ISO 16338:2013
(Main)Welding for aerospace applications — Resistance spot and seam welding
Welding for aerospace applications — Resistance spot and seam welding
ISO 16338:2013 specifies requirements for resistance spot and seam welding for aerospace applications. It does not apply if resistance welding is simply an intermediate operation and does not affect the quality of the end product, for example when tacking basic parts prior to assembly with another process. Resistance welding of dissimilar material group combinations is not covered by ISO 16338:2013.
Soudage pour applications aérospatiales — Soudage par résistance par points et à la molette
General Information
Relations
Buy Standard
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 16338
First edition
2013-01-15
Welding for aerospace applications —
Resistance spot and seam welding
Soudage pour applications aérospatiales — Soudage par résistance
par points et à la molette
Reference number
ISO 16338:2013(E)
©
ISO 2013
---------------------- Page: 1 ----------------------
ISO 16338:2013(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any
means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the
address below or ISO’s member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 16338:2013(E)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 4
5 Specific engineering requirements . 4
6 Classification of the joint . 4
7 Production requirements . 4
8 Welding personnel requirements . 5
9 Person responsible for welding procedure qualification and welding machine
qualification tests . 5
10 Material groups . 5
11 Preparation of parts to be welded . 5
11.1 General . 5
11.2 Cleaning requirements . 5
11.3 Surface coatings . 6
11.4 Assembly . 6
12 Equipment requirements . 6
12.1 Welding machines . 6
12.2 Electrodes . 6
12.3 Shear testing machines . 6
12.4 Jigs and fixtures . 6
13 Welding machines . 6
13.1 Qualification requirements . 6
13.2 Test piece configuration and examination requirements . 8
14 Welding procedure (pWPS) . 9
14.1 Qualification requirements . 9
14.2 Test piece configuration and examination requirements .11
15 Quality requirements for production .12
15.1 General .12
15.2 Production witness testing .12
15.3 Production parts .15
16 Test pieces .16
16.1 Standard test pieces.16
16.2 Test pieces for specific purposes .19
17 Examination, testing and acceptance criteria .19
17.1 General .19
17.2 Visual examination .19
17.3 Radiographic examination .21
17.4 Metallographic examination .22
17.5 Mechanical testing .26
18 Welding procedure qualification record (WPQR) .30
Annex A (informative) Machine qualification test report form .31
Annex B (informative) WPS form .33
Annex C (informative) Forms for welding procedure qualification record (WPQR) — Examples .34
© ISO 2013 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 16338:2013(E)
Annex D (informative) Commentary on machine qualification .36
Bibliography .40
iv © ISO 2013 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 16338:2013(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 16338 was prepared by Technical Committee ISO/TC 44, Welding and allied processes.
Requests for official interpretations of any aspect of this International Standard should be directed to
the Secretariat of ISO/TC 44 via your national standards body, a complete listing of which can be found
at www.iso.org.
© ISO 2013 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 16338:2013(E)
Welding for aerospace applications — Resistance spot
and seam welding
1 Scope
This International Standard specifies requirements for resistance spot and seam welding for aerospace
applications.
This International Standard does not apply if resistance welding is simply an intermediate operation and
does not affect the quality of the end product, for example when tacking basic parts prior to assembly
with another process.
Resistance welding of dissimilar material group combinations is not covered by this International Standard.
Safety and health issues and concerns are not covered by this International Standard.
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.
ISO 6520-2, Welding and allied processes — Classification of geometric imperfections in metallic materials —
Part 2: Welding with pressure
ISO 10447:2006, Resistance welding — Peel and chisel testing of resistance spot and projection welds
ISO 14373:2006, Resistance welding — Procedure for spot welding of uncoated and coated low carbon steels
ISO 14731, Welding coordination — Tasks and responsibilities
ISO 14732, Welding personnel — Approval testing of welding operators for fusion welding and of resistance
weld setters for fully mechanized and automatic welding of metallic materials
ISO 15609-5, Specification and qualification of welding procedures for metallic materials — Welding
procedure specification — Part 5: Resistance welding
ISO 17677-1:2009, Resistance welding — Vocabulary — Part 1: Spot, projection and seam welding
ISO/TR 25901:2007, Welding and related processes — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6520-2, ISO 14731, ISO 17677-1,
ISO/TR 25901 and the following apply.
