EN 1366-5:2021

Fire resistance tests for service installations - Part 5: Service ducts and shafts

This document specifies a method for determining the fire resistance of horizontal service ducts and vertical service shafts, which pass through walls or floors and enclose pipes and cables, to classify them according to EN 13501-2. The test scenario examines the behaviour of ducts and shafts exposed to fire either from outside or from inside the system. This document is intended to be read in conjunction with EN 1363-1.
This document does not examine the risk of fire spread as a result of thermal conduction along the piping or cabling installed in service ducts or shafts or thermal conduction through the media these pipes carry. It does not cover the risk of damage produced by thermal elongation or shortening of tubes and cables as a result of fire or damaged pipe suspensions. This document does not give guidance on how to test one, two or three sided service ducts or shafts.
NOTE Guidance on testing service ducts and shafts of less than four sides will be covered in the extended field of application rules being developed by CEN/TC 127.
This test can be used for systems with boards and also for such systems with continuous covering with intumescent materials on the boards. It cannot be used for systems where intumescent material is only applied in the range of the penetration.
This test is unsuitable for evaluating service ducts or shafts with internal barriers at walls and floors.
This test is unsuitable for evaluating fire protective systems for cable systems and associated components with maintenance of integrity in case of fire. This is covered by EN 1366-11: Fire protective systems for cable systems and associated components - Part 11: Fire protective systems for cable systems and associated components.
Whilst the walls of service ducts or shafts tested to this method may provide specified levels of integrity or insulation, testing according this document does not replace the testing of the functional endurance of small electrical cables which is covered in EN 50200.
Fire resistance testing of ducts for air distribution systems is covered in EN 1366-1.

Feuerwiderstandsprüfungen für Installationen - Teil 5: Installationskanäle und -schächte

Dieses Dokument legt ein Prüfverfahren für die Ermittlung der Feuerwiderstandsfähigkeit von horizontalen Installationskanälen und vertikalen Installationsschächten, die Wände oder Decken durchqueren und Rohre und Kabel beinhalten, fest mit dem Ziel, eine Klassifizierung nach EN 13501-2 vorzunehmen. Die Prüfung ermittelt das Verhalten von Installationskanälen und -schächten bei Brandbeanspruchung sowohl von außerhalb als auch von innerhalb des Systems. Dieses Dokument gilt in Verbindung mit EN 1363 1.
Dieses Dokument befasst sich nicht mit der Gefahr der Brandübertragung infolge von Wärmeleitung durch die Rohrleitungen oder Kabel, die in Installationskanälen oder –schächten installiert sind, oder infolge von Wärmeleitung über die Medien, welche diese Rohrleitungen führen. Diese Prüfung deckt auch nicht die Gefahr der Beschädigung durch die thermische Verlängerung oder Verkürzung von Rohren oder Kabeln infolge eines Brandes oder durch beschädigte Rohraufhängungen ab. Dieses Dokument enthält keine Anleitung zum Prüfen von ein-, zwei- oder dreiseitigen Installationskanälen oder Installationsschächten.
ANMERKUNG   Eine Anleitung zum Prüfen von Installationskanälen und –schächten mit weniger als vier Seiten wird von den Regeln zum erweiterten Anwendungsbereich abgedeckt werden, die im CEN/TC 127 in Erarbeitung sind.
Die Prüfung kann sowohl für Systeme mit Platten als auch für Systeme mit einer durchgehenden Abdeckung aus intumeszierenden Materialien auf den Platten angewendet werden. Sie kann nicht für Systeme angewendet werden, in denen intumeszierendes Material nur im Bereich der Durchführung aufgebracht wird.
Diese Prüfung eignet sich nicht für die Bewertung von Installationskanälen oder –schächten mit inneren Abschottungen im Bereich von Wänden und Decken.
Die Prüfung ist ungeeignet für die Bewertung von Brandschutzsystemen für Kabelsysteme und zugehörige Komponenten zur Aufrechterhaltung des Raumabschlusses im Brandfall. Dies wird in EN 1366 11, Feuerwiderstandsprüfungen für Installationen — Teil 11: Brandschutzsysteme für Kabelanlagen und zugehörige Komponenten, behandelt.
Obwohl die Wände der nach diesem Verfahren geprüften Installationskanäle oder -schächte eine bestimmte Klasse des Raumabschlusses oder der Wärmedämmung liefern können, ersetzt eine Prüfung nach diesem Dokument nicht die Prüfung des Funktionserhalts von elektrischen Kabeln nach EN 50200.
Die Feuerwiderstandsprüfung von Lüftungsleitungen wird in EN 1366 1 behandelt.

