SIST-TS CEN/TS 15223:2008
(Main)Plastics piping systems - Validated design parameters of buried thermoplastics piping systems
Plastics piping systems - Validated design parameters of buried thermoplastics piping systems
This document covers thermoplastics pipe material related properties and design topics to be taken into account when carrying out any static pipe calculation. It also provides guidance to applying structural design of thermoplastics piping systems for pressure and non-pressure applications. It furthermore provides documentation based on long term experience, to be used in justifying and/or verification of any structural design method.
NOTE For piping systems for the conveyance of gaseous fluids additional guidance is given in EN 12007-2.
Kunststoff-Rohrleitungssysteme - Gültige Berechnungsparameter von erdverlegten thermoplastischen Rohrleitungssystemen
Dieses Dokument behandelt Eigenschaften von thermoplastischen Rohrwerkstoffen und Berechnungsaspekte,
die bei der Durchführung von statischen Berechnungen der Rohrleitung zu berücksichtigen sind. Es
enthält ebenfalls Empfehlungen für die Anwendung der statischen Berechnungen von thermoplastischen
Rohrleitungssystemen für Anwendungen unter und ohne Druck. Darüber hinaus bietet es eine auf Langzeit-
Erfahrungen beruhende Dokumentation zur Verwendung bei der Rechtfertigung und/oder Verifizierung eines
beliebigen statischen Berechnungsverfahrens.
ANMERKUNG Für Rohrleitungssysteme zum Transport gasförmiger Fluide werden zusätzliche Empfehlungen in
EN 12007-2 gegeben.
Systèmes de canalisations en matières plastiques - Paramètres de calcul validés pour les systèmes enterrés de canalisations en matières thermoplastiques
Le présent document décrit les propriétés liées à la matière des tubes en thermoplastiques ainsi que les points à prendre en compte dans tout calcul de tube à l'état statique. Il fournit également un guide pour appliquer les calculs de résistance mécanique des systèmes de canalisations en thermoplastiques aux applications avec ou sans pression. Il fournit, en outre, la documentation, établie sur une expérience à long terme, nécessaire pour justifier et/ou vérifier toute méthode de calcul de la résistance mécanique.
Cevni sistemi iz polimernih materialov - Veljavni parametri za načrtovanje plastomernih cevnih sistemov, položenih v zemljo
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TS CEN/TS 15223:2008
01-junij-2008
&HYQLVLVWHPLL]SROLPHUQLKPDWHULDORY9HOMDYQLSDUDPHWUL]DQDþUWRYDQMH
SODVWRPHUQLKFHYQLKVLVWHPRYSRORåHQLKY]HPOMR
Plastics piping systems - Validated design parameters of buried thermoplastics piping
systems
Kunststoff-Rohrleitungssysteme - Gültige Berechnungsparameter von erdverlegten
thermoplastischen Rohrleitungssystemen
Systèmes de canalisations en matières plastiques - Paramètres de calcul validés pour
les systèmes enterrés de canalisations en matières thermoplastiques
Ta slovenski standard je istoveten z: CEN/TS 15223:2008
ICS:
23.040.01 Deli cevovodov in cevovodi Pipeline components and
na splošno pipelines in general
SIST-TS CEN/TS 15223:2008 en,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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TECHNICAL SPECIFICATION
CEN/TS 15223
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
April 2008
ICS 23.040.01
English Version
Plastics piping systems - Validated design parameters of buried
thermoplastics piping systems
Systèmes de canalisations en matières plastiques - Kunststoff-Rohrleitungssysteme - Gültige
Paramètres de calcul validés pour les systèmes enterrés Berechnungsparameter von erdverlegten
de canalisations en matières thermoplastiques thermoplastischen Rohrleitungssystemen
This Technical Specification (CEN/TS) was approved by CEN on 25 September 2007 for provisional application.
The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.
CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available
promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)
until the final decision about the possible conversion of the CEN/TS into an EN is reached.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 15223:2008: E
worldwide for CEN national Members.
