EN 13941-1:2019/prA1

SLOVENSKI STANDARD
01-junij-2021
Cevi za daljinsko ogrevanje - Projektiranje in vgradnja toplotno izoliranih spojenih
eno- in dvocevnih sistemov za neposredno zakopana vročevodna omrežja - 1. del:
Projektiranje - Dopolnilo 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 Bauausführung von gedämmten Ein- und Doppelrohr-
Verbundsystemen für direkt erdverlegte 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/prA1
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
EN 13941-1:2019
NORME EUROPÉENNE
EUROPÄISCHE NORM
prA1
April 2021
ICS 23.040.07; 23.040.10; 91.140.10
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 Bauausführung von
des systèmes bloqués de monotubes ou bitubes isolés gedämmten Ein- und Doppelrohr-Verbundsystemen
thermiquement pour les réseaux d'eau chaude enterrés für direkt erdverlegte Fernwärmenetze - Teil 1:
directement - Partie 1 : Conception Auslegung
This draft amendment is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 107.

This draft amendment A1, if approved, will modify the European Standard EN 13941-1:2019. If this draft becomes an
amendment, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for
inclusion of this amendment into the relevant national standard without any alteration.

This draft amendment was established by CEN 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.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

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/prA1:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
1 Modification to Clause 2 "Normative references" . 5
2 Modifications to Table 1 of Clause 3 "Terms and definitions, units and symbols". 5
3 Modifications to Table 9 of subclause 6.4.2 "Classification of actions and load
combinations" . 6
4 Modification to subclause 6.5.5 "Combined lateral stiffness of steel service pipe,
PUR, expansion cushions and soil" . 6
5 Modifications to subclause 6.5.7 " Thermal expansion of buried pipe sections:" . 6
6 Modification to subclause 6.5.9.2.4 "Excavations over the pipes" . 6
7 Modifications to subclause 6.6.2 "Cross section analyses, steel" . 7
8 Modification to subclause 6.6.3 "Assessment on the basis of a resultant (equivalent)
stress" . 7
9 Modification to subclause 6.6.5 "Deflection" . 7
10 Modification to subclause 6.6.6 "Bends" . 7
11 Modifications to subclause 6.6.7 "T-pieces" . 7
12 Modifications to subclause 6.7.1 "Action cycles" . 7
13 Modifications to subclause 7.2.2.2 "Limit state A1: Ultimate limit state for force
controlled actions (load bearing capacity)" . 7
14 Modifications to subclause 7.2.2.3 "Limit state A2: Ultimate limit state reached by
stepwise plastic deformation caused by cyclical actions" . 9
15 Modifications to subclause 7.2.3.2 "Limit state B1:SN curves for low cycle fatigue
(repeated yielding)" . 9
16 Modifications in subclause 7.2.6 "Survey of limit states for steel" .10
17 Modifications to subclause 7.3.2 "Limit state for shear stress".15
18 Modification to Annex A, A.2.1 "Straight pipes" .15
19 Modification to Annex A, A.3.2.5 "Reinforcement by increased wall thickness" .15
20 Modifications to Annex A, A.3.2.6 "Reinforcement by compensating plates" .15
21 Modification to Annex A, A.4 "Reducers and extensions" .15
22 Modification to Annex A, A.5.2 "Ellipsoidal Dished Head Minimum required wall
thickness for internal pressure" .15
23 Modification to Annex C, C.2.1 "Bends" .16
24 Modifications to Annex C, C.3.2.1 "Stress concentration factors for bends: Simplified
method" .16
25 Modifications to Annex C, C.3.3.1 "General" .16
26 Modifications to Annex D, D.2.1 "Pair of single pipes — calculation of specific heat
loss" .16
27 Modification to Annex D, D.2.3 "Using Zero-order approximation for (s) symmetrical
and (a) antisymmetrical problem the heat resistance can be calculated:" . 17
28 Modification to Annex D, D.2.4 "Specific heat loss of pipes" . 18
29 Modification to Figures D.3 "Calculation model for the specific heat loss of twin
pipes" and D.4 "Superposition of calculation cases". 18
30 Modification to Annex D, D.2.6 "Temperatures of pipes" . 19
31 Modifications to Annex D, D.2.7 "(s) symmetrical and (a) antisymmetrical heat loss
factors according to first-order multipole formula:" . 19
32 Modifications to Annex D, D.2.8 "Specific heat loss of pipes" . 19
33 Modification to Annex E, E.3.2 "Soil friction, twin pipe friction length and pipe
expansion" . 20
34 Modifications to Annex E, E.3.3 "Axial stress in the flow and return steel service
pipes" . 20
35 Modification to Annex E, E.3.4.2 "loads on the fixing bars type A" . 20
36 Modification to Annex E, E.3.4.3 "loads on the fixing bars type B" . 20
37 Modification to Annex G, G.2 "General considerations for determination of test
values for bending moments" . 20
38 Addition to the Bibliography . 21

European foreword
This document (EN 13941-1:2019/prA1:2021) has been prepared by Technical Committee CEN/TC 107
“Prefabricated district heating and district cooling pipe system”, the secretariat of which is held by DS.
This document is currently submitted to the CEN Enquiry.
EN 13941, District heating pipes — Design and installation of thermal insulated bonded single and twin
pipe systems for directly buried hot water networks consists of the following parts:
— Part 1: Design;
— Part 2: Installation.
In comparison to EN 13941:2019, the following changes have been made:
a) minor corrections throughout the document.

