oSIST prEN 15632-1:2021

District heating pipes - Pre-insulated flexible pipe systems - Part 1: Classification, general requirements and test methods

This document provides classification, general requirements and test methods for flexible, factory made, buried district heating pipe systems.
This document is intended to be used in conjunction with part 2, 3 or 4, as applicable.
Depending on the pipe assembly (see Table 4), this document is valid for maximum media temperature of 95 °C (part 2 and 3) and maximum media temperature of 120 °C (for part 4) and design pressures of 0,6 MPa to 2,5 MPa.
The pipe systems are designed for a service life of at least 30 years. For pipe systems with plastic service pipes, the respective temperature profiles are defined in EN 15632-2 and EN 15632-3.
NOTE   For the transport of other liquids, for example potable water, additional requirements may be applicable.

Fernwärmerohre - Werkmäßig gedämmte flexible Rohrsysteme - Teil 1: Klassifikation, allgemeine Anforderungen und Prüfungen

Dieses Dokument enthält die Klassifikation, allgemeine Anforderungen und Prüfverfahren für flexible, werkmäßig hergestellte, erdverlegte Fernwärmenetze.
Dieses Dokument ist, wie jeweils zutreffend, für die Anwendung in Verbindung mit Teil 2, Teil 3 oder Teil 4 vorgesehen.
In Abhängigkeit von der Rohrbaugruppe (siehe Tabelle 4) gilt dieses Dokument für maximale Medientemperaturen von 95 °C (Teil 2 und Teil 3) sowie 120 °C (Teil 4) und zulässige Betriebsdrücke von 0,6 MPa bis 2,5 MPa.
Die Rohrsysteme sind für eine Nutzungsdauer von 30 Jahren ausgelegt. Für Rohrsysteme mit Mediumrohren aus Kunststoff sind die entsprechenden Temperaturprofile in EN 15632-2 und EN 15632-3 festgelegt.
ANMERKUNG   Für den Transport von anderen Flüssigkeiten, wie z. B. Trinkwasser, können zusätzliche Anforderungen gelten.

Tuyaux de chauffage urbain - Systèmes de tuyaux flexibles préisolés - Partie 1 : Classification, exigences générales et méthodes d'essai

Le présent document fournit la classification, les exigences générales et les méthodes d’essai pour les systèmes de réseaux de tuyaux de chauffage urbain flexibles, manufacturés, enterrés directement.
Le présent document est prévu pour être utilisé conjointement avec les Parties 2, 3 ou 4, si applicable.
En fonction de l'assemblage des tuyaux (voir Tableau 4), le présent document est valable pour une température maximale du fluide de 95 °C (parties 2 et 3) et une température maximale du fluide de 120 °C (pour la partie 4) et des pressions de conception de 0,6 MPa à 2,5 MPa.
Les systèmes de tuyaux sont conçus pour une durée de vie prévue d’au moins 30 ans. Pour les systèmes de tuyaux avec des tubes de service en plastique, les profils de température respectifs sont définis dans l’EN 15632-2 et l’EN 15632-3.
NOTE   Pour le transport d’autres liquides, par exemple de l’eau potable, des prescriptions supplémentaires peuvent s’appliquer.

Cevi za daljinsko ogrevanje - Izolirani gibki cevni sistemi - 1. del: Klasifikacija, splošne zahteve in preskusne metode

General Information

• Status: Not Published
• Public Enquiry End Date: 31-Jan-2021
• ICS: 23.040.01 - Pipeline components and pipelines in general
• ICS: 23.040.07 - Pipeline and its parts for district heat
• ICS: 91.140.10 - Central heating systems
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 03-Dec-2020
• Due Date: 22-Apr-2021
• Completion Date: 01-Feb-2021
• Ref Project: prEN 15632-1 - District heating pipes - Pre-insulated flexible pipe systems - Part 1: Classification, general requirements and test methods