3.1
chisel test
destructive or non-destructive test in which welds are tested by applying a predominantly tensile force
that results in stresses primarily normal to the surface of the joint interface
[SOURCE: ISO 10447:2006, 3.1]
3.2
close spaced welds
spot welds with weld pitch of less than two diameters
© ISO 2013 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 16338:2013(E)
3.3
coring
incipient melting
melting and resolidification of material at the grain boundaries of the heat affected zone and/or in
the weld nugget
Note 1 to entry: These features appear to be cracks when examined at low magnification, but when examined at
high magnification, are seen to be completely filled. This occurs primarily in nickel alloys.
3.4
design authority
engineering authority
organization having the responsibility for the structural integrity or maintenance of airworthiness of
the hardware and compliance with all relevant documents
3.5
foil
joint member with a thickness of 0,20 mm or less
3.6
metallographic section
transverse cut on the diameter of a spot weld or across
a seam weld, or a longitudinal cut down the centre of a seam weld
3.7
nugget
zone in spot, projection or seam weld where the metal has been melted
[SOURCE: ISO 17677-1:2009, 4.10, modified — “See Figure 2.” following the term has been deleted.]
3.8
nugget diameter
diameter of nugget measured at the faying surface
3.9
nugget penetration
extent of the nugget or fusion zone into the thickness of a joined member
3.10
peel test
destructive test in which a resistance-welded lap joint is tested by applying a peel force which results in
stresses mainly in the thickness direction of the weld
[SOURCE: ISO/TR 25901:2007, 2.265]
3.11
preliminary welding procedure specification
pWPS
document containing the required variables of the welding procedure which has to be qualified
[SOURCE: ISO/TR 25901:2007, 2.280]
3.12
production witness test specimen
weld of test specimen made in production setups and destructively tested to provide data on the qualities
of production welds
2 © ISO 2013 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 16338:2013(E)
3.13
resistance seam welding
resistance welding process which produces coalescence
at the faying surfaces by the heat obtained from resistance to electric current through the work parts
held together under pressure by electrodes
Note 1 to entry: The resulting weld is a series of overlapping resistance spot welds made progressively along a
joint by turning wheel electrodes or indexing the part under fixed electrodes.
3.14
resistance spot welding
resistance welding process that produces a weld at the faying surfaces between overlapping parts by the
heat obtained from resistance to the flow of welding current through the workpieces from electrodes
that serve to concentrate the welding current and pressure at the weld area
[SOURCE: ISO 17677-1:2009, 1.12]
3.15
roll spot welding
resistance welding process variant that makes intermittent spot welds using one or more rotating
circular electrodes
Note 1 to entry: The rotation of the electrodes might or might not be stopped during the making of a weld.
[SOURCE: ISO 17677-1:2009, 3.5]
3.16
seam weld width
width of the weld metal in the plane of the faying surfaces in a direction normal to the longitudinal axis
of the linear seam weld
[SOURCE: ISO 17677-1:2009, 4.14]
3.17
sheet
joint member with a thickness of more than 0,20 mm
3.18
weld pitch
centre-to-centre distance between adjacent spot welds
[SOURCE: ISO 14373:2006, 3.5]
3.19
welding condition
provision for the manufacture of a given weld, including
material, configuration, material preparation, cooling, electrode material, electrode geometry, welding
machine number, and all weld parameters that have a direct influence on the quality of the weld
3.20
welding parameter
machine setting or adjustment
EXAMPLE Examples are electrode force, welding current, welding speed, welding time.
