SIST-TP CEN/TR 1046:2014

Thermoplastics piping and ducting systems - Systems outside building structures for the conveyance of water or sewage - Practices for underground installation

This Technical Report is applicable to the installation of thermoplastics piping systems to be used for the conveyance of water or sewage under gravity and pressure conditions underground. It is intended to be used for pipes of nominal size up to and including DN 1600. Wherever the term “pipe” is used in this Technical Report, it also serves to cover any “fittings”, “ancillary” products and “components” if not otherwise specified.
NOTE 1 This document does not apply to pipelines for gas supply (see EN 12007–2, Gas infrastructure - Pipelines for maximum operating pressure up to and including 16 bar - Part 2: Specific functional requirements for polyethylene (MOP up to and including 10 bar).
NOTE 2 It is assumed that additional recommendations and/or requirements are detailed in the individual materials voluntary product standards. Instances where this is expected to apply include those indicated in this Technical Report as follows:
a) any special transportation requirements (see 5.2);
b) maximum storage height (see 5.2 and 5.4);
c) maximum storage period in direct sunlight (see 5.4);
d) any climatic conditions requiring special storage (see 5.4);
e) limiting initial and/or long-term deflections (see 6.1.1 and 6.1.2);
f) information on mole ploughing and boring (see and 6.2), if applicable;
g) selection of appropriate jointing system (see Clause 7);
h) recommended radii of curvature for cold bending (see 8.1);
i) permitted rates of loss of water under test (see 9.2.1);
j) if applicable the relationship between SDR and stiffness.
Requirements and instructions concerning commissioning of systems can be found in EN 805 and EN 1610 and the relevant national and/or local regulations.

Thermoplastische Rohrleitungs- und Schutzrohr-Systeme - Systeme außerhalb der Gebäudestruktur zum Transport von Wasser oder Abwasser - Verfahren zur unterirdischen Verlegung

Systèmes de canalisations et de gaines en plastique - Système d'adduction d'eau ou d'assainissement à l'extérieur de la structure des bâtiments - Pratiques pour la pose en aérien et en enterré

Le présent Rapport technique s'applique à la pose de systèmes de canalisations et de gaines en matières thermoplastiques destinés à être utilisés pour l'adduction d'eau ou l'assainissement, gravitaire ou avec pression, en enterré. Il est destiné à être utilisé pour des tubes de dimension nominale allant jusqu'à DN 1600 inclus.
Lorsque le terme « tube » est utilisé dans le présent Rapport technique, sauf spécification contraire il couvre également les « raccords », les produits « auxiliaires » et les « composants ».
NOTE   Il est entendu que des recommandations et/ou des exigences supplémentaires sont détaillées dans les différentes Normes de produits d’application volontaire concernant chaque matériau. Ceci peut s'appliquer aux cas suivants traités dans le présent Rapport technique :
a)   les exigences particulières relatives au transport (voir 4.2.6) ;
b)   la hauteur maximale de stockage (voir 4.4.3 et 4.4.4) ;
c)   la durée maximale de stockage en plein soleil (voir 4.4.6) ;
d)   les conditions climatiques exigeant un stockage particulier (voir 4.4.7) ;
e)   la déformation limite initiale et/ou à long terme (voir 5.1.1 et 5.1.2) ;
f)   les informations concernant l'emploi de charrue-taupe et le forage (voir 5.2), le cas échéant ;
g)   le choix du système d'assemblage approprié (voir l'article 6) ;
h)   les rayons de flexion recommandés pour le cintrage à froid (voir 7.1) ;
i)   les taux admis de perte d'eau (ou de perte de pression) au cours de l'essai (voir 8.2.1) ;
j)   le cas échéant, la relation entre SDR et rigidité.
On peut trouver des instructions et des prescriptions sur la réception des réseaux dans l'EN 805 et l'EN 1610, ainsi que dans la réglementation nationale et/ou locale.

