SlideShare a Scribd company logo
1 of 26
Download to read offline
WELDING

Welding is a process of metal joining
by applying heat and sometimes pressure
Classification of welding processes:
(i). Arc welding
•
Carbon arc
•
Metal arc
•
Metal inert gas
•
Tungsten inert gas
•
Plasma arc
•
Submerged arc
•
Electro-slag
(ii). Gas Welding
•
•
•

Oxy-acetylene
Air-acetylene
Oxy-hydrogen

(iii). Resistance Welding
•
Butt
•
Spot
•
Seam
•
Projection
•
Percussion

(iv)Thermit Welding
(v)Solid State Welding

Friction
Ultrasonic
Diffusion
Explosive
(vi)Newer Welding
Electron-beam
Laser
(vii)Related Process
Oxy-acetylene cutting
Arc cutting
Hard facing
Brazing
Soldering
Arc welding
• Equipments:
•
•
•
•
•
•
•
•
•

A welding generator (D.C.) or Transformer (A.C.)
Two cables- one for work and one for electrode
Electrode holder
Electrode
Protective shield
Gloves
Wire brush
Chipping hammer
Goggles
Arc Welding Equipments
Arc welding process

Fig : Schematic illustration of the shielded metal-arc
welding process ( also known as stick welding,
because the electrode is in the shape of a
stick).

Fig : Schematic illustration of the shielded metal-arc
welding process. About 50% of all large-scale
industrial welding operations use this process.
WELDING
Metal arc welding
The Arc Welding Circuit
• The electricity flows
from the power source,
through the electrode
and across the arc,
through the base
material to the work
lead and back to the
power source

8
WELDING
Functions of Coated Electrodes( flux coated )

1. Protects the weld from oxidizing with atmosphere by producing a
shield of gas around the arc and weld pool
2. Provide the slag which floats at the top of molten metal so as to
protect the weld from rapid cooling and to protect weld from
atmosphere. The slag is then brushed off after weld gets cooled.
Terms used in welding :
Weld Pool :- Nature of deposition of the filler material in fusion zone
is know as weld pool
Slag :- molten or fused flux is called as slag
Flux :- mixture of Borax and sodium carbonate is coated to electrode
for shielding purpose.

Electric arc between the electrode and work piece closes the
electric circuit. The arc temperature may reach 10000°F
(5500°C), which is sufficient for fusion the work piece edges
and joining them.
What is Arc Welding?
• Arc welding is most commonly used to join two
pieces of metal
– The welder creates an electric arc that melts the base
metals and filler metal (consumable) together so that they
all fuse into one solid piece of metal

Steel Pipe – Tack
Welded
11

Root Pass or
“Stringer Bead”

Final weld after
several beads are
made
Why is Welding Important?
• Many things around us are welded …
– Pipelines that bring fresh water
– Towers that carry electricity to houses
– Cars and buses that take people where they need
to go

12
Arc Welding Safety
• Protect yourself and
others from potential
hazards including:
– Fumes and Gases
– Electric Shock
– Arc Rays
– Fire and Explosion
Hazards
– Noise
– Hot objects
13
Arc welding Advantages and
limitations
Advantages
– Most efficient way to join
metals
– Lowest-cost joining method
– Affords lighter weight through
better utilization of materials
– Joins all commercial metals
– Provides design flexibility

Limitations
• Manually applied, therefore high
labor cost.
• Need high energy causing danger
• Not convenient for disassembly.
• Defects are hard to detect at
joints.
GAS WELDING
• Sound weld is obtained by selecting proper size of flame, filler material
and method of moving torch
• The temperature generated during the process is 33000c
• When the metal is fused, oxygen from the atmosphere and the torch
combines with molten metal and forms oxides, results defective weld
• Fluxes are added to the welded metal to remove oxides
• Common fluxes used are made of sodium, potassium. Lithium and borax.
• Flux can be applied as paste, powder,liquid.solid coating or gas.
GAS WELDING EQUIPMENT...
1. Gas Cylinders
2. Regulators
3. Pressure Gauges
4. Hoses
5. Welding torch
6. Check valve
7. Non return valve
Oxy-Acetylene welding
Torch Used in Oxyacetylene Welding