3.21
welding procedure specification
WPS
document that has been qualified and provides the required variables of the welding procedure to
ensure repeatability during production welding
[SOURCE: ISO/TR 25901:2007, 2.457]
© ISO 2013 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 16338:2013(E)
4 Symbols and abbreviated terms
D minimum required nugget diameter or seam weld width (see Table 11)
s
e lower electrode indentation
l
e upper electrode indentation
u
F force
l length of test specimen
s actual nugget diameter or seam weld width, as determined by metallographic examination
M
t thickness of the thinner sheet
t thickness of outer member
o
w test specimen width/overlap
Ac test lot average
NDT non-destructive testing
pWPS preliminary welding procedure specification
QA quality assurance
SPC statistical process control
WPQR welding procedure qualification record
WPS welding procedure specification
5 Specific engineering requirements
In the event of any conflict between the requirements of this specification and those requirements
specified in the engineering definition, the engineering definition shall take precedence.
The classification of the joint (see Clause 6) shall be designated on the part specification or drawing.
6 Classification of the joint
Classification of the joint is based on the following.
— Class I: a welded joint whose failure under operating conditions causes the loss of the
aircraft/spacecraft or one of its main components, or constitutes a direct hazard to people.
— Class II: a welded joint whose failure causes malfunctions without compromising continued safe
flight until the end of the mission.
— Class III: a welded joint whose failure does not affect the safety and the transport function of the
aircraft/spacecraft.
7 Production requirements
Prior to production, the following requirements shall be met:
a) personnel qualification,
4 © ISO 2013 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 16338:2013(E)
b) welding machine qualification,
c) welding procedure qualification.
8 Welding personnel requirements
The welding personnel shall be trained and be competent for the process. If requested by the
design/engineering authority, ISO 14732 may be invoked.
9 Person responsible for welding procedure qualification and welding machine
qualification tests
The welding coordinator (see ISO 14731) shall be designated, in writing, as responsible for welding
procedure qualification and welding machine qualification test. The welding coordinator shall have
knowledge and experience relevant to the welding process, and be acceptable to the responsible
design/engineering authority or recognized examining body.
It is recommended that the welding coordinator be qualified as International Welding Engineer (IWE)
according to IIW IAB-252-11.
The welding coordinator may authorize another person to administer the welding procedure qualification
or welding machine qualification test.
10 Material groups
Material group A: unalloyed steel, low-alloyed steels, high-alloyed ferritic steels.
Material group B: high-alloyed austenitic and martensitic steels, nickel and nickel alloys, cobalt alloys.
Material group C: titanium and titanium alloys, niobium, zirconium and other reactive metals.
Material group D: aluminium and aluminium alloys, magnesium and magnesium alloys.
Material group E: materials that do not conform to material groups A to D (e.g. molybdenum, tungsten
and copper alloys).
11 Preparation of parts to be welded
11.1 General
External and faying surfaces of the parts to be welded shall be free from contaminants, such as heavy
oxides, scale, ink, grease, dirt or other substances, or surface conditions detrimental to the welding process.
The surfaces shall be regular, this being a determining factor in ensuring good reproducibility of the weld.
11.2 Cleaning requirements
A specific cleaning procedure (e.g. pickling) shall be determined according to the materials and precisely
defined by each manufacturer in line with the design/engineering authority requirements.
The cleaning procedure used to prepare materials for welding procedure qualification shall be specified
on the pWPS. For materials in group D, surface resistance requirements shall be specified by the
design/engineering authority.
Time limits between cleaning and welding shall be specified in the pWPS or other manufacturing
documentation.
© ISO 2013 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO 16338:2013(E)
11.3 Surface coatings
Surface coatings, specified by the design/engineering authority, shall be identified in the pWPS.
11.4 Assembly
Mating parts assembled for welding shall fit so that before the first and each subsequent weld is made,
the surfaces to be joined by the weld are in contact with one another or can be made to contact one
another by manual pressure.
12 Equipment requirements
12.1 Welding machines
The welding machine shall be qualified according to Clause 13, calibrated and maintained
according to manufacturer recommendations and/or any other requirements as defined by the
design/engineering authority.
A preventative maintenance procedure shall be established and maintenance records kept.
12.2 Electrodes
All electrodes in use shall be permanently marked with the electrode material designator, as a minimum.
12.3 Shear testing machines
12.3.1 General
Shear testing machines shall be accurate to within ±2 % of the indicated reading. The shear testing
speed shall not exceed 13 mm/min.
