EN 253:2019+A1:2023
(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 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.
Fernwärmerohre - Einzelrohr-Verbundsysteme für direkt erdverlegte Fernwärmenetze - Werkmäßig gefertigte Verbundrohrsysteme, bestehend aus Stahl-Mediumrohr, einer Wärmedämmung aus Polyurethan und einer Ummantelung aus Polyethylen
Dieses Dokument legt die Anforderungen und Prüfverfahren fest für gerade Abschnitte von werkmäßig gedämmten Einzelrohrsystemen für Fernwärmenetzwerke in Übereinstimmung mit EN 13941-1, die aus einem Stahl-Mediumrohr, einer Polyurethan-Schaumstoffwärmedämmung und einem Polyethylenmantel bestehen.
Das Verbundrohrsystem kann darüber hinaus die folgenden zusätzlichen Bauteile umfassen: Messdrähte, Abstandhalter 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
Le présent document 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 à l’EN 13941-1, comprenant un tube de service en acier, une isolation thermique en mousse 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 (vključno z dopolnilom A1)
Ta dokument določa zahteve in preskusne metode za ravne odseke tovarniško izdelanih toplotno izoliranih enocevnih sestavov za vročevodna omrežja v skladu s standardom EN 13941-1, ki so sestavljeni iz jeklene delovne cevi, poliuretanske pene za toplotno izolacijo 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
01-maj-2024
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
(vključno z dopolnilom A1)
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
Fernwärmerohre - Einzelrohr-Verbundsysteme für direkt erdverlegte Fernwärmenetze -
Werkmäßig gefertigte Verbundrohrsysteme, bestehend aus Stahl-Mediumrohr, einer
Wärmedämmung aus Polyurethan und einer Ummantelung 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 253:2019+A1:2023
ICS:
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN 253:2019+A1
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2023
EUROPÄISCHE NORM
ICS 23.040.07; 23.040.10 Supersedes EN 253:2019
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 - Einzelrohr-Verbundsysteme für
tuyaux pour les réseaux d'eau chaude enterrées direkt erdverlegte Fernwärmenetze - Werkmäßig
directement - Assemblages de tubes de service en acier gefertigte Verbundrohrsysteme, bestehend aus Stahl-
manufacturés, isolation thermique en polyuréthane et Mediumrohr, einer Wärmedämmung aus Polyurethan
tube de protection en polyéthylène und einer Ummantelung aus Polyethylen
This European Standard was approved by CEN on 26 August 2019 and includes Amendment approved by CEN on 1 October
2023.
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, Türkiye 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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 253:2019+A1:2023 E
worldwide for CEN national Members.
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Requirements . 7
4.1 General . 7
4.2 Steel service pipe . 8
4.2.1 Specification . 8
4.2.2 Diameter . 8
4.2.3 Wall thickness . 8
4.2.4 Surface condition . 9
4.2.5 !Pipe ends . 9
4.3 Casing. 10
4.3.1 Material properties . 10
4.3.2 Casing properties . 10
4.4 Polyurethane (PUR) foam thermal insulation . 12
4.4.1 Composition . 12
4.4.2 Cell structure . 12
4.4.3 Compressive strength . 12
4.4.4 Foam density . 13
4.4.5 Water absorption at elevated temperature . 13
4.5 Pipe assembly . 13
4.5.1 General . 13
4.5.2 Thermal insulation series . 13
4.5.3 Pipe ends without thermal insulation . 14
4.5.4 Diameter and wall thickness of the casing . 14
4.5.5 Centre line deviation . 15
4.5.6 Expected thermal life and long term temperature resistance . 15
4.5.7 Thermal conductivity in unaged condition. 16
4.5.8 Thermal conductivity at artificially aged condition . 16
4.5.9 Impact resistance . 16
4.5.10 Surface conditions at delivery . 16
4.5.11 Measuring wires for surveillance systems . 17
4.5.12 Linear water tightness . 17
5 Test methods . 17
5.1 General conditions and test specimens . 17
5.1.1 General conditions . 17
5.1.2 Test specimens . 17
5.2 Casing. 18
5.2.1 Appearance and surface finish . 18
5.2.2 Elongation at break . 18
5.2.3 Carbon black dispersion, homogeneity . 19
5.2.4 Stress crack resistance test . 19
5.3 Polyurethane (PUR) foam thermal insulation . 20
5.3.1 Composition . 20
5.3.2 Cell structure . 20
5.3.3 Compressive strength . 21
5.3.4 Foam density . 21
5.3.5 Water absorption . 21
5.4 Pipe assembly . 22
5.4.1 Axial shear strength . 22
5.4.2 Shear strength of the pipe assembly after ageing . 24
5.4.3 Thermal conductivity in unaged condition . 24
5.4.4 Thermal conductivity at artificially aged condition . 25
5.4.5 Impact resistance. 25
5.4.6 Linear water tightness . 25
6 Marking . 27
6.1 General . 27
6.2 Steel service pipe . 28
6.3 Casing . 28
6.4 Pipe assembly . 28
Annex A (informative) Relation between actual continuous operating conditions and
accelerated ageing test conditions . 29
Annex B (informative) Guidelines for inspection and testing . 33
Annex C (normative) Thermal conductivity of factory made pipe assemblies — Test procedure . 38
Annex D (informative) Waste treatment and recycling . 43
Bibliography . 44
European foreword
This document (EN 253:2019+A1:2023) 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 June 2024, and conflicting national standards shall be
withdrawn at the latest by June 2024.
