EN 253:2009+A2:2015

SLOVENSKI STANDARD
01-december-2015
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District heating pipes - Preinsulated bonded pipe systems for directly buried hot water
networks - Pipe assembly of steel service pipe, polyurethane thermal insulation and
outer casing of polyethylene
Fernwärmerohre - 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 préisolés pour les réseaux
d'eau chaude enterrés directement - Tube de service en acier, isolation thermique en
polyuréthane et tube de protection en polyéthylène
Ta slovenski standard je istoveten z: EN 253:2009+A2:2015
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 253:2009+A2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2015
EUROPÄISCHE NORM
ICS 23.040.10 Supersedes EN 253:2009+A1:2013
English Version
District heating pipes - Preinsulated bonded pipe systems
for directly buried hot water networks - Pipe assembly of
steel service pipe, polyurethane thermal insulation and
outer casing of polyethylene
Tuyaux de chauffage urbain - Systèmes bloqués de Fernwärmerohre - Werkmäßig gedämmte
tuyaux préisolés pour les réseaux d'eau chaude Verbundmantelrohrsysteme für direkt erdverlegte
enterrés directement - Tube de service en acier, Fernwärmenetze - Verbund-Rohrsystem, bestehend
isolation thermique en polyuréthane et tube de aus Stahl-Mediumrohr, Polyurethan-Wärmedämmung
protection en polyéthylène und Außenmantel aus Polyethylen
This European Standard was approved by CEN on 14 December 2012 and includes Amendment 2 approved by CEN on 17 July
2015.
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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 253:2009+A2:2015 E
worldwide for CEN national Members.

Contents Page
European foreword . 5
Introduction . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Requirements . 10
4.1 General . 10
4.2 Steel service pipe . 11
4.2.1 Specification . 11
4.2.2 Diameter . 11
4.2.3 Wall thickness . 12
4.2.4 Surface condition . 13
4.3 Casing. 14
4.3.1 Material properties . 14
4.3.2 Casing properties . 14
4.4 Polyurethane rigid foam insulation (PUR) . 16
4.4.1 Composition . 16
4.4.2 Cell structure . 16
4.4.3 Compressive strength . 16
4.4.4 Foam density . 16
4.4.5 Water absorption at elevated temperature . 16
4.5 Pipe assembly . 17
4.5.1 General . 17
4.5.2 Pipe ends . 17
4.5.3 Diameter and wall thickness of the casing . 17
4.5.4 Centre line deviation . 18
4.5.5 Expected thermal life and long term temperature resistance . 18
4.5.6 Thermal conductivity in unaged condition. 18
4.5.7 Thermal conductivity at artificially aged condition . 19
4.5.8 Impact resistance . 19
4.5.9 Long term creep resistance and modulus . 19
4.5.10 Surface conditions at delivery . 19
4.5.11 Measuring wires for surveillance systems . 19
5 Test methods . 19
5.1 General conditions and test specimens . 19
5.1.1 General conditions . 19
5.1.2 Test specimens . 19
5.2 Casing. 20
5.2.1 Appearance and surface finish . 20
5.2.2 Elongation at break . 20
5.2.3 Carbon black dispersion, homogeneity . 21
5.2.4 Stress crack resistance test . 21
5.3 Polyurethane rigid foam insulation (PUR) . 22
5.3.1 Composition . 22
5.3.2 Cell structure . 22
5.3.3 Compressive strength . 22
5.3.4 5.3.4 Foam density . 23
5.3.5 5.3.5 Water absorption . 23
5.4 Pipe assembly . 23
5.4.1 Axial shear strength . 23
5.4.2 Tangential shear strength . 25
5.4.3 Shear strength of the pipe assembly after ageing . 27
5.4.4 Thermal conductivity in unaged condition . 27
5.4.5 Thermal conductivity at artificially aged condition . 27
5.4.6 Impact resistance. 27
5.4.7 Long term creep resistance and modulus at 140 °C . 27
6 Marking . 30