Cevni in kanalski sistemi iz plastomernih materialov - Sistemi zunaj stavb za transport vode ali kanalizacije - Postopki za vgradnjo pod zemljo

General Information

• Status: Withdrawn
• Public Enquiry End Date: 14-Feb-2013
• Publication Date: 12-Jan-2014
• Withdrawal Date: 02-Jun-2021
• ICS: 23.040.03 - Pipeline and its parts for external water conveyance systems
• ICS: 93.025 - External water conveyance systems
• ICS: 93.030 - External sewage systems
• Technical Committee: PCV - Plastic pipes, fittings and valves
• Current Stage: 9900 - Withdrawal (Adopted Project)
• Start Date: 03-Jun-2021
• Due Date: 26-Jun-2021
• Completion Date: 03-Jun-2021
• Ref Project: CEN/TR 1046:2013 - Thermoplastics piping and ducting systems - Systems outside building structures for the conveyance of water or sewage - Practices for underground installation

RELATIONS

• Replaced By: SIST-TS CEN/TS 1046:2021 - Thermoplastics piping and ducting systems - Outside the building structures for gravity and pressurised systems - Trench installation
• Effective Date: 02-Jun-2021
• Replaces: SIST ENV 1401-3:2002 - Plastics piping systems for non-pressure underground drainage and sewerage - Unplasticized poly(vinyl chloride) (PVC-U) - Part 3: Guidance for installation
• Effective Date: 01-Feb-2014
• Replaces: SIST ENV 1046:2002 - Plastics piping and ducting systems - Systems outside building structures for the conveyance of water or sewage - Practices for installation above and below ground
• Effective Date: 01-Feb-2014
• Replaces: SIST-TS CEN/TS 1852-3:2003/A1:2005 - Plastics piping systems for non-pressure underground drainage and sewerage - Polypropylene (PP) - Part 3: Guidance for installation
• Effective Date: 01-Feb-2014
• Replaces: SIST-TS CEN/TS 14758-3:2006 - Plastics piping systems for non-pressure underground drainage and sewerage - Polypropylene with mineral modifier(s) (PP-MD) - Part 3: Guidance for installation
• Effective Date: 01-Feb-2014
• Replaces: SIST-TS CEN/TS 1852-3:2003 - Plastics piping systems for non-pressure underground drainage and sewerage - Polypropylene (PP) - Part 3: Guidance for installation
• Effective Date: 01-Feb-2014

Standards Content (sample)

SLOVENSKI STANDARD
SIST-TP CEN/TR 1046:2014
01-februar-2014
1DGRPHãþD
SIST ENV 1046:2002
SIST ENV 1401-3:2002
SIST-TS CEN/TS 14758-3:2006
SIST-TS CEN/TS 1852-3:2003
SIST-TS CEN/TS 1852-3:2003/A1:2005
Cevni in kanalski sistemi iz plastomernih materialov - Sistemi zunaj stavb za
transport vode ali kanalizacije - Postopki za vgradnjo pod zemljo

Thermoplastics piping and ducting systems - Systems outside building structures for the

conveyance of water or sewage - Practices for underground installation
Thermoplastische Rohrleitungs- und Schutzrohr-Systeme - Systeme außerhalb der
Gebäudestruktur zum Transport von Wasser oder Abwasser - Verfahren zur
unterirdischen Verlegung

Systèmes de canalisations et de gaines en plastique - Système d'adduction d'eau ou

d'assainissement à l'extérieur de la structure des bâtiments - Pratiques pour la pose en

aérien et en enterré
Ta slovenski standard je istoveten z: CEN/TR 1046:2013
ICS:
23.040.20 Cevi iz polimernih materialov Plastics pipes
93.025 Zunanji sistemi za prevajanje External water conveyance
vode systems
93.030 Zunanji sistemi za odpadno External sewage systems
vodo
SIST-TP CEN/TR 1046:2014 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP CEN/TR 1046:2014
TECHNICAL REPORT
CEN/TR 1046
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
December 2013
ICS 23.040.01 Supersedes CEN/TS 14758-3:2006, CEN/TS 1852-
3:2003, ENV 1046:2001, ENV 1401-3:2001
English Version
Thermoplastics piping and ducting systems - Systems outside
building structures for the conveyance of water or sewage -
Practices for underground installation

