SIST EN 253:2020
(Main)District heating pipes - Bonded single pipe systems for directly buried hot water networks - Factory made pipe assembly of steel service pipe, polyurethane thermal insulation and a casing of polyethylene
District heating pipes - Bonded single pipe systems for directly buried hot water networks - Factory made pipe assembly of steel service pipe, polyurethane thermal insulation and a casing of polyethylene
This European Standard specifies requirements and test methods for straight lengths of factory made thermally insulated bonded single pipe assemblies for hot water networks in accordance with prEN 13941-1:2016, comprising a steel service pipe, rigid polyurethane foam insulation and a casing of polyethylene.
The pipe assembly may also include the following additional elements: measuring wires, spacers and diffusion barriers.
Fernwärmerohre - Werkmäßig gedämmte Verbundmantelrohrsysteme für direkt erdverlegte Fernwärmenetze - Verbund-Rohrsystem bestehend aus Stahl-Mediumrohr, Polyurethan-Wärmedämmung und Außenmantel aus Polyethylen
Diese Europäische Norm legt Anforderungen und Prüfverfahren fest für gerade Abschnitte von werkmäßig gedämmten Einrohrsystemen für Fernwärmenetzwerke in Übereinstimmung mit prEN 13941 1:2016, die aus einem Stahlmediumrohr, einer Polyurethan-Hartschaumstoffdämmung und einem Polyethylenmantel bestehen.
Das Verbund-Rohrsystem darf darüber hinaus folgende Bauteile umfassen: Messdrähte, Abstandshalter und Diffusionsbarrieren.
Tuyaux de chauffage urbain - Systèmes bloqués de tuyaux pour les réseaux d'eau chaude enterrées directement - Assemblages de tubes de service en acier manufacturés, isolation thermique en polyuréthane et tube de protection en polyéthylène
La présente Norme européenne spécifie les exigences et les méthodes d’essai applicables aux longueurs droites des assemblages de tubes bloqués manufacturés isolés thermiquement pour les réseaux d'eau chaude conformes au prEN 13941-1, comprenant un tube de service en acier, une isolation en mousse rigide de polyuréthane et un tube de protection en polyéthylène.
L’assemblage de raccord peut également comprendre les éléments supplémentaires suivants : câbles de mesure, entretoises et barrières anti-diffusion.
Cevi za daljinsko ogrevanje - Poviti enocevni sistemi za neposredno vkopana vročevodna omrežja - Tovarniško izdelan cevni sestav iz jeklene delovne cevi, obdane s poliuretansko toplotno izolacijo in zaščitnim plaščem iz polietilena
Ta evropski standard določa zahteve in preskusne metode za ravne odseke tovarniško izdelanih toplotno izoliranih enocevnih sestavov za vročevodna omrežja v skladu s standardom prEN 13941-1:2016, ki so sestavljeni iz jeklenih cevi, trde poliuretanske izolacijske pene in polietilenskega plašča. Cevni sestav lahko vključuje tudi naslednje dodatne elemente: merilne žice, distančnike in difuzijske pregrade.
