prEN 15254-5

Extended application of results from fire resistance tests - Non-loadbearing walls - Part 5: Metal sandwich panel construction

This document defines rules for extended applications, provides guidance, and, where appropriate, defines procedures, for variations of certain parameters and factors associated with the design of internal and external non-loadbearing walls constructed of metal sandwich panels and that have been tested in accordance with EN 1364-1, which could generate a classification in accordance with EN 13501-2.
EN 15254-5 applies for double skin metal faced sandwich panels having an insulating core bonded to both facings as defined in EN 14509 not stabilizing a whole building or parts of it.

Erweiterter Anwendungsbereich der Ergebnisse von Feuerwiderstandsprüfungen - Nichttragende Wände - Teil 5: Sandwichelemente in Metallbauweise

Dieses Dokument definiert Regeln für erweiterte Anwendungsbereiche, enthält Leitlinien und legt, falls erfor
derlich, Verfahren für Änderungen von bestimmten Parametern und Faktoren fest, die mit der Bauweise von nichttragenden Innen- und Außenwänden zusammenhängen, die aus Sandwichelementen in Metallbauweise (im Folgenden als „Sandwichelement“ bezeichnet) bestehen und die nach EN1364-1 geprüft wurden, was zu einer Klassifizierung nach EN13501-2 führen könnte.
EN15254-5 gilt für Sandwichelemente mit beidseitigen Metalldeckschichten und einem Kern aus Wärmedämmstoff, der, wie in EN14509 definiert, mit beiden Deckschichten verklebt ist und kein ganzes Gebäude oder einen Teil desselben stabilisiert.

Application étendue des résultats d'essais de résistance au feu - Murs non porteurs - Partie 5 : Panneaux sandwiches métalliques pour la construction

Le présent document définit les règles pour les applications étendues, expose les lignes directrices et, le cas échéant, définit des procédures pour les modifications de certains paramètres et facteurs liés à la conception de murs internes et externes non porteurs en panneaux sandwiches métalliques et qui ont été soumis à essai conformément à l’EN 1364-1, pouvant générer une classification conformément à l’EN 13501-2.
L’EN 15254-5 s’applique aux panneaux sandwiches double peau à parements métalliques comportant une âme isolante liée aux deux parements tels que définis dans l’EN 14509, qui ne stabilisent pas un bâtiment entier ou des parties de celui-ci.

Razširjena uporaba rezultatov preskusov požarne odpornosti - Nenosilne stene - 5. del: Konstrukcije iz kovinskih sendvič panelov

General Information

• Status: Not Published
• Publication Date: 22-Jun-2026
• ICS: 13.220.50 - Fire-resistance of building materials and elements
• ICS: 91.060.10 - Walls. Partitions. Facades
• Technical Committee: CEN/TC 127 - Fire safety in buildings
• Drafting Committee: CEN/TC 127/WG 1 - Structural and separating elements
• Current Stage: 4599 - Dispatch of FV draft to CMC - Finalization for Vote
• Start Date: 23-Dec-2025
• Due Date: 27-Nov-2025
• Completion Date: 23-Dec-2025
• 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: oSIST prEN 15254-5:2025 - Extended application of results from fire resistance tests - Non-loadbearing walls - Part 5: Metal sandwich panel construction

Relations

• Revises: EN 15254-5:2018 - Extended application of results from fire resistance tests - Non-loadbearing walls - Part 5: Metal sandwich panel construction
• Effective Date: 13-Dec-2023

Overview

prEN 15254-5 is a forthcoming European standard developed by CEN under Technical Committee CEN/TC 127, titled "Extended application of results from fire resistance tests - Non-loadbearing walls - Part 5: Metal sandwich panel construction." Scheduled for publication in 2025, this document supersedes the previous EN 15254-5:2018. It provides a comprehensive framework for extending the application of fire resistance test results specifically for metal sandwich panel constructions used in non-loadbearing walls. The panels considered are double skin metal-faced with an insulating core bonded between facings as per EN 14509.

This standard defines rules, procedures, and guidance for assessing variations in materials and constructions that may differ from the original tested product, while maintaining or predicting equivalent fire resistance performance classified under EN 13501-2.

Key Topics

• Scope and Purpose
  prEN 15254-5 applies to internal and external non-loadbearing walls made of metal sandwich panels that have been tested according to EN 1364-1 for fire resistance. It addresses how to extend the validity of fire resistance classifications to variations in panel design, material composition, and construction parameters without retesting.

• Extended Application Analysis
  The standard outlines when and how an extended application is necessary-typically, when the design or materials vary beyond the direct field of application covered by test reports. It uses principles of interpolation or extrapolation based on reference fire tests to predict fire resistance.

