prEN 12799

SLOVENSKI STANDARD
01-september-2017
Trdo spajkanje - Neporušitveno preskušanje trdo spajkanih spojev
Brazing - Non-destructive examination of brazed joints
Hartlöten - Zerstörungsfreie Prüfung von Hartlötverbindungen
Brasage fort - Contrôles nob destructifs des assemblages réalisés par brasage fort
Ta slovenski standard je istoveten z: prEN 12799
ICS:
25.160.50 Trdo in mehko lotanje Brazing and soldering
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2017
ICS 25.160.50 Will supersede EN 12799:2000
English Version
Brazing - Non-destructive examination of brazed joints
Brasage fort - Contrôles nob destructifs des Hartlöten - Zerstörungsfreie Prüfung von
assemblages réalisés par brasage fort Hartlötverbindungen
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 121.
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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

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

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 12799:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 General principles . 6
4 Visual examination . 6
4.1 General . 6
4.2 Principle . 7
4.3 Qualification of personnel . 7
4.4 Requirements specific to the examination . 7
4.5 Information to be supplied for visual inspection . 7
4.6 Inspection aids and equipment . 8
4.7 Extent of visual inspection on each workpiece . 8
4.8 Acceptance guidelines . 10
4.9 Examination procedure . 11
4.10 Test results and information to be reported. 11
5 Ultrasonic examination . 12
5.1 General . 12
5.2 Principle . 12
5.3 Requirements specific to the examination . 15
5.4 Information to be supplied to the operator . 15
5.5 Equipment . 15
5.6 Preparation for examination . 16
5.7 Examination . 16
5.8 Examination procedure . 17
5.9 Test results and information to be reported. 17
6 Radiographic examination . 18
6.1 General . 18
6.2 Principle . 18
6.3 Examination procedure . 18
6.4 Test results and information to be reported. 18
7 Penetrant detection . 18
7.1 General . 18
7.2 Principle . 19
7.3 Preparation . 19
7.4 Examination procedure . 19
7.5 Safety precautions . 19
7.6 Test report and information to be reported . 20
8 Leak testing . 20
8.1 General . 20
8.2 Principle . 20
8.3 Preparation . 20
8.4 Examination procedure . 20
8.5 Safety and environmental factors . 21
8.6 Test results and information to be reported. 21
9 Proof testing . 22
9.1 General . 22
9.2 Principle . 22
9.3 Preparation of the test piece . 22
9.4 Examination procedure . 22
9.5 Test results and information to be reported . 23
10 Thermography . 23
10.1 General . 23
10.2 Preparation of the test piece . 24
10.3 Procedure . 24
10.4 Test results and information to be reported . 24
Annex A (informative) Imperfections in brazed joints . 25
Bibliography . 29

European foreword
This document (prEN 12799:2017) has been prepared by Technical Committee CEN/TC 121 “Welding
and allied processes”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 12799:2000.
In comparison with the previous edition, the main changes are:
a) the normative references have been updated;
b) the document has been revised editorially.
1 Scope
This European Standard describes non-destructive examination procedures and test piece types
necessary to perform the tests on brazed joints.
The non-destructive examination methods described are as follows:
a) visual examination (see Clause 4);
b) ultrasonic examination (see Clause 5);
c) radiographic examination (see Clause 6);
d) penetrant examination (see Clause 7);
e) leak testing (see Clause 8);
f) proof testing (see Clause 9);
g) thermography (see Clause 10).
The brazed joints to which these tests are applied can either be test samples manufactured to obtain
brazed joint design data, or manufactured as part of the approval testing of a brazing procedure, or
parts of a brazed assembly. The type of test piece described for each test can be quoted or incorporated
in engineering application standards that deal with brazed assemblies.
This European Standard does not recommend the number of samples to be tested or the repeat tests
allowed. Neither does it specify methods of sampling brazed joints, except to give guidance regarding
the precautions necessary, nor does it comment on the acceptance criteria applicable to any of the tests.
No attempt is made to define which test or tests, if any, should be applied in any situation. This is a
matter to be established before any particular method of test is selected.
The methods of non-destructive examination are not associated with any particular type of brazed
assembly but lay down the general principles of the types of testing described. It is emphasized that a
satisfactory examination method can only be developed and used after taking into account all the
relevant factors regarding the equipment to be used and the characteristics of the test piece being
examined.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
EN 1593, Non-destructive testing - Leak testing - Bubble emission techniques
EN 12668-1, Non-destructive testing - Characterization and verification of ultrasonic examination
equipment - Part 1: Instruments
EN 12668-2, Non-destructive testing - Characterization and verification of ultrasonic examination
equipment - Part 2: Probes
EN 12668-3, Non-destructive testing - Characterization and verification of ultrasonic examination
equipment - Part 3: Combined equipment
EN 13184, Non-destructive testing - Leak testing - Pressure change method
EN 13185, Non-destructive testing - Leak testing - Tracer gas method
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 9712:2012, Non-destructive testing - Qualification and certification of NDT personnel (ISO
9712:2012)
EN ISO 16810:2014, Non-destructive testing - Ultrasonic testing - General principles (ISO 16810:2012)
EN ISO 16811, Non-destructive testing - Ultrasonic testing - Sensitivity and range setting (ISO 16811)
EN ISO 16823, Non-destructive testing - Ultrasonic testing - Transmission technique (ISO 16823)
3 General principles
Imperfections may be observed when brazed joints are examined non-destructively. They may reduce
the quality and performance characteristics of the joint or the brazed assembly.