RELATIONS

• Revised: SIST EN 15632-1:2009 - District heating pipes - Pre-insulated flexible pipe systems - Part 1: Classification, general requirements and test method
• Effective Date: 13-May-2014
• Revised: SIST EN 15632-1:2009+A1:2015 - District heating pipes - Pre-insulated flexible pipe systems - Part 1: Classification, general requirements and test methods
• Effective Date: 22-Oct-2014

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN 15632-1:2021
01-januar-2021

Cevi za daljinsko ogrevanje - Izolirani gibki cevni sistemi - 1. del: Klasifikacija,

splošne zahteve in preskusne metode

District heating pipes - Pre-insulated flexible pipe systems - Part 1: Classification,

general requirements and test methods

Fernwärmerohre - Werkmäßig gedämmte flexible Rohrsysteme - Teil 1: Klassifikation,

allgemeine Anforderungen und Prüfungen
Tuyaux de chauffage urbain - Systèmes de tuyaux flexibles préisolés - Partie 1 :
Classification, exigences générales et méthodes d'essai
Ta slovenski standard je istoveten z: prEN 15632-1
ICS:
23.040.07 Cevovodi za daljinsko Pipeline and its parts for
ogrevanje in njihovi deli district heat
91.140.10 Sistemi centralnega Central heating systems
ogrevanja
oSIST prEN 15632-1:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN 15632-1:2021
---------------------- Page: 2 ----------------------
oSIST prEN 15632-1:2021
DRAFT
EUROPEAN STANDARD
prEN 15632-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2020
ICS 23.040.07 Will supersede EN 15632-1:2009+A1:2014
English Version
District heating pipes - Pre-insulated flexible pipe systems
- Part 1: Classification, general requirements and test
methods

Tuyaux de chauffage urbain - Systèmes de tuyaux Fernwärmerohre - Werkmäßig gedämmte flexible

flexibles préisolés - Partie 1 : Classification, exigences Rohrsysteme - Teil 1: Klassifikation, allgemeine

générales et méthodes d'essai Anforderungen und Prüfungen

This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee

CEN/TC 107.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other

language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC

Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are

aware and to provide supporting documentation.

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

notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 15632-1:2020 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
oSIST prEN 15632-1:2021
prEN 15632-1:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 4

Introduction .................................................................................................................................................................... 5

1 Scope .................................................................................................................................................................... 6

2 Normative references .................................................................................................................................... 6

3 Terms and definitions and symbols ......................................................................................................... 7

3.1 Terms and definitions ................................................................................................................................... 7

3.2 Symbols, indices and abbreviations ......................................................................................................... 7

4 Classification .................................................................................................................................................. 12

5 Design requirements .................................................................................................................................. 12

5.1 Thermal insulation properties ................................................................................................................ 12

5.2 Bending test ................................................................................................................................................... 12

5.2.1 Flexibility ........................................................................................................................................................ 12

5.2.2 Ovality .............................................................................................................................................................. 13

5.2.3 Cracks ............................................................................................................................................................... 13

5.2.4 Centre line deviation of service pipe..................................................................................................... 13

5.3 Resistance to external load....................................................................................................................... 13

5.3.1 Ring stiffness .................................................................................................................................................. 13

5.3.2 Impact resistance ......................................................................................................................................... 13

5.4 Thermal insulation ...................................................................................................................................... 13

5.4.1 Compressive creep....................................................................................................................................... 13

5.4.2 Water absorption at elevated temperatures ..................................................................................... 13

5.4.3 Density of thermal insulation .................................................................................................................. 14

5.5 Casing ............................................................................................................................................................... 14

5.5.1 UV stability ..................................................................................................................................................... 14

5.5.2 Thermal stability of the material ........................................................................................................... 14

5.5.3 Stress crack resistance of the material ................................................................................................ 14

5.5.4 Use of rework material .............................................................................................................................. 14

5.6 Surveillance systems ................................................................................................................................... 15

