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

Status
Withdrawn
Publication Date
02-Jan-2013
Withdrawal Date
02-Jan-2013
Current Stage
9599 - Withdrawal of International Standard
Start Date
03-Jan-2017
Completion Date
03-Jan-2017
Ref Project

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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
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ISO 16338:2013(E)

Annex D (informative) Commentary on machine qualification ............................................................................................36

Bibliography .............................................................................................................................................................................................................................40

iv © ISO 2013 – All rights reserved
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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
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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
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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
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ISO 16338:2013(E)
4 Symbols and abbreviated terms
D minimum required nugget diameter or seam weld width (see Table 11)
e lower electrode indentation
e upper electrode indentation
F force
l length of test specimen

s actual nugget diameter or seam weld width, as determined by metallographic examination

t thickness of the thinner sheet
t thickness of outer member
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
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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
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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
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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
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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

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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
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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.
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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

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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.
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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)
e lower electrode indentation
e upper electrode indentation
F force
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ISO/DIS 16338
l length of test specimen
N recommended (standard) number of spots per 25 mm

N actual number of spots per 25 mm on a production part or representative specimen or test piece

s actual nugget diameter or seam weld width, as determined by metallographic examination

S minimum shear force of test specimen (see Table 15), N/mm

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
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.
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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.
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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.
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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
...

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