SIST EN 488:2011+A1:2014
(Main)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
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
This European Standard specifies requirements and test methods for valves of prefabricated thermally insulated valve assemblies comprising a steel valve, rigid polyurethane foam insulation and an outer casing of polyethylene for use in directly buried hot water networks with pre-insulated pipe assemblies in accordance with EN 253. This European Standard applies only to insulated valve assemblies for continuous operation with hot water at various temperatures in accordance with EN 253:2009, Clause 1 and the valve assemblies with a maximum operation pressure of 25 bar. For higher pressures, additional demands apply. Guidelines for quality inspection are given in Annex A of this European Standard. NOTE For this application, the following valve types are commonly used: ball valves, gate valves, and butterfly valves. This European Standard does not include calculation rules for loads and stresses. These depend on the configuration of the system as it is installed. The design and installation rules are given in EN 13941:2009+A1:2010.
Fernwärmerohre - Werkmäßig gedämmte Verbundmantelrohrsysteme für direkt erdverlegte Fernwärmenetze - Vorgedämmte Absperrarmaturen für Stahlmediumrohre mit Polyurethan-Wärmedämmung und Außenmantel aus Polyethylen
Diese Europäische Norm legt Anforderungen an und Prüfverfahren für vorgefertigte, wärmegedämmte
Absperrarmaturen fest, die eine Stahlarmatur, eine Wärmedämmung aus Polyurethan-Hartschaumstoff und
eine Ummantelung aus Polyethylen umfassen und in direkt erdverlegten Fernwärmenetzen mit werkmäßig
gedämmten Verbund-Rohrsystemen nach EN 253 verwendet werden.
Diese Norm gilt nur für wärmegedämmte Absperrarmaturen für einen Dauerbetrieb mit Warmwasser bei
verschiedenen Betriebstemperaturen in Übereinstimmung mit EN 253:2009, Abschnitt 1, sowie Absperrarmaturen
mit einem maximalen Betriebsdruck von 25 bar. Für höhere Drücke gelten zusätzliche Anforderungen.
Leitlinien für die Qualitätsprüfung sind in Anhang A dieser Norm enthalten.
ANMERKUNG Für diese Anwendung werden gewöhnlich folgende Grundbauarten von Armaturen eingesetzt:
Kugelventile, Klappen und Schieber.
Diese Norm enthält keine Regeln zur Berechnung von Belastungen und Spannungen. Diese sind von der
Konfiguration des Systems bei dessen Installation abhängig. Regeln für Auslegung und Installation sind
EN 13941:2009+A1:2010 zu entnehmen.
Tuyaux de chauffage urbain - Systèmes bloqués de tuyaux préisolés pour les réseaux d'eau chaude enterrés directement - Robinets préisolés pour tubes de service en acier, isolation thermique en polyuréthane et tube de protection en polyéthylène
La présente Norme européenne spécifie les caractéristiques et les méthodes d’essai des robinets préisolés
préfabriqués isolés thermiquement constitués d’un appareil de robinetterie en acier, d’un isolant en mousse
rigide de polyuréthanne et d’une protection en polyéthylène pour une utilisation sur des réseaux d’eau chaude
enterrés directement comportant des assemblages de tuyaux préisolés conformes à l’EN 253.
La présente Norme européenne s'applique uniquement aux assemblages d'appareils de robinetterie isolés
destinés à un fonctionnement en continu avec de l'eau chaude aux diverses températures indiquées dans
l'EN 253:2009, Article 1, mais également aux assemblages de robinetterie avec une pression de service
maximale de 25 bar. Pour des pressions supérieures, des exigences supplémentaires s'appliquent.
Les lignes directrices relatives au contrôle qualité sont données à l'Annexe A de la présente Norme
européenne.
NOTE Les types de robinet suivants sont communément utilisés dans ce genre d’application : robinets à tournant
sphérique, robinets-vannes et robinets à papillon.
La présente Norme européenne ne comprend pas de règles de calcul pour les charges et les contraintes.
Celles-ci dépendent de la configuration du système lors de son installation. Les règles de conception et
d'installation sont données dans l'EN 13941:2009+A1:2010.