General Information
RELATIONS
Standards Content (sample)
SLOVENSKI STANDARD
SIST EN 253:2020
01-januar-2020
Nadomešča:
SIST EN 253:2009+A2:2015
Cevi za daljinsko ogrevanje - Poviti enocevni sistemi za neposredno vkopana
vročevodna omrežja - Tovarniško izdelan cevni sestav iz jeklene delovne cevi,
obdane s poliuretansko toplotno izolacijo in zaščitnim plaščem iz polietilena
District heating pipes - Bonded single pipe systems for directly buried hot water networks
- Factory made pipe assembly of steel service pipe, polyurethane thermal insulation and
a casing of polyethyleneFernwärmerohre - Werkmäßig gedämmte Verbundmantelrohrsysteme für direkt
erdverlegte Fernwärmenetze - Verbund-Rohrsystem bestehend aus Stahl-Mediumrohr,
Polyurethan-Wärmedämmung und Außenmantel aus Polyethylen
Tuyaux de chauffage urbain - Systèmes bloqués de tuyaux pour les réseaux d'eau
chaude enterrées directement - Assemblages de tubes de service en acier
manufacturés, isolation thermique en polyuréthane et tube de protection en polyéthylène
Ta slovenski standard je istoveten z: EN 253:2019ICS:
23.040.07 Cevovodi za daljinsko Pipeline and its parts for
ogrevanje in njihovi deli district heat
23.040.10 Železne in jeklene cevi Iron and steel pipes
91.140.65 Oprema za ogrevanje vode Water heating equipment
SIST EN 253:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 253:2020
EN 253
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2019
EUROPÄISCHE NORM
ICS 23.040.07; 23.040.10 Supersedes EN 253:2009+A2:2015
English Version
District heating pipes - Bonded single pipe systems for
directly buried hot water networks - Factory made pipe
assembly of steel service pipe, polyurethane thermal
insulation and a casing of polyethylene
Tuyaux de chauffage urbain - Systèmes bloqués de Fernwärmerohre - Werkmäßig gedämmte
tuyaux pour les réseaux d'eau chaude enterrées Verbundmantelrohrsysteme für direkt erdverlegte
directement - Assemblages de tubes de service en acier Fernwärmenetze - Verbund-Rohrsystem bestehend
manufacturés, isolation thermique en polyuréthane et aus Stahl-Mediumrohr, Polyurethan-Wärmedämmung
tube de protection en polyéthylène und Außenmantel aus PolyethylenThis European Standard was approved by CEN on 26 August 2019.
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
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 253:2019 E
worldwide for CEN national Members.---------------------- Page: 3 ----------------------
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EN 253:2019 (E)
Contents Page
European foreword ................................................................................................................................................................ 3
Introduction ............................................................................................................................................................................. 4
1 Scope ............................................................................................................................................................................. 5
2 Normative references ............................................................................................................................................. 5
3 Terms and definitions ............................................................................................................................................ 6
4 Requirements ............................................................................................................................................................ 6
5 Test methods .......................................................................................................................................................... 16
6 Marking ..................................................................................................................................................................... 26
Annex A (informative) Relation between actual continuous operating conditions and
accelerated ageing test conditions.................................................................................................................. 28
Annex B (informative) Guidelines for inspection and testing .............................................................................. 32
Annex C (normative) Thermal conductivity of factory made pipe assemblies — Test procedure ........ 36
Annex D (informative) Waste treatment and recycling ......................................................................................... 41
Bibliography .......................................................................................................................................................................... 42
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EN 253:2019 (E)
European foreword
This document (EN 253:2019) has been prepared by Technical Committee CEN/TC 107 “Prefabricated
district heating and district cooling pipe systems”, the secretariat of which is held by DS.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by April 2020, and conflicting national standards shall be withdrawn at
the latest by April 2020.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 EN 253:2009+A2:2015.In comparison with the previous edition, the main changes in this new edition of EN 253 are:
— editorial changes to the new structure of standards prepared by the Technical Committee CEN/TC 107;
— specification of steel grade moved into EN 13941-1;— added thermal insulation series;
— added linear water tightness: requirements and test method;
— revised description of expected thermal life and long term temperature resistance in balance with
EN 13941-1;— revised description on shear strength: requirements and test method;
— removed Tangential shear strength and long-term creep resistance and modulus;
— revised Annex A, “Relation between actual continuous operating condition and accelerated ageing test
conditions”;— removed Annex C, “Calculated Continuous Operating Temperature (CCOT)”.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the following
countries are bound to implement this European Standard: 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 the United Kingdom.
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EN 253:2019 (E)
Introduction
This specification is part of the standards for bonded pipe systems for district heating using polyurethane
(PUR) foam thermal insulation applied to bond to a steel service pipe and a polyethylene (PE) casing.
