CEN/TS 15223:2017

SLOVENSKI STANDARD
01-januar-2018
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SIST-TS CEN/TS 15223:2008
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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 15223:2017
ICS:
23.040.20 Cevi iz polimernih materialov Plastics pipes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TS 15223
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
November 2017
TECHNISCHE SPEZIFIKATION
ICS 23.040.01 Supersedes CEN/TS 15223:2008
English Version
Plastics piping systems - Validated design parameters of
buried thermoplastics piping systems
Systèmes de canalisations en matières plastiques - Kunststoff-Rohrleitungssysteme - Bestätigte
Paramètres de calcul validés pour les systèmes Berechnungsparameter von erdverlegten
enterrés de canalisations en matières thermoplastischen Rohrleitungssystemen
thermoplastiques
This Technical Specification (CEN/TS) was approved by CEN on 4 September 2017 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, 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. CEN/TS 15223:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions, symbols and abbreviations . 7
3.1 Terms and definitions . 7
3.2 Symbols . 8
3.3 Abbreviations . 9
4 Route for structural design. 9
4.1 General . 9
4.2 Structural design based on practical experience . 12
4.3 Structural design based on design calculations . 13
5 Functional design non-pressure . 13
5.1 General . 13
5.2 Material . 13
5.3 Strain . 14
5.4 Flow capacity . 14
5.5 Temperature . 15
5.6 Ring buckling . 15
5.7 Longitudinal effects . 16
5.7.1 General . 16
5.7.2 Axial bending . 17
5.7.3 Allowable cold bending . 17
6 Functional design pressure . 17
6.1 General . 17
6.2 Material . 17
6.3 Design coefficient . 18
6.4 Pressure rating PN . 18
6.5 Flow capacity . 18
6.6 Temperature . 19
6.6.1 Temperature dependence of the nominal working pressure of PE piping systems . 19
6.6.2 Temperature dependence of the nominal working pressure of PVC piping systems . 19
6.7 Working pressure . 20
6.7.1 Buckling resistance for negative pressure applications . 20
6.7.2 PFA, PMA and PEA . 20
6.8 Water hammer . 20
6.9 Ring buckling . 21
6.10 Longitudinal effects . 22
6.10.1 Axial bending . 22
6.10.2 Cold bending limits . 22
6.11 Joints . 23
7 Structural design . 23
7.1 General . 23
7.2 Behaviour of installed plastic pipes in soil . 24
7.3 Structural design based on practical experience . 25
7.3.1 General . 25
7.3.2 Values for installation phase . 26
7.3.3 Values for final deflection . 27
7.4 Structural design based on a design calculations . 28
8 Guidance for verification of installation . 28
9 Commissioning . 29
9.1 General . 29
9.2 Non pressure pipe . 29
9.3 Pressure pipe . 29
Annex A (informative) Time dependency of stress and strain in buried flexible piping
systems . 30
Annex B (informative) Soil / pipe behaviour . 31
Annex C (informative) Verification against limit states for non-pressure pipes . 33
Annex D (informative) Flow capacity charts (non-pressure) . 34
Bibliography . 36

European foreword
This document (CEN/TS 15223:2017) has been prepared by Technical Committee CEN/TC 155 “Plastics
piping systems and ducting systems”, the secretariat of which is held by NEN.
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 CEN/TS 15223:2008.
According to the CEN/CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to announce this Technical Specification: 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.
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 researches, graphs have been
made that show the deflection in the pipes immediately after installation. In addition, 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 compactible soil groups are used, granular and
cohesive.
If applicable, reference is made to EN 1295-1, EN 1610, CEN/TR 1046 and national practices.
1 Scope
This Technical Specification covers validated design parameters of buried thermoplastics piping
systems for functional and structural design for the following applications:
– pressure (excluding piping systems for gaseous fluids and industrial applications);
– non-pressure.
The functional design is based on relevant standards and commonly used practices.
Depending on the project parameters, the route for structural design can be
– either established by long term experience (within certain limitations),
– or calculated according to CEN/TR 1295-2 [8] by using thermoplastic pipe material related
properties and design criteria.
NOTE 1 The route for the structural design is shown in the flowchart given in Figure 1 in 4.1.
