District heating pipes - Design and installation of thermal insulated bonded single and twin pipe systems for directly buried hot water networks - Part 1: Design

This European Standard specifies requirements for design, calculation and installation of factory made thermal insulated bonded single and twin pipe systems for directly buried hot water networks for continuous operation with treated hot water at various temperatures up to 120 ºC and occasionally with peak temperatures up to 140 ºC and maximum internal pressure 2,5 MPa. Flexible pipe systems according to EN 15632 are not under the scope of this standard.
The standard EN 13941, Design and installation of thermal insulated bonded single and twin pipe systems for directly buried hot water networks consists of two parts:
a)   prEN 13941-1: Design;
b)   prEN 13941-2: Installation.
The requirements and stipulations in this part: EN 13941-1, form an unbreakable unity with those of prEN 13941-2. This part shall therefore exclusively be used in combination with prEN 13941-2.
The principles of the standard may be applied to thermal insulated pipe systems with pressures higher than 2,5 MPa, provided that special attention is paid to the effects of pressure.
Adjacent pipes, not buried, but belonging to the network (e. g. pipes in ducts, valve chambers, road crossings above ground etc.) may be designed and installed according to this standard.
This standard presupposes the use of treated water, which by softening, demineralisation, de-aeration, adding of chemicals, or otherwise has been treated to effectively prevent internal corrosion and deposits in the pipes.
NOTE   For further information on water qualities to be used in district heating pipe systems see also [1].
This standard is not applicable for such units as:
a)   pumps;
b)   heat exchangers;
c)   boilers, tanks;
d)   systems behind domestic substations.

Fernwärmerohre - Auslegung und Installation von gedämmten Einzel- und Doppelrohr-Verbundsystemen für direkt erdverlegte Fernwärmenetze - Teil 1: Auslegung

Dieses Dokument legt Auslegungs-, Berechnungs- und Installationsanforderungen für werkmäßig gefertigte wärmegedämmte Einzel- und Doppelrohrverbundsysteme für erdverlegte Warmwassernetze fest, die für den Dauerbetrieb mit aufbereitetem Wasser bei unterschiedlichen Temperaturen bis 120 °C und gelegentlichen Spitzentemperaturen bis 140 °C für höchstens 300 h/a sowie bei maximalem Innendruck von 2,5 MPa vorgesehen sind.
Flexible Rohrsysteme nach der Normenreihe EN 15632 liegen nicht im Anwendungsbereich dieser Norm.
Die Norm EN 13941, Fernwärmerohre — Auslegung und Installation von gedämmten Einzel- und Doppelrohr-Verbundsystemen für direkt erdverlegte Fernwärmenetze besteht aus zwei Teilen:
a)   EN 13941 1: Auslegung
b)   EN 13941 2: Installation
Die Anforderungen in diesem Teil, EN 13941 1, bilden eine Einheit mit jenen aus EN 13941 2.
Die Grundsätze der Norm können auf wärmegedämmte Rohrleitungssysteme mit Drücken über 2,5 MPa angewendet werden, vorausgesetzt, die Auswirkungen der Drücke werden besonders beachtet.
Angrenzende Rohre, die zum Netz gehören, aber nicht erdverlegt sind (z. B. Rohre in unterirdischen Einbauten, Armaturenschächten, oberirdische Straßenüberquerungen usw.), können entsprechend dieser Norm ausgelegt und installiert werden.
Dieses Dokument setzt die Verwendung von aufbereitetem Wasser voraus, das durch Enthärtung, Entsalzung, Entlüftung, Zusatz von Chemikalien oder auf andere Art und Weise so behandelt worden ist, dass innere Korrosion und Ablagerungen in den Leitungen effektiv vermieden werden.
ANMERKUNG   Für weitere Informationen zur Qualität des Wassers, welches bei Fernwärmesystemen eingesetzt wird, siehe auch Literaturhinweis [2].
Diese Norm gilt nicht für Geräte bzw. Anlagen wie z. B.:
a)   Pumpen;
b)   Wärmeübertrager;
c)   Kessel, Speicher;
d)   Systeme hinter Hausregelstationen.