Cevi za daljinsko ogrevanje - Izolirani vezani cevni sistemi za podzemeljska toplovodna omrežja - Sestav jeklenih ventilov za jeklene cevi, poliuretanske toplotne izolacije in zunanjega polietilenskega plašča
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 488:2011+A1:2014
01-april-2014
1DGRPHãþD
SIST EN 488:2011
&HYL]DGDOMLQVNRRJUHYDQMH,]ROLUDQLYH]DQLFHYQLVLVWHPL]DSRG]HPHOMVND
WRSORYRGQDRPUHåMD6HVWDYMHNOHQLKYHQWLORY]DMHNOHQHFHYLSROLXUHWDQVNH
WRSORWQHL]RODFLMHLQ]XQDQMHJDSROLHWLOHQVNHJDSODãþD
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
Fernwärmerohre - Werkmäßig gedämmte Verbundmantelrohrsysteme für direkt
erdverlegte Fernwärmenetze - Vorgedämmte Absperrarmaturen für Stahlmediumrohre
mit Polyurethan-Wärmedämmung und Außenmantel aus Polyethylen
Tuyaux de chauffage urbain - Systèmes bloqués de tuyaux préisolés pour les réseaux
d'eau chaude enterrés directement - Robinets préisolés pour tubes de service en acier,
isolation thermique en polyuréthane et tube de protection en polyéthylène
Ta slovenski standard je istoveten z: EN 488:2011+A1:2014
ICS:
23.040.10 Železne in jeklene cevi Iron and steel pipes
23.060.01 Ventili na splošno Valves in general
91.140.65 Oprema za ogrevanje vode Water heating equipment
SIST EN 488:2011+A1:2014 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 488:2011+A1:2014
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SIST EN 488:2011+A1:2014
EUROPEAN STANDARD
EN 488:2011+A1
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2014
ICS 23.060.01 Supersedes EN 488:2011
English Version
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
Tuyaux de chauffage urbain - Systèmes bloqués de tuyaux Fernwärmerohre - Werkmäßig gedämmte
préisolés pour les réseaux d'eau chaude enterrés Verbundmantelrohrsysteme für direkt erdverlegte
directement - Robinets préisolés pour tubes de service en Fernwärmenetze - Vorgedämmte Absperrarmaturen für
acier, isolation thermique en polyuréthane et tube de Stahlmediumrohre mit Polyurethan-Wärmedämmung und
protection en polyéthylène Außenmantel aus Polyethylen
This European Standard was approved by CEN on 19 February 2011 and includes Amendment 1 approved by CEN on 30 November 2013.
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
© 2014 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 488:2011+A1:2014 E
worldwide for CEN national Members.
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SIST EN 488:2011+A1:2014
EN 488:2011+A1:2014 (E)
Contents Page
Foreword .4
1 Scope .7
2 Normative references .7
3 Terms and definitions .8
4 Requirements .9
4.1 Pressure ratings for valves .9
4.1.1 General .9
4.1.2 Valves without indicated flow direction . 10
4.2 Service temperatures for valves . 10
4.3 Steel parts . 10
4.3.1 General . 10
4.3.2 Valve . 10
4.3.3 Valve extension pipe . 10
4.3.4 Welding ends . 10
4.3.5 Welding of steel parts . 10
4.4 Casing . 10
4.4.1 General . 10
4.4.2 Requirements for polyethylene welding . 10
4.4.3 Diameter and wall thickness of the casing . 11
4.5 Polyurethane rigid foam insulation (PUR) . 11
4.5.1 General . 11
4.5.2 Minimum insulation thickness . 11
4.6 Valve assembly . 11
4.6.1 Ends of valve assembly . 11
4.6.2 End of stem construction . 11
4.6.3 Main dimensions of the valve assembly . 12
4.6.4 Installation of measuring elements. 13
4.7 Requirements for effective operation and maintenance . 13
4.8 Resistance to axial forces and bending moments . 13
5 Testing, test methods and test requirements . 13
5.1 General . 13
5.2 Test specimens . 13
5.2.1 General . 13
5.2.2 Test specimens for type testing steel parts of valve . 14
5.2.3 Test specimens from casings and polyurethane foam. 14
5.3 Steel parts . 14
5.3.1 General . 14
5.3.2 Type test of the steel parts . 14
5.3.3 Production testing of valves . 16
5.4 Casing . 17
5.4.1 General . 17
5.4.2 Leak-tightness of the welded casing . 17
5.5 Polyurethane rigid foam insulation . 17
5.6 Valve assembly . 17
5.7 Surveillance system . 17
6 Marking . 17
6.1 General . 17
2
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SIST EN 488:2011+A1:2014
EN 488:2011+A1:2014 (E)
6.2 Steel valve . 17
6.3 Casing . 17
6.4 Valve assembly . 18
7 Installation and maintenance . 18