6.1 General . 30
6.2 Steel service pipe . 30
6.3 Casing . 30
6.4 Pipe assembly . 31
Annex A (informative)  Relation between actual continuous operating conditions and
accelerated ageing test conditions . 32
Annex B (informative)  Calculation of the minimum expected thermal life with operation at
various temperatures with respect to PUR foam performance . 34
Annex C (normative)  !Calculated Continuous Operating Temperature (CCOT)". 35
C.1 General . 35
C.2 Principle . 35
C.3 Symbols . 35
C.4 Ageing and shear strength determinations . 36
C.5 Calculations . 36
C.5.1 Determination of the thermal life at different ageing temperatures . 36
C.5.2 Adoption to the Arrhenius relation. 36
C.5.3 Calculated continuous operating temperature, CCOT . 37
Annex D (informative) Guidelines for inspection and testing . 38
D.1 General . 38
D.2 Manufacturer's type test . 38
D.3 Manufacturer’s quality control . 38
D.4 External inspection . 38
D.5 Manufacturer's responsibility . 38
Annex E (informative) Radial creep behaviour of the polyurethane foam (PUR) . 42
Annex F (normative)  Thermal conductivity of pre-insulated pipes - Test procedure . 43
F.1 Scope . 43
F.2 Requirements (EN ISO 8497:1996, Clause 5) . 43
F.2.1 Test specimen (EN ISO 8497:1996, 5.1) . 43
F.2.2 Operating temperature (EN ISO 8497:1996, 5.2) . 43
F.2.3 Types of apparatus (EN ISO 8497:1996, 5.5) . 43
F.3 Apparatus (EN ISO 8497:1996, Clause 7) . 43
F.3.1 Guarded end apparatus . 43
F.3.2 Calibrated end apparatus . 43
F.3.3 Dimensions (EN ISO 8497:1996, 7.2) . 44
F.3.4 Heater pipe surface temperature . 44
F.4 Test specimens (EN ISO 8497:1996, Clause 8). 44
F.4.1 Conditioning (EN ISO 8497:1996, 8.4) . 44
F.4.2 Dimension measurement (EN ISO 8497:1996, 8.5) . 44
F.4.3 Surface temperature measurement . 44
F.4.4 Location of temperature sensors (EN ISO 8497:1996, 8.6) . 44
F.5 Procedure (EN ISO 8497:1996, Clause 9) . 44
F.5.1 Test length (EN ISO 8497:1996, 9.1.1) . 44
F.5.2 Diameter (EN ISO 8497:1996, 8.5) . 44
F.5.3 Thickness of casing . 44
F.5.4 Ambient requirements (EN ISO 8497:1996, 9.2) . 45
F.5.5 Test pipe temperature (EN ISO 8497:1996, 9.3) . 45
F.5.6 Power supply (EN ISO 8497:1996, 7.9) . 45
F.5.7 #Axial heat loss$ . 45
F.5.8 Test period and stability (EN ISO 8497:1996, 9.5.3) . 45
F.6 Calculations (EN ISO 8497:1996, Clause 11). 45
F.6.1 Thermal conductivity (EN ISO 8497:1996, 3.5) . 45
F.7 Symbols and units (EN ISO 8497:1996 Clause 4) . 46
Annex G (informative) National A-deviations . 48
G.1 Swedish national legislative deviations on steel service pipes . 48
Annex H (informative) Main changes from the previous edition of EN 253 . 49
Annex I (informative) Waste treatment and recycling . 52
Bibliography . 53

European foreword
This document (EN 253:2009+A2:2015) has been prepared by Technical Committee CEN/TC 107
“Prefabricated district heating 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 2016, and conflicting national standards shall be withdrawn at
the latest by April 2016.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document includes Amendment 1, approved by CEN on 2012-12-14, and Amendment 2, approved by
CEN on 2015-07-17.
The start and finish of text introduced or altered by amendment is indicated in the text by tags !" and
#$.
This document supersedes #EN 253:2009+A1:2013$.
Annex H provides details of significant technical changes between this European Standard and the previous
editions.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Introduction
This specification is part of the standards for bonded systems using polyurethane foam thermal insulation
applied to bond to a steel service pipe and a polyethylene casing.