Tuyaux de chauffage urbain - Conception et installation des systèmes bloqués de monotubes ou bitubes isolés thermiquement pour les réseaux d'eau chaude enterrés directement - Partie 1 : Conception

Le présent document spécifie les exigences relatives à la conception, au calcul et à l'installation de systèmes manufacturés bloqués de monotubes ou bitubes isolés thermiquement pour les réseaux d'eau chaude enterrés directement, pour un service continu avec de l'eau chaude traitée à différentes températures jusqu’à 120 °C, et occasionnellement avec des pics de température jusqu’à 140 °C pendant 300 h/a au maximum, et une pression interne maximale de 2,5 MPa.
Les systèmes de tuyaux flexibles conformes à la série de normes EN 15632 ne relèvent pas du domaine d'application de la présente norme.
La norme EN 13941, Conception et installation des systèmes bloqués de monotubes et bitubes isolés thermiquement pour les réseaux d'eau chaude enterrés directement comprend deux parties :
a)   EN 13941-1 : Conception ;
b)   EN 13941-2 : Installation.
Les exigences et stipulations de la présente partie, EN 13941-1, sont indissociables de celles de l'EN 13941-2.
Les principes de la présente norme peuvent être appliqués à des systèmes de tuyaux isolés thermiquement avec des pressions supérieures à 2,5 MPa, pourvu qu’il soit porté une attention spéciale aux effets de la pression.
Les tuyaux adjacents non enterrés, mais appartenant au réseau (par exemple, tubes en caniveaux, chambres de vanne, traversée de route en aérien, etc.) peuvent être conçus et installés conformément à la présente norme.
Le présent document présuppose l'utilisation d'eau traitée, par adoucissement, déminéralisation, désaération, ajout de substances chimiques, ou par tout autre moyen permettant d'éviter efficacement la corrosion interne et les dépôts dans les tuyaux.
NOTE   Pour de plus amples informations sur les qualités d'eau à utiliser dans les systèmes de tuyaux pour le chauffage urbain, voir également la référence bibliographique [2].
La présente norme n'est pas applicable aux éléments tels que :
a)   pompes ;
b)   échangeurs de chaleur ;
c)   chaudières, réservoirs ;
d)   systèmes en aval des postes de raccordement.

Cevi za daljinsko ogrevanje - Projektiranje in vgradnja toplotno izoliranih spojenih eno- in dvocevnih sistemov za neposredno zakopana vročevodna omrežja - 1. del: Projektiranje (vključno z dopolnilom A1)

Ta evropski standard določa zahteve za projektiranje, izračun in vgradnjo tovarniško izdelanih toplotno izoliranih spojenih eno- in dvocevnih sistemov za neposredno zakopana vročevodna omrežja za neprekinjeno delovanje z obdelano vročo vodo pri različnih temperaturah do 120 °C in občasnih najvišjih temperaturah do 140 °C ter najvišjem notranjem tlaku 2,5 MPa. Ta standard ne zajema gibkih cevnih sistemov v skladu s standardom EN 15632.
Standard EN 13941, Projektiranje in vgradnja toplotno izoliranih spojenih eno- in dvocevnih sistemov za neposredno zakopana vročevodna omrežja je sestavljen iz dveh delov:
a)   prEN 13941-1: Projektiranje
b)   prEN 13941-2: Vgradnja
Zahteve in določbe iz tega dela standarda: EN 13941-1 je neločljivo povezan z zahtevami in določbami standarda prEN 13941-2. Ta del se zato uporablja izključno skupaj s standardom prEN 13941-2.
Načela standarda se lahko uporabljajo za toplotno izolirane cevne sisteme s tlaki, višjimi od 2,5 MPa, če je posebna pozornost namenjena učinkom tlaka.
Sosednje cevi, ki niso zakopane, vendar pripadajo omrežju (npr. cevi v jaških, ventilskih komorah, cestnih prehodih nad tlemi itd.), je mogoče projektirati in vgraditi na podlagi tega standarda.
Ta standard predpostavlja uporabo obdelane vode, ki z mehčanjem, demineralizacijo, razzračevanjem, dodajanjem kemikalij ali z drugo obdelavo učinkovito preprečuje notranjo korozijo in nastajanje oblog na ceveh.
OPOMBA:   Za dodatne informacije o kakovosti vode za uporabo v cevnih sistemih za daljinsko ogrevanje glej tudi [1].
Ta standard se ne uporablja za enote, kot so:
a)   črpalke;
b)   toplotni izmenjevalniki;
c)   kotli, rezervoarji;
d)   sistemi za domačimi razdelilnimi postajami.

