EN 253:2019

SLOVENSKI STANDARD
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 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 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
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
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 Polyethylen
This 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.

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

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.
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 — Preinsulated bonded pipe systems for directly 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)
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)
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 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 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.
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, 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.
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
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.
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 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 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).
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.
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 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 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 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
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 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
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
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 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 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.
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 determine cell structure (4.4.2), compressive
strength (4.4.3), foam density (4.4.4) and water absorption (4.4.5), the foam adjacent to the service pipe
surface and casing surface shall be excluded; a clearance of at least 5 mm and 3 mm respectively shall be
allowed.
5.1.2.5 The outside dimensions of the test specimens shall be measured with an accuracy of ± 0,1 mm.
5.1.2.6 On test specimens cut from the casing to determine casing properties, any visible surface
irregularities that influence the test result, such as diffusion barrier, scratches, weld seams or foam remains,
may be cut or machined away from the test specimen.
If cutting or machining on multilayer casing is not possible, it is allowed to produce a single-layer casing
without additional layers. The same PE raw material and processing parameters as for the multilayer casing
have to be used.
5.2 Casing
5.2.1 Appearance and surface finish
The internal and external surfaces of the casing shall be visually examined without magnification (see
4.3.2.3).
5.2.2 Elongation at break
The test bars shall be stamped or machined according to Figure 1, type A. Any diffusion barrier shall be cut
or machined away from the test bar.
Test bars may be cut in the longitudinal or circumferential direction and shall be equally distributed over the
circumference of the casing in the same cross section.
Depending on the diameter of the pipe, the number of test bars to be cut and tested shall be in accordance
with Table 7.
Table 7 — Number of test bars related to the nominal diameters
Nominal outside diameter of casing Number of test bars
mm
90 to 250 5
280 to 400 7
450 to 630 10
710 to 1 400 12
Using an ink or wax crayon, the two reference lines shall be drawn equidistant from the ends of the
calibrated length of the test bar. See Figure 1.
The test bars shall be tested at (23 ± 2) °C to which temperature the test bars shall be conditioned for not
less than 2 h before the testing.
Using a suitable tensile testing machine, the test bars shall be elongated at a speed of (100 ± 10) mm/min
until break.
The distance between the reference lines shall be measured after the test and the elongation shall be
calculated according to EN ISO 6259-1.