Essais de résistance au feu des installations de service - Partie 5 : Gaines pour installation technique

Le présent document spécifie une méthode de détermination de la résistance au feu des gaines horizontales ou verticales pour installation technique qui traversent les murs ou les planchers et qui enferment des tuyaux et des câbles, afin de les classer conformément à l’EN 13501-2. Le scénario d’essai examine le comportement des gaines exposées à un feu depuis l’extérieur ou depuis l’intérieur du système. Le présent document est destiné à être lu conjointement avec l’EN 1363-1.
Le présent document ne traite pas des risques de propagation du feu dus à la conduction de chaleur le long des canalisations ou des câblages installés dans les gaines pour installation technique ou au transfert de chaleur à travers les fluides qu’ils véhiculent. Il ne traite pas non plus des risques de dégradation produite par allongement ou raccourcissement thermique des tubes et des câbles suite à un incendie, ni de la détérioration des dispositifs de suspension des tuyaux. Ce document ne fournit pas de conseils sur la manière d’essayer les gaines pour installation technique à un, deux ou trois côtés.
NOTE Les conseils relatifs à l’essai des gaines pour installation technique ayant moins de quatre côtés seront traités dans les règles de domaine d’application étendue actuellement en cours d’élaboration au sein du CEN/TC 127.
Cet essai peut être utilisé pour les systèmes munis de plaques et également pour les systèmes dont les plaques comportent une couverture continue en matériaux intumescents. Il ne peut pas être utilisé pour des systèmes dans lesquels le matériau intumescent est seulement appliqué dans la zone de pénétration.
Le présent essai ne convient pas à l’évaluation des gaines pour installation technique avec recoupements internes au niveau des murs et planchers.
Le présent essai ne convient pas à l’évaluation des systèmes de protection incendie pour les systèmes de câbles et composants associés dont la fonctionnalité électrique est maintenue en cas d’incendie. Ces derniers sont couverts par l’EN 1366-11 : Systèmes de protection incendie pour les systèmes de câbles et composants associés - Partie 11 : Systèmes de protection incendie pour les systèmes de câbles et composants associés.
Bien que les parois des gaines pour installation technique soumises à l’essai selon la présente méthode puissent fournir des niveaux spécifiés d’étanchéité au feu ou d’isolation thermique, l’essai conformément au présent document ne remplace pas les essais de résistance fonctionnelle des petits câbles électriques traités dans l’EN 50200.
Les essais de résistance au feu des conduits de ventilation sont traités dans l’EN 1366-1.

Preskusi požarne odpornosti servisnih inštalacij - 5. del: Servisni kanali in jaški

General Information

• Status: Published
• Publication Date: 02-Feb-2021
• Withdrawal Date: 30-Aug-2021
• ICS: 13.220.50 - Fire-resistance of building materials and elements
• ICS: 91.060.40 - Chimneys, shafts, ducts
• Technical Committee: CEN/TC 127 - Fire safety in buildings
• Drafting Committee: CEN/TC 127/WG 2 - Services
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 03-Feb-2021
• Due Date: 01-Dec-2020
• Completion Date: 03-Feb-2021
• Directive: 305/2011 - Regulation (eu) No 305/2011 of the European Parliament and of the Council of 9 march 2011 laying down harmonised conditions for the marketing of construction products and repealing council directive 89/106/eec
• Mandate: M/117 - Horizontal complement to the mandates to CEN/CENELEC concerning the execution of standardization work for the valuation of construction products and elements in respect of their resistance to fire
• Ref Project: SIST EN 1366-5:2021 - Fire resistance tests for service installations - Part 5: Service ducts and shafts

Relations

• Replaces: EN 1366-5:2010 - Fire resistance tests for service installations - Part 5: Service ducts and shafts
• Effective Date: 09-Feb-2021

Overview

EN 1366-5:2021 - Fire resistance tests for service installations (Part 5: Service ducts and shafts) is a CEN test method defining how to determine the fire resistance of horizontal service ducts and vertical service shafts that pass through walls or floors and enclose pipes and cables. The standard focuses on classifying ducts and shafts for fire resistance performance (for use in EN 13501-2 classification) and defines test scenarios where the assembly is exposed to fire from either inside or outside the system. EN 1366-5:2021 is intended to be read alongside EN 1363-1 (general test requirements).

