This document provides information about welding processes and safety. It defines welding as a material joining process using heat and/or pressure. It describes different welding processes such as oxy-fuel gas welding, arc welding, and resistance welding. It discusses welding hazards, defects, joint types, and types of welds. The document outlines safety practices for welding, including personal protective equipment and ventilation. It also covers fire prevention and safe operation of welding equipment.

1. Group Assignment
welding
Prepared by:
ABDUL JABBAR KHAN
PANDIARAJ A/L RETENAM

2. 2
WELDING
Definition: Material joining process. Two
parts connected at their contacting
surfaces by suitable heat and pressure.
Many welding processes are
accomplished by heat alone, some others
by heat and pressure, and some with
pressure only.
In some welding operations a filler
material is used.
Welding operation usually applied to
metals but also used for plastics.

3. Parts produced by any of the manufacturing processes
can be made into larger, more complex bodies via Joining
processes
• Creating a metallurgical bond by adhesion and diffusion
• Joining by fusion with the use of various heat sources
• Brazing or soldering with a lower-melting metal
• Mechanical fastening
Joining ProcessesJoining Processes

4. Fusion Welding Processes

5. Sources of Energy for Fusion Welding
• Chemical reactions
– Burning gases
– GAS WELDING
• Heat from electricity
– Arc
– ARC WELDING
SYSTEMS
– Resistance welding
• LightLight
LASERLASER

6. Three Specific Types of Welding
Modules
• In this Welding, Cutting, and Brazing
module, three specific types of welding are
covered. These are listed below:
– Oxygen-fuel gas welding and cutting
– Arc welding and cutting
– Resistance welding

7. • Definition:
–This is a group of fusion welding
processes that use heat and pressure to
make the coalescence.
• The heat comes from electrical
resistance to current flow at the site of
the weld.
– The processes include:
• Spot Welding
• Projection Welding
• Seam Welding
Resistance Welding

8. • Spot Welding
–A process typically used in high-
volume, rapid welding applications.
•The pieces to be joined are
clamped between two electrodes
under force, and an electrical
current is sent through them.
Resistance Welding

9. Welding/Cutting Hazards
• Potential Hazards
– Fires may start by hot materials igniting
nearby combustibles.
– Burns to the operator may occur if unprotected
skin comes into contact with the extremely hot
work.
– Magnetic fields could easily
destroy/disrupt electronic
components, stored data if not
careful.

10. Weldability and Weld Quality
- Welding Defects-

11. 1. Fusion welding defects due wrong heat input, insufficient
rate of weld metal deposition, and cooling.
2. Lack of bonding or gas porosity due to surface
contaminants, including oxides, oils, etc.
3. Undesirable reactions with surface contaminants
4. Solidification cracks in the weld.
5. Solidification shrinkage coupled with solid shrinkage
imposes internal tensile stresses on the structure, may
lead to distortion.
6. Gases released or formed during welding (eg CO) can
lead to porosity which weakens the joint and acts as a
stress raiser.
Welding Defects

12. 12
Weld joint
There are 5 basic joint types in welding
• Butt joint: Two materials are in the same
plane, joined from the edges.
• Corner joint:The corners of two materials
form a right angle and joined.
• Lap joint: Two parts overlaps.
• Tee joint: One part is perpendicular to
the other, making a T shape.
• Edge joint: Edges of the two materials
joined.

13. 13
Weld Joints

14. 14
Types of weld
1. Fillet weld: Used in T joints,corner joints, lap
joints.
2. Groove weld:Used in butt joints.
3. Plug weld: Used in lap joints.
4. Slot weld: Used in lap joints.
5. Spot weld: Used in lap joints.
6. Seam weld: Used in lap joints.
7. Flange weld:Used in edge joints.
8. Surfacing weld:Not a joining process, it is used
to increase the thickness of the plate, or
provide a protective coating on the surface.

15. 15
Fillet Weld
Groove weld
Slot and Plug Weld

16. Oxyacetylene Gas Welding
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. (d) The principle of the oxyfuel-gas welding operation.

17. Oxygen-fuel gas welding & Cutting
• The elements of Oxygen-fuel gas welding
and cutting:
– General Requirements
– Cylinders
– Service Pipe Systems
– Pipe System Protection

18. Oxygen-fuel gas welding and cutting
• General Requirements
– Focuses on using Acetylene Safely
• Flammable
• Unstable
• Cannot be adjusted above 15 psi
– Safe Work Practices
• Blow out cylinder valve
• Turn on cylinder valve first and
then adjust the regulator pressure screw.
• Never stand in front or behind
a regulator when opening the cylinder valve
• Open cylinder valve slowly
• The pressure adjusting screw:
– Turning clockwise allows the gas
allows to flow.
– Turning counterclockwise reduces
or stop the gas flow.