Fig : (a) General view of and (b)
cross-section of a torch
used in oxyacetylene valve
is opened and the flame
adjusted. (c) Basic
equipment used in oxyfuelgas welding. To ensure
correct connections, all
threads on acetylene
fittings are left-handed,
whereas those for oxygen
are right-handed. Oxygen
regulators are usually
painted green acetylene
regulators red.
TYPES OF FLAMES…
• Oxygen is turned on, flame immediately changes into a long white inner
area (Feather) surrounded by a transparent blue envelope is called
Carburizing flame (30000c)
• Addition of little more oxygen give a bright whitish cone surrounded by
the transparent blue envelope is called Neutral flame (It has a balance of
fuel gas and oxygen) (32000c)
• Used for welding steels, aluminium, copper and cast iron
• If more oxygen is added, the cone becomes darker and more pointed,
while the envelope becomes shorter and more fierce is called Oxidizing
flame
• Has the highest temperature about 34000c
• Used for welding brass and brazing operation
Three basic types of oxyacetylene flames used in oxyfuel-gas welding and cutting
operations: (a) neutral flame; (b) oxidizing flame; (c) carburizing, or reducing flame.
Three basic types of oxyacetylene flames used in oxyfuel-gas welding and cutting
operations:
(a) neutral flame; (b) oxidizing flame; (c) carburizing, or reducing flame.
Oxyfuel Gas Welding

Fig : Three basic types of oxyacetylene flames used in oxyfuel-gas welding and cutting operations: (a)
neutral flame; (b) oxidizing flame; (c) carburizing, or reducing flame. The gas mixture in (a) is basically
equal volumes of oxygen and acetylene.
WELDING
Arc Welding
WELDING
Protective Clothing
Welders must wear protective
clothing for
– Protection from sparks, spatter and UV radiation
– Insulation from electric shock

• Protective clothing includes …
– Fire-proof clothing without rolled sleeves, cuffs or
frays
– Work boots
– Welding gloves, jackets, bibs, and fire-proof pants
– Welding cap, helmet and safety glasses
– Ear protection – ear plugs and muffs

26

More Related Content

What's hot (20)

WELDING PROCESS
WELDING PROCESSWELDING PROCESS
WELDING PROCESS
 
Soldering and brazing
Soldering and brazingSoldering and brazing
Soldering and brazing
 
Welding Introduction
Welding IntroductionWelding Introduction
Welding Introduction
 
Smaw
SmawSmaw
Smaw
 
Flux cored arc welding ppt
Flux cored arc welding pptFlux cored arc welding ppt
Flux cored arc welding ppt
 
Gass tungsten Arc Welding (GTAW)/ Tungsten Inert Gas Welding (TIG)
Gass tungsten Arc Welding (GTAW)/ Tungsten Inert Gas Welding (TIG) Gass tungsten Arc Welding (GTAW)/ Tungsten Inert Gas Welding (TIG)
Gass tungsten Arc Welding (GTAW)/ Tungsten Inert Gas Welding (TIG)
 
Gas welding
Gas weldingGas welding
Gas welding
 
Different types of welding techniques
Different types of welding techniquesDifferent types of welding techniques
Different types of welding techniques
 
Tig welding
Tig welding Tig welding
Tig welding
 
Welding process
Welding processWelding process
Welding process
 
Welding defects
Welding defectsWelding defects
Welding defects
 
WELDING Presentation.ppt
WELDING Presentation.pptWELDING Presentation.ppt
WELDING Presentation.ppt
 
Welding
WeldingWelding
Welding
 
welding
 welding welding
welding
 
Arc Welding
Arc WeldingArc Welding
Arc Welding
 
Tungsten Inert Gas Welding
Tungsten Inert Gas WeldingTungsten Inert Gas Welding
Tungsten Inert Gas Welding
 