NOTE 2 Industrial applications also includes district heating
Since in practice precise details of types of soil and installation conditions are not always available at
the design stage, the choice of design assumptions is left to the judgement of the designer/specifier. In
this connection, this guide can only provide general indications and advice.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. 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 drains and sewers
EN 805, Water supply - Requirements for systems and components outside buildings
EN 1295-1, Structural design of buried pipelines under various conditions of loading - Part 1: General
requirements
EN 1610:2015, Construction and testing of drains and sewers
CEN/TR 1046:2013, Thermoplastics piping and ducting systems - Systems outside building structures for
the conveyance of water or sewage - Practices for underground installation
EN ISO 9969, Thermoplastics pipes - Determination of ring stiffness (ISO 9969)
EN ISO 12162, Thermoplastics materials for pipes and fittings for pressure applications - Classification,
designation and design coefficient (ISO 12162)
EN ISO 13968, Plastics piping and ducting systems - Thermoplastics pipes - Determination of ring
flexibility (ISO 13968)
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
deflection
deviation of the circle cross section of the pipe
Note 1 to entry: Deflection is expressed as percentage [%].
3.1.2
minimum required strength
MRS
value of σLPL at 20 °C and 50 years, rounded down to the next lower value of the R10 series when σ
LPL
is below 10 MPa, or to the next lower value of the R20 series when σLPL is 10 MPa or greater
Note 1 to entry: R10 and R20 series are the Renard number series according to ISO 3 [1] and ISO 497 [2]
3.1.3
lower confidence limit of the predicted hydrostatic strength
σ
LPL
quantity, with the dimensions of stress, which represents the 97,5 % lower confidence limit of the
predicted hydrostatic strength at a temperature θ and time t
Note 1 to entry: It is expressed in megapascals.
3.1.4
design coefficient
C
design coefficient with a value greater than 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
3.1.5
nominal pressure
PN
numerical designation used for reference purposes related to the mechanical characteristics of the
component of a piping system
For plastic piping systems conveying water, it corresponds to the allowable operating pressure (PFA) in
bar, which can be sustained with water at 20 °C with a design basis of 50 years, and based on the
minimum design coefficient:
20× MRS
PN=
C×(SDR-1)
3.1.6
critical buckling pressure
q
crit
critical internal pressure causing buckling of the pipe
3.1.7
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 1 to entry: It is designated by the letters “SN” followed by the appropriate number.
3.1.8
standard dimension ratio
SDR
numerical designation of a pipe series, which is a convenient round number, approximately equal to the
dimension ratio of the nominal outside diameter, d , and the nominal wall thickness, e
n n
3.1.9
allowable maximum operating pressure
PMA
maximum pressure occurring from time to time, including surge, that a component is capable of
withstanding in service
3.1.10
allowable operating pressure
PFA
maximum hydrostatic pressure that a component is capable of withstanding continuously in service
3.1.11
allowable site test pressure
PEA
maximum hydrostatic pressure that a newly installed component is capable of withstanding for a
relatively short duration, in order to ensure the integrity and tightness of the pipeline
3.2 Symbols
For the purposes of this document, the following symbols apply.
C design coefficient
C deflection factor depending on compaction level, in percent
f
d nominal outside diameter of the pipe, in millimetres
n
dem mean outside diameter of the pipe, in millimetres
e wall thickness of the pipe, in millimetres
E the Young’s modulus of the pipe, in megapascals
p
E tangent modulus, in kilopascals
t
e Nominal wall thickness of the pip, in millimetres
n
f application rating factor
a
f temperature rating factor
τ
g gravity, in m/s
K compressive modus [N/m2]
k absolute roughness, in millimetres
k viscosity of water, in m /s
water
q critical buckling pressure, in kilopascals
crit
R bending radius of the pipe, in millimetres
R maximum bending radius of the pipe, in millimetres
max
S geometrical pipe characteristic defined as S = (d - e) / (2e)
n
ß deflection correction factor
δ deflection of the pipe, in millimetres
ε tangential strain
ε maximum acceptable strain
max
3.3 Abbreviations
For the purposes of this document, the following abbreviations apply.
HDS Hydrostatic design stress
MRS Minimum required strength
PE Polyethylene
PEA Allowable site test pressure
PFA Allowable operating pressure
PMA Allowable maximum operating
pressure
PN Nominal pressure
PP Polypropylene
PP-B Polypropylene block copolymer
PP-H Polypropylene homopolymer
PP-MD Polypropylene mineral modified
PVC-HI High impact poly(vinyl chloride)
PVC-O Poly(vinyl chloride) oriented
unplasticized
PVC-U Poly(vinyl chloride) unplasticized
SDR Standard dimension ratio
4 Route for structural design
4.1 General
At the start of a project, first the parameters need to be investigated as given in Clause 5.
In general creating a validated structural design of a thermo-plastics pipeline construction by applying
analytical or numerical methods is not needed – provided the parameters of the project are within the
value range given in Table 1.
