INTRODUCTION TO
WELDING
Mr. S.A Rizvi
Ph.D(P) Welding, IIT(BHU)
ME-Production, MIIW,MISTE,MIE
Workshop Superintendent UP
FoE&T Jamia Millia Islamia,New Delhi India
sarizvi1@jmi.ac.in
17/10/14
What is Welding
A weld is defined by the American Welding society
(AWS) as “a localized coalescence (the fusion or
growing together of the grain structure of the
materials being welded) of materials or nonmetals
produced either by heating the materials to the
required welding temperatures with or without
the application of pressure, or by the application
of pressure alone, and with or without the use of
filler materials”
 Welding—a
joining process that produces
coalescence of materials by heating them to the
welding temperature, with or without the
application of pressure alone, and with or without
the use of filler material.

Classification of welding process
Welding classification
Welding Processes

Oxyacetylene Welding (OAW)

Shielded Metal Arc Welding (SMAW)

Gas Metal Arc Welding (MIG/GMAW)

Gas Tungsten Arc Welding (TIG/GTAW)

Flux Cored Arc Welding (FCAW)

Resistance welding

Submerged Arc Welding (SAW)
Principle of Electric arc welding
Comparison of welding with other
joining process.




Welding is a permanent joint where as
riveting and bolting is a temporary joint.
Welding joint are lighter in weight as
compared to riveting and bolting.
Welding joint have more tensile strength
and rigid as compared to riveting and
bolting.
Welding produce 100% efficient joint
which is not possible by any other joining
process.
Advantage of welding

Welding is a permanent joint.

Efficiency of welding joint is 100%

Welding produce equal strength as parent
metal.

Portable welding equipment is available.

A lot of similar or dissimilar metal can be
join by welding.

Welding joint is stronger as base metal

Welding joint are lighter in weight.

Appearance of weld bead is very smooth.

Machining operation such as grinding etc can be
performed very easy on welding surface.

Alteration and amendment is possible in existing
structure by welding process

Cost of welding joint is very economical.
Limitation of welding




Edge preparation is required before
welding.
Ultraviolet and infrared rays produce
during welding process.
Thermal stresses are produce in the weld
material.
Heat treatment process is required to
remove these stress.

Skill operator is need to operate the
welding machine.

HAZ produce.
Welding joints

(i) Butt joint

(ii) Tee joint

(iii) Lap joint

(iv) Corner joint

(v) Edge joint

(vi) Strap joint

(vii) Plug joint

Special jigs & fixture are required for holding a job for
welding purpose

Fumes and smokes produce during welding process.

Proper lighting arrangement is required for welding
process.

Proper ventilation also required.
Welding Positions

(i) Flat position

(ii) Horizontal position

(iii) Vertical position

(iv) Overhead position
Welding defects

External Defect
Welding defects
Internal Defect
(I) Incorrect Profile
(i) Below holes & Internal
(ii) Cracks
porosity
(iii) Crater
(ii) Cracks
(iv) Spatters and
(iii) Inclusions
(v) surface porosity
(iv) Lack of fusion
(vi) Incomplete filling groove (v) Incomplete penetration.
(vii) Distortion
Inspection of a welding joint

Inspection before welding

Inspection during welding

Inspection after welding
Testing and inspection of
welding joint
Testing and inspection of welding joint is
very important as joint carry load of
various nature in which the weld is
subjected to stress of either a simple or
complex character. inspection and testing
are the two different things. we should
confused with each other.
Welding inspection and
testing
Welding joint can be tested by two way.
 Destructive way and Non destructive way

In destructive testing welding joint may
get permanent deformation. means
welding object is no longer further use.
 In Non destructive testing no physical
change in welding structure it can be
further used.

Testing
Welding joint testing
Destructive testing
Non destructive testing
Destructive testing
Destructive testing are such as
(1)
Tensile test
(2)
Compression test
(3)
Bend test
(4)
Impact test
(5)
Nick break test
(6)
Hardness test
Non destructive testing

(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
Non destructive testing are such as
Florescent test
Dye penetration test
Visual inspection test
Ultrasonic test
Cycle test
X- ray test/γ-ray test Radiography Test)
Magnetic test
Eddy current test.
Selection of Joining Process

What determines what equipment to use for a job.

Availability equipment

Repetitiveness of the operation (how many passes)

Quality requirements (pipeline)

Location of the weld

Materials to be joined

Appearance of the finished products

Size of the parts

Time Available
Application of welding

Automobile industries

Building industries

Railroad industries

Pressure vessel and storage tank manufacturing

Aircraft industries

Petrochemical industries

Ship building industries

Pipe line industries.

Occupational
Opportunities in Welding










Welders
Tack Welders
Welding Operators
Welding Helper
Welder Assemblers/welder fitters
Welding Inspection
Welding Shop Supervisor
Welding Salesperson
Welding Shop Owners
Welding Engineers
Related sides









Welding Technology Institute Of Australia
www.wtia.com.au Central Metallurgical Research And
Development Institute www.cmrdi-egypt.org
Association Of Engineers And Architects In Israel
www.bgu.ac.il
Japan Institute Of Welding www.jwes.or.jp
New Zealand Welding Committee www.hera.org.nz
Chinese Welding Society www.china-weldnet.com
Singapore Welding Society www.sws.org.sg
Welding Institute Of Thailand www.wit.kmitnb.ac.th
Swedish Welding Commission www.svets.se
UK Section Of The IIW TWI www.twi.co.uk
Cont.







Bulgarian Welding Society www.bsz-bg.org
National Institute R & D Of Welding And
Materials Testing (ISIM) www.isim.ro
The Danish Welding Society www.dslsvejs.dk
Nederland's Institute Voor Lastechniek
www.nil.nl
The Russian Welding Society www.rntso.com
Welding Institute Of Yugoslavia
www.zzz.co.yu
American Welding Society www.aws.org
Thank you