19. • General Requirements Cont.:
– Safe Work Practices
• Purge oxygen and acetylene passages
• Light the acetylene
• Never use oil or grease
• Do not use oxygen as a substitute for air
• Keep your work area clean
Oxygen-fuel gas welding and cutting

20. 20
Arc Welding

21. t
Arc Welding and Cutting
• Definition:
– A fusion process wherein the coalescence of
the metals is achieved from the heat of an
electric arc formed between an electrode and
the work.
• Application
• Installation
• Operation & Maintenance

22. • Application
– Applies to a large and varied group of
processes that use an electric arc as the
source of heat to melt and join metals.
• Installation
– Arc welding requires proper installation of
equipment.
– A critical part of installation is ensuring that
proper grounding is completed.
Arc Welding & Cutting

23. Arc Welding & Cutting
• Operation & Maintenance
– All connections to the machine shall be checked
to make certain that they are properly made.
– The work lead shall be firmly attached to the
work.
– Magnetic work clamps shall be free from
adherent metal particles of spatter on contact
surfaces.
– Coiled welding cable shall be
spread out before use to avoid
serious overheating and
damage to insulation.

24. Methods of Arc Welding
• Three Types of Welding Methods:
– Tungsten Inert Gas Welding (TIG)
– Gas Metal Arc Welding (MIG)
– Shielded Metal Arc Welding (SMAW)/ Stick
Welding

25. • Heat is produced from electric
arc between workpiece and
electrode material for melting
the workpiece material.
• AC and DC are used
• An Inert gas shields both
electrodes
• Most heat energy is due to
electron flow to metal
Direct Current Electrode Negative
(DCEN): Deeper weld.
Direct Current Electrode Positive
(DCEP): Shallower and Wider
Heat input
v
EI
H = H- heat input, E, Voltage, I, Current, and v the
velocity of the arc travels along the weld line
Electric Arc Welding

26. • Electron Beam welding (EBW)
– Heat is produced by high velocity
electron gun in a narrow beam
– No filler material
– High rate of heating results in greater
depth and heat-affected zone is very
small
– Suitable for welding refractory materials
like: molybdenum and zirconium
– Requires a vacuum (limitation)
– x-ray will be generated around the
welding gun which may be cancerous
Other Welding Processes
High Energy Beam Welding

27. Safe Work Practices
• Electric & Gas Welding
– Safety Check:
• Ensure electrical cord, electrode holder
and cables are free from defects
– No cable splices within 10 feet of electrode holder.
• Ensure welding unit is properly grounded.
This helps to avoid over heating.
• All defective equipment shall be repaired
or replaced before using.

28. Safe Work Practices
• Electric & Gas Welding Cont.:
– Safety Check:
• Remove all jewelry – rings, watches, bracelets,
etc…
• Ensure PPE e.g.. welding hood, gloves, rubber
boots or safety shoes, apron are available and in
good condition.
• Ensure fire extinguisher is charged and available.
• Ensure adequate ventilation and lighting is in place.
• Set Voltage Regulator to Manufacture’s
specifications.
• Avoid electrical shock DON’T wrap cables around
any body part.
• Ensure fittings are tight.

29. Safe Work Practices
• Electric & Gas Welding Cont.:
– Safety Check:
• Inspect hoses for cuts and frayed areas.
• Set gauges to desired PSI.
• Ensure that sufficient PPE is made
available.
• Locate welding screens to protect
employee’s – DON’T block your exit.
• Ensure that adequate ventilation and
lighting are in place.

30. Fire Protection & Prevention
• Fire hazards must be removed, or
– Guards installed, or
– Welding/cutting must NOT take place
• Hot work permit should be used
outside designated areas to ensure
that all fire hazards are controlled
• Use of fire watch
– 1/2 hour after operation ceases

31. L10 : Joining processesL10 : Joining processesProper Ventilation for Welding
• Ensure protection from fumes
and gases by one or a
combination of the following:
– Good general ventilation.
– Use of a booth.
– Local exhaust ventilation
on the hand piece.
– Air supply to the helmet.

32. U
Welding Operators Protection
• Welding involves specialized personal
protection that must be worn every time
you perform welding operations. The
following is a list of basic PPE:
– Fire-resistant gloves
– Aprons
– Safety shoes
– Helmet
– Ultraviolet radiation filter plate (arc welding)
– Goggles with filter lenses

33. Sequences of welding
1.Do not over weld
2.Control fit up
4.For groove welds, use joints that will minimize the volume of weld metal.
Consider double-sided joints instead of single-sided joints
5.Weld alternately on either side of the joint when possible with multiple-pass
welds
6.Use minimal number of weld passes
7.Use low heat input procedures. This generally means high deposition rates
and higher travel speeds
9.Use welding positioners to achieve the maximum amount of flat-position
welding.
10.Balance welds about the neutral axis
11.Distribute the welding heat as evenly as possible through a planned welding
sequence
12.Weld toward the unrestrained part of the member
13.Use clamps, fixtures, and strong backs to maintain fit up and alignment
14. welds being made continually balance each other

34. Any Questions
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