The other standards from CEN/TC 107 covering this subject are:— EN 448, District heating pipes – Bonded single pipe systems for directly buried hot water networks –
Factory made fitting assemblies of steel service pipes, polyurethane thermal insulation and a casing of
polyethylene;— EN 488, District heating pipes – Bonded single pipe systems for directly buried hot water networks –
Factory made steel valve assembly for steel service pipes, polyurethane thermal insulation and a casing of
polyethylene;— EN 489-1, District heating pipes – Bonded single and twin pipe systems for directly buried hot water
networks – Part 1: Joint casing assemblies and thermal insulation for hot water networks in accordance
with EN 13941-1;— EN 13941-1, District heating pipes – Design and installation of thermal insulated bonded single and twin
pipe systems for directly buried hot water networks – Part 1: Design;— EN 13941-2, District heating pipes – Design and installation of thermal insulated bonded single and twin
pipe systems for directly buried hot water networks – Part 2: Installation;— EN 14419, District heating pipes – Bonded single and twin pipe systems for directly buried hot water
networks – Surveillance systems;— EN 15698-1, District heating pipes – Bonded twin pipe systems for directly buried hot water networks –
Part 1: Factory made twin pipe assembly of steel service pipes, polyurethane thermal insulation and one
casing of polyethylene;— EN 15698-2, District heating pipes – Bonded twin pipe systems for directly buried hot water networks –
Part 2: Factory made fitting and valve assemblies of steel service pipes, polyurethane thermal insulation
and one casing of polyethylene;— EN 17248, District heating and district cooling pipe systems – Terms and definitions.
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EN 253:2019 (E)
1 Scope
This document specifies requirements and test methods for straight lengths of factory made thermally
insulated bonded single pipe assemblies for hot water networks in accordance with EN 13941-1, comprising
a steel service pipe, polyurethane foam thermal insulation and a casing of polyethylene.
The pipe assembly can also include the following additional elements: measuring wires, spacers and
diffusion barriers.2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN 10204, Metallic products — Types of inspection documentsEN 10216-2, Seamless steel tubes for pressure purposes — Technical delivery conditions — Part 2: Non-alloy
and alloy steel tubes with specified elevated temperature propertiesEN 10217-2, Welded steel tubes for pressure purposes — Technical delivery conditions — Part 2: Electric
welded non-alloy and alloy steel tubes with specified elevated temperature properties
EN 10217-5, Welded steel tubes for pressure purposes — Technical delivery conditions — Part 5: Submerged
arc welded non-alloy and alloy steel tubes with specified elevated temperature properties
EN 10220, Seamless and welded steel tubes — Dimensions and masses per unit length
EN 13941-1, District heating pipes — Design and installation of thermal insulated bonded single and twin pipe
systems for directly buried hot water networks — Part 1: DesignEN 14419, District heating pipes — Preinsulated bonded pipe systems for directly buried hot water networks —
Surveillance systemsEN 17248, District heating and district cooling pipe systems — Terms and definitions
EN ISO 845, Cellular plastics and rubbers — Determination of apparent density (ISO 845)
EN ISO 1133 (all parts), Plastics — Determination of the melt mass-flow rate (MFR) and melt volume-flow rate
(MVR) of thermoplastic (ISO 1133 series)EN ISO 2505, Thermoplastics pipes — Longitudinal reversion — Test method and parameters (ISO 2505)
EN ISO 3126, Plastics piping systems — Plastics components — Determination of dimensions (ISO 3126)
EN ISO 4590, Rigid cellular plastics — Determination of the volume percentage of open cells and of closed cells
(ISO 4590)EN ISO 6259-1, Thermoplastics pipes — Determination of tensile properties — Part 1: General test method (ISO