Welding
WeldingWelding
Welding
 
Welding technology
Welding  technologyWelding  technology
Welding technology
 
Welding shop
Welding shopWelding shop
Welding shop
 
Welding Basics
Welding BasicsWelding Basics
Welding Basics
 

Similar to WELDING

Types of welding
Types of welding Types of welding
Types of welding Sabik T S
 
welding system.............30.07.1997
welding system.............30.07.1997welding system.............30.07.1997
welding system.............30.07.1997ashwinwarade30
 
fdocuments.in_introduction-to-weldingppt-56c13478bad3b.ppt
fdocuments.in_introduction-to-weldingppt-56c13478bad3b.pptfdocuments.in_introduction-to-weldingppt-56c13478bad3b.ppt
fdocuments.in_introduction-to-weldingppt-56c13478bad3b.pptPraveen Kumar
 
Gas and other Welding Shailesh Dewangan.pptx
Gas and other Welding Shailesh Dewangan.pptxGas and other Welding Shailesh Dewangan.pptx
Gas and other Welding Shailesh Dewangan.pptxShailesh Dewangan
 
METAL JOINING PROCESS
METAL JOINING PROCESSMETAL JOINING PROCESS
METAL JOINING PROCESSlaxtwinsme
 
WELDING Presentation.ppt
WELDING Presentation.pptWELDING Presentation.ppt
WELDING Presentation.pptIzzatTammam
 
Introduction to WELDING Technology Presentation.ppt
Introduction to WELDING Technology  Presentation.pptIntroduction to WELDING Technology  Presentation.ppt
Introduction to WELDING Technology Presentation.pptVidyaTiwari2
 
Metal Joining Process- Welding, Brazing and Soldering
Metal Joining Process- Welding, Brazing and SolderingMetal Joining Process- Welding, Brazing and Soldering
Metal Joining Process- Welding, Brazing and SolderingLearnwithus2
 
Welding process
Welding processWelding process
Welding processArunMK17
 

Similar to WELDING (20)

Types of welding
Types of welding Types of welding
Types of welding
 
Welding ppt
Welding pptWelding ppt
Welding ppt
 
Welding 2
Welding 2Welding 2
Welding 2
 
welding system.............30.07.1997
welding system.............30.07.1997welding system.............30.07.1997
welding system.............30.07.1997
 
FUSION WELDING PROCESS
FUSION WELDING PROCESSFUSION WELDING PROCESS
FUSION WELDING PROCESS
 
fdocuments.in_introduction-to-weldingppt-56c13478bad3b.ppt
fdocuments.in_introduction-to-weldingppt-56c13478bad3b.pptfdocuments.in_introduction-to-weldingppt-56c13478bad3b.ppt
fdocuments.in_introduction-to-weldingppt-56c13478bad3b.ppt
 
Arc welding
Arc weldingArc welding
Arc welding
 
arc welding
arc weldingarc welding
arc welding
 
arc welding.pptx
arc welding.pptxarc welding.pptx
arc welding.pptx
 
Welding techniques
Welding techniquesWelding techniques
Welding techniques
 
WELDING FOUNDATION LEVEL
WELDING FOUNDATION LEVELWELDING FOUNDATION LEVEL
WELDING FOUNDATION LEVEL
 
Gas and other Welding Shailesh Dewangan.pptx
Gas and other Welding Shailesh Dewangan.pptxGas and other Welding Shailesh Dewangan.pptx
Gas and other Welding Shailesh Dewangan.pptx
 
METAL JOINING PROCESS
METAL JOINING PROCESSMETAL JOINING PROCESS
METAL JOINING PROCESS
 
WELDING Presentation.ppt
WELDING Presentation.pptWELDING Presentation.ppt
WELDING Presentation.ppt
 
Introduction to WELDING Technology Presentation.ppt
Introduction to WELDING Technology  Presentation.pptIntroduction to WELDING Technology  Presentation.ppt
Introduction to WELDING Technology Presentation.ppt
 
W1.ppt
W1.pptW1.ppt
W1.ppt
 
Metal Joining Process- Welding, Brazing and Soldering
Metal Joining Process- Welding, Brazing and SolderingMetal Joining Process- Welding, Brazing and Soldering
Metal Joining Process- Welding, Brazing and Soldering
 