Annex A (informative) Guidelines for inspection and testing . 19
A.1 General . 19
A.2 Manufacturer’s type test . 19
A.3 Manufacturer’s quality control . 19
A.4 External inspection . 19
A.5 Extent of inspection . 19
A.6 Manufacturer’s responsibility . 19
Annex B (normative) Resistance to axial force and bending moment . 22
B.1 Axial strength test . 22
B.2 Bending test . 22
Annex C (normative) Resistance to bending forces . 24
C.1 Resistance to bending forces . 24
Bibliography . 30
3
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SIST EN 488:2011+A1:2014
EN 488:2011+A1:2014 (E)
Foreword
This document (EN 488:2011+A1:2014) 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 August 2014, and conflicting national standards shall be withdrawn at
the latest by August 2014.
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 2013-11-30.
!This document includes Amendment A1 to EN 488:2011, that comprises technical changes to:
- Sub-Clause 4.6.2, End of stem construction."
This document supersedes !EN 488:2011".
The start and finish of text introduced or altered by amendment is indicated in the text by tags
!".
Annex A is informative, Annexes B and C are normative.
This document includes a Bibliography.
The first edition of EN 488 was approved in 1994. The first revised standard was published in 2003. In this
second revision, in general the whole standard has been edited to make it more readable. Requirements and
test methods have been separated; therefore, clause numbers have changed and some clauses have been
split up in several clauses. Exact references for changes are not always possible. The main areas of the
current revision are:
a) The scope has been amended. The standard applies no longer only to insulated valve assemblies for
continuous operation with hot water at various temperatures in accordance with EN 253:2009, Clause 1
but also to the valve assemblies with a maximum operation pressure of 25 bar. For higher pressure,
additional demands apply. It is also explained that the calculation rules of loads and stresses are not
included. They depend on the configuration of the system as it is installed. The design and installation
rules are given in EN 13941:2009+A1:2010.
b) In Clause 3, “terms and definitions”, definitions for the nominal pressure (PN), nominal size (DN) and
maximum operation pressure have been added. A figure “Example valve assembly components” of a
valve assembly, its components and definitions has been added.
c) Clause 4, “requirements”
1) material of the steel parts in the pressurized parts of the valve shall be certified in accordance with
EN 10204, the 3.1 certificate (4.3.1);
2) it is added that flanged or screwed connections, except sealing system at the stem, shall not be used
except in the non-pressurized area e.g. for the stem extensions (4.3.2);
3) the requirements for the use of stop devices are amended (4.7);
4) the minimum water temperature has been adjusted to 4 °C (4.2);
4
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SIST EN 488:2011+A1:2014
EN 488:2011+A1:2014 (E)
5) 4.3.5 “Welding of steel parts” has been changed and adjusted to EN 13941:2009+A1:2010 and the
text in EN 448;
6) 4.1.6 has become 4.8 “resistance to axial forces bending moments” and has been rewritten in
Annex B;
7) additions have been made to the requirements to the corrosion protection of the stem (see 4.6);
8) the Clause “increase in diameter” has been changed to “diameter and wall thickness of the casing”
(see 4.4.3);
9) a table with the tolerances of the main dimensions has been added together with a figure to explain
the dimensions (see 4.6.3);
10) a clause was added about the installation of measuring elements for surveillance (see 4.6.4).
d) Clause 5, “test methods”
1) the clause “Testing, test methods and test requirements” has been adjusted to make the order of test
clearer;
2) a test for the surveillance system is added (see 5.7).
e) Clause 6, “marking”
1) for the steel valve pressure and temperature and marking with closed and open position;
2) for the casing the date of manufacture has been changed to year and week of manufacture (see 6.3);
3) for the valve assembly, the type of blowing agent and diffusion barrier has been added (see 6.4).