6259-1)EN ISO 8497:1996, Thermal insulation — Determination of steady-state thermal transmission properties of
thermal insulation for circular pipes (ISO 8497:1994)---------------------- Page: 7 ----------------------
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EN ISO 8501-1, Preparation of steel substrates before application of paints and related products — Visual
assessment of surface cleanliness — Part 1: Rust grades and preparation grades of uncoated steel substrates
and of steel substrates after overall removal of previous coatings (ISO 8501-1)EN ISO 3127:2017, Thermoplastics pipes — Determination of resistance to external blows — Round-the-clock
method (ISO 3127:1994)EN ISO 9080, Plastics piping and ducting systems — Determination of the long-term hydrostatic strength of
thermoplastics materials in pipe form by extrapolation (ISO 9080)EN ISO 11357-6, Plastics — Differential scanning calorimetry (DSC) — Part 6: Determination of oxidation
induction time (isothermal OIT) and oxidation induction temperature (dynamic OIT) (ISO 11357-6)
EN ISO 12162, Thermoplastics materials for pipes and fittings for pressure applications — Classification,
designation and design coefficient (ISO 12162)EN ISO 844, Rigid cellular plastics — Determination of compression properties
ISO 6761, Steel tubes — Preparation of ends of tubes and fittings for welding
ISO 6964, Polyolefin pipes and fittings — Determination of carbon black content by calcination and pyrolysis —
Test methodISO 11414:2009, Plastics pipes and fittings — Preparation of polyethylene (PE) pipe/pipe or pipe/fitting test
piece assemblies by butt fusionISO 13953, Polyethylene (PE) pipes and fittings — Determination of the tensile strength and failure mode of
test pieces from a butt-fused jointISO 16770, Plastics — Determination of environmental stress cracking (ESC) of polyethylene — Full notch
creep test (FNCT)ISO 18553, Method for the assessment of the degree of pigment or carbon black dispersion in polyolefin pipes,
fittings and compounds3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 17248 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/• ISO Online browsing platform: available at https://www.iso.org/obp
4 Requirements
4.1 General
Unless otherwise specified, the requirements shall be valid for each single measurement.
For information on suitable guidelines for inspection, see Annex B.---------------------- Page: 8 ----------------------
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4.2 Steel service pipe
4.2.1 Specification
Steel grades are specified in EN 13941-1.
All steel pipes and components used for manufacturing of pipe assemblies under the scope of this document
shall as a minimum be delivered to the manufacturer with an inspection certificate 3.1 according to
EN 10204. The inspection certificate shall on request be passed on to the customer.
In case a material related inspection certificate 3.1 according to EN 10204 is required by the client who
orders the pipe assemblies, this request shall be given whilst placing the order with the manufacturer of the
pipe assemblies.NOTE Any later request for provision of such documentation could be too late and possibly can't be met by the
manufacturer, since the manufacturer has to organize the assignment of 3.1 certificates to the steel service pipes before
starting the production.A length of pipe shall not include a circular weld.
4.2.2 Diameter
The diameter shall be in accordance with Table 1 which is derived from EN 10220.
The tolerances on the outside diameter, d , of the steel service pipe at the pipe ends, shall be in accordance
with EN 10216-2, EN 10217-2 or EN 10217-5. Diameter measurements shall be made using a
circumferential tape. The diameter shall be calculated as the actual circumference divided by π. Outside
diameter, d , 168,3 and smaller may be measured using a slide calliper.The out-of-roundness shall be determined in accordance with EN 10216-2, EN 10217-2 or EN 10217-5.