General Information

Status
Published
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
15-Dec-2021
Completion Date
15-Dec-2021

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SLOVENSKI STANDARD
SIST EN 13941-1:2019+A1:2022
01-marec-2022

Cevi za daljinsko ogrevanje - Projektiranje in vgradnja toplotno izoliranih spojenih

eno- in dvocevnih sistemov za neposredno zakopana vročevodna omrežja - 1. del:
Projektiranje (vključno z dopolnilom A1)

District heating pipes - Design and installation of thermal insulated bonded single and

twin pipe systems for directly buried hot water networks - Part 1: Design

Fernwärmerohre - Auslegung und Installation von gedämmten Einzel- und Doppelrohr-

Verbundsystemen für direkt erdverlegte Heißwasser-Fernwärmenetze - Teil 1:
Auslegung
Tuyaux de chauffage urbain - Conception et installation des systèmes bloqués de
monotubes ou bitubes isolés thermiquement pour les réseaux d'eau chaude enterrés
directement - Partie 1 : Conception
Ta slovenski standard je istoveten z: EN 13941-1:2019+A1:2021
ICS:
23.040.07 Cevovodi za daljinsko Pipeline and its parts for
ogrevanje in njihovi deli district heat
91.140.10 Sistemi centralnega Central heating systems
ogrevanja
SIST EN 13941-1:2019+A1:2022 en,fr,de

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

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SIST EN 13941-1:2019+A1:2022
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SIST EN 13941-1:2019+A1:2022
EN 13941-1:2019+A1
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2021
EUROPÄISCHE NORM
ICS 23.040.07; 23.040.10; 91.140.10 Supersedes EN 13941-1:2019
English Version
District heating pipes - Design and installation of thermal
insulated bonded single and twin pipe systems for directly
buried hot water networks - Part 1: Design

Tuyaux de chauffage urbain - Conception et installation Fernwärmerohre - Auslegung und Installation von

des systèmes bloqués de monotubes ou bitubes isolés gedämmten Einzel- und Doppelrohr-Verbundsystemen

thermiquement pour les réseaux d'eau chaude enterrés für direkt erdverlegte Heißwasser-Fernwärmenetze -

directement - Partie 1 : Conception Teil 1: Auslegung

This European Standard was approved by CEN on 14 December 2018 and includes Amendment 1 approved by CEN on 15

October 2021.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, 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: Rue de la Science 23, B-1040 Brussels

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 13941-1:2019+A1:2021 E

worldwide for CEN national Members.
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SIST EN 13941-1:2019+A1:2022
EN 13941-1:2019+A1:2021 (E)
Contents Page

European foreword ............................................................................................................................................. 8

Introduction ........................................................................................................................................................10

1 Scope ........................................................................................................................................................11

2 Normative references ........................................................................................................................11

3 Terms and definitions, units and symbols .................................................................................12

3.1 Terms and definitions .......................................................................................................................12

3.1.1 Symbols ...................................................................................................................................................13

3.1.2 Abbreviations .......................................................................................................................................19

4 General requirements .......................................................................................................................19

4.1 Functional requirements..................................................................................................................19

4.2 Service life ..............................................................................................................................................19

4.3 Preliminary investigations ..............................................................................................................20

4.4 Determination of project class .......................................................................................................21

4.4.1 Risk assessment ...................................................................................................................................21

4.4.2 Project classes ......................................................................................................................................21

4.5 Design documentation ......................................................................................................................23

4.5.1 General ....................................................................................................................................................23

4.5.2 Operational data ..................................................................................................................................24

4.5.3 Data related to the pipe system .....................................................................................................24

4.6 Route selection and positioning of the pipes ............................................................................26

4.6.1 Minimum distances between parallel pipes ..............................................................................26

4.6.2 Parallel excavations and works of third parties ......................................................................27

4.6.3 Minimum distance between district heating pipes and underground structures ......27

4.7 Venting and draining .........................................................................................................................27

4.8 Valves.......................................................................................................................................................27

4.9 Procurement of materials ................................................................................................................28

4.9.1 Manufacturer of pipeline components ........................................................................................28

4.10 Quality control .....................................................................................................................................28

4.10.1 General ....................................................................................................................................................28

4.10.2 Design phase .........................................................................................................................................28

4.10.3 Installation phase ................................................................................................................................28

5 Requirements for components and materials ..........................................................................29

5.1 Basic requirements ............................................................................................................................29

5.2 Steel service pipe components .......................................................................................................29

5.2.1 General ....................................................................................................................................................29

5.2.2 Specification ..........................................................................................................................................30

5.2.3 Characteristic values for steel ........................................................................................................30

5.2.4 Specific requirements for bends and T-pieces .........................................................................31

5.2.5 Specific requirements for small angular deviations ..............................................................32

5.2.6 Specific requirements for reducers ..............................................................................................33

5.3 Polyurethane foam thermal insulation .......................................................................................33