f) Annex A, “guidelines for inspection and testing”
1) the clause about quality surveillance had been changed in quality control (see A.3);
2) a table for the valve assembly inspection had been added.
g) Former Annex B, the guidelines for installation of the valves has been deleted. New Annexes B and C
have been added, in which the actual testing is included.
h) The former Table 1, “Service pipe dimensions and test forces” has been changed due to cold laying
conditions. Therefore, the compressive forces have been adapted. In this table the maximum allowable
bending moments have been included and the table has been moved to Annex B.
i) A description of the test method for bending forces has been added in Annex C.
In general, references were changed were needed. If possible references to European standards were used.
For information on the minimum expected thermal life with operation at various temperatures with respect to
PUR foam performance see EN 253.
The other standards from CEN/TC 107 covering this subject are:
— EN 253, 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;
5
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SIST EN 488:2011+A1:2014
EN 488:2011+A1:2014 (E)
— 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 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 13941:2009+A1:2010, 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 15632 (all parts), District heating pipes — Pre-insulated flexible pipe 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.
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, 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.
6
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SIST EN 488:2011+A1:2014
EN 488:2011+A1:2014 (E)
1 Scope
This European Standard specifies requirements and test methods for valves of prefabricated thermally
insulated valve assemblies comprising a steel valve, rigid polyurethane foam insulation and an outer casing of
polyethylene for use in directly buried hot water networks with pre-insulated pipe assemblies in accordance
with EN 253.
This European Standard applies only to insulated valve assemblies for continuous operation with hot water at
various temperatures in accordance with EN 253:2009, Clause 1 and the valve assemblies with a maximum
operation pressure of 25 bar. For higher pressures, additional demands apply.
Guidelines for quality inspection are given in Annex A of this European Standard.
NOTE For this application, the following valve types are commonly used: ball valves, gate valves, and butterfly
valves.
This European Standard does not include calculation rules for loads and stresses. These depend on the
configuration of the system as it is installed. The design and installation rules are given
in EN 13941:2009+A1:2010.
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 19, Industrial valves - Marking of metallic valves
EN 253:2009, 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
EN 448:2009, 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 736-1:1995, Valves - Terminology - Part 1: Definition of types of valves
!EN 10088-1:2005, Stainless steels - Part 1: List of stainless steels"
EN 10204:2004, Metallic products - Types of inspection documents
EN 12266-1:2003, Industrial valves — Testing of valves — Part 1: Pressure tests, test procedures and
acceptance criteria — Mandatory requirements
EN 13941:2009+A1:2010, 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 12944-2, Paints and varnishes — Corrosion protection of steel structures by protective paint
systems — Part 2: Classification of environments (ISO 12944-2)
EN ISO 12944-5, Paints and varnishes — Corrosion protection of steel structures by protective paint systems
— Part 5: Protective paint systems (ISO 12944-5)"
7
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SIST EN 488:2011+A1:2014
EN 488:2011+A1:2014 (E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 253:2009 and EN 448:2009 and the
following apply. For types of valves, the terms and definitions given in EN 736-1:1995 apply.
3.1
nominal pressure (PN) class
alphanumeric designation used for reference purposes related to a combination of mechanical and
dimensional characteristics of a component of a pipe work system
NOTE 1 It comprises the letters PN followed by a dimensionless number.
NOTE 2 The number following the letters PN does not represent a measurable value and should not be used for
calculation purposes except where specified in the relevant standard.
NOTE 3 The designation PN is not meaningful unless it is related to the relevant component standard number.
NOTE 4 The allowable pressure of a pipe work component depends on the PN number, the material and design of the
component, its allowable temperature, etc., and is given in tables of pressure/temperature ratings specified in the
appropriate standards.
NOTE 5 Definition is according to EN 1333.
3.2
maximum operation pressure
maximum internal pressure acting against the pipe wall at any point or in any section of the pipeline at a given
operating temperature
NOTE Definition is according to EN 13941:2009+A1:2010.
3.3
nominal size (DN)
numerical metric designation of size is common to components in piping systems of any one size
NOTE Definition is according to EN ISO 6708.