Systèmes de canalisations et de gaines en matières Thermoplastische Rohrleitungs- und Schutzrohr-Systeme -

thermoplastiques - Systèmes d'adduction d'eau ou Systeme außerhalb der Gebäudestruktur zum Transport

d'assainissement à l'extérieur de la structure des bâtiments von Wasser oder Abwasser - Verfahren zur unterirdischen

- Pratiques pour la pose en enterré Verlegung

This Technical Report was approved by CEN on 9 March 2013. It has been drawn up by the Technical Committee CEN/TC 155.

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, 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

© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 1046:2013 E

worldwide for CEN national Members.
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Contents Page

Foreword ..............................................................................................................................................................3

Introduction .........................................................................................................................................................4

1 Scope ......................................................................................................................................................5

2 Normative references ............................................................................................................................5

3 Terms and definitions ...........................................................................................................................6

4 Symbols and abbreviations ..................................................................................................................7

5 Transport, handling and storage at depots and sites ........................................................................7

5.1 General ....................................................................................................................................................7

5.2 Transportation of pipes .........................................................................................................................8

5.3 Handling ..................................................................................................................................................9

5.4 Storage ................................................................................................................................................. 10

6 Installation ........................................................................................................................................... 10

6.1 Pipes in trenches ................................................................................................................................ 10

6.2 Special installation techniques ......................................................................................................... 30

7 Methods of assembly (jointing) ......................................................................................................... 30

7.1 General ................................................................................................................................................. 30

7.2 Joints using an elastomeric seal ...................................................................................................... 31

7.3 Mechanical compression joints ........................................................................................................ 32

7.4 Other joints and jointing methods .................................................................................................... 33

8 Bends ................................................................................................................................................... 33

8.1 Cold bending ....................................................................................................................................... 33

8.2 Hot bending ......................................................................................................................................... 33

9 Inspection and testing ........................................................................................................................ 33

9.1 Inspection ............................................................................................................................................ 33

9.2 Testing ................................................................................................................................................. 34

Annex A (normative) Classification of soils .................................................................................................. 35

Annex B (informative) Behaviour of buried flexible pipes ........................................................................... 37

Annex C (normative) Joint and jointing examples ....................................................................................... 39

C.1 General ................................................................................................................................................. 39

C.2 Joints capable of resisting end thrust .............................................................................................. 39

C.3 Mechanical threaded joints ................................................................................................................ 45

Bibliography ..................................................................................................................................................... 47

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Foreword

This document (CEN/TR 1046:2013) 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 [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.

This document supersedes ENV 1046:2001, ENV 1401-3:2001, CEN/TS 1852-3:2003 and
CEN/TS 14758-3:2006.

This Technical Report is based on the results of the work being undertaken in ISO/TC 138 “Plastics pipes,

fittings and valves for the transport of fluids”, which is a Technical Committee of the International Organization

for Standardization (ISO) (see Bibliography), modified as necessary to be applicable to piping systems of any

thermoplastics materials and any relevant application.
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Introduction

This Technical Report contains guidance for installation procedures for thermoplastics piping systems and

their components intended to be used below ground for pressure and non-pressure applications outside

building structures. It is intended to be used in conjunction with general standards for installation

recommendations, for example those issued by CEN/TC 164 “Water supply” and CEN/TC 165 “Waste water

engineering” as stated in EN 805 and EN 1610 respectively.

NOTE Guidelines for installation of pipelines made out of thermosetting materials can be found in the ISO 10465

series [11, 12, 13].

This Technical Report is based on the results from research with full-scale trials undertaken by the

thermoplastics pipes industry and expressed in CEN/TS 15223.