6 Test methods ................................................................................................................................................. 15

6.1 General ............................................................................................................................................................. 15

6.2 Bending test ................................................................................................................................................... 15

6.2.1 Flexibility ........................................................................................................................................................ 15

6.2.2 Ovality test ...................................................................................................................................................... 16

6.2.3 Cracks in the thermal insulation ............................................................................................................ 17

6.3 Compressive creep....................................................................................................................................... 18

6.3.1 General ............................................................................................................................................................. 18

6.3.2 Principles of testing ..................................................................................................................................... 18

6.3.3 Test apparatus............................................................................................................................................... 18

6.3.4 Test specimen ................................................................................................................................................ 20

6.3.5 Test procedure .............................................................................................................................................. 20

6.3.6 Test force and expression of results ..................................................................................................... 20

7 Marking ............................................................................................................................................................ 22

7.1 General marking aspects ........................................................................................................................... 22

7.2 Minimum marking information .............................................................................................................. 22

---------------------- Page: 4 ----------------------
oSIST prEN 15632-1:2021
prEN 15632-1:2020 (E)

8 Manufacturer's information ..................................................................................................................... 22

Annex A (normative) Thermal conductivity of factory made pipes – Test procedure ....................... 24

A.1 General ............................................................................................................................................................. 24

A.2 Requirements ................................................................................................................................................. 24

A.2.1 Test specimen ................................................................................................................................................ 24

A.2.2 Operating temperature .............................................................................................................................. 24

A.2.3 Types of apparatus ....................................................................................................................................... 24

A.3 Apparatus ........................................................................................................................................................ 24

A.3.1 Guarded end apparatus .............................................................................................................................. 24

A.3.2 Calibrated end apparatus .......................................................................................................................... 24

A.3.3 Dimensions ..................................................................................................................................................... 25

A.3.4 Heater pipe surface temperature ........................................................................................................... 25

A.4 Test specimen ................................................................................................................................................ 25

A.4.1 Conditioning ................................................................................................................................................... 25

A.4.2 Surface temperature measurement ....................................................................................................... 25

A.4.3 Location of temperature sensors ............................................................................................................ 25

A.5 Procedure ........................................................................................................................................................ 25

A.5.1 Test length ....................................................................................................................................................... 25

A.5.2 Diameter and dimension measurement............................................................................................... 25

A.5.3 Thickness of casing ...................................................................................................................................... 27

A.5.4 Ambient requirements ............................................................................................................................... 27

A.5.5 Test pipe temperature ................................................................................................................................ 27

A.5.6 Power supply .................................................................................................................................................. 27

A.5.7 Axial heat loss ................................................................................................................................................ 28

A.5.8 Test period and stability ............................................................................................................................ 28

A.6 Calculations - Thermal conductivity ...................................................................................................... 28

Annex B (informative) Determination of design values for the radial thermal resistance .............. 30

Annex C (informative) Guideline for testing ...................................................................................................... 31

Bibliography ................................................................................................................................................................. 33

---------------------- Page: 5 ----------------------
oSIST prEN 15632-1:2021
prEN 15632-1:2020 (E)
European foreword

This document (prEN 15632-1:2020) has been prepared by Technical Committee CEN/TC 107

“Prefabricated district heating and district cooling pipe system”, the secretariat of which is held by DS.

This document is currently submitted to the CEN Enquiry.
This document will supersede EN 15632-1:2009+A1:2014.