Key topics and technical requirements

• Scope and purpose
  • Defines a laboratory test method to assess the ability of service ducts/shafts to resist fire spread between compartments.
  • Covers specimens that include joints, service outlets and access openings, suspended as they would be in practice.
• Test scenarios
  • Fire exposure may be applied from inside the duct/shaft or from outside.
• Specimen preparation
  • Standard representative loads are included (not full operational loading) to simulate typical services.
  • Suitable for systems with board constructions and those with continuous intumescent coatings on boards; not suitable where intumescent material is only applied locally around the penetration.
• Exclusions and limitations
  • Does not address fire spread caused by thermal conduction along pipes/cables or through transported media, nor thermal elongation effects.
  • Not applicable to ducts/shafts with internal barriers at walls or floors.
  • Not intended for assessing fire-protective systems for cable systems and components (see EN 1366-11).
  • Does not replace functional endurance testing of small electrical cables (EN 50200).
• Instrumentation and performance criteria
  • Requires thermocouples and measurements for integrity and insulation criteria; references EN 1363-1 for general test conditions.

Applications

• Use EN 1366-5:2021 when you need validated fire resistance data for:
  • Vertical service shafts (risers) and horizontal service ducts that penetrate compartmentation elements.
  • Product development and third-party fire testing of shaft and duct systems.
  • Supporting fire safety design documentation and compliance with building regulations where fire compartmentation depends on service installations.

Who uses this standard

• Fire test laboratories and certification bodies
• Manufacturers of service ducts, shaft systems and fire protective linings (including intumescent board systems)
• Fire safety engineers, consultants and specifiers preparing fire strategy reports
• Building designers and authorities verifying compartmentation performance for compliance and classification (EN 13501-2)

Related standards

• EN 1363-1 - Fire resistance tests: General requirements
• EN 13501-2 - Fire classification using fire resistance tests
• EN 1366-1 - Fire resistance tests for ducts for air distribution systems
• EN 1366-11 - Fire protective systems for cable systems and components
• EN 50200 - Endurance of small cables in fire

Keywords: EN 1366-5:2021, fire resistance tests, service ducts, service shafts, fire classification, EN 13501-2, CEN, fire safety, intumescent materials, test method.

Standards Content (Sample)

SLOVENSKI STANDARD
01-marec-2021
Nadomešča:
SIST EN 1366-5:2010
Preskusi požarne odpornosti servisnih inštalacij - 5. del: Servisni kanali in jaški
Fire resistance tests for service installations - Part 5: Service ducts and shafts
Feuerwiderstandsprüfungen für Installationen - Teil 5: Installationskanäle und -schächte
Essais de résistance au feu des installations de service - Partie 5 : Gaines pour
installation technique
Ta slovenski standard je istoveten z: EN 1366-5:2021
ICS:
13.220.50 Požarna odpornost Fire-resistance of building
gradbenih materialov in materials and elements
elementov
91.060.40 Dimniki, jaški, kanali Chimneys, shafts, ducts
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 1366-5
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2021
EUROPÄISCHE NORM
ICS 13.220.50; 91.060.40 Supersedes EN 1366-5:2010
English Version
Fire resistance tests for service installations - Part 5:
Service ducts and shafts
Essais de résistance au feu des installations de service - Feuerwiderstandsprüfungen für Installationen - Teil 5:
Partie 5 : Gaines pour installation technique Installationskanäle und -schächte
This European Standard was approved by CEN on 27 December 2020.

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
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 1366-5:2021 E
worldwide for CEN national Members.

Contents        Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Test equipment . 7
4.1 General . 7
4.2 Furnace . 7
4.3 Loading equipment . 7
4.4 Gas extraction equipment (optional). 7
5 Test conditions . 8
5.1 Furnace . 8
5.2 Loading. 8
6 Test specimen . 8
6.1 Size . 8
6.1.1 General . 8
6.1.2 Length . 8
6.1.3 Cross-section . 8
6.2 Number . 8
6.3 Design . 9
6.3.1 General . 9
6.3.2 Duct and shaft arrangement. 9
7 Installation of test specimen .10
7.1 General .10
7.2 Standard supporting construction .11
7.3 Non-standard supporting constructions .11
8 Conditioning .11
8.1 General .11
8.2 Water based sealing materials .11
9 Application of instrumentation .11
9.1 Thermocouples .11
9.1.1 Furnace thermocouples (plate thermometers) .11
9.1.2 Thermocouple locations .12
9.2 Pressure .12
10 Test procedure .12
10.1 General . 12
10.2 Test measurements and observations . 13
10.2.1 General . 13
10.2.2 Integrity . 13
10.2.3 Insulation (temperature of the surfaces outside the furnace – for both fire exposure
at the inside and exposure at the outside) . 13
10.2.4 Additional observations . 13
10.3 Termination of the test . 14
11 Performance criteria . 14
11.1 Integrity . 14
11.2 Insulation . 14
11.2.1 Insulation criteria for service ducts and shafts with combustible and
noncombustible services . 14
12 Test report . 14
13 Field of direct application of test results . 15
13.1 Walls or floors through which the service ducts or shafts lead . 15
13.2 Sizes of ducts or shafts . 15
13.3 Shapes . 15
13.4 Admissible services . 15
13.5 Suspension devices for ducts. 15
13.5.1 Material and sizing . 15
13.5.2 Elongation . 16
13.6 Distances . 16
13.6.1 Distance to the supporting construction . 16
13.6.2 Distance of the first joint after the supporting construction . 16
13.6.3 Distance between service ducts or service shafts in practice . 16
13.6.4 Distance between service outlets and penetrated wall or floor . 16
13.7 Access panels . 16
13.8 Service outlets . 16
Bibliography . 27