This Technical Report is a guidance document only. It provides a set of general guidelines which gives best

practices for installation of thermoplastics piping and ducting systems outside building structures underground.

This Technical Report includes recommendations for the pipe surround and backfilling procedures but not

road base and road sub-base details. Attention is drawn to any national regulations which may cover these or

other aspects of installation.

This Technical Report does not cover matters relating to renovation of existing pipeline systems using lining

techniques, or replacement of existing pipeline systems using trenchless techniques.

This Technical Report is intended to be used by authorities, design engineers, installation contractors and

manufacturers.

In this Technical Report, much of the guidance is expressed as requirements, e.g. by use of “shall” or by

instructions in the imperative. It is strongly recommended that these be followed whenever applicable.

Other guidance is presented for consideration as a matter of judgement in each case, e.g. by use of “should”.

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1 Scope

This Technical Report is applicable to the installation of thermoplastics piping systems to be used for the

conveyance of water or sewage under gravity and pressure conditions underground. It is intended to be used

for pipes of nominal size up to and including DN 1600.

Wherever the term “pipe” is used in this Technical Report, it also serves to cover any “fittings”, “ancillary”

products and “components” if not otherwise specified.

NOTE 1 This document does not apply to pipelines for gas supply (see EN 12007–2, Gas infrastructure - Pipelines for

maximum operating pressure up to and including 16 bar - Part 2: Specific functional requirements for polyethylene (MOP

up to and including 10 bar).

NOTE 2 It is assumed that additional recommendations and/or requirements are detailed in the individual materials

voluntary product standards. Instances where this is expected to apply include those indicated in this Technical Report as

follows:
a) any special transportation requirements (see 5.2);
b) maximum storage height (see 5.2 and 5.4);
c) maximum storage period in direct sunlight (see 5.4);
d) any climatic conditions requiring special storage (see 5.4);
e) limiting initial and/or long-term deflections (see 6.1.1 and 6.1.2);
f) information on mole ploughing and boring (see and 6.2), if applicable;
g) selection of appropriate jointing system (see Clause 7);
h) recommended radii of curvature for cold bending (see 8.1);
i) permitted rates of loss of water under test (see 9.2.1);
j) if applicable the relationship between SDR and stiffness.

Requirements and instructions concerning commissioning of systems can be found in EN 805 and EN 1610

and the relevant national and/or local regulations.
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 681 (all parts), Elastomeric seals - Materials requirements for pipe joint seals used in water and drainage

applications
EN 805, Water supply - Requirements for systems and components outside buildings
EN 1610, Construction and testing of drains and sewers

CEN/TS 15223, Plastics piping systems - Validated design parameters of buried thermoplastics piping

systems
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3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
deflection
deviation of the circle cross section of the pipe (in percent)
3.2
average deflection

measured average deflection over the inspected length of the pipeline (in percent)

3.3
trench
excavation of the soil for the underground embedment of the pipeline

Note 1 to entry: See Figure 1 for an illustration of the meaning and limits of the terms used in this Technical Report.

Key
b width of the cross section
b horizontal clearance between the pipe or fitting and the trench sidewall or an
adjacent pipe or fitting
de external diameter of a pipe
1 depth of cover above the pipe
2 height of embedment above the pipe 100 mm to 300 mm
3 ground surface
4 native soil
5 embedment
6 main backfil
7 pipe zone
8 upper bedding (according EN 1610, also known as haunch zone, of which the
height is 1/3 of the pipe diameter)
9 trench bottom
10 lower bedding (according EN 1610)
Figure 1 — Trench cross-section showing terminology
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Key
1 slope (0/00, m/km, mm/m)
Figure 2 — Trench axial-section showing slope of the pipeline
4 Symbols and abbreviations
For the purposes of this Technical Report, the following symbols apply:
b width of a trench cross-section (see Figure 1);
b horizontal clearance between the pipe or fitting and the trench sidewall or an
adjacent pipe or fitting (see Figure 1, Figure 7 and Table 4);
d (mean) external diameter of a pipe (see Figure 1 and Figure 8);
DN/OD nominal outside diameter of a pipe and associated fittings (see Table 4);
pipe wall thickness;
M compaction classification: Moderate (see Figure 9 and Table 7);
N compaction classification: Not (see Figure 9 and Table 7);
S initial specific stiffness (see Table 3);
SN stiffness number or classification (see Table 3);
SDR standard dimension ratio (see Table 3)
W compaction classification: Well (see Figure 9 and Table 7);
5 Transport, handling and storage at depots and sites
5.1 General