Any calculated prediction of the pipe behaviour and reality is strongly dependent on the conditions
used for the calculation being the same as used for the installation. Therefore, it is important that effort
is put into controlling the input values by extensive soil surveys and monitoring the installation.
In many cases, practical and/or reference information is available and results in a sound prediction of
the pipe performance.
The flowchart in Figure 1 provides the necessary steps to establish the structural design of a pipeline.
Figure 1 — Flowchart for structural design of a pipeline
Table 1 — Value range for design parameters
Parameter Value (range) Remark
a
Installation depth 0,80 m to 6,0 m As defined in CEN/TR 1046

Depth of cover above the pipe ≥ 0,60 m  As defined in CEN/TR 1046
crown.
AND
Soil cover / pipe diameter
ratio ≥ 2
b
Soils Granular-cohesive
c
Installation type Well, moderate, none Combination of soil, compaction,
and degree of care
Pipe stiffness ≥ SN 2 For non-pressure pipes
≥ 2 kN/m For pressure pipes – required
during installation and
commissioning
Pipe types Structured wall pipes with a ring Pressure pipes are regarded as
flexibility ≥ 30 % solid wall pipes.
Solid wall pipes
d
Traffic load All classes Railways are excluded and
should be calculated.
Diameter For diameters ≤ DN 1100
See also applicable product
standard,
Ground water table No limitation
a
In special conditions, shallower installation depths (until 0,6 m) are allowed, but only in combination with
installation type 'well compaction”.
b
The soil specification can be found in CEN/TR 1046.
c
Installation type 'None' is not recommended.
d
Traffic classes according to EN 124
If the parameters of the project are within the value range as given in Table 1, the structural design can
be based on practical experience as given in 4.2.
If the parameters of the project are outside the value range as given in Table 1, the structural design can
be calculated according to 4.3.
4.2 Structural design based on practical experience
Extensive studies performed by the Plastics Pipes industry in Europe (TEPPFA / APME study [16]) and
by verification of other studies performed in various countries have shown that flexible pipes behave
differently than rigid pipes. The current theories describing the performance of flexible pipes do not
reflect the true physics of the process of pipe deflection.
The background and the results of the TEPPFA / APME study [16] are given in Clause 7.
The most important practical output of the studies is given in the design graph in Clause 7 (Figure 6).
The performance of the flexible pipes can be found in the applicable product standards of CEN/TC 155.
4.3 Structural design based on design calculations
Structural design calculations are required in cases where installation conditions are outside the
validity of Table 1. When installation conditions are outside the range in Table 1, EN 1295-1 provides
the method that shall be used. The calculation methods proposed in CEN/TR 1295-2 [8] require
material properties that are given in Clause 5.
5 Functional design non-pressure
5.1 General
According to EN 476, the information on following aspects, when relevant, shall be provided in product
standards.
5.2 Material
Functional design calculation may require material properties. In Table 2, typical values are given,
which are valid for pressure and non-pressure applications.
a
Table 2 —Typical material values for functional design calculations
Material Poisson's Coefficient of linear Young’s Relaxation Tensile strength
ratio expansion modulus coefficient at yield
[-] [1/ °C] [MPa] [-] [MPa]
−5
PVC-HI 0,4 8 × 10 3 200 0,05 50
−5
PVC 250 0,4 8 × 10 3 200 0,05 50
−5
PVC 315 0,4 8 × 10 3 200 0,05 50
−5
PVC 355 0,4 8 × 10 3 200 0,05 50
−5
PVC 400 0,4 8 × 10 3 200 0,05 50
−5
PVC 450 0,4 8 × 10 3 200 0,05 50
−5
PVC 500 0,4 8 × 10 3 200 0,05 50
−5
PE 40 0,45 19 × 10 300 0,07 8
−5
PE 80 0,45 19 × 10 850 0,07 19
−5
PE 100 0,45 19 × 10 1 100 0,08 21
−5 b
PP-B 0,42 12 × 10 1 250–2 500 0,07 27
−5
PP-H 0,42 12 × 10 1 250 0,07 30
−5 c c
PP-MD 0,42 12 × 10 1 600–3 600 0,07 23–32
a
If specific values are needed related to specific products, these shall be acquired from the manufacturer or specific
standards.
b
A range has been specified according to EN 1852-1 [10]
.
c
A range has been specified depending on the filling degree.
5.3 Strain
Non-pressure pipes do not require a stress analysis because of the visco-elastic behaviour and
redistribution of stresses. A study of Janson [4] shows whether thermoplastics are strain limited or not.