Welding process
Welding processWelding process
Welding process
 
Welding revision
Welding revisionWelding revision
Welding revision
 
Gas Welding
Gas WeldingGas Welding
Gas Welding
 

Recently uploaded

Apres-Cyber - The Data Dilemma: Bridging Offensive Operations and Machine Lea...
Apres-Cyber - The Data Dilemma: Bridging Offensive Operations and Machine Lea...Apres-Cyber - The Data Dilemma: Bridging Offensive Operations and Machine Lea...
Apres-Cyber - The Data Dilemma: Bridging Offensive Operations and Machine Lea...Will Schroeder
 
The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...
The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...
The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...Aggregage
 
Artificial Intelligence & SEO Trends for 2024
Artificial Intelligence & SEO Trends for 2024Artificial Intelligence & SEO Trends for 2024
Artificial Intelligence & SEO Trends for 2024D Cloud Solutions
 
Cybersecurity Workshop #1.pptx
Cybersecurity Workshop #1.pptxCybersecurity Workshop #1.pptx
Cybersecurity Workshop #1.pptxGDSC PJATK
 
AI Fame Rush Review – Virtual Influencer Creation In Just Minutes
AI Fame Rush Review – Virtual Influencer Creation In Just MinutesAI Fame Rush Review – Virtual Influencer Creation In Just Minutes
AI Fame Rush Review – Virtual Influencer Creation In Just MinutesMd Hossain Ali
 
Using IESVE for Loads, Sizing and Heat Pump Modeling to Achieve Decarbonization
Using IESVE for Loads, Sizing and Heat Pump Modeling to Achieve DecarbonizationUsing IESVE for Loads, Sizing and Heat Pump Modeling to Achieve Decarbonization
Using IESVE for Loads, Sizing and Heat Pump Modeling to Achieve DecarbonizationIES VE
 
Salesforce Miami User Group Event - 1st Quarter 2024
Salesforce Miami User Group Event - 1st Quarter 2024Salesforce Miami User Group Event - 1st Quarter 2024
Salesforce Miami User Group Event - 1st Quarter 2024SkyPlanner
 
Meet the new FSP 3000 M-Flex800™
Meet the new FSP 3000 M-Flex800™Meet the new FSP 3000 M-Flex800™
Meet the new FSP 3000 M-Flex800™Adtran
 
NIST Cybersecurity Framework (CSF) 2.0 Workshop
NIST Cybersecurity Framework (CSF) 2.0 WorkshopNIST Cybersecurity Framework (CSF) 2.0 Workshop
NIST Cybersecurity Framework (CSF) 2.0 WorkshopBachir Benyammi
 
UiPath Studio Web workshop series - Day 7
UiPath Studio Web workshop series - Day 7UiPath Studio Web workshop series - Day 7
UiPath Studio Web workshop series - Day 7DianaGray10
 
Basic Building Blocks of Internet of Things.
Basic Building Blocks of Internet of Things.Basic Building Blocks of Internet of Things.
Basic Building Blocks of Internet of Things.YounusS2
 
Spring24-Release Overview - Wellingtion User Group-1.pdf
Spring24-Release Overview - Wellingtion User Group-1.pdfSpring24-Release Overview - Wellingtion User Group-1.pdf
Spring24-Release Overview - Wellingtion User Group-1.pdfAnna Loughnan Colquhoun
 
RAG Patterns and Vector Search in Generative AI
RAG Patterns and Vector Search in Generative AIRAG Patterns and Vector Search in Generative AI
RAG Patterns and Vector Search in Generative AIUdaiappa Ramachandran
 
GenAI and AI GCC State of AI_Object Automation Inc
GenAI and AI GCC State of AI_Object Automation IncGenAI and AI GCC State of AI_Object Automation Inc
GenAI and AI GCC State of AI_Object Automation IncObject Automation
 
UiPath Platform: The Backend Engine Powering Your Automation - Session 1
UiPath Platform: The Backend Engine Powering Your Automation - Session 1UiPath Platform: The Backend Engine Powering Your Automation - Session 1
UiPath Platform: The Backend Engine Powering Your Automation - Session 1DianaGray10
 