This document is one of a series of standards which form several parts of EN 15632, District heating

pipes — Factory made flexible pipe systems:
Part 1: Classification, general requirements and test methods;
Part 2: Bonded system with plastic service pipes; requirements and test methods;

Part 3: Non bonded system with plastic service pipes; requirements and test methods;

Part 4: Bonded system with metal service pipes; requirements and test methods.
In comparison to EN 15632-1:2009+A1:2014 the following changes have been made:
a) improved description of the bending test in 5.2 and 6.2;
b) improved description of the thermal insulation in 5.4;
c) improved description of the compressive creep test in 6.3;
d) improved calculation of the thermal conductivity in Annex A, A.6;
e) improved calculation of the radial thermal resistance in Annex B;
f) completely revised “guideline for testing” in the informative Annex C.
---------------------- Page: 6 ----------------------
oSIST prEN 15632-1:2021
prEN 15632-1:2020 (E)
Introduction

Flexible pipe systems in district heating networks are of common technical usage. In order to ensure

quality including product-related service life, to ensure safety in use, economical energy usage and to

facilitate comparability in the market, CEN/TC 107 decided to set up standards for these products.

---------------------- Page: 7 ----------------------
oSIST prEN 15632-1:2021
prEN 15632-1:2020 (E)
1 Scope

This document provides classification, general requirements and test methods for flexible, factory

made, buried district heating pipe systems.

This document is intended to be used in conjunction with part 2, 3 or 4, as applicable.

Depending on the pipe assembly (see Table 4), this document is valid for maximum media temperature

of 95 °C (part 2 and 3) and maximum media temperature of 120 °C (for part 4) and design pressures of

0,6 MPa to 2,5 MPa.

The pipe systems are designed for a service life of at least 30 years. For pipe systems with plastic

service pipes, the respective temperature profiles are defined in EN 15632-2 and EN 15632-3.

NOTE For the transport of other liquids, for example potable water, additional requirements can be

applicable.
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 253, District heating pipes — Bonded pipe systems for directly buried hot water networks — Factory

made pipe assembly of steel service pipe, polyurethane thermal insulation and outer casing of polyethylene

EN 1605, Thermal insulating products for building applications — Determination of deformation under

specified compressive load and temperature conditions

EN 1606, Thermal insulating products for building applications — Determination of compressive creep

EN 12085, Thermal insulating products for building applications — Determination of linear dimensions of

test specimens

EN 13941, District heating pipes — Design and installation of thermal insulated bonded single and twin

pipe systems for directly buried hot water networks

EN 14419, District heating pipes — Bonded single and twin pipe systems for buried hot water networks —

Surveillance systems

EN 60811-4-1:2004, Electric and optical fibre cables — Test methods for non-metallic materials — Part

406: Miscellaneous tests — Resistance to environmental stress cracking of polyethylene and polypropylene

compounds (IEC 60811-406-1:2012)

EN ISO 845, Cellular plastics and rubbers — Determination of apparent density (ISO 845:2006)

EN ISO 3127, Thermoplastics pipes — Determination of resistance to external blows — Round-the-clock

method (ISO 3127)
EN ISO 9967, Thermoplastics pipes — Determination of creep ratio (ISO 9967)
EN ISO 9969, Thermoplastics pipes — Determination of ring stiffness (ISO 9969)

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)

---------------------- Page: 8 ----------------------
oSIST prEN 15632-1:2021
prEN 15632-1:2020 (E)

EN ISO 16871, Plastics piping and ducting systems — Plastics pipes and fittings — Method for exposure to

direct (natural) weathering (ISO 16871)

EN ISO 23993, Thermal insulation products for building equipment and industrial installations —

Determination of design thermal conductivity (ISO 23993)

ISO 6964, Polyolefin pipes and fittings — Determination of carbon black content by calcination and

pyrolysis — Test method

ISO 16770, Plastics — Determination of environmental stress cracking (ESC) of polyethylene — Full-notch

creep test (FNCT)
3 Terms and definitions and symbols
3.1 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
3.2 Symbols, indices and abbreviations