12.3.2 Stationary shear testing machines
Stationary shear testing machines shall be calibrated for accuracy at intervals not to exceed one year.
12.3.3 Portable shear testing machines
Portable shear testing machines shall be calibrated for accuracy at intervals not to exceed two months.
12.4 Jigs and fixtures
Jigs and fixtures shall be so designed as to minimize the shunting of welding current through them
instead of passing through the workpieces. All tooling that is required to locate welds or assist in the
assembly of welded parts that passes through the magnetic field during the welding operation should be
made of nonmagnetic materials insofar as possible.
13 Welding machines
13.1 Qualification requirements
13.1.1 General
Existing machine qualifications to other standards prior to the release of this International Standard
are considered qualified, unless otherwise specified by the design/engineering authority.
6 © ISO 2013 – All rights reserved
---------------------- Page: 11 ----------------------
ISO 16338:2013(E)
Prior to production, qualification shall be performed on each resistance spot or seam welding machine to
determine its ability and consistency of operation. The purpose of qualification is to identify and verify
the range of welding for which a welding machine may be considered capable. Welding conditions shall
be documented on a WPS as part of a machine qualification test report. Typical examples of report forms
are given in Annexes A and B. Such forms may be modified or expanded as required. After approval is
obtained, these reports shall be available for review.
Machines shall be qualified to meet the weld requirements for the most critical class (see Clause 6) in
each material group (see Clause 10) for which it is intended to be used in production. A welding machine
qualified to weld to the requirements of one class in a material group shall be automatically considered
qualified for less critical classes in the same material group. A spot welding machine qualified for spot
welding is also qualified for overlap spot welding. Machines used for class III foil welding may be qualified
by establishing a WPS. Machines qualified to a class for seam welding shall be considered qualified for
roll spot welding to the same class.
13.1.2 Method of welding machine qualification
13.1.2.1 General
No maintenance work or control adjustments are permitted during the welding of test specimens.
13.1.2.2 Test materials
Test materials for material groups A, B, C and D qualification may be any material from that group
commonly used in production.
Qualification with material of group A qualifies for welding material of group A only.
Qualification with material of group B qualifies for welding material of group B only.
Qualification with material of group C qualifies for welding material of group C only.
Qualification with material of group D qualifies for welding material of group D only.
Qualification with a specific material of group E qualifies for welding with the same material only.
13.1.2.3 Test requirements
Weld tests listed in 13.2 shall be performed and shall meet applicable acceptance criteria. For each material
group, two test sets shall be required: the high-end (thickest) machine qualification test and the low-end
(thinnest) machine qualification test. Typically, the high-end and low-end machine qualification tests are
each made up of two members of equal thickness. Alternatively, members of different thicknesses and/or
a weld combination of more than two members may be used. The following requirements shall be used
to determine the required machine qualification tests to cover production work:
a) The total thickness of all members in a production weld combination shall not be more than the
total thickness of all members in the high-end machine qualification test and shall not be less than
the total thickness of all members in the low-end machine qualification test.
b) The thinnest contact member (member in contact with the electrode) of any production weld
combination shall not be thicker than the thinnest member in the high-end machine qualification test
c) The thinnest contact member (member in contact with the electrode) of any production weld
combination shall not be thinner than the thinnest member in the low-end machine qualification test.
d) If a machine is used for a specific weld combination then it need only be qualified for that weld
combination according to the quantities and methods specified in 13.2.
NOTE 1 For examples of the application of rules stated in this subclause, see Annex D.
© ISO 2013 – All rights reserved 7
---------------------- Page: 12 ----------------------
ISO 16338:2013(E)
NOTE 2 If more than one welding machine of the same type is to be qualified, the extent of testing can be
reduced at the discretion of the design/engineering authority.
13.1.2.4 Welding machine requalification
Requalification shall be required if the welding machine is rebuilt or if significant operational changes
(e.g. replacement of main components, facility relocation and change of power supply) are made. The
number of test specimens for sheet welding may be reduced (see Table 2).
Unless otherwise authorized by the design/engineering authority, when welding machine requalification
is required, all WPS shall be requalified prior to production use.