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CEN/TS 15223:2008 (E)
Contents
Page
Foreword.3
Introduction.4
1 Scope .5
2 Normative references .5
3 Terms, definitions, symbols and abbreviations .5
3.1 Terms and definitions.5
3.2 Symbols .6
3.3 Abbreviations .7
4 General material properties .8
4.1 General material properties .8
4.2 Pressure pipes (stress design basis).9
4.3 Non-pressure pipes (strain design based).10
4.4 Piping systems for gaseous fluids .10
5 System and operation related aspects .10
5.1 General .10
5.2 Tightness.11
5.3 Flow capacity .11
5.4 Temperature .13
5.5 Design procedure of pressure pipes.14
5.6 Water hammer (pressure pipes) .14
5.7 Deflection .16
6 Design approach.16
6.1 Design approach based on experience .16
6.2 Longitudinal effects.19
6.3 Joints.20
7 Guidance for verification of installation .22
8 Commissioning .23
8.1 Non pressure pipe.23
8.2 Pressure pipe.23
Annex A (informative) Time dependency of stress and strain in buried flexible piping systems .24
Annex B (informative) Soil / pipe behaviour.25
Annex C (informative) Soil and installation parameters .27
Bibliography.28
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CEN/TS 15223:2008 (E)
Foreword
This document (CEN/TS 15223:2008) has been prepared by Technical Committee CEN/TC 155 “Plastics
piping systems and ducting systems”, the secretariat of which is held by NEN.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this CEN Technical Specification: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and United Kingdom.
3
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CEN/TS 15223:2008 (E)
Introduction
In Europe several design methods exist and some are still under development. The plastics pipes industry has
carried out a lot of research with full-scale trials. From these research graphs have been made that shows the
deflection in the pipes immediately after installation. Also the so-called settlement period is measured. This
settlement will always take place. In case that heavy traffic is present, the final deflection will be reached
faster.
It is strongly advised to check any calculated deflection with the values in the two design graphs.
The information compiled is meant to be used by designers. The values given are meant for general guidance.
For the purpose of design using simple methods, two soil groups are used, granular and cohesive. For more
detailed and sophisticated design, more soil groups are used, for which reason reference is made to
[11]
EN 1295-1 and to national methods.
4
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CEN/TS 15223:2008 (E)
1 Scope
This document covers thermoplastics pipe material related properties and design topics to be taken into
account when carrying out any static pipe calculation. It also provides guidance to applying structural design
of thermoplastics piping systems for pressure and non-pressure applications. It furthermore provides
documentation based on long term experience, to be used in justifying and/or verification of any structural
design method.
NOTE For piping systems for the conveyance of gaseous fluids additional guidance is given in EN 12007-2.
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.
EN 476, General requirements for components used in discharge pipes, drains and sewers for gravity
systems
EN 773:1999, General requirements for components used in hydraulically pressurized discharge pipes,
drains and sewers
EN 805:2000, Water supply — Requirements for systems and components outside buildings
CEN/TR 1295-2, Structural design of buried pipelines under various conditions of loading — Part 2: Summary
of nationally established methods of design
CEN/TR 1295-3, Structural design of buried pipelines under various conditions of loading — Part 3: Common
method
EN 1446, Plastics piping and ducting systems — Thermoplastics pipes — Determination of ring flexibility
EN 12007-2, Gas supply systems — Gas pipelines for maximum operating pressure up to and including
16 bar — Part 2: Specific functional recommendations for polyethylene (MOP up to and including 10 bar)
EN ISO 9080, Plastics piping and ducting systems — Determination of the long-term hydrostatic strength of
thermoplastics materials in pipe form by extrapolation (ISO 9080:2003)
EN ISO 12162, Thermoplastics materials for pipes and fittings for pressure applications — Classification and
designation — Overall service (design) coefficient (ISO 12162:1995)
3 Terms, definitions, symbols and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
constant load
load on a pipe, e.g. from internal pressure, that is not changing with time
3.1.2
constant deformation
deformation due to deflection of the pipe that is not changing with time, e.g. due to constraint from the soil
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CEN/TS 15223:2008 (E)
3.1.3
design stress
σ
s
allowable stress, in megapascals, for a given application. It is derived from the MRS by dividing it by the
overall service coefficient C
3.1.4
minimum required strength
MRS
value of σ , rounded down to the next smaller value of the R10 series or of the R20 series depending on the
LPL
value of σ
LPL
NOTE R10 and R20 series are the Renard number series according to ISO 3 [1] and ISO 497 [2].