4.2.3 Wall thicknessThe wall thicknesses, t, and masses shall be in accordance with EN 10220 with a minimum as indicated in
Table 1. The tolerances on the wall thickness of the steel service pipe, shall be in accordance with
EN 10216-2, EN 10217-2 or EN 10217-5.---------------------- Page: 9 ----------------------
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Table 1 — Steel service pipe dimensions
Nominal diameter Outside diameter Wall thickness
DN d t
mm
15 21,3 2,0
20 26,9 2,0
25 33,7 2,3
32 42,4 2,6
40 48,3 2,6
50 60,3 2,9
65 76,1 2,9
80 88,9 3,2
100 114,3 3,6
125 139,7 3,6
150 168,3 4,0
200 219,1 4,5
250 273,0 5,0
300 323,9 5,6
350 355,6 5,6
400 406,4 6,3
450 457,0 6,3
500 508,0 6,3
600 610,0 7,1
700 711,0 8,0
800 813,0 8,8
900 914,0 10,0
1 000 1 016,0 11,0
1 200 1 219,0 12,5
4.2.4 Surface condition
In order to ensure proper bonding between the steel service pipe and the thermal insulation, the following
procedure shall be followed:Prior to thermal insulation, the outer surface of the pipe shall be cleaned so that it is free from rust, mill
scale, oil, grease, dust, paint, moisture and other contaminants.Before cleaning the steel service pipe, the outer surface shall comply with rust grade A, B or C according to
EN ISO 8501-1, without pitting.---------------------- Page: 10 ----------------------
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4.3 Casing
4.3.1 Material properties
4.3.1.1 Material composition
The casing material shall be black coloured PE virgin or rework material containing only those anti-oxidants,
UV-stabilizers and carbon black necessary for the manufacture and use of pipe assemblies to this
specification. The black coloured PE material to be extruded shall be tested in accordance with EN ISO 9080
and classified at least a PE 80 material in accordance with EN ISO 12162.The casing may be a separately manufactured pipe or be applied directly onto the PUR thermal insulation by
extrusion.The carbon black content shall, when tested in accordance with ISO 6964, be (2,5 ± 0,5) % by mass.
The carbon black shall be finely dispersed in the material. When tested in accordance with 5.2.3, the
following requirements shall be met:— Carbon black agglomerates and particles shall be grade ≤ 3.
— Dispersion rating shall be A1, A2 or A3 according to ISO 18553.
NOTE The required carbon black content ensures UV stability for the service life.
4.3.1.2 Melt mass-flow rateThe melt mass-flow rate (MFR), in g/10 min, of black PE materials used for the manufacturing of casings
shall lie within 0,2 < MFR ≤ 1,0 g/10 min determined in accordance with EN ISO 1133 (all parts), condition
5 kg, 190 °C.Black coloured PE materials conforming to 4.3.1.1, which do not differ more than 0,5 g/10 min in MFR shall
be considered fusible to each other.Casings made of PE materials outside this MFR range of 0,5 g/10 min may be fusion welded provided that
the manufacturer of the pipe assembly has demonstrated fusion compatibility by preparing a butt fusion
joint using the parameters as specified in Annex A of ISO 11414:2009. The requirement of fusion
compatibility is a ductile failure mode of the joint when tested at 23 °C in accordance with ISO 13953.
4.3.1.3 Thermal stabilityThe thermal stability is determined by oxygen induction time (OIT) of the black coloured PE material and
shall be at least 20 min when tested at 210 °C according to EN ISO 11357-6.4.3.1.4 Use of rework material
Only clean, not degraded, rework material, generated from the manufacturer's own production, shall be
used.4.3.2 Casing properties
4.3.2.1 Nominal outside diameter
The nominal outside diameter of the casing should be selected from Table 2.
The actual outside diameter shall be measured in accordance with EN ISO 3126.
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4.3.2.2 Wall thickness
If the casing includes a diffusion barrier the wall thickness of one single PE layer of the casing shall be in
accordance with Table 2.The actual wall thickness shall be measured in accordance with EN ISO 3126.