• Material Variations
  Acceptable changes include variations in metal facings (such as changes in coating or color, within defined limits), adhesive types, and the insulating core materials. Limitations apply to parameters such as sheet thickness, where only minor variations (±0.2 mm) are permissible without needing additional validation.

• Construction Variations
  The document specifies rules for changes in panel thickness, orientation, span length (the distance between supports), longitudinal joint construction, fixing methods, and boundary conditions. Each of these factors can impact fire resistance and is considered in extended application assessments.

• Calculation Methods
  Procedures are provided for calculating strength properties at elevated temperatures according to EN 1993-1-2, to support theoretical predictions where direct testing is impractical.

• Assumptions
  The extended application assumes the wall is exposed on one side to standardized fire conditions (EN 1363-1), with no vertical deflection from adjacent structures during fire, and that after facing delamination, the panel’s dead load is supported correctly by the support structure.

Applications

• Fire Safety Design in Buildings
  Architects and engineers use prEN 15254-5 to assess how design modifications to metal sandwich panel walls will affect fire resistance without repeating costly fire tests. This aids in building code compliance and safety planning.

• Product Development and Certification
  Manufacturers of metal sandwich panels utilize this standard to extend their product’s certification scope, allowing for flexibility in product variations while maintaining trust in safety classifications.

• Construction and Installation
  Construction professionals reference this standard to verify that changes in installation methods, joint designs, or fixing systems do not compromise fire resistance, ensuring safer building envelopes.

• Building Renovation and Refurbishment
  When upgrading building facades or partitions, the extended application rules help assess the impact of substituting materials or adjusting structural layouts on fire safety, optimizing refurbishment solutions without full reassessment.

Related Standards

• EN 1364-1 – Fire resistance tests for non-loadbearing walls; source of the reference fire test.
• EN 13501-2 – Defines fire classification using fire resistance data.
• EN 14509 – Specifies self-supporting double skin metal-faced insulating panels.
• EN 15725 – Provides general rules for extended application reports on fire performance.
• EN 1993-1-2 – Eurocode for steel structures, including structural fire design calculations.
• EN 1363-1 and EN 1363-2 – Specify general and alternative fire resistance test procedures.
• prEN 14509-3:2024 – Test methods for mechanical strength and durability of factory-made sandwich panels.

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Keywords: prEN 15254-5, fire resistance tests, metal sandwich panels, non-loadbearing walls, extended application, EN 1364-1, EN 13501-2, fire safety, construction materials, building standards, CEN, fire classification, insulation panels, steel panel fire resistance.

Standards Content (Sample)

SLOVENSKI STANDARD
01-februar-2025
Razširjena uporaba rezultatov preskusov požarne odpornosti - Nenosilne stene -
5. del: Konstrukcije iz kovinskih sendvič panelov
Extended application of results from fire resistance tests - Non-loadbearing walls - Part
5: Metal sandwich panel construction
Erweiterter Anwendungsbereich der Ergebnisse von Feuerwiderstandsprüfungen -
Nichttragende Wände - Teil 5: Sandwichelemente in Metallbauweise
Application étendue des résultats d'essais de résistance au feu - Murs non porteurs -
Partie 5 : Panneaux sandwiches métalliques pour la construction
Ta slovenski standard je istoveten z: prEN 15254-5
ICS:
13.220.50 Požarna odpornost Fire-resistance of building
gradbenih materialov in materials and elements
elementov
91.060.10 Stene. Predelne stene. Walls. Partitions. Facades
Fasade
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2024
ICS 13.220.50; 91.060.10 Will supersede EN 15254-5:2018
English Version
Extended application of results from fire resistance tests -
Non-loadbearing walls - Part 5: Metal sandwich panel
construction
Application étendue des résultats d'essais de Erweiterter Anwendungsbereich der Ergebnisse von
résistance au feu - Murs non porteurs - Partie 5 : Feuerwiderstandsprüfungen - Nichttragende Wände -
Panneaux sandwiches métalliques pour la construction Teil 5: Sandwichelemente in Metallbauweise
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 127.
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, Türkiye 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
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 15254-5:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions, symbols and abbreviations . 4
3.1 Terms and definitions . 4
3.2 Symbols and abbreviations . 6
4 Establishing the field of extended application . 7
4.1 General . 7
4.2 Assumptions in the extended application . 7
5 Rules for extended applications of the tested product/construction . 8
5.1 General . 8
5.2 Variations in the materials of the product . 10
5.2.1 General . 10
5.2.2 Variations in the metal sheets . 10
5.2.3 Variations in the adhesive . 11
5.2.4 Variations in the core material . 11
5.3 Variations in the construction . 12
5.3.1 Variations in span length . 12
5.3.2 Variations in orientation . 16
5.3.3 Variations in the panel thickness . 16
5.3.4 Variations in the longitudinal joint construction . 17
5.3.5 Variations in the boundary conditions and fixing system . 17
5.3.6 Length and height of wall construction . 17
5.4 Interaction between the factor influences . 17
5.5 Support structure . 17
5.6 Heating conditions . 18
6 Calculation methods and additional measurements. 18
6.1 Calculation methods . 18
6.1.1 General . 18
6.1.2 Calculation of strength properties . 18
6.2 Additional measurements to be carried out in the reference test . 18
7 Report of the extended application analysis . 19
Annex A (informative) Typical behaviour of a metal faced sandwich panel wall when
exposed to fire . 20
Annex B (normative) Evaluation of extension of span length . 21
Bibliography . 24