3.1.5
overall service coefficient
C
overall service coefficient with a value greater that one, which takes into consideration service conditions as
well as properties of the components of a piping system others than those represented in the lower confidence
limit
3.1.6
nominal pressure
PN
numerical designation used for reference purposes related to the mechanical characteristics of the component
of a piping system. It corresponds to the maximum continuous operating pressure in bars
3.1.6
pipe stiffness
S
p
theoretical pipe stiffness determined with the Young’s modulus and the Poisson ratio
3.1.7
critical buckling pressure
q
crit
critical internal pressure causing buckling of the pipe
3.1.8
nominal stiffness
SN
numerical designation of the ring stiffness of a pipe or fitting, which is a convenient round number indicating
the minimum required ring stiffness of the pipe or fitting
NOTE It is designated by the letters “SN” followed by the appropriate number.
3.2 Symbols
For the purposes of this document, the following symbols apply.
C overall service coefficient
ß deflection correction factor
C 100 year overall service coefficient
100
C 50 year overall service coefficient
50
C deflection factor, in percent
f
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CEN/TS 15223:2008 (E)
d nominal outside diameter of the pipe, in millimetres
n
δ deflection of the pipe, in millimetres
d mean outside diameter of the pipe, in millimetres
em
d the midwall diameter, in millimetres
m
d outside diameter of the pipe, in millimetres
e
e wall thickness of the pipe, in millimetres
ε strain
E the Young’s modulus of the pipe material, in megapascals
p
E tangent modulus, in kilopascals
t
f application rating factor
a
F maximum tensile force, in newton
fitting
f temperature rating factor
τ
2
g gravity, in m/s
K value of the measured molecular weight
k absolute roughness, in millimetres
2
k viscosity of water, in m /s
water
ν poisson ratio
q critical buckling pressure, in kilopascals
crit
ρ density, in kilograms per cubic meter
R bending radius of the pipe, in millimetres
R maximum bending radius of the pipe, in millimetres
max
ρ density of water
S geometrical pipe characteristic defined as: S = (d − e)/(2e)
n
2 −1
S pipe stiffness value determined by (1 − υ ) /E ⋅(d /e − 2), in [MPa ]
p p em
σ design stress, in newtons per square millimetre
s
σ tensile strength, in megapascals
tensile strength
3.3 Abbreviations
HDS hydrostatic design stress
MRS minimum required strength
PE Polyethylene
PEA allowable site test pressure
PFA allowable operating pressure
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CEN/TS 15223:2008 (E)
PMA allowable maximum operating pressure
PN nominal pressure
PP polypropylene
PVC poly(vinyl chloride)
SDR standard dimension ratio
4 General material properties
4.1 General material properties
Plastics pipe properties related to design are given in Table 1.
a
Table 1 — Material properties: values typical for calculations
Material Poisson Coefficient of Young’s Relaxation Tensile
ratio linear expansion modulus coefficient strength
[-] [1/ °C] [MPa] [-] [MPa]
-5
PVC-HI 0,4 6×10 2 500 0,06 40
-5
PVC 250 0,4 8×10 3 200 0,05 50
-5
PVC 315 0,4 8×10 3 500 0,05 60
-5
PVC 355 0,4 8×10 3 500 0,05 60
-5
PVC 400 0,4 8×10 3 500 0,05 60
-5
PVC 450 0,4 8×10 3 500 0,05 60
-5
PVC 500 0,4 8×10 3 500 0,05 60
-5
PE 63 0,45 19×10 800 0,06 17
-5
PE 80 0,45 19×10 850 0,07 19
-5
PE 100 0,45 19×10 1 100 0,08 21
-5
PP-B 0,42 12×10 1 250 0,07 27
-5
PP-HM 0,42 12×10 1 700 0,07 31
-5
PP-H 0,42 12×10 1 250 0,07 30
-5
PP-R 0,42 12×10 950 0,07 23
a
If values are needed related to specific products, these shall be acquired from the manufacturer or
specific standards.