3.4
valve assembly
assembly of valve, valve extension pipe, PE-casing and PUR-foam
NOTE Figure 1 gives an example a valve assembly and its components.
8
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SIST EN 488:2011+A1:2014
EN 488:2011+A1:2014 (E)
Key
a valve
b valve extension pipe
c valve assembly
d service pipe
e insulation
Figure 1 — Example valve assembly components
3.5
valve
part of the valve assembly supplied by the valve manufacturer (with or without valve extension pipe)
3.6
valve extension pipe
pipe part of the valve assembly welded to the valve
NOTE The valve extension may be required before the insulation process. This can be done by the valve
manufacturer or the insulation manufacturer. The valve can be extended with valve extension pipes before insulation or
delivered by the valve manufacturer with extensions.
3.7
welding end on valve
welding end of the valve
3.8
steel service pipe
service pipe according to EN 253
4 Requirements
4.1 Pressure ratings for valves
4.1.1 General
The valves shall be designed for use in pipe systems with a maximum operating pressure of 16 bar or 25 bar.
The valves shall be able to withstand a strength test pressure of the district heating system of 1,5 times the
maximum operating pressure at ambient temperature in open and closed position.
9
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SIST EN 488:2011+A1:2014
EN 488:2011+A1:2014 (E)
4.1.2 Valves without indicated flow direction
Valves without an indicated flow direction shall support the pressure load in both directions.
4.2 Service temperatures for valves
The valves shall be able to withstand continuous operation with hot water at various temperatures in
accordance with EN 253:2009, Clause 1 and at a minimum water temperature of 4 °C.
4.3 Steel parts
4.3.1 General
The material in the pressurized parts of the valve shall be certified, with a 3.1 certificate, in accordance with
EN 10204. If traceability on materials is required by the end user it shall be specified at the time of ordering.
Corresponding material certificates shall be delivered to the end user if specified at the time of ordering.
All components shall be designed in accordance with EN 13941:2009+A1:2010, for the actions and stresses
that normally occur during a system's entire service life
4.3.2 Valve
The valve shall be fully welded. Detachable joints, such as flanged or screwed connections, except sealing
system at the stem, shall not be used in the pressurized area.
4.3.3 Valve extension pipe
The quality of the valve body shall match with the quality of the valve extension pipe.
4.3.4 Welding ends
The welding ends of the valve assembly shall match with the service pipe in accordance with EN 253:2009,
4.2.2.
Pipe ends shall be prepared in accordance with EN 448:2009, 4.1.9.3.
4.3.5 Welding of steel parts
Fusion welding between valves and valve extension pipe, respectively between valve steel pipe and steel
service pipes shall be carried out in accordance with EN 448:2009, 4.1.9.
The quality of the steel at the weld ends of the valve or valve assembly shall match with steel of the service
pipes.
Welding of pressurized parts of the valve shall comply with EN 448:2009, 4.1.9.2 and 4.1.9.5.
4.4 Casing
4.4.1 General
The casing shall be in accordance with EN 448 and EN 253.
4.4.2 Requirements for polyethylene welding
The general requirements for polyethylene welding shall be in accordance with EN 448:2009, 4.4.3.
10
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SIST EN 488:2011+A1:2014
EN 488:2011+A1:2014 (E)
4.4.3 Diameter and wall thickness of the casing
The outside diameter and the minimum wall thickness of the PE casing shall be in accordance with
EN 448:2009, 4.4.5.
4.5 Polyurethane rigid foam insulation (PUR)
4.5.1 General
The requirements for PUR shall be the same as in EN 448:2009, 4.3 when tested in accordance with 5.5 of
this standard.
4.5.2 Minimum insulation thickness
The minimum insulation thickness shall be in accordance with EN 448:2009, 4.4.6.
4.6 Valve assembly
4.6.1 Ends of valve assembly
4.6.1.1 General
The ends of the valve extension pipe of the valve assembly shall be prepared for welding according 4.3.3 and
shall be free from insulation for a minimum length of 150 mm. The tolerance in the declared value shall be
+ 10 mm.
4.6.1.2 Centre line deviation
The distance between the centre lines of the valve extension pipe and the casing at the ends of the valve
asse
...
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