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 253:2019".
This document includes Amendment 1 approved by CEN on 01 October 2023.
The start and finish of text introduced or altered by amendment is indicated in the text by tags !".
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)”.
Any feedback and questions on this document should be directed to the users’ national standards body. A
complete listing of these bodies can be found on the CEN website.
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, Türkiye and the United Kingdom.
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.
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 documents
EN 10216-2, Seamless steel tubes for pressure purposes — Technical delivery conditions — Part 2: Non-alloy
and alloy steel tubes with specified elevated temperature properties
EN 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: Design
EN 14419, District heating pipes - Bonded single and twin pipe systems for buried hot water networks -
Surveillance systems
EN 17248, District heating and district cooling pipe systems - Terms and definitions
EN ISO 845, Cellular plastics and rubbers - Determination of apparent density (ISO 845:2006)
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 1923, Cellular plastics and rubbers - Determination of linear dimensions (ISO 1923:1981)"
EN ISO 2505, Thermoplastics pipes - Longitudinal reversion - Test method and parameters (ISO 2505:2005)
EN ISO 3126, Plastics piping systems - Plastics components - Determination of dimensions (ISO 3126:2005)
EN ISO 4590, Rigid cellular plastics - Determination of the volume percentage of open cells and of closed cells
(ISO 4590:2016)
EN ISO 6259-1, Thermoplastics pipes - Determination of tensile properties - Part 1: General test method (ISO
6259-1:2015)
EN ISO 8497:1996, Thermal insulation - Determination of steady-state thermal transmission properties of
thermal insulation for circular pipes (ISO 8497:1994)
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 8501-1:2007)
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 9080:2012)
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 11357-6:2018)
EN ISO 12162, Thermoplastics materials for pipes and fittings for pressure applications - Classification,
designation and design coefficient (ISO 12162:2009)
EN ISO 844, Rigid cellular plastics - Determination of compression properties (ISO 844:2021)
!Deleted tex"t"
ISO 6964, Polyolefin pipes and fittings — Determination of carbon black content by calcination and pyrolysis —
Test method
ISO 11414:2009, Plastics pipes and fittings — Preparation of polyethylene (PE) pipe/pipe or pipe/fitting test
piece assemblies by butt fusion
ISO 13953, Polyethylene (PE) pipes and fittings — Determination of the tensile strength and failure mode of
test pieces from a butt-fused joint
ISO 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 compounds
3 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 https://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.
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
o
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.
o
The out-of-roundness shall be determined in accordance with EN 10216-2, EN 10217-2 or EN 10217-5.
4.2.3 Wall thickness
!The wall thicknesses, t, 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.
Table 1 — Steel service pipe dimensions
Nominal diameter Outside diameter Wall thickness
DN d t
o
mm
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
Nominal diameter Outside diameter Wall thickness
DN d t
o
mm
mm
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
!NOTE The nominal diameter DN 15 is not relevant for factory made pipe, fitting and valve assemblies of the
European Standards EN 253, 448 and 488-series. The European Standards EN 15698 for pipe, fitting and valve
assemblies take reference to this nominal diameter."
4.2.4 Surface condition
!The outer surface of the steel service pipe shall comply with rust grade A, B or C according to
EN ISO 8501-1, without pitting.
In order to ensure bonding between the steel service pipe and the thermal insulation prior to thermal
insulation, the outer surface of the pipe should be clean from rust, mill scale, oil, grease, dust, paint, moisture
and other contaminants."
4.2.5 !Pipe ends
Steel service pipes used for the manufacturing of pipe assemblies shall be delivered with bevelled ends
according to EN 10217-2, EN 10216-2 and EN 10217-5. The bevel shall have an angle ⍺ of with a root
face of 1,6 mm ± 0,8 mm.
Bevelling is applicable for specified nominal wall thicknesses ≥ 3,2 mm.
For this, the relevant order options according to EN 10216-2, EN 10217-2 or EN 10217-5 should be
agreed."