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CEN/TS 15223:2008 (E)
4.2 Pressure pipes (stress design based)
4.2.1 Minimum Required Strength (MRS)
The minimum required strength shall be classified according to EN ISO 12162. The classification shall be
determined out of the lower confidence limit tangential stress, which divides the MRS values into ranges. In
the pressure test according to EN ISO 9080 the LPL-value shall be determined for the pipe material. This LPL-
value gives the classification for the MRS value. For classification reasons 50 year have been taken and the
relevant design coefficient is applied. In practise the lifetime will be longer. Therefore also the remaining
design factor 100 year is given. For the different thermoplastics materials used in buried pipes, the MRS
values are given in Table 2.
Table 2 — Material properties relevant for pressure pipes at 20 °C
a
Material MRS Overall service Overall design Allowable
b c
σσσσ classification design coefficient coefficient approximately one
C C hour stress
50 100
[MPa] [-] [-] [MPa]
PVC-HI 18 1,4 1,38 35
PVC 250 25,0 2,0 1,94 42
PVC 315 31,5 1,6 1,58 45
PVC 355 35,5 1,6 1,58 51
PVC 400 40,0 1,6 1,58 57
PVC 450 45,0 1,4 1,38 64
PVC 500 50,0 1,4 1,38 71
PE 63 6,3 1,25 ― 10
PE 80 8,0 1,25 1,23 12,6
PE 100 10,0 1,25 1,23 16
a
If values are needed related to specific products, these shall be acquired from the manufacturer or
specific standards.
b
The overall design coefficient is determined in EN ISO 12162 and the values shown in the table are
minimum values. The values may be increased by users when specific fluids which are harmful for the
environment or mankind.
c
Based on regression curves it is shown that the C coefficients slightly differ from the C values.
100 50
NOTE At temperatures below 20 °C the values will be higher than those shown.
4.2.2 Overall service (design) coefficient C
Minimum overall service design coefficients shall be determined in accordance with EN ISO 12162. The
overall service design coefficient lowers the nominal pressure (PN) as given in the following equation:
10σ / S
s
PN = e (1)
C
where
S = (d − e) / 2e (2)
n
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CEN/TS 15223:2008 (E)
4.2.3 Design stresses
The design stress of the pipe is determined with the MRS divided by the overall service coefficient.
4.2.4 Pressure rating PN
The pressure rating shall be determined using Equation (1).
4.3 Non-pressure pipes (strain design based)
Non-pressure pipes do not require a stress analysis because of the visco-elastic behaviour and redistribution
of stresses. Studies of Moser [3] and Janson [4] have discussed whether thermoplastics are strain limited or
not. In these studies strain by bending as well as through-wall strains have been evaluated. It was shown that
for all practical purposes these materials are not strain limited. Nevertheless, Moser [3] has proposed rather
conservative values that are not based on the occurrence of a failure. If one wishes to calculate the material
strain value then the table below supplies conservative guidance about the levels that can be accepted.
The combination of pipe construction and integrity shall be tested by means of a ring flexibility test up to 30 %
deflection as described in EN 1446. Passing this test ensures stability against buckling.
Table 3 (taken from Janson [4]) Strainability, εεεε, for non-pressure pipes
Material ε
%
PVC-U 2,5
PE 5,0
PP 5,0
4.4 Piping systems for gaseous fluids
For guidance for the design of gas supply systems EN 12007-2 shall apply.
5 System and operation related aspects
5.1 General
According to EN 476, EN 773 and EN 805 the information on following aspects, when relevant, shall be
provided in product standards.
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CEN/TS 15223:2008 (E)
5.2 Tightness
5.2.1 Non pressure pipes
For elastomeric sealing ring joints in non-pressure systems the tightness is normally tested for deformation of
the socket and spigot and angular deflection. Table 4 gives an overview of typical values.