The other standards from CEN/TC 107 covering this subject are:
EN 448, District heating pipes – Preinsulated bonded pipe systems for directly buried hot water networks –
Fitting assemblies of steel service pipes, polyurethane thermal insulation and outer casing of polyethylene;
EN 488, District heating pipes – Preinsulated bonded pipe systems for directly buried hot water networks –
Steel valve assembly for steel service pipes, polyurethane thermal insulation and outer casing of polyethylene;
EN 489, District heating pipes – Preinsulated bonded pipe systems for directly buried hot water networks – Joint
assembly for steel service pipes, polyurethane thermal insulation and outer casing of polyethylene;
EN 13941, Design and installation of preinsulated bonded pipe systems for district heating;
EN 14419, District heating pipes – Preinsulated bonded pipe systems for directly buried hot water networks –
Surveillance systems;
EN 15698-1, District heating pipes – Preinsulated bonded twin pipe systems for directly buried hot water
networks – Part 1: Twin pipe assembly of steel service pipe, polyurethane thermal insulation and outer casing of
polyethylene
1 Scope
This European Standard specifies requirements and test methods for straight lengths of prefabricated
thermally insulated pipe-in-pipe assemblies for directly buried hot water networks, comprising a steel
service pipe from DN 15 to DN 1200, rigid polyurethane foam insulation and an outer casing of polyethylene.
The pipe assembly may also include the following additional elements: measuring wires, spacers and
diffusion barriers.
This standard applies only to insulated pipe assemblies, for continuous operation with hot water at various
temperatures up to 120 °C and occasionally with a peak temperature up to 140 °C.
The estimation of expected thermal life with continuous operation at various temperatures is outlined in
Annex B.
2 Normative references
The following referenced documents are indispensable for the application 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 489, District heating pipes – Preinsulated bonded pipe systems for directly buried hot water networks – Joint
assembly for steel service pipes, polyurethane thermal insulation and outer casing of polyethylene
EN 728, Plastics piping and ducting systems – Polyolefin pipes and fittings – Determination of oxidation
induction time
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 10217-1, Welded steel tubes for pressure purposes – Technical delivery conditions - Part 1: Non-alloy steel
tubes with specified room 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, Design and installation of preinsulated bonded pipe systems for district heating
EN 14419, District heating pipes – Preinsulated bonded pipe systems for directly buried hot water networks –
Surveillance systems
EN ISO 1133:2005, Plastics – Determination of the melt mass-flow rate (MFR) and the melt volume-flow rate
(MVR) of thermoplastics (ISO 1133:2005)
EN ISO 2505, Thermoplastics pipes – Longitudinal reversion – Test methods and parameters (ISO 2505:2005)
EN ISO 3126, Plastics piping systems – Plastics components – Determination of dimensions (ISO 3126:2005)
EN ISO 8497:1996, Thermal insulation – Determination of steady-state thermal transmission properties of
thermal insulation for circular pipes (ISO 8497:1994)
EN ISO 8501-1:2007, 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 9080, Plastics piping and ducting systems – Determination of the long-term hydrostatic strength of
thermoplastic materials in pipe form by extrapolation (ISO 9080:2003)
EN ISO 9692-1, Welding and allied processes – Recommendations for joint preparation – Part 1: Manual metal-
arc welding, gas-shielded metal-arc welding, gas welding, TIG welding and beam welding of steels (ISO 9692-
1:2003)
EN ISO 12162, Thermoplastics materials for pipes and fittings for pressure applications – Classification and
designation – Overall service (design) coefficient (ISO 12162:1995)
ISO 844, Rigid cellular plastics – Determination of compression properties
ISO 3127:1994, Thermoplastics pipes – Determination of resistance to external blows – Round-the-clock
method
ISO 6964, Polyolefin pipes and fittings – Determination of carbon black content by calcination and pyrolysis –
Test method and basic specification
ISO 11414:1996, 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)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1133:2005 and the following
apply.