UiPath Solutions Management Preview - Northern CA Chapter - March 22.pdf
UiPath Solutions Management Preview - Northern CA Chapter - March 22.pdfUiPath Solutions Management Preview - Northern CA Chapter - March 22.pdf
UiPath Solutions Management Preview - Northern CA Chapter - March 22.pdfDianaGray10
 
20200723_insight_release_plan_v6.pdf20200723_insight_release_plan_v6.pdf
20200723_insight_release_plan_v6.pdf20200723_insight_release_plan_v6.pdf20200723_insight_release_plan_v6.pdf20200723_insight_release_plan_v6.pdf
20200723_insight_release_plan_v6.pdf20200723_insight_release_plan_v6.pdfJamie (Taka) Wang
 
9 Steps For Building Winning Founding Team
9 Steps For Building Winning Founding Team9 Steps For Building Winning Founding Team
9 Steps For Building Winning Founding TeamAdam Moalla
 
Bird eye's view on Camunda open source ecosystem
Bird eye's view on Camunda open source ecosystemBird eye's view on Camunda open source ecosystem
Bird eye's view on Camunda open source ecosystemAsko Soukka
 
COMPUTER 10: Lesson 7 - File Storage and Online Collaboration
COMPUTER 10: Lesson 7 - File Storage and Online CollaborationCOMPUTER 10: Lesson 7 - File Storage and Online Collaboration
COMPUTER 10: Lesson 7 - File Storage and Online Collaborationbruanjhuli
 

Recently uploaded (20)

Apres-Cyber - The Data Dilemma: Bridging Offensive Operations and Machine Lea...
Apres-Cyber - The Data Dilemma: Bridging Offensive Operations and Machine Lea...Apres-Cyber - The Data Dilemma: Bridging Offensive Operations and Machine Lea...
Apres-Cyber - The Data Dilemma: Bridging Offensive Operations and Machine Lea...
 
The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...
The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...
The Data Metaverse: Unpacking the Roles, Use Cases, and Tech Trends in Data a...
 
Artificial Intelligence & SEO Trends for 2024
Artificial Intelligence & SEO Trends for 2024Artificial Intelligence & SEO Trends for 2024
Artificial Intelligence & SEO Trends for 2024
 
Cybersecurity Workshop #1.pptx
Cybersecurity Workshop #1.pptxCybersecurity Workshop #1.pptx
Cybersecurity Workshop #1.pptx
 
AI Fame Rush Review – Virtual Influencer Creation In Just Minutes
AI Fame Rush Review – Virtual Influencer Creation In Just MinutesAI Fame Rush Review – Virtual Influencer Creation In Just Minutes
AI Fame Rush Review – Virtual Influencer Creation In Just Minutes
 
Using IESVE for Loads, Sizing and Heat Pump Modeling to Achieve Decarbonization
Using IESVE for Loads, Sizing and Heat Pump Modeling to Achieve DecarbonizationUsing IESVE for Loads, Sizing and Heat Pump Modeling to Achieve Decarbonization
Using IESVE for Loads, Sizing and Heat Pump Modeling to Achieve Decarbonization
 
Salesforce Miami User Group Event - 1st Quarter 2024
Salesforce Miami User Group Event - 1st Quarter 2024Salesforce Miami User Group Event - 1st Quarter 2024
Salesforce Miami User Group Event - 1st Quarter 2024
 
Meet the new FSP 3000 M-Flex800™
Meet the new FSP 3000 M-Flex800™Meet the new FSP 3000 M-Flex800™
Meet the new FSP 3000 M-Flex800™
 
NIST Cybersecurity Framework (CSF) 2.0 Workshop
NIST Cybersecurity Framework (CSF) 2.0 WorkshopNIST Cybersecurity Framework (CSF) 2.0 Workshop
NIST Cybersecurity Framework (CSF) 2.0 Workshop
 
UiPath Studio Web workshop series - Day 7
UiPath Studio Web workshop series - Day 7UiPath Studio Web workshop series - Day 7
UiPath Studio Web workshop series - Day 7
 
Basic Building Blocks of Internet of Things.
Basic Building Blocks of Internet of Things.Basic Building Blocks of Internet of Things.
Basic Building Blocks of Internet of Things.
 