This European Standard does not give guidance regarding the cause of the imperfection or its effect
upon the joint quality or the effects of single or multiple imperfections upon the performance
characteristics of the brazed assembly. This will depend upon the life-limiting processes to which the
joint is subjected and the life requirements and performance specific to the brazed assembly.
The majority of brazed joints are designed with the component parts in a lap configuration. Because of
the capillary nature of a brazed joint, most imperfections will be contained within the joint region, with
the principal axes parallel to the plane of the joint. Any other imperfections are caused by stresses in the
brazing metal or the parent materials, or were already present before brazing. Guidance is given
regarding the types of imperfections that are observed when non-destructive tests are applied; these
are defined diagrammatically in Annex A.
NOTE The importance of tolerances to typical imperfections, the cause for rejection, the method of
imperfection interpretation and the method of presentation of observations have to be established before a
specific method of test is selected.
The use of any method should always be considered in relation to testing as a whole. The benefits of
using any particular method can only be obtained by consideration of the results in conjunction with
results obtained by using other test methods. The most appropriate method or methods of examination
should be selected.
4 Visual examination
4.1 General
Simple visual examination is the most fundamental and commonly used method of non-destructive
examination. The examination described in this Clause relates to the quality of the joint and does not
include dimensional inspection.
Consideration shall be given at the design stage to the provision of adequate access to permit visual
examination.
Before any visual examination is undertaken it shall be established which joints (and fillets of joints) are
accessible for inspection; a suggested criterion for accessibility for satisfactory inspection, either
directly by eye or viewed in a mirror, is shown in Figure 1.
4.2 Principle
The brazed joint and adjacent parent material are visually examined (unaided and aided) to check the
appearance, soundness and contour.
4.3 Qualification of personnel
Personnel who carry out visual examination shall:
a) be informed about the braze process used and the possible imperfections;
b) have vision tested in accordance with EN ISO 9712:2012, 7.4;
c) have received instruction in the specific requirements in accordance with 4.4;
d) have received instruction in the general application standard.
When training records are kept, they shall verify compliance with items a) to d) and contain a
supervisor’s statement that an acceptable level of attainment has been achieved. Visual examination
does not require personnel with qualifications in addition to that detailed in items a) to d).
4.4 Requirements specific to the examination
The following shall be established before any examination is undertaken.
a) Manufacturing stage at which visual examination is to be carried out; this should include
consideration as to whether inspection is carried out on-line;
b) Requirements for surface preparation for inspection;
NOTE There is usually no such preparation after fluxless brazing processes. After brazing, flux and flux
residues are normally removed (see 4.8).
c) Minimum relevant imperfection size;
The recommended minimum relevant imperfection size for visual examination is 0,5 mm as defined
in 4.8 b), unless otherwise specified.
d) Extent of visual examination as defined in 4.7;
e) Acceptance criteria (see 4.8);
f) Any requirements for a written inspection procedure;
g) Reporting requirements;
h) Any aids to visual inspection additional to those listed in 4.6.
4.5 Information to be supplied for visual inspection
Before commencing examination, the following shall be available to the operator.
a) All the information required in 4.4;
b) A written inspection procedure, if applicable.
4.6 Inspection aids and equipment
The following are likely to be required.
a) Suitable illumination;
b) A wide-angle low-magnification (x5) viewer, e.g. a standard universal bench-mounted device that
leaves both hands free and may also incorporate illumination;
c) A comparison gauge for the minimum relevant imperfection size, e.g. either:
1) a mounted wire of this diameter to hold alongside the imperfection, the end of which may be
bent for easy alignment with the major axes of the imperfection; or
2) an x8 loupe with graticule;
d) A plain small mirror, e.g. a dental mirror, for partially accessible joints;
e) Means of locally illuminating areas in shadow, e.g. optic fibre light guides;
f) Approved methods of marking individual joints if detailed in 4.9, e.g. certain types of waterproof
felt marker pens.
4.7 Extent of visual inspection on each workpiece
As many work pieces have a proportion of fillets that either have difficult access or can be examined
only by special techniques, the extent of inspection shall be defined for each workpiece and shall be
established before the examination is undertaken and not left to the discretion of the inspector.
The specified inspection sites shall be shown on the assembly drawing or, in complex cases, on a
drawing prepared for this purpose. The drawing shall also state, or reference, the acceptance criteria.