3.1
ageing
keeping the service pipe at a certain, elevated temperature for a certain time while the casing is exposed to a
temperature of (23 ± 2) °C
3.2
artificial ageing
keeping the complete pipe assembly at a certain, elevated temperature for a certain time
3.3
batch
specified quantity of raw material made under the same uniform production conditions in one production
run by one manufacturer
3.4
bonded system
service pipe, insulating material and casing which are bonded by the insulating material
3.5
calculated continuous operating temperature
CCOT
temperature for which the thermal life of 30 years can be calculated assuming an Arrhenius relationship
between temperature and thermal life
3.6
casing
outer layer made of polyethylene to protect the insulation and the service pipe from ground water, moisture
and mechanical damage
3.7
centre line deviation
deviation between the centre line of the service pipe and the centre line of the casing
3.8
continuous temperature
temperature at which the hot water network is designed to operate continuously
3.9
creep
slow progressive strain under the influence of stresses
3.10
density
mass of a body of a material divided by the volume of the body
3.11
diffusion barrier
layer in the pipe assembly of another material than PE, installed between the thermal insulation and the PE
casing, with the aim to restrict the diffusion of gases through the casing
3.12
foam density
apparent density of the foam of the insulating layer at any position
3.13
fusion compatibility
ability of two PE materials to be fused together to form a joint which conforms to the performance
requirements of this European Standard
3.14
insulation material
material which reduces the heat loss
3.15
Polymeric Methylendiphenyl Diisocyanate-Index
MDI-index
quotient of the actual amount of isocyanate used and the stoichiometrically required amount, multiplied
by 100
3.16
peak temperature
highest temperature at which a system is designed to operate occasionally, see Annex B
3.17
physical blowing agent
additive in the mixture of isocyanate and polyole which evaporate without reacting during the
polymerisations
3.18
pipe assembly
assembled product, consisting of a service pipe, insulating material and a casing
3.19
polyurethane rigid foam
PUR
material resulting from the chemical reaction of polyisocyanates with hydroxyl containing compounds in the
presence of catalysts having mainly closed cell structure
NOTE: The foaming can be assisted by a physical blowing agent
3.20
service pipe
steel pipe that contains the water
3.21
shear strength
ability of the pipe assembly to withstand a shear force acting between the casing and the service pipe
3.22
thermal life
time elapsed before the tangential shear stress at 140 °C falls below 0,13 MPa when exposing the pipe
continuously to the ageing temperature
NOTE The limit value for the tangential shear strength, 0,13 MPa, used in the definition of the thermal life is clearly
higher than the shear strength level necessary in service. As a consequence the useful service life of the pipe system can
be expected to exceed the thermal life value.
3.23
virgin material
material in a form such as granules that has not been subjected to use or processing other than that required
for its manufacture and to which no reprocessable or recyclable material has been added.
4 Requirements
4.1 General
Unless otherwise specified, the requirements shall be valid for each single measurement.
For information on suitable guidelines for inspection of manufactured preinsulated pipes see Annex D.
4.2 Steel service pipe
#
4.2.1 Specification
The technical delivery conditions of the steel service pipe shall be in accordance with Table 1.
Table 1 — Steel service pipe specification
a
Type of pipe Diameter EN standard Material
Seamless All EN 10216-2 P235GH
b
P235TR1
≤ 60,3 mm (DN 50) EN 10217-1 or
ERW
P235TR2
ERW All EN 10217-2 P235GH
SAW All EN 10217-5 P235GH
a
Equivalent or higher steel grades according to approved EN standards may be used by
agreement.
b
If P235TR1 material is used an impact test at 0 ºC according EN 10217-1 as for P235TR2
shall be performed.
For higher steel grades than those given in Table 1 the yield strength is defined in their related standards. If
such higher steel grades are used for medium pipes, it shall be verified that all components used in the
involved part of the system are compatible to the higher yield strength of the pipes.
NOTE 1 Further information on the required steel grades is given in EN 13941.
All steel pipes and components used for manufacturing of pipe assemblies under the scope of this standard
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 preinsulated pipe assemblies, this request shall be given whilst placing the order with the
manufacturer of the preinsulated pipe assemblies.
NOTE 2 Any later request for provision of such documentation can be too late and can possibly not be met by the
manufacturer, since the manufacturer has to organize the assignment of 3.1 certificates to pipes and part of pipes
before starting the production.
A length of pipe shall not include a circular joint.$
!
4.2.2 Diameter
The diameter shall be in accordance with Table 2 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
s
with Table 3. 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
s
measured using a slide calliper.
NOTE To avoid stresses due to temperature differences and misalignment, the tolerances given in Table 3 are
more stringent than the tolerances for D given in EN 10216-2, EN 10217-1, EN 10217-2 or EN 10217-5.
s
The out-of-roundness shall be determined in accordance with EN 10216-2, EN 10217-1, EN 10217-2 or
EN 10217-5 and shall be within the limits given in these standards."
4.2.3 Wall thickness
The nominal wall thicknesses, T, and masses shall be in accordance with EN 10220 with a minimum as
indicated in Table 2.
Subject to design considerations, cf. EN 13941, other wall thicknesses may be used, but in no case shall these
be less than the minima indicated in Table 2.
