EN 448:2019

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

This document specifies requirements and test methods for factory made thermally insulated bonded fitting assemblies for hot water networks in accordance with EN 13941 1, comprising a steel service fitting, rigid polyurethane foam thermal insulation and a casing of polyethylene.
The fitting assembly could also include the following additional elements: measuring wires, spacers and diffusion barriers.
This document covers the following fitting assemblies: bend, tee, reducer, single use compensator and anchor.
This document applies to fitting assemblies with a minimum design pressure of 1,6 MPa (overpressure).

Fernwärmerohre - Einzelrohr-Verbundsysteme für direkt erdverlegte Fernwärmenetze - Werkmäßig gefertigte Verbundformstücke, bestehend aus Stahl-Mediumrohren, einer Wärmedämmung aus Polyurethan und einer Ummantelung aus Polyethylen

Dieses Dokument legt die Anforderungen und Prüfverfahren für werkmäßig gefertigte, wärmegedämmte Verbundformstücke für Fernwärmenetze in Übereinstimmung mit EN 13941-1 fest, die aus einer Stahlarmatur, einer Polyurethan-Hartschaumstoffwärmedämmung und einem Polyethylenmantel bestehen.
Das Verbundformstück könnte darüber hinaus die folgenden zusätzlichen Bauteile umfassen: Messdrähte, Abstandhalter und Diffusionsbarrieren.
Dieses Dokument behandelt folgende Verbundformstücke: Bogen, T-Stück, Reduzierstück, Einmalkompen-sator und Festpunktelement.
Dieses Dokument gilt für Verbundformstücke mit einem Mindestauslegungsdruck von 1,6 MPa (Überdruck).

Tuyaux de chauffage urbain - Systèmes bloqués monotubes pour des réseaux d'eau chaude enterrés directement - Assemblages de raccords manufacturés pour tubes de service en acier, isolation thermique en polyuréthane et tube de protection en polyéthylène

Le présent document spécifie les exigences et les méthodes d’essai applicables aux assemblages de raccords bloqués manufacturés isolés thermiquement pour les réseaux d'eau chaude, conformes à l’EN 13941-1, comprenant un raccord de service en acier, une isolation thermique en mousse rigide de polyuréthane et un tube de protection en polyéthylène.
L’assemblage de raccord peut également comprendre les éléments supplémentaires suivants : câbles de mesure, entretoises et barrières anti-diffusion.
Le présent document couvre les assemblages de raccords suivants : coude, té, réducteur, compensateur à usage unique et pièce d’ancrage.
Le présent document s’applique aux assemblages de raccords de pression minimale de calcul de 1,6 MPa (surpression).

Cevi za daljinsko ogrevanje - Poviti enocevni sistemi za neposredno vkopana vročevodna omrežja - Tovarniško izdelana armatura iz jeklenih delovnih cevi, obdanih s poliuretansko toplotno izolacijo in zaščitnim plaščem iz polietilena

Ta dokument določa zahteve in preskusne metode za tovarniško izdelane toplotno izolirane sestave fitingov za vročevodna omrežja v skladu s standardom prEN 13941-1, ki so sestavljeni iz jeklenih fitingov, trde poliuretanske izolacijske pene in polietilenskega plašča. Sestav fitingov lahko vključuje tudi naslednje dodatne elemente: merilne žice, distančnike in difuzijske pregrade. Ta dokument zajema naslednje sestave fitingov: kolena, T-komade, reducirne priključke, kompenzatorje za enkratno uporabo in sidra. Ta dokument se uporablja za sestave fitingov z minimalnim predvidenim tlakom 16 barov (nadtlak).