Table 4 — Typical parameter values for tightness testing
Deflection Socket: ≥ 5 [%]
Spigot: ≥ 10 [%]
Difference: ≥ 5 [%]
Angular deflection d ≤ 315 : 2°
e
315 < d ≤ 630 : 1,5°
e
630 < d : 1°
e
Special cases Manufacturer’s recommendation
For joints using fusing techniques and adhesive bonding are considered to be leak tight. The test for
evaluating the jointing quality is defined in the product standards by pressure or tensile testing.
All lines of the system have to be tested in commissioning.
5.2.2 Pressure pipes
For elastomeric sealing ring joints in pressure systems the tightness is normally tested for deformation of the
socket and spigot in combination with angular deflection. Test conditions relate to infiltration and ex-filtration.
For joints using fusing techniques and adhesive bonding are considered to be leak tight. The test for
evaluating the jointing quality is defined in the product standards by pressure or tensile testing.
All lines of the system have to be tested in commissioning.
5.3 Flow capacity
5.3.1 General
The flow capacity is dependent on both the material of the pipe and of the design of the system. Plastic piping
system with their narrow tolerances for diameters and wall thickness for pipe joint fittings and chambers
reduce considerably the influence on the flow capacity.
The flow capacity is influenced by the change of wall roughness and the pipe deformation. For thermoplastics
pipes, wear and corrosion are non-relevant phenomena and hence ageing of the pipe has no effect on flow
performance.
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CEN/TS 15223:2008 (E)
Table 5 Typical values of k to determine the flow capacity
a
Pipe k
mm
Plastics d < 100 mm 0,01
Plastics pipe d > 100 mm 0,05
a
Values are valid for straight pipes without connections and other fittings. They are taken
from “Stromingsweerstanden in leidingen, Prof. Ir. L. Huisman, KIWA 1969”.
NOTE 1 The so-called system roughness is considerably higher then the values mentioned in
the table.
NOTE 2 Prof. Janson recommends the use of a k-value of 0,1 for plastics water piping systems.
NOTE 3 For sewer systems a k-value of 0,4 seems to be more appropriate for plastics.
As far as the deformation is concerned, it is a fact that the discharge capacity is decreasing with 2 % when at
the same time the pipe is deflected up to an average deflection of 10 %. Figure 1 shows the effect of
deformation on discharge capacity.
Key
A discharge capacity, in percent
B pipe deflection, in percent
Figure 1 Discharge capacity as a function of average pipe deflection
5.3.2 Flow capacity for non pressure pipes
In some regions, one is more used to utilise the Manning approach instead of the Colebrook procedures.
Although there is no clear relation between the two, from practical experience the following values for k
(Colebrook) and n (Manning) are coincident with each other.
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CEN/TS 15223:2008 (E)
Table 6 — Relation between Colebrook and Manning values
Colebrook Manning
k n
0,2 100
1,0 80
5,0 60
5.4 Temperature
5.4.1 General
In case where the pipe material is exposed to temperatures other than 20 °C, rating factors shall be used.
NOTE Normally this is only done when the temperature is higher than 20 °C. When the temperature is lower than
20 °C, such a re-rating is not normally applied. It should be realised that in most situations the temperature is lower than
20 °C, meaning that a higher factor of safety is achieved.
5.4.2 Temperature dependence of PE
[5]
The temperature dependence of PE is given in Table 7, where the values are taken from EN 12201-1 .
Table 7 Pressure rating for PE
Temperature f
t
[°C]
20 1,0
30 0,87
40 0,74
NOTE 1 For other temperatures between each step a linear interpolation is applied. The coefficients mentioned are
[6]
valid for PE 80 and PE 100. For other PE types see ISO 13761 .
NOTE 2 Unless analysis according to EN ISO 9080 demonstrates that less reduction is applicable, in which case
higher factors and hence higher pressures can be applied.
5.4.3 Temperature dependence of PVC
[7]
For PVC-O the same values can be used as for PVC-U (EN 1452-2 ).
Table 8 Pressure rating for PVC
Temperature f
t
[°C]
25 1,0
30 0,9
35 0,8
40 0,7
45 0,6
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CEN/TS 15223:2008 (E)
NOTE 1 For other temperatures between each step a linear interpolation is allowed.
NOTE 2 Unless analysis according to EN ISO 9080 demonstrates that less reduction is applicable, in which case
higher factors and hence higher pressures can be applied.