5.4 Casing ......................................................................................................................................................33

5.5 Materials for casing and thermal insulation of field joints ..................................................33

5.6 Expansion cushions ............................................................................................................................33

5.6.1 General ....................................................................................................................................................33

5.6.2 Materials .................................................................................................................................................34

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5.6.3 Stiffness properties ............................................................................................................................ 34

5.6.4 Selecting required thickness of expansion cushions ............................................................. 35

5.6.5 Marking .................................................................................................................................................. 35

5.7 Valves and accessories ...................................................................................................................... 35

5.7.1 General requirements ....................................................................................................................... 35

5.7.2 Marking and documentation .......................................................................................................... 36

6 Design and calculation ...................................................................................................................... 36

6.1 General procedure ............................................................................................................................. 36

6.2 Pipeline components, areas, conditions and interfaces to be included in the

analyses .................................................................................................................................................. 37

6.2.1 Components .......................................................................................................................................... 37

6.2.2 Areas requiring specific analyses ................................................................................................. 38

6.2.3 Special conditions ............................................................................................................................... 38

6.2.4 Interfaces ............................................................................................................................................... 38

6.3 Simplified analysis procedure ....................................................................................................... 39

6.4 Actions .................................................................................................................................................... 39

6.4.1 General ................................................................................................................................................... 39

6.4.2 Classification of actions and load combinations ..................................................................... 39

6.4.3 Temperature variations ................................................................................................................... 41

6.4.4 Top load from soil............................................................................................................................... 42

6.4.5 Traffic loads .......................................................................................................................................... 42

6.5 Global analysis and pipe-soil interaction .................................................................................. 44

6.5.1 General ................................................................................................................................................... 44

6.5.2 Modelling pipe-soil interaction ..................................................................................................... 44

6.5.3 Pipe to soil friction (axial) ............................................................................................................... 46

6.5.4 Horizontal soil reaction (lateral) .................................................................................................. 48

6.5.5 Combined lateral stiffness of steel service pipe, PUR, expansion cushions and soil . 53

6.5.6 Soil properties ..................................................................................................................................... 56

6.5.7 Thermal expansion of buried pipe sections: ............................................................................ 56

6.5.8 Pipe systems with single use compensators (SUC’s) .............................................................. 58

6.5.9 Specific requirements for vertical and horizontal stability ................................................ 60

6.5.10 Parallel excavations ........................................................................................................................... 63

6.5.11 Requirements for soft soils and settlement areas .................................................................. 64

6.5.12 Specific design requirements for above-ground pipelines with factory made pipe

and fitting assemblies ....................................................................................................................... 64

6.5.13 Insertion into protection pipe........................................................................................................ 64

6.6 Determination of stresses and strains ........................................................................................ 65

6.6.1 General ................................................................................................................................................... 65

6.6.2 Cross section analyses, steel ........................................................................................................... 65

6.6.3 Assessment on the basis of a resultant (equivalent) stress ................................................ 66

6.6.4 Stresses and ovalization from top load ....................................................................................... 67

6.6.5 Deflection .............................................................................................................................................. 69

6.6.6 Bends ....................................................................................................................................................... 70

6.6.7 T-pieces .................................................................................................................................................. 71

6.6.8 Single Use Compensators (SUC’s) .................................................................................................. 73

6.6.9 PUR and casing .................................................................................................................................... 76

6.7 Fatigue analyses .................................................................................................................................. 76

6.7.1 General ................................................................................................................................................... 76

6.7.2 Action cycles ......................................................................................................................................... 76

6.8 Further actions .................................................................................................................................... 79

7 Limit states ............................................................................................................................................ 79

7.1 General ................................................................................................................................................... 79

7.2 Limit states for service pipes of steel .......................................................................................... 80

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7.2.1 General ....................................................................................................................................................80

7.2.2 Limit state A: Failure caused by plastic deformation .............................................................80

7.2.3 Limit state B: Failure caused by fatigue ......................................................................................83

7.2.4 Limit state C: Failure caused by instability of the system or part of it .............................86

7.2.5 Limit state D: Serviceability limit state .......................................................................................88

7.2.6 Survey of limit states for steel ........................................................................................................88

7.3 Limit states for PUR and PE .............................................................................................................91

7.3.1 Compressive stress .............................................................................................................................91

7.3.2 Limit state for !axial" shear stress.......................................................................................91

7.3.3 Limit state for PE .................................................................................................................................91

7.4 Limit states for valves ........................................................................................................................91

Annex A (normative) Design of piping components under internal pressure .............................93

A.1 General ....................................................................................................................................................93