European foreword
This document (prEN 15254-5:2024) has been prepared by Technical Committee CEN/TC 127
“Fire safety in buildings”, the secretariat of which is held by BSI.
This document is currently submitted to the CEN Enquiry.
This document supersedes EN 15254-5:2018.
This document has been prepared under a standardization request addressed to CEN by the
European Commission. The Standing Committee of the EFTA States subsequently approves these
requests for its Member States.
This series is currently composed of the following parts:
— EN 15254-2, Extended application of results from fire resistance tests — Non-loadbearing walls
— Part 2: Masonry and Gypsum Blocks;
— EN 15254-4, Extended application of results from fire resistance tests — Non-loadbearing walls
— Part 4: Glazed constructions;
— EN 15254-5, Extended application of results from fire resistance tests — Non-loadbearing walls
— Part 5: Metal sandwich panel construction;
— EN 15254-6, Extended application of results from fire resistance tests — Non-loadbearing walls
— Part 6: Curtain walling;
— EN 15254-7, Extended application of results from fire resistance tests — Non-loadbearing walls
— Part 7: Non-load bearing sandwich panels — Ceilings.
1 Scope
This document defines rules for extended applications, provides guidance, and, where
appropriate, defines procedures, for variations of certain parameters and factors associated with
the design of internal and external non-loadbearing walls constructed of metal sandwich panels
and that have been tested in accordance with EN 1364-1, which could generate a classification in
accordance with EN 13501-2.
EN 15254-5 applies for double skin metal faced sandwich panels having an insulating core
bonded to both facings as defined in EN 14509 not stabilizing a whole building or parts of it.
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, Fire resistance tests — Part 1: General Requirements
EN 1363-2, Fire resistance tests — Part 2: Alternative and additional procedures
EN 1364-1, Fire resistance tests for non-loadbearing elements — Part 1: Walls
EN 1993-1-2, Eurocode 3: Design of steel structures — Part 1-2: General rules — Structural fire
design
EN 13501-2, Fire classification of construction products and building elements — Part 2:
Classification using data from fire resistance tests, excluding ventilation services
EN 14509:2013, Self-supporting double skin metal faced insulating panels — Factory made
products - Specifications
EN 15725, Extended application reports on the fire performance of construction products and
building elements
EN ISO 13943, Fire safety — Vocabulary (ISO 13943)
prEN 14509-3:2024, Factory-made double skin metal faced insulating sandwich panels - Part 3:
Test methods for determining mechanical strength, building physical behaviour and durability
3 Terms and definitions, symbols and abbreviations
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 14509, EN 15725,
EN 1364-1, EN 1363-1 and EN ISO 13943 the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1.1
direct field of application of test results
outcome of a process (involving the application of defined rules) whereby a test result is deemed
to be equally valid for variations in one or more of the product properties and/or intended end-
use applications
3.1.2
extended field of application of test results
outcome of a process (involving the application of defined rules that can incorporate calculation
procedures) that predicts, for a variation of a product property and/or its intended end-use
application(s), a test result on the basis of one or more test results to the same test standard
3.1.3
factor
variation that can be applied to a parameter, e.g. a change in the core thickness
3.1.4
factor influence
potential cause of a change in the fire resistance when the factor is changed, e.g. an increase in
fire resistance as result of an increase of the thickness of the core
3.1.5
fastening
fixing
component that fastens the panels to a support structure or to the test frame
3.1.6
fixing system
system consisting of fastenings and possible other means to fasten the panels to a support
structure or to the test frame
3.1.7
height of assembly
height of the wall in the reference test or in the end-use application for horizontally or vertically
installed wall panels
3.1.8
length of assembly
length of the wall in the reference test or in the end-use application for horizontally or vertically
installed wall panels
3.1.9
reference test
fire resistance test in accordance with EN 1363-1 and EN 1364-1, and where applicable
EN 1363-2, on which the extended application is based and the results of which are used as the
main source of data for the extended application
3.1.10
stitching
component for fixing panels to panels in the longitudinal joint
3.1.11
span length
centre to centre distance between the supports of a panel and/or intermediate supports to which
the sandwich panel is fixed
3.1.12
support structure
construction onto which the panel wall is fastened in the end-use application
3.1.13
test frame
frame containing the test construction for the purpose of mounting onto the furnace