Changes that do not require requalification of the welding machine are:
a) change of location within a plant, which maintains the same electrical circuit;
b) general machine maintenance;
c) replacement of parts, such as electrodes and electrode holders, which do not affect the pressure or
power characteristics.
13.2 Test piece configuration and examination requirements
Tests shall be as specified in Table 1 and as shown in Figure 1 and Figures 3 to 5.
Table 1 — Welding machine qualification test pieces and examination requirements
Examination
Class Test piece Amount per test set
Visual Radiographic Mechanical Metallographic
Spot welds — Sheet
Figure 1 a)
I 105 weld spots all all 100 shear 5 microsection
...
DRAFT INTERNATIONAL STANDARD ISO/DIS 16338
ISO/TC 44 Secretariat: AFNOR
Voting begins on Voting terminates on
2011-08-22 2012-01-22
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ ORGANISATION INTERNATIONALE DE NORMALISATION
Welding for aerospace applications — Resistance spot and
seam welding
Soudage pour applications aérospatiales —Soudage par résistance par points et à la molette
ICS 25.160.01
In accordance with the provisions of Council Resolution 15/1993 this document is circulated in
the English language only.
Conformément aux dispositions de la Résolution du Conseil 15/1993, ce document est distribué
en version anglaise seulement.
To expedite distribution, this document is circulated as received from the committee
secretariat. ISO Central Secretariat work of editing and text composition will be undertaken at
publication stage.
Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du
secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au
Secrétariat central de l'ISO au stade de publication.
THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE
REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME
STANDARDS TO WHICH REFERENCE MAY BE MADE IN NATIONAL REGULATIONS.
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.
© International Organization for Standardization, 2011
---------------------- Page: 1 ----------------------
ISO/DIS 16338
Copyright notice
This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as permitted
under the applicable laws of the user’s country, neither this ISO draft nor any extract from it may be
reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic,
photocopying, recording or otherwise, without prior written permission being secured.
Requests for permission to reproduce should be addressed to either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
Case postale 56 CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Reproduction may be subject to royalty payments or a licensing agreement.
Violators may be prosecuted.
ii © ISO 2011 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/DIS 16338
Contents Page
Foreword .v
1 Scope.1
2 Normative References.1
3 Terms and definitions .1
4 Symbols and abbreviated terms .3
5 Specific engineering requirements .4
6 Classification of the joint.4
7 Production requirements.4
8 Welding personnel requirements .5
9 Person responsible for welding procedure qualification and welding machine
qualification tests.5
10 Material groups.5
11 Preparation of parts to be welded .5
11.1 General.5
11.2 Cleaning requirements.5
11.3 Surface coatings.6
11.4 Assembly.6
12 Equipment requirements .6
12.1 Welding machines.6
12.2 Electrodes.6
12.3 Shear testing machines .6
12.3.1 General.6
12.3.2 Stationary shear testing machines.6
12.3.3 Portable shear testing machines.6
12.4 Jigs and fixtures.6
13 Welding machines.7
13.1 Qualification requirements.7
13.1.1 General.7
13.1.2 Method of welding machine qualification.7
13.2 Test piece configuration and examination requirements .8
14 Welding procedure (pWPS) .9
14.1 Qualification requirements.9
14.1.1 General.9
14.1.2 Determination of weld settings .9
14.1.3 Methods of welding procedure qualification.9
14.1.4 Thickness combination limits .10
14.1.5 Welding procedure specification (WPS) .10
14.1.6 Welding procedure requalification .11
14.2 Test piece configuration and examination requirements .11
15 Quality requirements for production.12
15.1 General.12
15.2 Production witness testing .12
15.2.1 General.12
15.2.2 Witness test specimens.12
15.2.3 Surface resistance.13
© ISO 2011 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/DIS 16338
15.2.4 Parameter adjustments . 13
15.2.5 Production witness test specimen configuration and examination. 13
15.2.6 Alternate testing requirements in lieu of production witness testing. 15
15.3 Production parts . 16
15.3.1 Examination requirements. 16
15.3.2 Deterioration of welding. 16
15.3.3 Tack welds. 16
16 Test pieces . 17
16.1 Standard test pieces. 17
16.2 Test pieces for specific purposes. 19
17 Examination, testing and acceptance criteria .20
17.1 General. 20
17.2 Visual examination . 20
17.2.1 Visual imperfections in test specimens or production parts. 20
17.2.2 Sheet separation between welded members . 20
17.2.3 Electrode indentation . 21
17.3 Radiographic examination. 21
17.4 Metallographic examination . 23
17.4.1 General. 23
17.4.2 Internal imperfections . 23
17.4.3 Nugget penetration. 24
17.4.4 Nugget diameter or seam weld width . 25
17.5 Mechanical testing. 26
17.5.1 Spot welds — Sheet . 26
17.5.2 Spot welds—Foil. 30
17.5.3 Seam welds — Foil . 31
17.5.4 Multiple members test specimen . 32
18 Welding Procedure Qualification Record (WPQR). 32
Annex A (informative) Machine Qualification Test Report form. 33
Annex B (informative) WPS form. 35
Annex C (informative) Example forms for Welding Procedure Qualification Record (WPQR) . 36
Bibliography. 38
iv © ISO 2011 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/DIS 16338
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 16338 was prepared by Technical Committee ISO/TC 44, Welding and allied processes .