General Information

• Status: Withdrawn
• Publication Date: 15-Oct-2019
• Withdrawal Date: 13-Apr-2025
• ICS: 23.040.07 - Pipeline and its parts for district heat
• ICS: 23.040.40 - Metal fittings
• Technical Committee: CEN/TC 107 - Pre-fabricated district heating pipe systems
• Drafting Committee: CEN/TC 107/WG 5 - Fittings and valves
• Current Stage: 9960 - Withdrawal effective - Withdrawal
• Start Date: 19-Mar-2025
• Completion Date: 14-Apr-2025
• Ref Project: SIST EN 448:2020 - 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

Relations

• Replaces: EN 448:2015 - 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
• Effective Date: 14-Jun-2017
• Replaced By: EN 448:2025 - 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
• Effective Date: 19-Jan-2023

Standards Content (Sample)

SLOVENSKI STANDARD
01-januar-2020
Nadomešča:
SIST EN 448:2016
Cevi za daljinsko ogrevanje - Poviti enocevni sistemi za neposredno vkopana
vročevodna omrežja - Tovarniško izdelana armatura iz jeklenih delovnih cevi,
obdanih s poliuretansko toplotno izolacijo in zaščitnim plaščem iz polietilena
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
Fernwärmerohre - Werkmäßig gedämmte Verbundmantelrohrsysteme für direkt
erdverlegte Fernwärmenetze - Verbundformstücke, bestehend aus Stahl-Mediumrohr,
Polyurethan-Wärmedämmung und Außenmantel aus Polyethylen
Tuyaux de chauffage urbain - Systèmes bloqués monotubes pour des réseaux d'eau
chaude enterrés directement - Assemblages de raccords manufacturés pour tubes de
service en acier, isolation thermique en polyuréthane et tube de protection en
polyéthylène
Ta slovenski standard je istoveten z: EN 448:2019
ICS:
23.040.07 Cevovodi za daljinsko Pipeline and its parts for
ogrevanje in njihovi deli district heat
23.040.40 Kovinski fitingi Metal fittings
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 448
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2019
EUROPÄISCHE NORM
ICS 23.040.07; 23.040.40 Supersedes EN 448:2015
English Version
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
Tuyaux de chauffage urbain - Systèmes bloqués Fernwärmerohre - Verbund-Rohrsysteme mit einem
monotubes pour des réseaux d'eau chaude enterrés Mediumrohr für direkt erdverlegte Fernwärmenetze -
directement - Assemblages de raccords manufacturés Werkmäßig hergestellte Formstücke bestehend aus
pour tubes de service en acier, isolation thermique en Stahl-Mediumrohren, einer Wärmedämmung aus
polyuréthane et tube de protection en polyéthylène Polyurethan und einer Ummantelung aus Polyethylen
This European Standard was approved by CEN on 12 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 448:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 7
4 Requirements . 7
5 Test methods . 17
6 Marking . 21
Annex A (informative) Guidelines for inspection and testing . 23
Annex B (informative) Procedures for casing welding . 26
Annex C (informative) Waste treatment and recycling . 30
Bibliography . 31
European foreword
This document (EN 448:2019) 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 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 448:2015.
In comparison with the previous edition, the main changes in EN 448:2019 are:
— editorial changes to the new structure of standards prepared by the Technical Committee
CEN/TC 107.
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
EN 448 has been aligned with EN 488 and other relevant European Standards.
Other standards from CEN/TC 107 are:
— EN 253, 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;
— 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 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 15632 (all parts), District heating pipes — Pre-insulated flexible pipe 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 factory made thermally insulated bonded fitting
assemblies for hot water networks in accordance with EN 13941-1, comprising a steel service fitting, rigid
polyurethane foam thermal insulation and a casing of polyethylene.
The fitting assembly could also include the following additional elements: measuring wires, spacers and
diffusion barriers.
This document covers the following fitting assemblies: bend, tee, reducer, single use compensator and
anchor.
This document applies to fitting assemblies with a minimum design pressure of 1,6 MPa (overpressure).
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 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
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 10253-2, Butt-welding pipe fittings — Part 2: Non alloy and ferritic alloy steels with specific inspection