The tolerance on the actual wall thickness, T, of the steel service pipe shall be in accordance with Table 4.
NOTE To avoid stresses due to temperature differences and misalignment, the tolerances given in Table 4 are
more stringent than the tolerances for T given in EN 10216 2, EN 10217-1, EN 10217 2 or EN 10217 5.
Table 2 — Steel service pipe dimensions
Nominal diameter Outside diameter Minimum nominal wall thickness
DN D T
s
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
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
Table 3 — Tolerances on outside diameter D at pipe ends
s
Welded pipe Seamless pipe
D Tolerance D Tolerance
s s
mm mm
mm mm
D ≤ 48,3 ±0,3 D ≤ 114,3 ±0,4
s s
48,3 < D ≤ 168,3 ±0,005 D 114,3 < D ≤ 219,1 ±0,005 D
s s s s
168,3 < D ≤ 323,9 ±1,0 219,1 < D ≤ 711,0 ±0,006 D
s s s
323,9 < D ≤ 1219,0 ±1,6
s
Table 4 — Tolerances on the actual wall thickness
Welded pipe Seamless pipe
T ±ΔT T +ΔT -ΔT
mm mm mm mm mm
2,0 0,3 2,0 0,3 0,2
2,3 0,3 2,3 0,4 0,2
2,6 0,3 2,6 0,4 0,3
2,9 0,3 2,9 0,4 0,3
3,2 0,3 3,2 0,4 0,4
3,6 0,4 3,6 0,5 0,5
4,0 0,5 4,0 0,5 0,5
4,5 0,5 4,5 0,6 0,6
5,0 0,5 5,0 1,0 0,6
5,6 0,5 5,6 1,1 0,7
6,3 0,5 6,3 1,3 0,9
7,1 0,5 7,1 1,4 1,1
8,0 0,5 8,0 1,4 1,1
8,8 0,5 8,8 1,4 1,1
10,0 0,5 10,0 1,4 1,1
11,0 0,5 11,0 1,4 1,1
12,5 0,5 12,5 1,4 1,1
4.2.4 Surface condition
In order to ensure proper bonding between the steel service pipe and the PUR-foam insulation, the following
procedure shall be followed:
Prior to 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 pipe, the outer surface of the pipe shall comply with rust grade A, B or C according to
EN ISO 8501-1:2007, without pitting.
4.3 Casing
4.3.1 Material properties
4.3.1.1 Material composition
The casing may be a separately manufactured pipe or be applied directly onto the insulation by extrusion.
The pipe 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 end use of pipes 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 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, bubbles, voids or foreign matter shall not exceed 100 μm in diameter. No white
or black stripes or smears may occur.
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 ≤ 1,4 g/10 min determined in accordance with EN ISO 1133, condition T (5kg, 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 pipe manufacturer has demonstrated fusion compatibility by preparing a but fusion joint using the
parameters as specified in Annex A of ISO 11414:1996.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 728.
4.3.1.4 Use of rework material
Only clean, not degraded, rework material, generated from the manufacturer's own production of pipes,
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 5.
The actual outside diameter shall be measured in accordance with EN ISO 3126.
4.3.2.2 Wall thickness
The wall thickness of the casing shall be in accordance with Table 5.
The actual wall thickness shall be measured in accordance with EN ISO 3126.
Table 5 — Casing dimensions
Nominal outside Minimum wall thickness
diameter
e
min
D
c
mm
mm
75 3.0
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, pipe ends
1)
The internal and external surfaces of the casing pipe shall be clean and free from such grooving or other
defects that might impair its functional properties (see 5.2.1).
The pipe ends shall be cleanly cut and shall be square within 2,5° with the axis of the pipe.

1)
Surface treatment to improve the shear strength between the PUR foam and casing pipe is permissible provided that the treated
pipe 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 %.
The test is to be applied only on casings that are produced partly or fully from rework material.
4.3.2.5 Heat reversion
When tested in accordance with EN ISO 2505, the longitudinal length at any position on the pipe shall not
change by more than 3 %. On inspection after testing, the pipe 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 rigid foam insulation (PUR)
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 foam from the production of pipe assemblies is of the same
composition as the foam sample used for the ageing test in 5.4.3 and meets the requirements of 4.4.
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4.4.2 Cell structure
The PUR-foam shall have a uniform cell structure free from smears. The average cell size of the cells in a
radial direction shall be less
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