Requests for official interpretations of any aspect of this International Standard should be directed to the
Secretariat of ISO/TC 44 via your national standards body, a complete listing which can be found at
www.iso.org.
© ISO 2011 – All rights reserved v
---------------------- Page: 5 ----------------------
DRAFT INTERNATIONAL STANDARD ISO/DIS 16338
Welding for aerospace applications — Resistance spot and
seam welding
1 Scope
This International Standard specifies requirements for resistance spot and seam welding for aerospace
applications.
This International Standard does not apply if resistance welding is simply an intermediate operation and does
not affect the quality of the end-product, for example when tacking basic parts prior to assembly with another
process.
Resistance welding of dissimilar material group combinations is not covered by this International Standard.
Safety and health issues and concerns are not covered by this International Standard.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 6520-2, Welding and allied processes — Classification of geometric imperfections in metallic materials —
Part 2: Welding with pressure
ISO 14373:2006, Resistance welding — Procedure for spot welding of uncoated and coated low carbon steels
ISO 14731, Welding coordination — Tasks and responsibilities
ISO 14732, Welding personnel — Approval testing of welding operators for fusion welding and of resistance
weld setters for fully mechanized and automatic welding of metallic materials
ISO 17677-1:2009, Resistance welding — Vocabulary — Part 1: Spot, projection and seam welding
ISO/TR 25901:2007, Welding and related processes — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6520-2, ISO 14731, ISO 17677-1
and the following apply.
3.1
close spaced welds
spot welds with centre to centre distance of less than two diameters between adjacent spots
© ISO 2011 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/DIS 16338
3.2
coring
indications appearing like a crack which when examined under high magnification are shown to be filled with
material
3.3
design/engineering authority
organization having the responsibility for the structural integrity or maintenance of airworthiness of the
hardware and compliance with all relevant documents
3.4
foil
joint member with a thickness of 0,20 mm or less
3.5
metallographic section
a transverse cut on the diameter of a spot weld or across a
seam weld, or a longitudinal cut down the centre of a seam weld
3.6
nugget
zone in spot, projection or seam weld where the metal has been melted
[ISO 17677-1:2009]
3.7
nugget diameter
diameter of nugget measured at the faying surface
3.8
nugget penetration
the extent of the nugget or fusion zone into the thickness of a joined member
3.9
peel test
destructive test in which a resistance-welded lap joint is tested by applying a peel force which results in
stresses mainly in the thickness direction of the weld
[ISO/TR 25901:2007]
3.10
preliminary welding procedure specification
pWPS
document containing the required variables of the welding procedure which has to be qualified
[ISO/TR 25901:2007]
3.11
production witness test specimen
welds of test specimens made in production setups and destructively tested to provide data on the qualities of
production welds
3.12
resistance seam welding (22)
resistance welding process which produces coalescence at
the faying surfaces by the heat obtained from resistance to electric current through the work parts held
together under pressure by electrodes
NOTE The resulting weld is a series of overlapping resistance spot welds made progressively along a joint by turning
wheel electrodes or indexing the part under fixed electrodes.