5.5 Design procedure of pressure pipes
5.5.1 Procedure
Pressure pipes are buried in soils after which they will be pressurised. Therefore the response to external and
internal pressure has to be verified in the design.
For thermoplastics materials, with its visco-elastic behaviour, it is not the combination of internal and external
load that provides the worse case condition.
Thermoplastics pressure pipes, such as those made out of PE and PVC-U, shall be designed in the following
way.
a) The pipe shall be considered without pressure and with a surge pressure of –0,8 bar, as required in
EN 805. The design shall be based on buckling resistance.
b) The pipe shall be designed as for a free creeping condition. The value to refer to is the Hydrostatic
Design Stress (HDS). The HDS is the stress referring to the Minimum Required Strength (MRS) of the
C) as given by the product standards.
raw material using the Overall Service Design Coefficient (
5.5.2 PFA, PMA and PEA
Following the request given by EN 805, relation between product related pressure classification and PFA,
PMA and PEA are given.
The product related pressure classification for thermoplastics is based on the worst condition under pressure,
which is free creep.
The following equation applies:
[PFA] = f × f × [PN]
τ a
For product standards the value of the application rating factor f in the equation can be set to 1 in case
a
potable water, gas and sewage is transported under normal condition. When chemicals are transported then
advice shall be sought at the manufacturer to obtain specific values for f .
a
The maximum allowable transient pressure including surge:
[PMA] = 2 × [PN]
The maximum test pressure:
[PEA] = 1,5 × [PN]
5.6 Water hammer (pressure pipes)
The maximum pressure occurring in pipelines is caused by unsteady flow, so-called water hammer The
maximum pressure occurring in a pipeline systems can be calculated by the Joukowski equation:
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CEN/TS 15223:2008 (E)
1
ρ( + S )
p
k
water
D = ×D (3)
p u
g
where
k is the stiffness of water (2 000 MPa);
water
2
S is the water hammer related stiffness value determined by (1 − ν ) /E (d /e − 2)
p p m
where
E is the Young’s modulus of the pipe, in megapascals [MPa];
p
3
ρ is the density of water, which equals 1 000 kgm ;
d is the midwall diameter, in millimetres [mm];
m
e is the wall thickness, in millimetres [mm].
Figure 2 shows the pressure increase as a function of the water hammer related stiffness S .
p
The figure is valid for a steady flow of 1 m/s.
Key
A pressure increase
B water hammer related stiffness × 1 000
Figure 2 — Pressure increase versus water hammer related stiffness
Table 9 shows S values for common plastics pipes.
p
Table 9 — Typical material related values for S
p
2 -1
Material S [(kN/m ) ]
p
PVC-U, SDR 41 11
PVC-U, SDR 26 6,8
PE, SDR 17 15
PE, SDR 11 9
Non-thermoplastics for 0,3
reference purposes
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CEN/TS 15223:2008 (E)
For systems where extreme transient conditions are unlikely, it may be safely assumed that the peak surge
pressure will never have a value more than twice the rated steady state pressure.
5.7 Deflection
For the deflection conditions see 6.1. For the limits see 0.
6 Design approach
6.1 Design approach based on experience
6.1.1 General
2 2
For the design of a system of flexible pipes in the stiffness range of 2 kN/m to 16 kN/m use is made of the
graph in Figure 3. On the vertical axis, the pipe deflection is shown and at the horizontal the pipe stiffness
classes. For each installation group (as defined in ENV 1046 [8] into well, moderate and none and described
in Annex C) an area is given in which the deflection after installation is expected. The upper edge of the area
represents the maximum deflection to be expected. The lower edge of the area shows the average deflection
to be expected.
Key
A nominal ring stiffness I well compacted
B initial deflection, as a percentage II moderate compaction
III non-granular
Figure 3 — Design graph for determining the pipe deflections immediately after installation
The graph shows the deflections immediately after installation. It does not include the effect of traffic load,
depth of cover and groundwater.
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CEN/TS 15223:2008 (E)
The soil will further compact in the course of time. This further compaction is caused by the own weight of the
soil, the percolat
...
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