Thermoplastics pipes may be supplied in straight lengths or coiled forms (either free standing or on drums).

Attention is drawn to the need for consideration of personnel safety during the transport, handling and storage,

especially in wet and cold weather conditions. Particular care should be exercised when decoiling coiled pipes

as considerable forces can be released.
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Additional information should be given in the System Standards, if applicable.

For additional explanations, see Figure 3 to Figure 5 which deal with transport, handling and storage.

5.2 Transportation of pipes

When transporting pipes or pipe package, vehicles should be used. The bed shall be free from nails and other

projections. When practicable, pipes should rest uniformly on the vehicle.

Secure the pipes or pipe package effectively before transporting. When pipes are transported in bundles, the

bundles should be secured effectively and off loaded as described hereunder.

When loading socketed pipes, the pipes should be stacked on the vehicle so that the sockets do not take

loads.
The largest diameter pipes should be placed on the bed of the vehicle.

Care should be taken to avoid positioning the pipes near to any exhaust systems or any other potential

hazards such as diesel oil.

Pipes should be inspected by the purchaser or his representative for damage and compliance with the order

during unloading at the destination.

When pipes and/or fittings require special transportation practices, the manufacturer shall notify the customer

of the procedures to be used.
Figure 3 — Transport
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Figure 4 — Handling and storage
Figure 5 — Preferred pipe packaging

NOTE Attention is drawn to the need to conform to national and/or local transport regulations.

5.3 Handling
When handling the pipes, care shall be taken to prevent damage.

When pipes are to be handled individually, they should be lifted, lowered and carried in a controlled fashion

and should never be thrown, dropped or dragged (see Figure 4).

It is preferable to use fabric slings or rope to lift the pipe or pipe bundle. Metal bars, slings, hooks or chains will

damage the pipe if they are used incorrectly. When loading or unloading pipes, pipe bundles with forklift

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equipment, only forklift trucks with smooth or suitably protected forks should be used. Care should be taken to

ensure that forks do not strike the pipe when lifting.

The impact resistance of thermoplastics pipes is reduced at low temperatures; under these conditions, take

more care during handling. Where cold conditions are expected, the advice of the manufacturer should be

sought.

When loosening a coil, personnel should be aware of potential danger in the operation.

5.4 Storage

Although thermoplastics pipes are light, durable and resilient, take reasonable precautions during storage.

When it is intended to store pipes or coils on site in stacks, the manufacturer's advice regarding correct

practice should be sought.

Stack the pipes or coils on reasonably flat surfaces free from sharp objects, stones or projections in order to

avoid localized deformation or damage to the pipes. For the maximum stacking height, see the manufacturer's

technical documentation.

Where pipes are supplied with end caps, plugs or wrappings, these should be removed prior to jointing.

Do not place pipes or rubber seals in close proximity to fuels, solvents, oils, greases, paints or heat sources.

Storage in direct sunlight for long periods and/or high temperatures could cause deformations affecting the

jointing.
To avoid this risk, the following precautions are recommended:
a) limit the height of the stacks of pipes;

b) shield the stacks of pipes from continuous and direct sunlight and arrange to allow the free passage of air

around the pipes;

c) store the fittings in boxes or sacks manufactured so as to permit the free passage of air.

The fading of the colour caused by outside storage does not affect the mechanical properties of pipes and

fittings.