1 Modification to Clause 2 "Normative references"
Delete footnote 1 "Under preparation. Stage at time of publication: prEN 17248:2018." at the entry of
"EN 17248, District heating and district cooling pipe systems - Terms and definitions".
2 Modifications to Table 1 of Clause 3 "Terms and definitions, units and
symbols"
In Table 1, these modifications are to be applied for the following symbols:
— D /D delete "or m" in the Unit column;
C i
— K add "for cohesive soil and mixed soils" at the end of column "Name";
c
— K add "for granular soil and mixed soils" at the end of column "Name";
q
— "t " is to be replaced by "T ";
s g
— Z replace the unit "m" with "mm".
c
Insert the following row between the rows of "L" and "L ": "
p
L
allowable length between the single use compensators m
all
".
Insert the following two rows between the rows of "q" and "q ": "
u
q
Flow line W/m
f
q
Return line W/m
r
".
Replace the following rows: "
σ
Design stress (allowable) MPa
d
σ
Design stress (allowable) of the compensating plate material MPa
dp
σ
Calculated hoop stress from internal (design) pressure MPa
dp
" with: "
σ Design stress ( )
R T/ γ
( ) MPa
d
e m
σ
Design stress (allowable) of the compensating plate material MPa
dp
σ
Calculated hoop stress from internal (design) pressure MPa
pd
".
And delete the following row: "
σ
Hoop stress from internal (over)pressure MPa
p
".
3 Modifications to Table 9 of subclause 6.4.2 "Classification of actions and load
combinations"
In Table 9, replace "safety" with "load" changing the title to read "Classification of actions, partial load
factor and Load Combinations (LC)" and the first heading to "PARTIAL LOAD FACTORS γ ".
a
Delete the term "(Max foam compression)" in the cell for operational phase LC 3 "Force controlled and
deformation controlled actions"
Replace the load factor "Operating pressure" from LC 2, LC 3 and LC 4 "1,2" with "1,25".
4 Modification to subclause 6.5.5 "Combined lateral stiffness of steel service
pipe, PUR, expansion cushions and soil"
To change " D " in Formula (20b) to " D " replace the formula with
0 c
" kk⋅ D (20b)"
2 h2, c
and insert "for D " at Formula (21b) in front of "see Figure 13" resulting in
cu
" kk⋅ D for D see Figure 13 (21b)".
cu
3 h,3 cu
5 Modifications to subclause 6.5.7 " Thermal expansion of buried pipe sections:"
In the last line of the key to Figure 16 "Partly and fully restrained pipe sections" replace "NR" with "N "
R .
Replace the undefined "N " in Formula (24) with "N " changing it from
r R
σ σ
p p
" N=NN+ =A⋅ + N " to " N=NN+ =A⋅+ N ".
x pr R x pR R
2 2
In the paragraph above Formula (27) and the one which follows, increment the numbering of "Figure 16"
and "Figure 15" by one to read as:
"For systems as Figure 17 where fixed points or other methods ensure that the distance l from the fixed
point to an expansion facility is shorter than or equal to the friction length L, or where the distance
between two expansion facilities is less than 2L, the axial stresses in the steel service pipe are calculated
as:

N
F 1
R
σσ=−−l − (27)
xp

A 2 A

Expansion at the free pipe end from the partly restrained pipe (see Figure 16) is calculated as:".
6 Modification to subclause 6.5.9.2.4 "Excavations over the pipes"
π ⋅ EI≤⋅
To replace the "≤" sign from Formula (44) with "·"replace theformula " L= " with "
γγ⋅⋅ N
aM
π ⋅ EI⋅
".
L=
γγ⋅⋅ N
aM
=
=
7 Modifications to subclause 6.6.2 "Cross section analyses, steel"
Replace "Figure 20" with "Figure 21" in the sentence "Stresses and internal forces are illustrated in
Figure 20." resulting in "Stresses and internal forces are illustrated in Figure 21.".
Replace “t-pieces” with “T-pieces” in the sentence after Formula (46), so that it reads “For T-pieces the
outside diameters d and d and the thickness t and t for run pipe and branch, respectively, are
ro bo r b
inserted.”.
Delete "normally" in the following note:
"NOTE The effect of vertical top load from soil pressure and traffic actions can normally be ignored for
pipe dimensions DN ≤ 300.".
8 Modification to subclause 6.6.3 "Assessment on the basis of a resultant
(equivalent) stress"
From the two sentences above Formula (47), delete the last one, thus replace
"The equivalent stress can be calculated both with the minimum distortion energy hypothesis (by von
Mises´ equation), or with the shear-stress hypothesis (by Tresca equation):
The equivalent stress is calculated from the axial and tangential stress components (calculated with sign)
by Tresca or by von Mises’ equation:" with
"The equivalent stress can be calculated both with the minimum distortion energy hypothesis (by von
Mises´ equation), or with the shear-stress hypothesis (by Tresca eq
...