Spring24-Release Overview - Wellingtion User Group-1.pdf
Spring24-Release Overview - Wellingtion User Group-1.pdfSpring24-Release Overview - Wellingtion User Group-1.pdf
Spring24-Release Overview - Wellingtion User Group-1.pdf
 
RAG Patterns and Vector Search in Generative AI
RAG Patterns and Vector Search in Generative AIRAG Patterns and Vector Search in Generative AI
RAG Patterns and Vector Search in Generative AI
 
GenAI and AI GCC State of AI_Object Automation Inc
GenAI and AI GCC State of AI_Object Automation IncGenAI and AI GCC State of AI_Object Automation Inc
GenAI and AI GCC State of AI_Object Automation Inc
 
UiPath Platform: The Backend Engine Powering Your Automation - Session 1
UiPath Platform: The Backend Engine Powering Your Automation - Session 1UiPath Platform: The Backend Engine Powering Your Automation - Session 1
UiPath Platform: The Backend Engine Powering Your Automation - Session 1
 
UiPath Solutions Management Preview - Northern CA Chapter - March 22.pdf
UiPath Solutions Management Preview - Northern CA Chapter - March 22.pdfUiPath Solutions Management Preview - Northern CA Chapter - March 22.pdf
UiPath Solutions Management Preview - Northern CA Chapter - March 22.pdf
 
20200723_insight_release_plan_v6.pdf20200723_insight_release_plan_v6.pdf
20200723_insight_release_plan_v6.pdf20200723_insight_release_plan_v6.pdf20200723_insight_release_plan_v6.pdf20200723_insight_release_plan_v6.pdf
20200723_insight_release_plan_v6.pdf20200723_insight_release_plan_v6.pdf
 
9 Steps For Building Winning Founding Team
9 Steps For Building Winning Founding Team9 Steps For Building Winning Founding Team
9 Steps For Building Winning Founding Team
 
Bird eye's view on Camunda open source ecosystem
Bird eye's view on Camunda open source ecosystemBird eye's view on Camunda open source ecosystem
Bird eye's view on Camunda open source ecosystem
 
COMPUTER 10: Lesson 7 - File Storage and Online Collaboration
COMPUTER 10: Lesson 7 - File Storage and Online CollaborationCOMPUTER 10: Lesson 7 - File Storage and Online Collaboration
COMPUTER 10: Lesson 7 - File Storage and Online Collaboration
 