requirements
EN 12814-1, Testing of welded joints of thermoplastics semi-finished products — Part 1: Bend test
EN 13018, Non-destructive testing — Visual testing — General principles
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 — Preinsulated bonded pipe systems for directly buried hot water networks —
Surveillance systems
EN 14870-1, Petroleum and natural gas industries — Induction bends, fittings and flanges for pipeline
transportation systems — Part 1: Induction bends (ISO 15590-1)
EN 17248, District heating and district cooling pipe systems — Terms and definitions
EN ISO 3452-1, Non-destructive testing — Penetrant testing — Part 1: General principles (ISO 3452-1)
EN ISO 5579, Non-destructive testing — Radiographic testing of metallic materials using film and X- or gamma
rays — Basic rules (ISO 5579)
EN ISO 5817, Welding — Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding
excluded) — Quality levels for imperfections (ISO 5817)
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 9606-1, Qualification testing of welders — Fusion welding — Part 1: Steels (ISO 9606-1)
EN ISO 9692-1:2013, Welding and allied processes — Types of joint preparation — Part 1: Manual metal arc
welding, gas-shielded metal arc welding, gas welding, TIG welding and beam welding of steels
(ISO 9692-1:2013)
EN ISO 9934-1, Non-destructive testing — Magnetic particle testing — Part 1: General principles (ISO 9934-1)
EN ISO 10675-1, Non-destructive testing of welds — Acceptance levels for radiographic testing — Part 1: Steel,
nickel, titanium and their alloys (ISO 10675-1)
EN ISO 11666, Non-destructive testing of welds — Ultrasonic testing — Acceptance levels (ISO 11666)
EN ISO 14732, Welding personnel — Qualification testing of welding operators and weld setters for
mechanized and automatic welding of metallic materials (ISO 14732)
EN ISO 15607, Specification and qualification of welding procedures for metallic materials — General rules
(ISO 15607)
EN ISO 16810, Non-destructive testing — Ultrasonic testing — General principles (ISO 16810)
EN ISO 17636-1, Non-destructive testing of welds — Radiographic testing — Part 1: X- and gamma-ray
techniques with film (ISO 17636-1)
EN ISO 17636-2, Non-destructive testing of welds — Radiographic testing — Part 2: X- and gamma-ray
techniques with digital detectors (ISO 17636-2)
EN ISO 17637, Non-destructive testing of welds — Visual testing of fusion-welded joints (ISO 17637)
EN ISO 17638, Non-destructive testing of welds — Magnetic particle testing (ISO 17638)
EN ISO 17640, Non-destructive testing of welds — Ultrasonic testing — Techniques, testing levels, and
assessment (ISO 17640)
EN ISO 23277, Non-destructive testing of welds — Penetrant testing — Acceptance levels (ISO 23277)
EN ISO 23278, Non-destructive testing of welds — Magnetic particle testing — Acceptance levels (ISO 23278)
ISO 6761, Steel tubes — Preparation of ends of tubes and fittings for welding
3 Terms and definitions
For the purpose 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 Steel parts
4.1.1 General
The material of the fitting steel parts shall be certified in accordance with EN 10204. If traceability on
material 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.
4.1.2 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 fitting assemblies, this request shall be given whilst placing the order with the manufacturer of
the fitting assemblies.
Any later request for provision of such documentation can be too late and can possibly not be met by the
manufacturer, since the manufacturer shall organize the assignment of 3.1 certificates to pipes and part of
pipes before starting the production.
4.1.3 Wall thickness and diameter
According to the scope of this document, all components shall be designed for a minimum of 1,6 MPa.
If the fitting assemblies shall be used in situations with pressures higher than 1,6 MPa, extra calculations will
be necessary.
The minimum nominal wall thickness of all components shall prior to processing be at least the same as for
the service pipes regarding EN 253.
The nominal diameter, the outside diameter, the tolerances on the diameter of the pipe ends and the wall
thickness shall be the same as for the service pipes in accordance with EN 253.
Subject to design considerations other wall thicknesses than those given in EN 253 may be used, but in no
case shall these be less than the minima indicated in EN 253.
All components shall be designed in accordance with EN 13941-1, for the actions and stresses that normally
occur during the service life of the fitting assembly (or of the component).