If pipes are supplied in a bundle or in other packaging, the restraints and/or packaging should be removed as

late as possible prior to installation.
6 Installation
6.1 Pipes in trenches
6.1.1 Behaviour of flexible pipes under load

The behaviour of a pipe, when subject to a load, depends upon whether it is flexible, semi-rigid or rigid (see

EN 476). Thermoplastics pipes are flexible. When loaded, a flexible pipe deflects and presses into the

surrounding material without fracture. This generates a reaction in the surrounding material which controls

deflection of the pipe. The amount of deflection which occurs is limited by the care exercised in the selection

and laying of the bedding and side-fill materials. Hence, flexible pipes rely on the bedding and side-fill

materials for their load-bearing properties.
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The level of deflection reached by a buried pipe depends on the properties of the surrounding material and to

a much lesser extent on the stiffness of the pipe but not on its strength properties. Therefore, for flexible pipes,

the crushing strength test and design procedures applied to rigid pipes are not appropriate.

When a flexible pipe is installed and backfilled it will be deflected. This is called the initial deflection. The pipe

continues slowly to have an increase in deflection but reaches a limiting value within a reasonable period of

time. The use of the installation procedures detailed in this Technical Report will minimize the levels of both

the initial and final deflections. If the pipeline is pressurized then a reduction in the amount of deflection will

occur. A more detailed description of this behaviour is given in Annex B.
6.1.2 Limiting deflection

There are several methods of structural design (see EN 1295-1:1997 [1]) that are used to estimate the

deflection of a pipe under load but, though they are capable of being in reasonable agreement, they do not

give exactly the same answers for a given condition. The values calculated are usually the expected average

deflections.

Pipes made from different materials have different limiting deflection levels. For the applicable maximum

permissible initial and, if appropriate, long-term deflection see Table 1, Figure 6, Annex B and the relevant

System Standard. If this document is followed, it is expected that the deflections will be less than the limiting

values given in Table 1 or the relevant System Standards.

Table 1 — Recommended allowable average deflection for thermoplastic pipes for gravity applications

Way of installation Recommended allowable Remark
average deflection
Installation according to this ≤ 8 % Based on measured
Technical Report deflection values short after
installation, at commissioning

NOTE 1 Thermoplastics pipes allow high deflection because of the huge strain-ability of these

materials. Strain-ability and pipe wall stability are checked in the ring flexibility test during which the

pipes are deformed up to 30 % deflection.

NOTE 2 For pressure applications after pressurization a re-rounding effect takes place.

NOTE 3 For long-term deflection see Annex B.

At commissioning, local initial maximum deflection in pipelines may be allowed for PVC-U ≤ 10 %

and for PE and PP ≤ 12 %.

Where it can be expected that a product covered by the System Standard may be delivered with some

distortion, e.g. pipes delivered in coils, then this should be stated. The average deflection is to be assumed to

be in addition to this distortion.
6.1.3 Design considerations
6.1.3.1 General

If it is essential to determine the soil conditions that relate to trench construction and pipe installation prior to

construction; the native soil and the backfill material shall be classified in accordance with Annex A. The

classification shall be used to choose a suitable pipe stiffness in accordance with 6.1.3.2.

NOTE The classification will also indicate the areas of suitable materials for pipe zone backfill, so that importation of

material may be minimized. Native materials conforming to Table A.1 are all suitable as backfill in the pipe zone. If backfill

materials have to be imported, it is suggested that group 1 or 2 materials are used.

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6.1.3.2 Choice of pipe stiffness

The choice of pipe stiffness shall be made either using the tables or Figure 6 in this Technical Report or on the

basis of calculations in accordance with CEN/TS 15223 or on the basis of previous experience.

Where calculations show that a pipe stiffness lower than that given in Table 2 or Table 3 is appropriate, then

pipes with this lower stiffness may be used. Where pipes are intended to be used in conditions where they

have by previous experience proved to be satisfactory it is not necessary to verify this by detailed calculation

even though their stiffness may be lower than the appropriate value given in Table 2 or Table 3.