3.2 Symbols and abbreviations
For the purposes of this document, the following symbols and abbreviations apply.
E
etanchéité
F load
F ,E the tensile load on the fasteners
t d
F the shear load on the fasteners
v,Ed
F the design tensile load on the fastener at normal temperature
t,Rd
F the design shear load on the fastener at normal temperature
v,Rd
I isolation
L span length
L distance between midspan of two adjacent panels
L overlap of the metal facing at the panel to panel joint
PCS gross calorific potential
R resistance, loadbearing capacity
b width of panel
c opening in adjacent metal sheet joints at normal room temperature on unexposed side
c opening in adjacent metal sheet joints during the reference test on unexposed side
d depth of core
c
f deflection of panel to panel joint in the reference test (deflection into the furnace to be
j
taken as positive)
f , f deflection of two adjacent panels at midspan in the reference test (deflection into the
1 2
furnace to be taken as positive)
g panel weight per square meter
k yield strength factor
n number of fasteners
q pressure action on the panel in a fire situation
Δc relative increase in opening of the metal sheet joint in the reference test
Δf relative deflection of the joint compared to the adjacent panels in the reference test (to
be calculated taking into account the positive and negative directions of the deflections)
4 Establishing the field of extended application
4.1 General
An extended application analysis is required when the application differs in one or more
parameters from the tested one described in the test report and/or in the classification document,
and which is not covered by the direct field of application of the classification document.
Extended application is a prediction of the expected fire resistance of fire-resistant metal faced
sandwich panels. It may be based on interpolation between or extrapolation from test data. The
fundamental consideration shall be that the fire-resistant metal faced sandwich panels after
extension would achieve the required fire performance if it were to be tested according to
EN 1364-1.
The extended application of test results from metal faced sandwich panels used as a non-
loadbearing wall shall be based on the reference fire test results performed according to
EN 1364-1 and may be complemented by one or more additional tests. The general rules in
EN 15725 shall be followed.
The necessary information for extrapolation of test results shall be assessed during the sampling
and testing as specified in prEN 14509-3:2024, 13.5.1.
4.2 Assumptions in the extended application
The following assumptions are considered when evaluating extended applications for sandwich
panels:
a) the wall is required to provide fire resistance in the end-use condition; relevant classes are
given in EN 13501-2;
b) the wall is assumed to be exposed on the entire face of one side to the standardized heating
conditions given in the EN 1363-1 fire resistance test specification or to alternative and
additional procedures given in the EN 1363-2;
c) the structure above and below the wall does not deflect vertically during the fire exposure
period; this simulates the non-deflecting nature of the test frame which forms part of the
furnace test apparatus;
In reality constructions deflect and this should be taken into account by the building designer
when designing the building and planning the constructional details so that no vertical loads
are applied to the wall.
d) after delamination of the fire-exposed facing the dead load of the sandwich panels is carried
by a support structure to which the ends of the sandwich panels are attached;
e) the support structure has at least the same loadbearing capacity, R, of the resistance to fire
performance as the sandwich panel wall regarding integrity;
f) the self-weight of the facing and core is calculated from the volume and density of the
materials;
g) the calculation of the reduction in the strength properties of steel at elevated temperature
shall be in accordance with EN 1993-1-2.
5 Rules for extended applications of the tested product/construction
5.1 General
When performing extended applications for a tested wall changes can occur either in the
materials and/or in the construction. Both are dealt with in this document. Table 1 and Table 2
list the changes which may or may not be made in an extended application assessment. The rules
for the changes are given in 5.2 and 5.3.
Table 1 — Material changes relevant to extended application
Parameter Factors Factor influence on Rules
performance
Integrity E Insulation I
a
Changes in Chemical influence no influence 5.2.2.1
metal facings composition of
coating
Change of colour influence influence 5.2.2.1
Change between influence influence 5.2.2.1
coated and non-
coated metal
a
Sheet thickness influence no influence Allowed up
to ± 0,2 mm of
tested thickness.
Change from one no information no 5.2.2.2
metal to another information
Change in sheet no information no 5.2.2.3
geometry information
Changes in Amount influence influence 5.2.3