4.1.4 Bends
4.1.4.1 Butt welding bends
The dimensions shall be in accordance with EN 10253-2 with the exception that the bend radius shall
be ≥ 1,5 times the outer diameter.
4.1.4.2 Cold formed bends
Cold formed bends shall be produced from seamless pipe or longitudinal welded pipes. At cold formed bends
made of longitudinal welded pipes the weld bead shall be welded to factor V = 1 (calculation stress = 100 %).
After bending, the minimum wall thickness of the bent pipe shall be not less than 85 % of the wall thickness
of the straight pipe (see EN 253).
The maximum ovality in the bent area shall not exceed 6 %.
The formula for the calculation of the ovality is:
DD−
ss,max ,min
0 × 100 (1)
D
s
where
o is the ovality, in %;
is the maximum outside diameter;
D
s,max
is the minimum outside diameter in the same cross section in the bended
D
s,min
area;
is the specified outside diameter.
D
s
There shall be no folding in the bent area. Waves can be accepted, when the maximum height between
trough and crest of the wave does not exceed 25 % of the nominal wall thickness of the bent pipe.
4.1.4.3 Hot-formed bends
For hot-formed bends manufactured from straight pipes by means of inductive heating (induction bends), no
heat treatment is necessary as far as this method is applied with unalloyed or low-alloyed steel with
[Mo] < 0,65 %. Hot-formed bends shall be supplied in conformity with EN 14870-1.
If for the bending other heating methods are applied, heat treatment following the bending of the pipes is
required.
If a hot-formed bend shall be made from line pipe, this should be specified to the pipe manufacturer at the
time of ordering so that they can take this into account when selecting the (chemical) composition of the
pipe material and the welding filler material.
It is recommended to determine per batch, diameter, wall thickness and bend radius, through mechanical
testing, that the bends comply with the applicable material specifications. It is customary that a
representative bend or an (additional) section of a bend of adequate length be manufactured during the
production process and that 10 % of the bends be tested.
4.1.4.4 Tolerances of bending angles
The deviation from the nominal bending angle shall not exceed the tolerances given in Table 1.
Table 1 — Deviations from nominal bending angle
Deviation
Nominal diameter of
service pipe
≤ DN 200 ±2,0°
> DN 200 ±1,0°
=
4.1.5 T-pieces
4.1.5.1 Forged T-pieces
The wall thickness t and t see EN 10253-2, shall be at least the same as those for the straight pipes, see
1,
EN 253. All other dimensions shall be in accordance with EN 10253-2.
4.1.5.2 Welded T-pieces
Welded T-pieces shall be manufactured by drawing a collar on which the branch pipe is welded or by
welding the branch pipe directly to the main pipe. The wall thickness of the collar shall be at least the same
as that for the branch pipe, see EN 253. The collar shall be drawn opposite the welding seam in the main
pipe. When using branch pipe directly welded to the main pipe, compensating (reinforcement) plates can be
used according to EN 13941-1 requirements.
4.1.5.3 Tolerances of angles between branch pipes and main pipes
The branch pipes shall be perpendicular to the main pipes within a tolerance of ± 2,0°.
4.1.6 Reducers
Reducers shall be in accordance with EN 10253-2, except for the wall thicknesses T and T see EN 10253-2
1,
which shall be at least the same as for the straight pipes (see EN 253) to be welded to the fittings.
4.1.7 Anchors
The anchors shall be marked with the information concerning maximum loads for which the construction
was designed and calculated. The lifetime of the system shall not be influenced by the anchors construction.
4.1.8 Single use compensators
A single use compensator shall comply with the requirements of EN 13941-1.
4.1.9 Caps
Caps (dished ends) shall be in accordance with EN 10253-2 and comply with the requirements of
EN 13941-1.
4.1.10 Fusion welding of steel fittings
4.1.10.1 Filler material
Filler material shall after welding have mechanical characteristics comparable with the parent metal.
4.1.10.2 Welding process
All types of fusion welding are acceptable but arc welding with covered electrodes and gas-shielded metal-
arc welding are preferred. The welding process shall be specified and approved in accordance with
EN ISO 15607.
The method of approval may be chosen by the manufacturer.
Fittings of wall thickness ≥ 5,6 mm shall be welded in more than one pass.
4.1.10.3 Preparation for welding
Pipe ends shall be prepared in accordance with the welding procedure used. When using covered electrodes
