to be applied for specific piping systems shall be specified by the user. Recommended typical
values for f are
a) 0,67 for sustained loading conditions,
b) 0,83 for sustained loading plus self-limiting displacement conditions, and
c) 0,89 for occasional loading conditions.
Table 1 provides examples of loads experienced by a GRP piping system. The designer shall have
discretion in defining the load cases.
10 © ISO 2017 – All rights reserved

ISO 14692-3:2017(E)
Table 1 — Examples of loads experienced by a GRP piping system
Sustained, f = 0,67 Sustained + self-limiting Occasional, f = 0,89
2 2
displacements, f = 0,83
Hydrotest and other occasional
pressures
Operating and sustained internal, Thermal induced loads, electric
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