Table 2 — Casing dimensions
Nominal outside Minimum wall
diameter thickness
D e
c min
mm mm
90 3,0
110 3,0
125 3,0
140 3,0
160 3,0
180 3,0
200 3,2
225 3,4
250 3,6
280 3,9
315 4,1
355 4,5
400 4,8
450 5,2
500 5,6
560 6,0
630 6,6
710 7,2
800 7,9
900 8,7
1 000 9,4
1 100 10,2
1 200 11,0
1 400 12,5
4.3.2.3 Appearance, surface finish, casing ends
The internal and external surfaces of the casing shall be clean and free from such grooving or other defects
that might impair its functional properties (see 5.2.1).---------------------- Page: 12 ----------------------
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The casing ends shall be cleanly cut and shall be square within 2,5° with the axis of the pipe.
Surface treatment to improve the shear strength between the PUR foam and casing is permissible provided
that the treated pipe assembly still complies with the specification.4.3.2.4 Elongation at break
The elongation at break determined in accordance with 5.2.2 shall not be less than 350 %.
4.3.2.5 Heat reversionWhen tested in accordance with EN ISO 2505, the longitudinal length at any position on the casing shall not
change by more than 3 %. On inspection after testing, the casing shall not show any faults, cracks, cavities or
blisters.4.3.2.6 Stress crack resistance
When tested in accordance with 5.2.4, the time to failure shall not be less than 300 h.
4.4 Polyurethane (PUR) foam thermal insulation4.4.1 Composition
The manufacturer of the pipe assembly shall be responsible for the choice of raw materials, composition and
manufacturing conditions.The manufacturer shall keep records, documenting the raw materials used, the prescribed mixing ratio and
the tests performed.The records shall demonstrate that the PUR foam from production of pipe assemblies is of the same
composition as the foam sample used for the ageing test in 5.4.2 and meets the requirements of 4.4.
4.4.2 Cell structure4.4.2.1 General appearance
The PUR foam shall have a uniform cell structure free from smears.
4.4.2.2 Cell size
The average cell size of the cells in a radial direction shall be less than 0,5 mm, determined in accordance
with 5.3.2.1.4.4.2.3 Closed cell content
The closed cell content determined in accordance with 5.3.2.2 shall be not less than 88 %.
4.4.2.4 Voids and bubblesThe average area of voids and bubbles determined on the five cross sections in accordance with 5.3.2.3 shall
not constitute more than 5 % of the cross sectional area of the PUR foam. No single void shall be larger than
2/3 of the insulation thickness between the steel service pipe and the casing at the position of the void.
4.4.3 Compressive strengthThe compressive strength or the compressive stress at 10 % relative deformation as defined in EN ISO 844
shall be not less than 0,3 MPa in a radial direction when tested in accordance with 5.3.3.
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4.4.4 Foam density
The density of the foam at any position shall comply with the criteria below when calculated in accordance
with 5.3.4.At both pipe ends, all three specimens shall each have a density of minimum 55 kg/m .
4.4.5 Water absorption at elevated temperatureWhen tested in accordance with 5.3.5, the water absorption after 90 min of immersion in boiling water shall
not exceed 10 % of the original volume. The volume of each specimen after the test shall not be less than
75 % of the original volume.4.5 Pipe assembly
4.5.1 General
All requirements are valid including the diffusion barrier, if any.
4.5.2 Thermal insulation series
For thermal insulation series, Table 3 gives the allocation of the nominal diameter of service pipes and
casing diameters.Table 3 — Thermal insulation series
Nominal diameter of Casing diameter, Casing diameter, Casing diameter,
service pipes thermal insulation thermal insulation thermal insulation
series 1 series 2 series 3
a b b b
DN D D D
C C C
mm mm mm
20 90 110 125
25 90 110 125
32 110 125 140
40 110 125 140
50 125 140 160
65 140 160 180
80 160 180 200
100 200 225 250
125 225 250 280
150 250 280 315
200 315 355 400
250 400 450 500
300 450 500 560
350 500 560 630
400 560 630 710
450 630 710 800
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Nominal diameter of Casing diameter, Casing diameter, Casing diameter,
service pipes thermal insulation thermal insulation thermal insulation
series 1 series 2 series 3
a b b b
DN D D D
C C C
mm mm mm
500 710 800 900
600 800 900 1 000
700 900 1 000 1 100
800 1 000 1 100 1 200
900 1 100 1 200
1 000 1 200
1 200 1 400
Dimensions, see Table 1
Dimensions, see Table 2
4.5.3 Pipe ends without thermal insulation
Both ends of the service pipe shall be free from thermal insulation. The manufacturer shall declare a value
for the length of this free ends between 150 mm and 250 mm. The tolerance on the declared value within
this range shall be ± 10 mm.Service pipe ends shall be prepared for welding in accordance with ISO 6761.