Key
1 axis
a
viewing angle
Figure 1 — Access for visual inspection: joints to be viewable within a stated angle of joint axis
or exit plane
Key
1 bottom of recess to be visible at 45° to the joint axis
Figure 2 — Access for visual inspection: recessed fillet, when recessed fillets are permitted
4.8 Acceptance guidelines
The following points should be considered.
a) Flux and flux residues (when appropriate to the brazing process used). The extent of removal of flux
and flux residues to permit inspection should be detailed;
b) Minimum relevant imperfection size. Imperfections having a maximum dimension smaller than an
agreed minimum size are to be disregarded. It is recommended that the minimum relevant
imperfection size is 0,5 mm;
The acceptability for service of brazed assemblies which may require greater integrity should be
determined by additional tests, e.g. leak tightness.
c) Continuity of fillets. It should be stated whether complete or incomplete fillets are acceptable.
Where incomplete fillets are acceptable, the description should be as direct as possible and avoid
possible errors. For example, ‘incomplete fillets with x gaps maximum each not exceeding y mm’ is
preferable to ‘incomplete fillets with gaps not exceeding 20 % of total length’;
d) Recessed fillets. Recessed fillets may be due to brazing gaps at the upper limit for the braze process
employed or insufficient filler metal. It is difficult to estimate the depth of recess and if the
condition is acceptable it is suggested the criterion shown in Figure 2 is adopted;
e) Excess filler metal. When it is a requirement that filler metal does not encroach on a surface
adjacent to a brazed joint, that area has to be accurately indicated on the assembly drawing. This is
necessary firstly as a guide to the application of stop-off agents during preparation before brazing
and secondly for inspection purposes;
f) Surface erosion. Certain processes, such as brazing aluminium, may be characterized by erosion of
parent metal by filler metal. When applicable, acceptable degrees of surface erosion should be
detailed by reference to a permanent record such as a sketch, photographs or samples. These
should illustrate conditions agreed as both acceptable and unacceptable;
g) Cosmetic appearance of braze fillets. If requirements exist controlling acceptance, these should be
established before any examination is undertaken. They may affect decisions on the detail and cost
of the braze process. A permanent record of such agreement is required, such as a sketch,
photographs or samples. These should illustrate conditions detailed as both acceptable and
unacceptable.
4.9 Examination procedure
The brazed joints shall be inspected according to the detailed extent of inspection (see 4.4 d)) and the
detailed inspection criteria (see 4.4e)).
Consideration shall be given to the use of low-power magnification to reduce eye strain and improve
productivity; bench-mounted wide-angle x5 magnifiers leave both hands free to handle workpieces and
manipulate them where necessary to best view fillets.
A minimum imperfection size gauge (see 4.6c)) shall be used. This is to ensure that the visual acuity of
individual operators does not determine the minimum size recognized.
Fibre optic light guides or other convenient means shall be used to illuminate joints in shadow.
A proper means shall be provided for both the segregation of uninspected and inspected workpieces
and the segregation of acceptable and unacceptable workpieces.
For workpieces having many joints to be inspected, an appropriate plan shall be used for methodical
inspection.
It is recommended that joints are marked in an acceptable manner to distinguish those that have been
inspected from those that have not and, further, to identify any individual joints that are found to be
defective. Spots from felt marker pens of a composition not deleterious to the workpiece are
recommended. They may be green for acceptable joints and red for unacceptable.
4.10 Test results and information to be reported
Records shall be kept of the extent of inspection, acceptance criteria and the result. Where it is agreed
that an inspection report separate from other records is required, the following minimum information
is recommended.
a) Name of organization carrying out visual inspection;
b) Workplace name and/or drawing number;
c) Unique identification number of the batch of components to which the report relates;
d) Extent of inspection;
e) Acceptance criteria applied;
NOTE  In cases where the information detailed in items d) and e) is described in a written procedure it is
sufficient to state its reference and issue number. Alternatively, a drawing may be referenced provided that it
gives sufficient specific information for inspection purposes.
f) Total batch quantity inspected and the number passing;
g) Name and signature of the inspector;
h) Date of inspection.
5 Ultrasonic examination
5.1 General
This Clause describes the ultrasonic examination of brazed joints by the ultrasonic pulse echo
technique; techniques other than the pulse echo technique may be applicable to brazed joints, in
particular the transmission technique as described in EN ISO 16823.
General requirements relating to ultrasonic examination are contained in EN ISO 16810.
The most common imperfections in a brazed joint that can be detected by ultrasonics are:
a) incomplete flow into the capillary gap;
b) large pores or flux inclusions;
c) longitudinal cracks;
d) fine pores;
e) incomplete wetting of the parent metal surfaces;
f) transverse cracking.
5.2 Principle
Examination is most commonly carried out using the direct echo technique, illustrated in Figure 3,
where the ultrasonic beam is normal to the plane of the joint.
In the case of a sound joint, relatively little ultrasonic energy is reflected from the joint line, and, where
the geometry of the joint is suitable, a large back-wall echo is obtained. Where the brazing is
unsatisfactory, a large signal is received from the joint line, accompanied by a reduction in or a total loss
of the back-wall signal.
Where the configuration of the joint does not allow the use of a normal beam probe, two angle probes,
operating as a separate transmitter and receiver, may be used, as illustrated in Figure 4.
When scanning normal to the joint plane, the reflection characteristics of the imperfections listed in 5.1
are summarized in Table 1.
In the case of
...