If such experience is not available then the minimum stiffness required shall be selected from Table 2 or

Table 3. These tables have been prepared to cover the following conditions:

a) non-trafficked areas with depths of cover between 1 m and 3 m and between 3 m and 6 m (see Table 2);

b) trafficked areas with depths of cover between 1 m and 3 m and between 3 m and 6 m (see Table 2).

In the absence of prior satisfactory experience, where pipes have a depth of cover less than 0,6 m or more

than 6 m, the pipe stiffness and the installation shall be designed by calculation.

Where a System Standard uses SDR for classification purposes instead of stiffness, it shall also give the

equivalent stiffness values in its relevant part.

Generally, the choice of pipe stiffness depends upon the native soil, the pipe zone backfill material and its

compaction, the depth of cover, the loading conditions and the limiting properties of the pipes.

In order to make a choice of pipe stiffness possible, the native soil and backfill materials have been classified

into six main groups as described in Annex A.

Based on the native soil, backfill details and depth of cover, the minimum pipe stiffness is selected from

Table 2 or Table 3. Using a pipe of this stiffness installed in an embedment formed from the appropriate

backfill material compacted to the specified degree of compaction should result in deflections of not more than

the limiting values given in the relevant System Standard.

Designers first need to establish permitted deflections, average and maximum. (National requirements product

standards, this Technical Report, etc. offer guidance.)

For the deflection mentioned in the design graph, the strain will be far below the design limit.

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Key
A nominal ring stiffness I well compacted
B initial deflection, as a percentage II moderate
III non-compacted

Figure 6 — Design graph for determining the pipe deflections depending on Installation type

Table 2 — Validity of the design graph

Pipe system Fulfilling requirements in EN 1401-1 [2], EN 1852-1 [3], EN 12666-1 [4],

EN 13476-2 [5], EN 13476-3 [6] or EN 14758-1 [10] as applicable.
Installation depth 0,8 m – 6,0 m
Traffic loading Included
Installation quality “Well” compaction
Embedment granular soil is carefully placed in the haunching zone and
Installation categories

compacted followed by placing the soil in shift of a maximum of 30 cm after which

“well”, “moderate” (and

each layer is compacted carefully. The pipe should be covered at least by a layer

“none”) should reflect the

of 15 cm. The trench is further filled with soil of any type and compacted. Typical

workmanship on which
values for the standard proctor density are above 94 %.
the designer can rely.
“Moderate” compaction
Embedment granular soil is placed in shifts of a maximum of 50 cm, after which

each layer is compacted carefully. The pipe should at least be covered by a layer

of 15 cm. The trench is further filled with soil of any type and compacted. Typical

values for the standard proctor density are in the range of 87 % to 94 %.
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SIST-TP CEN/TR 1046:2014
CEN/TR 1046:2013 (E)
“None” compaction
Sheet piles should be removed before compaction, in accordance with the
recommendations in EN 1610. If, however, the sheet piles are removed after

compaction, one should realize that the “well” or “moderate” compaction level will

be reduced to the “none” compaction level.
Additional National rules may apply.

Deflections were verified for pipe diameters up to and including 1 600 mm. However, when applying the

volume approach technique, it was found that the graph is also valid for bigger diameters.

6.1.3.3 Selection of fitting stiffness or class

Because of their geometry, solid-wall fittings have a stiffness greater than the stiffness of the pipe with

corresponding wall-thickness series. Therefore, the recommended stiffness classes/wall-thickness series of

fittings for use with structured-wall pipes given in Table 3 applies:
Table 3 — Minimum fitting classes recommended for use with structured wall pipes

Pipe stiffness Minimum stiffness of fittings according Minimum wall-thickness series of fittings

class to: according to
EN 13476-2 [5]
and EN 13476-3 EN 14758-1 [10] EN 1852-1 [3] EN 1401-1 [2] EN 12666-1 [4]
[6]
SN 2 SN 2 SN 4 S 20 SDR 51 SDR 33
SN 4 SN 4 SN 4 S 20 SD
...