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 separately manufactured or be applied directly onto the PUR thermal insulation by
extrusion."
!The carbon black content shall, when tested according to ISO 6964, be (2,0 to 2,5) % 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 appearance rating not worse than 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 rate
The 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 stability
The 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.
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 surface of the casing shall be clean and free from such grooving or other defects that might impair its
functional properties. In case of separately manufactured casing, this applies for both internal and external
surfaces. In case of directly onto thermal insulation extruded casing this applies for the external surface."
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 reversion
When 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.
!If other tensides than Arkopal N 100R are used, the test conditions and related time to failure shall be
demonstrated."
4.4 Polyurethane (PUR) foam thermal insulation
4.4.1 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 structure
4.4.2.1 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 bubbles
The 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 strength
The 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.
4.4.4 Foam density
!The density of the foam at any position shall comply with the criteria below when determined 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 temperature
When 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 be 75 % to
150 % 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
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
a
Dimensions, see Table 1
b
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 4.2.5."
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
min
maximum diameter D as given in Table 4. The minimum wall thickness of the casing, e , shall at any
max min
point 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.
Table 4 — Casing dimensions of the pipe assembly
Nominal Minimum Maximum Minimum wall
outside outside outside thickness
diameter diameter diameter
e
min
D D D
c min max
mm
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
Nominal Minimum Maximum Minimum wall
outside outside outside thickness
diameter diameter diameter
e
min
D D D
c min max
mm
mm mm mm
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.
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
a
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 this document."
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 strength
Test temperature Test clause τ
ax
°C
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.
4.5.7 Thermal conductivity in unaged condition
When tested in accordance with 5.4.3, the thermal conductivity (λ50) shall not exceed 0,029 W/(m × K). The
thermal conductivity shall be reported together with the foam density, cell size, compressive strength and
composition of the gas in the cells of the insulation.
4.5.8 Thermal conductivity at artificially aged condition
When aged according to 5.4.4 the test shall be performed in accordance with 5.4.3. The thermal conductivity
at artificially aged condition shall be reported together with the foam density, cell size, compressive strength
and composition of the gas in the cells of the insulation.
4.5.9 Impact resistance
After testing in accordance with 5.4.5, the casing shall have no visible cracks.
4.5.10 Surface conditions at delivery
The surface flattening of the pipe assembly shall not exceed 15 % of the insulation thickness — measured
from the original surface.
Scratches in the casing from the handling and the storage shall not exceed 10 % of the original wall thickness
of the casing. On casings with a wall thickness exceeding 10 mm scratches shall not be deeper than 1 mm.
4.5.11 Measuring wires for surveillance systems
Measuring wires, if any, shall comply with the requirements of EN 14419.
4.5.12 Linear water tightness
When tested in accordance with 5.4.6 there shall be no water leaking at the bottom pipe end after 168 h.
5 Test methods
5.1 General conditions and test specimens
5.1.1 General conditions
!Where test requirements specified in this document differ from those in other standards referred to, the
requirements laid down in this document shall apply.
All test specimens shall be representative for the production.
For testing of foam and pipe assembly, the test specimen shall be cut from pipe assembly with dimensions of
service pipes and thermal insulation series as specified under the respective test requirements and in
Annex C.
When used production method does not cover the dimensions specified under the respective test
requirements and Annex C, the test specimen should be pipe assembly with the closest possible nominal
diameter of the service pipe for the entire range of pipes manufactured using this method.
All test on the pipe assembly shall include the diffusion barrier, if any, except those which are particularly
mentioned to be without."
5.1.2 Test specimens
5.1.2.1 Test specimens shall only be taken from the casing after it has been stored at a temperature of
(23 ± 2) °C for not less than 16 h, or from the PUR foam thermal insulation and pipe assembly after they have
been stored at a temperature of (23 ± 2) °C for not less than 72 h. Deviations from these periods are allowed,
e.g. for quality control purposes. However, in event of a dispute, the required periods shall be observed.
5.1.2.2 Test specimens to establish foam properties and to determine properties of the pipe assembly
shall be taken from pipe assemblies from regular production, but in such a way as to exclude at least 500 mm
from the end of the foam. Test specimens may be taken closer to the end of the foam, e.g. for quality control
purposes. However, in event of a dispute the result from test specimens taken at least 500 mm from the end
of the foam shall apply.
5.1.2.3 Test specimens to determine foam properties, except voids and bubbles, shall be taken from one
location at each end of the pipe assembly. At the location where test specimens are taken to determine cell
structure (4.4.2), compressive strength (4.4.3), foam density (4.4.4) and water absorption (4.4.5), 3 test
specimens shall be taken, from each end of the pipe assembly, equally distributed around the circumference.
5.1.2.4 When cutting test specimens from the foam to
...
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