European foreword
This document (EN 1366-5:2021) has been prepared by Technical Committee CEN/TC 127 “Fire safety
in buildings”, the secretariat of which is held by BSI.
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 2021, and conflicting national standards shall be
withdrawn at the latest by August 2021.
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 1366-5:2010.
Against EN 1366-5:2010 the following changes were introduced:
1) necessary dated references were updated;
2) clearer rules were given for the scope of the standard;
3) terms and definitions clarified and completed;
4) the location of thermocouples was clarified especially when testing the specimen including service
outlets and access panels;
5) drawings were improved and aligned to changes;
6) the thermocouple T3 from Version 2010 was deleted. It is not needed for measuring the property
„Integrity” and it leads to confusion concerning that property.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
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
The purpose of this test is to measure the ability of a service duct or shaft to resist the spread of fire from
one fire compartment to another with fire attack from inside or outside the duct or shaft. The test
specimens incorporate joints, service outlets and access openings as intended in practice and are
suspended as they would be in practice. Test specimens of service ducts are not loaded as in practice but
a standard load is included to represent a typical service load. Test specimens of service shafts are not
loaded as in practice, but a standard load is included to represent a typical service load.
CAUTION — The attention of all persons concerned with managing and carrying out this fire
resistance test is drawn to the fact that fire testing may be hazardous, and there is a possibility
that toxic and/or harmful smoke and gases may be involved during the test. Mechanical and
operational hazards may also arise during the construction of the test elements or structures,
their testing and disposal of test residues.
An assessment of all potential hazards and risks to health should be made, and safety precautions
should be identified and provided. Written safety instructions should be issued. Appropriate
training should be given to relevant personnel. Laboratory personnel should ensure that they
follow written safety instructions at all times.
1 Scope
This document specifies a method for determining the fire resistance of horizontal service ducts and
vertical service shafts, which pass through walls or floors and enclose pipes and cables, to classify them
according to EN 13501-2. The test scenario examines the behaviour of ducts and shafts exposed to fire
either from outside or from inside the system. This document is intended to be read in conjunction with
EN 1363-1.
This document does not examine the risk of fire spread as a result of thermal conduction along the piping
or cabling installed in service ducts or shafts or thermal conduction through the media these pipes carry.
It does not cover the risk of damage produced by thermal elongation or shortening of tubes and cables as
a result of fire or damaged pipe suspensions. This document does not give guidance on how to test one,
two or three sided service ducts or shafts.
NOTE Guidance on testing service ducts and shafts of less than four sides will be covered in the extended field
of application rules being developed by CEN/TC 127.
This test can be used for systems with boards and also for such systems with continuous covering with
intumescent materials on the boards. It cannot be used for systems where intumescent material is only
applied in the range of the penetration.
This test is unsuitable for evaluating service ducts or shafts with internal barriers at walls and floors.
This test is unsuitable for evaluating fire protective systems for cable systems and associated components
with maintenance of integrity in case of fire. This is covered by EN 1366-11: Fire protective systems for
cable systems and associated components - Part 11: Fire protective systems for cable systems and
associated components.
Whilst the walls of service ducts or shafts tested to this method may provide specified levels of integrity
or insulation, testing according this document does not replace the testing of the functional endurance of
small electrical cables which is covered in EN 50200.
Fire resistance testing of ducts for air distribution systems is covered in EN 1366-1.
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 1363-1:2020, Fire resistance tests — Part 1: General requirements
EN 13501-2, Fire classification of construction products and building elements — Part 2: Classification
using data from fire resistance tests, excluding ventilation services
EN ISO 898-1:2013, Mechanical properties of fasteners made of carbon steel and alloy steel — Part 1: Bolts,