4.5.4 Diameter and wall thickness of the casing
The outside diameter of the casing shall at any point be between the minimum diameter D and the
minmaximum diameter D as given in Table 4. The minimum wall thickness of the casing, e , shall at any
max minpoint be in accordance with Table 4. The measured values for the outside diameter and wall thickness shall
be rounded off to the next higher 0,1 mm.---------------------- Page: 15 ----------------------
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Table 4 — Casing dimensions of the pipe assembly
Nominal Minimum Maximum Minimum wall
outside outside outside thickness
diameter diameter diameter
min
D D D
c min max
mm mm mm
90 90 95 3,0
110 110 116 3,0
125 125 132 3,0
140 140 147 3,0
160 160 168 3,0
180 180 189 3,0
200 200 206 3,2
225 225 232 3,4
250 250 258 3,6
280 280 289 3,9
315 315 325 4,1
355 355 366 4,5
400 400 412 4,8
450 450 464 5,2
500 500 515 5,6
560 560 577 6,0
630 630 649 6,6
710 710 732 7,2
800 800 824 7,9
900 900 927 8,7
1 000 1 000 1 030 9,4
1 100 1 100 1 133 10,2
1 200 1 200 1 236 11,0
1 400 1 400 1 442 12,5
4.5.5 Centre line deviation
The distance between the centre lines of the steel service pipe and the casing at any point shall not exceed
the limits given in Table 5.---------------------- Page: 16 ----------------------
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Table 5 — Centre line deviation related to the nominal diameters
Nominal outside diameter of casings Maximum centre line deviation
mm mm
90 to 160 3,0
180 to 400 5,0
450 to 630 8,0
710 to 800 10,0
900 to 1 400 14,0
4.5.6 Expected thermal life and long term temperature resistance
4.5.6.1 General remarks
The decline in shear strength over time is a combination of thermal stresses and oxidative processes.
Annex A describes the state of the art knowledge on this subject.According to EN 13941-1, pipe systems for district heating shall be designed for a service life of minimum
30 years for continuous operation with hot water at various temperatures up to 120 °C and at individual
time intervals with a peak temperature up to 140 °C. The sum of these individual time intervals shall, in
average, not exceed 300 h a year.The estimation of service life at continuous operating temperatures lower than 120 °C requires assumptions
about the Arrhenius activation energy (E ), see Annex A. A service life of at least 50 years is generally
obtained at a continuous operating temperature lower than 115°C.The estimation of service life at continuous operating temperatures higher than 120 °C is outside the scope
of EN 253.4.5.6.2 Shear strength
The shear strength shall fulfil the minimum requirements of Table 6 in both unaged and aged condition.
The shear strength shall be tested in axial direction in unaged condition shall be tested in axial direction in
accordance with 5.4.1. The shear strength in aged condition shall be tested in accordance with 5.4.2.
Table 6 — Shear strengthTest temperature Test clause τ
min.
MPa
unaged aged
45 % of
(real) initial
23 ± 2 5.4.1.4 0,12
value and
0,12
140 ± 2 5.4.1.5 0,08 0,08
At the test temperature of (23 ± 2) °C, the shear strength in aged condition shall be minimum 45 % of the
shear strength in unaged condition. The shear strength shall be reported together with the foam density.
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