A.2 Straight pipe and bends ....................................................................................................................93

A.2.1 Straight pipes ........................................................................................................................................93

A.2.2 Bends .......................................................................................................................................................93

A.3 T-pieces and branch connections ..................................................................................................94

A.3.1 General aspects and limitations ....................................................................................................94

A.3.2 Reinforcement ......................................................................................................................................94

A.3.2.1 General ....................................................................................................................................................94

A.3.2.2 Dissimilar material of shell and reinforcement .......................................................................94

A.3.2.3 Thickness ratio ....................................................................................................................................95

A.3.2.4 Calculation method for reinforcement area ..............................................................................95

A.3.2.5 Reinforcement by increased wall thickness ..............................................................................95

A.3.2.6 Reinforcement by compensating plates......................................................................................96

A.4 Reducers and extensions ..................................................................................................................97

A.5 Dished ends ...........................................................................................................................................97

A.5.1 General ....................................................................................................................................................97

A.5.2 Ellipsoidal Dished Head Minimum required wall thickness for internal pressure ....98

A.5.3 Straight cylindrical shells .................................................................................................................98

Annex B (informative) Soil properties and geotechnical parameters for pipe/soil interaction

analyses ..................................................................................................................................................99

B.1 General requirements .......................................................................................................................99

B.2 Geotechnical parameters for global analysis (pipe-soil interaction) ..............................99

B.3 Geotechnical Study .......................................................................................................................... 100

B.3.1 Field study .......................................................................................................................................... 100

B.3.2 Typical values, referred to mean value .................................................................................... 100

B.3.3 Investigation of interface friction .............................................................................................. 100

B.4 Characteristic values for soil properties ................................................................................. 100

B.4.1 Typical values, referred to mean value .................................................................................... 100

B.4.2 Spatial variation of soil properties ............................................................................................ 101

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B.5 Model uncertainty when determining geotechnical parameters................................... 102

Annex C (informative) Flexibility and stress concentration of pipe components ................... 104

C.1 General ................................................................................................................................................ 104

C.2 Flexibility factors for pipe components................................................................................... 104

C.2.1 Bends .................................................................................................................................................... 104

C.2.2 T-pieces ............................................................................................................................................... 104

C.2.3 Other components ........................................................................................................................... 105

C.3 Stress concentration in pipe elements ..................................................................................... 105

C.3.1 Butt welds ........................................................................................................................................... 105

C.3.2 Bends .................................................................................................................................................... 105

C.3.2.1 Stress concentration factors for bends: Simplified method ............................................. 105

C.3.2.2 Stress concentration factors for bends: exact calculation ................................................ 106

C.3.3 T-pieces ............................................................................................................................................... 108

C.3.3.1 General ................................................................................................................................................ 108

C.3.4 Small angular deviations .............................................................................................................. 109

C.3.5 Reducers ............................................................................................................................................. 110

Annex D (informative) Calculation of heat losses ............................................................................... 112

D.1 General ................................................................................................................................................ 112

D.2 Heat losses of thermal insulated pipes .................................................................................... 112

D.2.1 Pair of single pipes — calculation of specific heat loss ...................................................... 112

D.2.2 symmetrical and (a) antisymmetrical heat loss factors according to zero-order

multipole formulae: ........................................................................................................................ 113

D.2.3 Using Zero-order approximation for (s) symmetrical and (a) antisymmetrical

problem the heat resistance can be calculated: ................................................................... 114

D.2.4 specific heat loss of pipes .............................................................................................................. 114

D.2.5 Twin Pipes — calculation of specific heat loss ...................................................................... 115

D.2.6 temperatures of pipes .................................................................................................................... 115

D.2.7 (s) symmetrical and (a) antisymmetrical heat loss factors according to first-order

multipole formula: .......................................................................................................................... 116

D.2.8 specific heat loss of pipes .............................................................................................................. 117

Annex E (informative) Specific requirements for twin pipe systems .......................................... 118

E.1 General ................................................................................................................................................ 118

E.2 Component and materials ............................................................................................................ 118

E.2.1 Twin Pipe assembly ........................................................................................................................ 118

E.2.2 Fixing bars .......................................................................................................................................... 119

E.3 Max. allowable stresses for specific twin pipe system elements: .................................. 120

E.3.1 Project classes ................................................................................................................................... 120

E.3.2 Soil friction, twin pipe friction length and pipe expansion .............................................. 120

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E.3.3 Axial stress in the flow and return steel service pipes ....................................................... 122

E.3.4 Dimensions of the fix
...

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