screws and studs with specified property classes — Coarse thread and fine pitch thread (ISO 898-1:2009)
EN ISO 13943, Fire safety — Vocabulary (ISO 13943)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1363-1, EN ISO 13943 and the
following 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
3.1
service duct
mainly horizontal duct enclosing combustible or non-combustible services, such as pipes or cables
3.2
service shaft
mainly vertical shaft enclosing combustible or non-combustible services, such as pipes or cables
3.3
shutter of access opening
openable door or panel allowing for access to the services within the duct or shaft
3.4
supporting construction
wall, partition or floor which the duct or the shaft passes through in the test
3.5
board
rigid product of cross section in which the thickness is uniform and substantially smaller than the other
dimensions of the installations
4 Test equipment
4.1 General
In addition to the test equipment specified in EN 1363-1, the following are required.
4.2 Furnace
The furnace shall be capable of subjecting service ducts and shafts to the standard heating and pressure
conditions specified in EN 1363-1 and be suitable for testing horizontal ducts (see Figures 1 and 2) or
vertical shafts (see Figures 3 and 4).
4.3 Loading equipment
Continuous stranded steel cables and/or the installations used in practice are used to apply load to the
service duct or shaft to represent service loading.
4.4 Gas extraction equipment (optional)
If for safety reasons a laboratory requires to extract gases away from the open end of the duct or shaft,
this shall not influence the test conditions.
5 Test conditions
5.1 Furnace
The heating and pressure conditions and the furnace atmosphere shall conform to those given in
EN 1363-1.
5.2 Loading
Horizontal service ducts shall be loaded when supporting service installations. In this case, the weight of
the load shall be representative of that used in practice.
Vertical service shafts shall not be loaded except in the two following situations:
— when supporting service installations. In this case, the weight of the load shall be representative of
that used in practice;
— when the service installation shaft is not supported on each floor or when the height between two
supports is greater than 5 m. In this case a weight load representative for the additional shaft weight
shall be added to the shaft top.
6 Test specimen
6.1 Size
6.1.1 General
Any cross section of duct or shaft may be tested as required by the sponsor.
6.1.2 Length
The minimum lengths of the parts of the test specimen inside and outside the furnace shall be as given in
Table 1.
Table 1 — Straight length of test specimen
Orientation Length
m
Inside furnace Outside furnace
fire outside fire inside fire outside fire inside
Horizontal duct ≥ 4,0 0,25 ± 0,05 2,0 ± 0,05 2,5 ± 0,05
a ≥ 2,0 0,25 ± 0,05 2,0 ± 0,05 2,0 ± 0,05
Vertical shaft
a
See also 5.2.
6.1.3 Cross-section
The service ducts and shafts of the same construction type shall be tested with the maximum width and
height and the minimum thickness as intended in practice.
6.2 Number
One test specimen shall be tested for each type of orientation, exposure conditions and cross-section.
6.3 Design
6.3.1 General
The test shall be made on a test specimen, representative of the complete service duct or shaft assembly.
6.3.2 Duct and shaft arrangement
6.3.2.1 General
The exposure condition (fire inside or fire outside) shall be as specified by the sponsor. Ducts shall be
arranged as shown in Figures 1 or 2 and shafts shall be arranged as shown in Figures 3 or 4. Service ducts
or shafts with fire exposure from outside will have no openings in the furnace (except access panels and
service outlets). For service ducts or shafts exposed to an internal fire, the end of the service duct or shaft
facing into the furnace shall be left open. No service ducts or service shafts shall contain anything other
than the loading defined in 4.3.
If a service outlet is part of the system this service outlet shall be tested with a distance to the penetration
through the wall or floor not lower than intended in practice.
Where used in practice, each service duct or shaft shall incorporate one access opening as follows:
— fire outside: inside furnace at mid-span of two suspensions;
— fire inside: as shown in Figure 2 (the dimensions may be applied also to vertical shafts).
For the test, the access opening shall be at the bottom of the duct except the access opening is in practice
only on a side or on the top. In this case the access opening shall be installed as in practice. The width and
height of the access opening shall be representative of the maximum dimensions used in practice, the
thickness shall be the minimum dimension used in practice.
Vertical shafts shall be arranged as shown in Figures 3 or 4 and shall penetrate through the furnace roof
slab/supporting construction. The shafts shall be supported at the furnace roo
...