2 © ISO 2011 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/DIS 16338
3.13
resistance spot welding (21)
resistance welding process that produces a weld at the faying surfaces between overlapping parts by the heat
obtained from resistance to the flow of welding current through the workpieces from electrodes that serve to
concentrate the welding current and pressure at the weld area
[ISO 17677-1:2009]
3.14
roll spot welding
resistance welding process variant that makes intermittent spot welds using one or more rotating circular
electrodes
NOTE The rotation of the electrodes might or might not be stopped during the making of a weld.
[ISO 17677-1:2009]
3.15
seam weld width
width of the weld metal in the plane of the faying surfaces in a direction normal to the longitudinal axis of the
linear seam weld
[ISO 17677-1:2009]
3.16
sheet
joint member with a thickness of more than 0,20 mm
3.17
welding condition
provision for the manufacture of a given weld, including
material, configuration, material preparation, cooling, electrode geometry, welding machine number, and all
weld parameters that have a direct influence on the quality of the weld
3.18
welding parameter
machine setting or adjustment
NOTE Examples are electrode force, welding current, welding speed, welding time.
3.19
welding procedure specification
WPS
document having been qualified and provides the required variables of the welding procedure to ensure
repeatability during production welding
[ISO/TR 25901:2007]
3.20
weld pitch
centre-to-centre distance between adjacent spot welds
[ISO 14373:2006]
4 Symbols and abbreviated terms
D minimum required nugget diameter or seam weld width (see Table 11)
s
e lower electrode indentation
l
e upper electrode indentation
u
F force
© ISO 2011 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO/DIS 16338
l length of test specimen
N recommended (standard) number of spots per 25 mm
o
N actual number of spots per 25 mm on a production part or representative specimen or test piece
p
s actual nugget diameter or seam weld width, as determined by metallographic examination
M
S minimum shear force of test specimen (see Table 15), N/mm
o
S modified minimum shear force of test specimen when the difference of N is > 15% of N , N/mm
x p o
t thickness of the thinner sheet
t thickness of outer member
o
w test specimen width/overlap
Ac test lot average
NDT non destructive testing
pWPS preliminary Welding Procedure Specification
QA Quality Assurance
SPC Statistical Process Control
WPQR Welding Procedure Qualification Record
WPS Welding Procedure Specification
5 Specific engineering requirements
In the event of any conflict between the requirements of this specification and those requirements specified in
the engineering definition, the engineering definition shall take precedence.
The classification of the joint (see Clause 6) shall be designated on the part specification or drawing.
6 Classification of the joint
Classification of the joint is based on the following:
⎯ Class I: A welded joint whose failure under operating conditions causes the loss of the
aircraft/spacecraft or one of its main components, or constitutes a direct hazard to people.
⎯ Class II: A welded joint whose failure causes malfunctions without compromising continued safe flight
until the end of the mission.
⎯ Class III: A welded joint whose failure does not affect the safety and the transport function of the
aircraft/spacecraft.
7 Production requirements
Prior to production, the following requirements shall be met:
a) personnel qualification,
b) welding machine qualification,
c) welding procedure qualification.
4 © ISO 2011 – All rights reserved
---------------------- Page: 9 ----------------------
ISO/DIS 16338
8 Welding personnel requirements
The welding personnel shall be trained and be competent for the process. If requested by the
design/engineering authority, ISO 14732 may be invoked.
9 Person responsible for welding procedure qualification and welding machine
qualification tests
The welding coordinator (see ISO 14731) shall be designated, in writing, as responsible for welding procedure
qualification and welding machine qualification test. The welding coordinator shall have knowledge and
experience relevant to the welding process, and be acceptable to the responsible design/engineering authority
or recognized examining body.
NOTE Example of relevant knowledge is International Welding Engineer (IWE) according to IIW IAB-252-11.
The welding coordinator may authorize another person to administer the welding procedure qualification or
welding machine qualification test.