adhesive
a
Type influence no influence 5.2.3
Changes in Type major influence major 5.2.4
core material influence
Change in major influence major 5.2.4.2 - 5.2.4.6
composition. influence
a
It is understood that when a change in a factor can influence the integrity of a joint, there is a possibility
that a change in the leakage of hot gases or in joint geometry can also influence the temperature rise near
the joint and therefore influence the insulation rating.
Table 2 — Constructional changes relevant to extended application
Parameter Factors Factor influence on Rules
performance
Integrity E Insulation I
a
Span length Decrease no influence no influence Allowed
a
Increase influence no influence 5.3.1
a
Orientation  influence no influence 5.3.2
a
Panel width Decrease no influence no influence Test results valid
a
Increase influence no influence Test results valid
up to + 20 %
Panel thickness Decrease no information major 5.3.3
e.g. core influence
Increase
thickness
Joint Type major influence major 5.3.4
construction influence
Stitching influence influence Not allowed
decreased
Stitching influence influence 5.3.4
increased
Sealants influence influence 5.3.4
a
Fixing system Type major influence no influence 5.3.5
a
Amount major influence no influence 5.3.5
decreased
a
Amount increased influence no influence Allowed
Protection major influence influence 5.3.5
decreased
Protection influence influence Allowed
increased
a
Length of Vertical no influence no influence 5.3.6
assembly installation
Horizontal   See span length
installation 5.3.1
Height of Vertical   See span length
assembly installation 5.3.1
a
Horizontal influence no influence 5.3.6
installation
a
Support Changes no information no influence 5.5
structure
a
It is understood that when a change in a factor can influence the integrity of a joint, there is a possibility
that a change in the leakage of hot gases or in joint geometry can also influence the temperature rise near
the joint and therefore influence the insulation rating.
5.2 Variations in the materials of the product
5.2.1 General
Metal faced sandwich panels consist of three main materials (facing metal sheets, adhesive and
core material). In the case of auto adhesively bonded panels the foamed core material also forms
the adhesive layer during the foaming process.
Changes in the properties of the metal sheets will not affect the fire resistance results significantly
and changes can therefore be allowed. On the other hand, even small changes in the core material
can result in big variations in the fire resistance test results. These facts are considered in the
following rules.
5.2.2 Variations in the metal sheets
5.2.2.1 Variations in the coatings
Organic surface coating on fire exposed side has no influence on fire resistance.
Organic surface coating on unexposed side has influence to fire resistance:
- Test results for very light colours are also valid for sandwich panels with light colours and
dark colours (colour definition acc. to EN 14509:2013, Annex E)
- Test results for light metallic colours are also valid for sandwich panels with very light
colours, light colours and dark colours (colour definition acc. to EN 14509:2013, Annex E)
- Test results for light colours are also valid for sandwich panels with dark colours (colour
definition acc. to EN 14509:2013, Annex E)
- Test results achieved with panels with organic coated metal sheet are not valid for panels
without organic coating.
- Test results achieved with panels without organic coating are valid for panels with organic
coating.
If modifications in the coatings on the unexposed side are made compared to the tested one, the
reaction to fire classification of the product shall be the same or better than the tested one.
5.2.2.2 Variations in the metal material
The following rules are valid for extended applications:
a) when steel is tested, the test results are valid for all grades of steel;
NOTE For more information regarding metal faces see EN 14509.
b) when stainless steel is tested, the test results are valid for all grades of stainless steel;
c) for other types of metals, the test result is valid for tested type only.
5.2.2.3 Changes in profile geometry of facing
The following rules are valid for extended applications:
a) Panels with different metal thicknesses on both sides are regarded as symmetrical if
difference in thickness is max. 0,2 mm.
b) For panels with flat or small profiling (between 0 mm and 5 mm) on one or both sides test
results are valid for any change in the range 0 mm to 5 mm profiling and panels are regarded
as symmetrical. This is allowable only if the declared cross panel tensile strength value is
equal or higher than for the tested panel.
c) For profiles greater than 5 mm test results are valid for variations ± 50 % of the depth of the
profile as long as d is not reduced. See Figure 1.
c
5.2.3 Variations in the adhesive
This paragraph is valid only for panels with adhesively bonded cores. The following rules apply
for an adhesive with no strength at high temperatures (>500 °C) which means that the metal
sheet on t
...