In this study, 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. If one wishes to calculate the material
strain value then Table 3 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 ISO 13968. Passing this test ensures stability against buckling.
Table 3 — Maximum acceptable strain, ε , for non-pressure pipes (table taken from Janson [4])
max
Material ε
max
%
PVC-U 2,5
PE 5,0
PP 5,0
5.4 Flow capacity
The flow capacity is depending of the design and influenced by the 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.
In Table 4 an indication is given about typically used k values in calculation for non-pressure systems.
Table 4 — Typical values for absolute roughness, k, to determine the flow capacity
Pipes for gravity sewerage k
mm
Material related 0,01–0,05
a
Plastic piping systems (straight pipeline) 0,25
a
Plastic piping systems (including fittings and manholes) 0,4
a
System roughness to be used for capacity calculation.
In Annex D (Figures D.1 and D.2), flow capacity charts are shown where different k values given in
Table 4 are used.
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 2 shows the
effect of deformation on discharge capacity (indicative).
Key
A discharge capacity, in percentage
B average pipe deflection, in percentage
Figure 2 — Discharge capacity as a function of average pipe deflection
5.5 Temperature
For non-pressure drainage and sewerage, allowed operating temperatures are given in EN 476:
— diameters ≤ 200 mm: temperatures: < 45 °C;
— diameters > 200 mm: temperatures: < 35 °C.
The plastic piping systems as covered by this Technical Specification can withstand these temperatures.
If during the application higher temperatures are expected, extra provisions should be made during the
design.
5.6 Ring buckling
The critical buckling pressure of a buried pipe can be calculated and verified against the sustained load
at the outside of the pipe. For buried pipes, sustained load is the load exerted by groundwater and part
of the soil load. The load to be taken into account is given by the relevant standards. The resistance
against buckling can be calculated for flexible pipes using the following formulae (see Alferink [9]).
Soft soils / mud: Condition [SN] > 0,0275 E
t
qE=24×+[SN]
crit t
(1)
Other soils:
qE5,63×[SN]
crit t
(2)
=
where
q is the critical buckling pressure, in kilopascals;
crit
[SN] is the value of the nominal ring stiffness class, expressed in kilonewtons per
square meter;
E is the tangent modulus, in kilopascals.
t
When a pipe is deflected, it will result in a lower buckling resistance of the pipe.
The value found shall then be corrected with β:
β = (1 - 3(δ/D )) (3)
m
Key
A correction factor ß
B deflection δ/Dm, in percent
Figure 3 — Correction factor for the buckling resistance as a function of the deflection of the
pipe
EXAMPLE Pipe (SN 4) buried in granular soil at 5 m depth and with 4 m groundwater above the top of the
pipe. The installation has been well done and the deflection stays below 2,2 %.
3 2
Sustained load due to groundwater; 4 m × ( 1 000 × 10) N/m = 40 000 N/m . The soil load is not the same as used
for the deflection calculations in most methods. If methods discriminate between the hydrostatic load component
and the shear related component, the hydrostatic component shall be taken into account.
In this example, the buckling will be checked for groundwater only.
q = 5,63 √ (2 800 × 4) kN/m
crit
q = 595 kN/m
crit
5.7 Longitudinal effects
5.7.1 General
An essential part of the design of a pipeline is to evaluate the longitudinal effects, which is not covered
in most of the recognized structural design methods as listed in EN 1295-1. Therefore, guidance is given
to this issue here.
5.7.2 Axial bending
When bending a pipe in the field, caused either during installation or by the occurrence of settlement
differences along the pipeline after installation, the following phenomena shall be checked:
The strain due to bending of a straight pipe can be calculated by Formula (4):
d
n
ε ×100
2R
(4)
where
ε is the tangential strain, as a percentage;
d is the nominal outside diameter of the pipe, in
n
millimetres;
R is the bending radius, in millimetres.
The allowable strain values are listed in Table 3.
5.7.3 Allowable cold bending
Pipes should preferably be installed straight (without bends). However, as thermoplastics pipes are
flexible, bending within certain limits, as given in Table 5, will not cause problems.
Table 5 — Allowable bending radii for pipes for cold bending
Pipe diameter PVC/PP-MD PE/PP
d ≤ 200 [mm] R ≥ 300 d R ≥ 250 d
n n n
d > 200 [mm] R ≥ 500 d R ≥ 400 d
n n n
Certain joints may offer extra bending capability to the piping system. The manufacturer’s
documentation or the relevant EN standards should be
...