WELDING

  • 1. WELDING Welding is a process of metal joining by applying heat and sometimes pressure
  • 2. Classification of welding processes: (i). Arc welding • Carbon arc • Metal arc • Metal inert gas • Tungsten inert gas • Plasma arc • Submerged arc • Electro-slag (ii). Gas Welding • • • Oxy-acetylene Air-acetylene Oxy-hydrogen (iii). Resistance Welding • Butt • Spot • Seam • Projection • Percussion (iv)Thermit Welding (v)Solid State Welding Friction Ultrasonic Diffusion Explosive (vi)Newer Welding Electron-beam Laser (vii)Related Process Oxy-acetylene cutting Arc cutting Hard facing Brazing Soldering
  • 3. Arc welding • Equipments: • • • • • • • • • A welding generator (D.C.) or Transformer (A.C.) Two cables- one for work and one for electrode Electrode holder Electrode Protective shield Gloves Wire brush Chipping hammer Goggles
  • 5. Arc welding process Fig : Schematic illustration of the shielded metal-arc welding process ( also known as stick welding, because the electrode is in the shape of a stick). Fig : Schematic illustration of the shielded metal-arc welding process. About 50% of all large-scale industrial welding operations use this process.
  • 8. The Arc Welding Circuit • The electricity flows from the power source, through the electrode and across the arc, through the base material to the work lead and back to the power source 8
  • 10. Functions of Coated Electrodes( flux coated ) 1. Protects the weld from oxidizing with atmosphere by producing a shield of gas around the arc and weld pool 2. Provide the slag which floats at the top of molten metal so as to protect the weld from rapid cooling and to protect weld from atmosphere. The slag is then brushed off after weld gets cooled. Terms used in welding : Weld Pool :- Nature of deposition of the filler material in fusion zone is know as weld pool Slag :- molten or fused flux is called as slag Flux :- mixture of Borax and sodium carbonate is coated to electrode for shielding purpose. Electric arc between the electrode and work piece closes the electric circuit. The arc temperature may reach 10000°F (5500°C), which is sufficient for fusion the work piece edges and joining them.
  • 11. What is Arc Welding? • Arc welding is most commonly used to join two pieces of metal – The welder creates an electric arc that melts the base metals and filler metal (consumable) together so that they all fuse into one solid piece of metal Steel Pipe – Tack Welded 11 Root Pass or “Stringer Bead” Final weld after several beads are made
  • 12. Why is Welding Important? • Many things around us are welded … – Pipelines that bring fresh water – Towers that carry electricity to houses – Cars and buses that take people where they need to go 12
  • 13. Arc Welding Safety • Protect yourself and others from potential hazards including: – Fumes and Gases – Electric Shock – Arc Rays – Fire and Explosion Hazards – Noise – Hot objects 13
  • 14. Arc welding Advantages and limitations Advantages – Most efficient way to join metals – Lowest-cost joining method – Affords lighter weight through better utilization of materials – Joins all commercial metals – Provides design flexibility Limitations • Manually applied, therefore high labor cost. • Need high energy causing danger • Not convenient for disassembly. • Defects are hard to detect at joints.
  • 15. GAS WELDING • Sound weld is obtained by selecting proper size of flame, filler material and method of moving torch • The temperature generated during the process is 33000c • When the metal is fused, oxygen from the atmosphere and the torch combines with molten metal and forms oxides, results defective weld • Fluxes are added to the welded metal to remove oxides • Common fluxes used are made of sodium, potassium. Lithium and borax. • Flux can be applied as paste, powder,liquid.solid coating or gas.
  • 16. GAS WELDING EQUIPMENT... 1. Gas Cylinders 2. Regulators 3. Pressure Gauges 4. Hoses 5. Welding torch 6. Check valve 7. Non return valve
  • 18. Torch Used in Oxyacetylene Welding Fig : (a) General view of and (b) cross-section of a torch used in oxyacetylene valve is opened and the flame adjusted. (c) Basic equipment used in oxyfuelgas welding. To ensure correct connections, all threads on acetylene fittings are left-handed, whereas those for oxygen are right-handed. Oxygen regulators are usually painted green acetylene regulators red.
  • 19. TYPES OF FLAMES… • Oxygen is turned on, flame immediately changes into a long white inner area (Feather) surrounded by a transparent blue envelope is called Carburizing flame (30000c) • Addition of little more oxygen give a bright whitish cone surrounded by the transparent blue envelope is called Neutral flame (It has a balance of fuel gas and oxygen) (32000c) • Used for welding steels, aluminium, copper and cast iron • If more oxygen is added, the cone becomes darker and more pointed, while the envelope becomes shorter and more fierce is called Oxidizing flame • Has the highest temperature about 34000c • Used for welding brass and brazing operation
  • 20. Three basic types of oxyacetylene flames used in oxyfuel-gas welding and cutting operations: (a) neutral flame; (b) oxidizing flame; (c) carburizing, or reducing flame.
  • 21. Three basic types of oxyacetylene flames used in oxyfuel-gas welding and cutting operations: (a) neutral flame; (b) oxidizing flame; (c) carburizing, or reducing flame.
  • 22. Oxyfuel Gas Welding Fig : Three basic types of oxyacetylene flames used in oxyfuel-gas welding and cutting operations: (a) neutral flame; (b) oxidizing flame; (c) carburizing, or reducing flame. The gas mixture in (a) is basically equal volumes of oxygen and acetylene.
  • 26. Protective Clothing Welders must wear protective clothing for – Protection from sparks, spatter and UV radiation – Insulation from electric shock • Protective clothing includes … – Fire-proof clothing without rolled sleeves, cuffs or frays – Work boots – Welding gloves, jackets, bibs, and fire-proof pants – Welding cap, helmet and safety glasses – Ear protection – ear plugs and muffs 26