10 Material groups
Material group A: Unalloyed steel, low-alloyed steels, high-alloyed ferritic steels.
Material group B: High-alloyed austenitic and martensitic steels, nickel and nickel alloys, cobalt alloys.
Material group C: Titanium and titanium alloys, niobium, zirconium and other reactive metals.
Material group D: Aluminium and aluminium alloys, magnesium and magnesium alloys.
Material group E: Materials that do not conform to material groups A to D (e.g. molybdenum, tungsten, copper
alloys).
11 Preparation of parts to be welded
11.1 General
External and faying surfaces of the parts to be welded shall be free from contaminants such as heavy oxides,
scale, ink, grease, dirt, or other substances, or surface conditions detrimental to the welding process. The
surfaces shall be regular, this being a determining factor in ensuring good reproducibility of the weld.
11.2 Cleaning requirements
A specific cleaning procedure (e.g. pickling) shall be determined according to the materials and precisely
defined by each manufacturer in line with the design/engineering authority requirements.
The cleaning procedure used to prepare materials for welding procedure qualification shall be specified on the
pWPS. For materials in group D, surface resistance requirements shall be specified by the design/engineering
authority.
Time limits between cleaning and welding shall be specified in the pWPS or other manufacturing
documentation.
© ISO 2011 – All rights reserved 5
---------------------- Page: 10 ----------------------
ISO/DIS 16338
11.3 Surface coatings
Surface coatings, specified by the design/engineering authority, shall be identified in the pWPS.
11.4 Assembly
Mating parts assembled for welding shall fit so that before the first and each subsequent weld is made, the
surfaces to be joined by the weld are in contact with one another or can be made to contact one another by
manual pressure.
12 Equipment requirements
12.1 Welding machines
The welding machine shall be qualified according to Clause 13, calibrated and maintained per manufacturer
recommendations and/or any other requirements as defined by the design/engineering authority.
A preventative maintenance procedure shall be established and maintenance records kept.
12.2 Electrodes
All electrodes in use shall be permanently marked with the electrode material designator, as a minimum.
12.3 Shear testing machines
12.3.1 General
Shear testing machines shall be accurate within ± 2% of the indicated reading. The shear testing speed shall
not exceed 13 mm/min.
12.3.2 Stationary shear testing machines
Stationary shear testing machines shall be calibrated for accuracy at intervals not to exceed one year.
12.3.3 Portable shear testing machines
Portable shear testing machines shall be calibrated for accuracy at intervals not to exceed two months.
12.4 Jigs and fixtures
Jigs and fixtures shall be so designed to minimize the shunting of welding current through them instead of
passing through the work pieces. All tooling that is required to locate welds or assist in the assembly of
welded parts that passes through the magnetic field during the welding operation should be made of
nonmagnetic materials insofar as possible.
6 © ISO 2011 – All rights reserved
---------------------- Page: 11 ----------------------
ISO/DIS 16338
13 Welding machines
13.1 Qualification requirements
13.1.1 General
Prior to production, qualification shall be performed on each resistance spot or seam welding machine to
determine its ability and consistency of operation. The purpose of qualification is to identify and verify the
range of welding for which a welding machine may be considered capable. Welding conditions shall be
documented on a WPS as part of a Machine Qualification Test Report. Typical examples of report forms are
given in Annexes A and B. Such forms may be modified or expanded as required. After approval is obtained,
these reports shall be available for review.
Machines shall be qualified to meet the weld requirements for the most critical class (see Clause 6) in each
material group (see Clause 10) for which it is intended to be used in production. A welding machine qualified
to weld to the requirements of one class in a material group shall be automatically considered qualified for less
critical classes in the same material group. A spot welding machine qualified for spot welding is also qualified
for overlap spot welding. Machines used for Class III foil welding may be qualified by establishing a WPS.
Machines qualified to a class for seam welding shall be considered qualified for roll spot welding to the same
class.
13.1.2 Method of welding machine qualification
13.1.2.1 General
No maintenance work or control adjustments are permitted during the welding of test specimens.
13.1.2.2 Test materials
Test materials for material groups A, B, C and D qualification may be any material from that group commonly
used in production.
Qualification
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.