For the purposes of this document, the following symbols in Table 1, indices in Table 2 and

abbreviations in Table 3 apply.
Table 1 — Symbols
Symbol Description Unit
projected area of the service pipe (length * width)
inner diameter of the service pipe mm
actual diameter of casing, measured with measuring tape mm
deviation of service pipe %
minimum casing diameter, measured with calliper mm
min
maximal casing diameter, measured with calliper mm
max
inner diameter of the service pipe at the peak of a corrugation mm
1p,
inner diameter of the service pipe at the trough of a corrugation mm
1,t
outer diameter of the service pipe mm
outer diameter of the service pipe at the peak of a corrugation mm
2,p
outer diameter of the service pipe at the trough of a corrugation mm
2,t
inner diameter of the casing mm
---------------------- Page: 9 ----------------------
oSIST prEN 15632-1:2021
prEN 15632-1:2020 (E)
Symbol Description Unit
inner diameter of the casing at the peak of a corrugation mm
3,p
inner diameter of the casing at the trough of a corrugation mm
3,t
outer diameter of the casing mm
outer diameter of the casing at the peak of a corrugation mm
4,p
outer diameter of the casing at the trough of a corrugation mm
4,t
force N
ageing factor /
corrective factor for differences between calculated and measured thermal
conductivities or
is the correction factor for existing open splits, thermal bridges or change of
cor
the factor for shape caused by influence of lying in the ground and the
relevant factors set up by EN ISO 23993.
force resulting from heat expansion N
exp
moisture factor /
is the force resulting from weight in N N
weight
acceleration due to gravity
m/s
length of the test specimen m
mass of the service pipe including the water inside kg
Ovality %
area related load on the thermal insulation resulting from heat expansion of
MPa
exp
the service pipe
area related test load MPa
test
area related load on the cross section of the test specimen of the thermal
MPa
weight
insulation material
heat flow rate W/m
radial heat flow rate for buried single pipe system in the flow pipe W/m
radial heat flow rate for buried single pipe system in the flow and return
W/m
fr+
pipe
radial heat flow rate for buried single pipe system in the return pipe W/m
radial heat flow rate for buried twin pipe system W/m
TPS
heat flow W
bending radius in the axis of the pipe mm
---------------------- Page: 10 ----------------------
oSIST prEN 15632-1:2021
prEN 15632-1:2020 (E)
Symbol Description Unit
radial thermal resistance m⋅K/W
thermal resistance from earth surface to ambient air
m ⋅K/W
design value for the radial resistance m⋅K/W
design
radial thermal resistance of the flow pipe m⋅K/W
radial thermal resistance of the return pipe m⋅K/W
radial thermal resistance of the soil m⋅K/W
soil
radial thermal resistance of a twin pipe system m⋅K/W
TPS
thickness mm
thickness of thermal insulation, mean value of 4 measurements at 3,6,9 and
12 o’clock position at test specimen end
S B
maximum thickness of the thermal insulation mm
thickness of test specimen after load testing and temperature testing mm
STB
axial shear stress MPa
thickness of the casing mm
coefficient of heat loss W/(m⋅K)
coefficient of heat loss for buried single pipe system in the flow pipe W/(m⋅K)

coefficient of heat loss for buried single pipe system in the return pipe W/(m⋅K)