Symbol Description Dimensions
mm
Type A Type B
l Distance between reference lines 25 ± 1 50 ± 2
l Calibrated length 33 ± 3 60 ± 2
l Total length 115 ≥ 150
l Initial distance 80 ± 2 115 ± 2
e Casing wall thickness - -
r Radius 14 ± 1 60 ± 1
b Calibrated width 6 ± 0,4 10 ± 0,4
b End part width > 15 > 20
Figure 1 — Tensile test bars
5.2.3 Carbon black dispersion, homogeneity
The carbon black dispersion shall be determined in accordance with ISO 18553.
Agglomerates and particles shall be graded in accordance with ISO 18553.
Dispersion shall be determined in accordance with ISO 18553.
5.2.4 Stress crack resistance test
The test shall be carried out in accordance with ISO 16770 with the following exceptions.
The test specimen shall be cut from the same circumference of the casing. They shall be cut in the axial
direction of the separately manufactured casing or the pipe assembly.
The test specimen form may be dumbbells according to Figure 1, type B, or they may be cut with parallel
sides and 10 mm wide. The thickness shall be the casing wall thickness. The test specimen may be produced
either by milling, cutting or punching.
The length of the test specimen shall be sufficient to leave four times the wall thickness between the clamps.
In the middle of the test specimen a notch shall be produced perpendicular to the axis in all four sides in the
same cross section (Full Notch Creep Test — FNCT).
Due to casing rounding the produced notch could have an uneven depth around the test specimen, but the
notch depth and position shall be chosen such that no part of the test specimen cross section is left
unnotched.
In case of wall thickness less than 6 mm the specimen may be notched only from the width of the specimen
(Two Notch Creep Test – 2NCT).
The number of the test specimen shall be four.
The test solution shall be water containing 2,0 % tenside.
The tenside shall be nonylphenol polyglycol-ether with the same effect as the tenside with the trade name ®
‘Arkopal N 100 ’.
NOTE Registered trade mark: Hoechst AG, Clariant GmbH: Extensive text experiences are available for this test
fluid which allows the comparison of test results and the definition of requirements. If other products are used the
number of the molecules of ethyleneoxide in the chain of polyglycolether shall be compared. [7]
The temperature shall be 80 °C.
The test load shall be 4,0 N/mm .
5.3 Polyurethane (PUR) foam thermal insulation
5.3.1 Composition
The MDI-index shall be calculated from the manufacturer's production data and be recorded.
5.3.2 Cell structure
5.3.2.1 Cell size
Test specimens shall be taken in accordance with 5.1.2.
The size of the cells shall be determined over a length of 10 mm measured in a radial direction with the
centre of the 10 mm measurement coinciding with the centre point of the applied insulation.
The size of the cells shall be the quotient of the test length and the number of cells counted along the radial
line of test length selected.
The test result shall be determined at each location as an average value of measurements performed on 3
test specimens.
5.3.2.2 Closed cell content
Test specimens shall be taken in accordance with 5.1.2.
The ratio of open to closed cells shall be determined in accordance with EN ISO 4590 (method 1).
Deviating from the procedure described in EN ISO 4590, the test specimen shall be a cube with an edge of
25 mm. If this size of cube cannot be cut from the thermal insulation, the dimensions shall be
25 mm × 25 mm × t, where t is the maximum radial thickness.
The test result shall be determined at each location as an average value of measurements performed on 3
test specimens.
5.3.2.3 Voids and bubbles
Voids and bubbles shall be determined on cross sections of the thermal insulation.
Minimum 1,5 m from the foam end, 5 circumferential cuts through the casing and the insulation shall be
made with a distance of 100 mm including a total of 400 mm casing.
The four 100 mm rings of casing and insulation shall be removed one by one and the five cross section
surfaces inspected for voids and bubbles.
All voids larger than 6 mm in any direction shall be measured in 2 directions perpendicular to each other,
and the product of the 2 measurements shall be defined as the area of the void.
Voids smaller than 6 mm shall be neglected.
The test result shall be expressed as the percentage of the total area of voids relative to the sum of the five
inspected cross-sectional areas of the insulation.
5.3.3 Compressive strength
The compressive strength in a radial direction shall be tested in accordance with EN ISO 844.
Test specimens shall be taken in accordance with 5.1.2.
The test specimen shall be 30 mm × 30 mm × t or a cylinder with a diameter of 30 mm and a length of t,
where t is the maximum obtainable dimension in the radial direction but minimum 10 mm and maximum
20 mm.
The test result shall be determined at each location as an average value of measurements performed on 3
test specimens.
For the Manufacturer’s quality control other qualified, fully documented correlated method may be used.
5.3.4 Foam density
The foam density shall be measured in accordance with EN ISO 845.
Test specimens shall be taken in accordance with 5.1.2.
Each test specimen shall be 30 mm × 30 mm × t where t is the maximum obtainable thickness but not
exceeding 30 mm. Alternatively, test specimens shall be cylindrical, 30 mm long in the axial direction of the
pipe and of diameter d where d is the maximum obtainable diameter but not exceeding 30 mm.
The test result shall be determined at each location as a set of three single measurements.
For the Manufacturer’s quality control other qualified — fully documented correlated method can be used.
5.3.5 Water absorption
Each test specimen shall be 25 mm × 25 mm × t where t is the maximum obtainable thickness but not
exceeding 25 mm. Alternatively, test specimens shall be cylindrical, 35 mm long in the axial direction of the
pipe and of diameter d where d is the maximum obtainable diameter but not exceeding 25 mm.
The mass (m ) of the test specimen shall be determined to an accuracy of 0,01 g and the volume (V ) shall be
0 0
determined to an accuracy of 0,1 ml. The specimen shall be immersed in boiling water for 90 min. After this,
it shall be immersed immediately in water at (23 ± 2) °C for 1 h. Surface water shall be removed from the
specimen by successively placing each side of the specimen for 3 s to 5 s on a tissue (e.g. Kleenex® No 7101
or similar). The mass (m ) shall then be determined to an accuracy of 0,01 g. The volume (V ) of the
1 1
specimen shall be determined to an accuracy of 0,1 ml.
All test specimens need to comply with the following criterion:
V > 0,75 × V
1 0
The water absorption percentage shall be calculated from:
mm−
× 100% (1)
V ×ρ
where
m is the mass of the test specimen before testing, in g;
m is the mass of the test specimen after the test period, in g;
ρ is the density of the water, in g/ml;
V is the original volume of the test specimen, in ml;
V is the volume of the test specimen after the test period, in ml;
The test result shall be determined at each location as an average value of measurements performed on 3
test specimens.
5.4 Pipe assembly
5.4.1 Axial shear strength
5.4.1.1 Test specimen
The test specimen shall be a length of pipe assembly equal to 2,5 times the thickness of the thermal
insulation but not less than 200 mm. The test specimen shall be cut in such a way that both ends of the
specimen are perpendicular to the axis of the pipe.
5.4.1.2 Test procedure
An axial force shall be applied. The speed of the testing machine shall be 5 mm/min. The axial force shall be
recorded and the shear strength calculated. This test may be performed with the axis of the pipe vertical or
horizontal (see Figure 2). The weight of the steel service pipe shall be taken into consideration when the axis
is vertical.
The test result shall be determined as an average value of 3 measurements. The 3 specimens for axial shear
strength measurements will be taken at both pipe ends (minimum 500 mm from each pipe end) and in the
middle of the pipe assembly.
5.4.1.3 Calculation of shear strength
The shear strength is calculated from the following formula:
F
ax
τ = (2)
ax
LD× ×π
s
where
τ  = axial shear strength, in MPa;
ax
F  = axial force, in N including weight of the steel service pipe for vertical testing see 5.4.1.2;
ax
L  = length of specimen, in mm;
D  = outside diameter of the steel service pipe, in mm.
s
5.4.1.4 Axial shear strength at 23 °C
The test shall be carried out in accordance with 5.4.1.1 to 5.4.1.3, with the entire test specimen kept at a
temperature of (23 ± 2) °C.
5.4.1.5 Axial she
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