or gas-shielded metal-arc welding, pipe ends and fittings with equal wall thickness shall be prepared in
accordance with EN ISO 9692-1.
Table 2 of this document is derived from EN ISO 9692-1:2013, Table 1 and gives the relation between wall
thickness and reference number.
Table 2 — Preparation of ends of pipes and fittings for weldings according to EN ISO 9692-1:2013
Symbol Type of preparation Wall thickness t of steel service Reference to
pipe fittings or fitting end EN ISO 9692-1:2013, Table 1
II Square preparation t < 3 mm 1.2.1
V Single V preparation 3 mm ≤ t ≤ 10 mm 1.3
Y Single Y preparation with t > 10 mm 1.5
broad root face
NOTE Symbols are in accordance with EN ISO 2553.
Pipe ends and fittings with different wall thicknesses shall be prepared and adapted for misalignment in
accordance with Table 3 and Figure 1 of this document.
Table 3 — Adaptation of misalignment and difference in wall thickness
Adaptation Required action
Misalignment
Misalignment h ≤ 0,3 t, max. 1 mm Figure 1 detail A
Misalignment 1 mm < h ≤ 10 mm  Adaptation of pipe ends
Misalignment h > 10 mm Extra fitting Extra prepared steel fitting minimum
length.
The seam spacing shall be such that the
heat-affected zones do not overlap or
interact. A spacing of 100 mm or more is
recommended. The minimum spacing is
50 mm.
Difference in wall thickness
Differences in wall thickness: t' ≤ 1,5 tn Figure 1 detail B Adaptation of thicker wall t'
Differences in wall thickness: t' > 1,5 t Figure 1 detail C Adaptation of both sides
n
Key
h misalignment
tn smallest wall thickness
t’ largest wall thickness
Figure 1 — Misalignment, difference in wall thickness and steel service pipe end preparation, in
accordance with EN 13941-2
When manufacturing T-pieces with the branch pipe welded directly to the main pipe, preparations shall
comply with Figure 2.
Key
a  section X at crotch of right angle branch c  section Y at flank of unequal branch. Ratios of
diameters > 2/3
b  section Y at flank of unequal branch. Ratios of
diameters ≤ 2/3 d  section W at flank of equal branch
Figure 2 — Preparation of set-on branches
4.1.10.4 Inspection of welds
4.1.10.4.1 Detail a – Visual surface examination
When visual surface examination is carried out, it shall be in accordance with 5.3.1. The examinations
include a check of surface, internal, joint geometry and multiple imperfections. The welding shall comply
with “quality level B” of EN ISO 5817.
4.1.10.4.2 Detail b – Leak tightness test
When a leak-tightness test is carried out in accordance with 5.3.2 or 5.3.3, the welds shall fulfil the
conditions stated there.
4.1.10.4.3 Detail c – Non-destructive examination of welds
When non-destructive is carried out, it shall be in accordance with 5.3.4. The weld shall comply with
“quality level B” of EN ISO 5817.
4.1.10.5 Competence of the welder
The welder shall have a valid certificate according to EN ISO 9606-1 for the techniques, material groups,
dimension ranges and welding position concerned. Welding personnel operating mechanized welding
equipment shall be qualified in accordance with EN ISO 14732.
4.1.11 Surface condition
In order to ensure proper bonding between the steel service pipe and the Polyurethan (PUR) foam thermal
insulation, the following procedure shall be followed:
a) prior to PUR foam, 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;
b) before cleaning the pipe, the outer surface of the pipe shall comply with rust grade A, B or C according to
EN ISO 8501-1, without pitting.
4.2 Casing
The casings shall meet the requirements of EN 253.
The casing shall be tested in accordance with 5.4 of this document.
4.3 Polyurethane (PUR) foam thermal insulation
The PUR foam thermal insulation for fitting assemblies shall meet the requirements of EN 253 and shall be
tested in accordance with 5.5 of this document. Test specimens from fitting assemblies to establish foam
properties shall be taken in accordance with 5.2 of this document.
4.4 Fitting assemblies
4.4.1 Fitting ends
4.4.1.1 Service pipe
The ends of the steel service pipes shall be free from thermal insulation according to EN 253 and shall be
prepared for welding in accordance with ISO 6761.
4.4.1.2 Centre line deviation
When tested in accordance with 5.6.1 the distance between centre lines of the steel service pipe and the
casing at fitting ends shall not exceed the limits given in EN 253.
4.4.1.3 Angular deviation between steel service pipe and casing
When tested in accordance with 5.6.1, the angular deviation between centre lines of the not insulated end of
the
...