coefficient of heat loss in a twin pipe system W/(m⋅K)
TPS
depth of laying distance from the centre line of the pipe to the surface m
is the soil coverage above the centre line of the pipe m
is a corrected value for the soil coverage m
corrected minimum value for thermal transmittance on the surface of the
cor
earth
thermal conductivity of the thermal insulation at 50 °C W/(m⋅K)
thermal conductivity of the casing W/(m⋅K)
calculation value of the thermal conductivity of the thermal insulation
W/(m⋅K)
design
material
thermal conductivity of the thermal insulation W/(m⋅K)
thermal conductivity of the soil W/(m⋅K)
soil
thermal conductivity of the service pipe W/(m⋅K)
---------------------- Page: 11 ----------------------
oSIST prEN 15632-1:2021
prEN 15632-1:2020 (E)
Symbol Description Unit
thermal conductivity of steel W/(m⋅K)
steel
thermal conductivity of a twin pipe system at any average temperature W/(m⋅K)
TPS,ϑav
temperature at the inner diameter of the service pipe K
temperature at the inner diameter of the service flow pipe K
1, f
temperature at the inner diameter of the service return pipe K
1,r
temperature at the outer diameter of the service pipe K
temperature at the inner diameter of the casing K
temperature at the outer diameter of the casing K
ambient temperature K
amb
flow temperature K
mean temperature of the thermal insulation K
i,mean
return temperature K
Compression of the thermal insulation %
---------------------- Page: 12 ----------------------
oSIST prEN 15632-1:2021
prEN 15632-1:2020 (E)
Table 2 — Indices
Symbol Definition
0 thermal transmittance (from earth surface to ambient air)
1 position at the inner diameter of the service pipe
2 position at the outer diameter of the service pipe
3 position at the inner diameter of the casing
4 position at the outer diameter of the casing
50 at 50 °C
a ageing
amb ambient
av average
ax axial
C casing or casing pipe
cor corrective
decl declared
design design
exp expansion
f flow
I thermal insulation
m moisture
mean mean
min minutes
p peak of a corrugation
r return
S service pipe
soil soil
steel steel
STB stability
t trough of a corrugation
test test
TPS twin Pipe System
weight weight
x placeholder for 1,2,3 or 4
average temperature
---------------------- Page: 13 ----------------------
oSIST prEN 15632-1:2021
prEN 15632-1:2020 (E)
Table 3 — Abbreviations
Abbreviation Name
PB-H polybutene
PE-HD high density polyethylene
PE-MD medium density polyethylene
PE-LD low density polyethylene
PE-LLD linear low density polyethylene
PE-X cross linked polyethylene
4 Classification

This document shall only be used in conjunction with part 2, 3 or 4, as applicable. Table 4 shows an

overview of the different classification systems and its field of application according to part 2, 3 and 4.

The detailed classification including the specific temperature profile and the design pressure is defined

in Clause 4 of the relevant part 2, 3 and 4.
Table 4 — Overview of Classification system
Part of this
Field of application
standard
Continuous Maximum
Design operating operating
Service Pipe
pressure temperatur temperatur
pipe assembly
e e
material design
MPa
°C °C
2 plastics bonded 0,6, 0,8 or 1,0 80 95
3 plastics non bonded 0,6, 0,8 or 1,0 80 95
4 metal bonded 1,6 or 2,5 120 140
5 Design requirements
5.1 Thermal insulation properties

The manufacturer shall submit values for the heat loss of buried pipe assemblies for all pipe dimensions

in accordance to EN 13941-1, rounded to 0,1 W/m.

NOTE Annex A specifies how to determine thermal conductivity, and Annex B informs about design values for

the radial thermal resistance.
5.2 Bending test
5.2.1 Flexibility

The flexibility of the pipe assembly is verified by testing at the minimum bending radius. The

manufacturer of the pipe assembly shall declare the minimum installation bending radii for all

dimensions produced, related to the central axis of the pipe assembly.
---------------------- Page: 14 ----------------------
oSIST prEN 15632-1:2021
prEN 15632-1:2020 (E)

The minimum declared installation bending radius of the pipe assembly according to this document

shall not exceed thirty times the outer diameter of the casing.

When bending to the minimum radius, the service pipe and the casing of the pipe assembly shall not

break.
5.2.2 Ovality

When bending to the minimum radius, the service pipe and the casing of the pipe assembly shall not

break.
5.2.3 Cracks

Cracks in the thermal insulation layer shall not exceed a width of 5 mm when tested according 6.2.3.

NOTE With a crack size below 5 mm the number of crack is not relevant for the integrity of the pipe system,

because the temperature on the casing will not be influenced.
5.2.4 Centre line deviation of service pipe

The deviation of the service pipe to the centre line of the pipe assembly shall not ex

...