Welding is a process that joins two or more metal pieces together by applying heat, pressure, or both. It is the primary way to join metal parts into a single piece. Some key equipment needed for gas welding includes oxygen and acetylene cylinders/valves, hoses, safety gear like gloves and goggles, and tools for cleaning and prepping the metal. There are different types of fusion welding that melt and fuse the base metal, and may add a filler metal, using heat sources like gas flames, electric arcs, plasma arcs, or lasers. A welding torch is used to direct the electrode, conduct welding power, and provide shielding of the arc during automatic welding.

1. PREPARED BY
ANAS MIRZA
APPRENTICE ENGINEER
BQPS-1
16-04-2020

2. What is Welding ?
Welding is an operation whereby two or more parts are united by means
of heat or pressure or both. It is usually used on metals and thermoplastics
but can also be used on wood.
It is the only way of joining two or more pieces of metal to make them
act as a single piece.

5. Equipment:
Few equipment needed for gas welding are
 Key for cylinders and valves
 Hoses for oxygen and acetylene
 Spanners for connecting hoses
 Safety equipment like goggles, screens, lather hand glove and lather apron
 Chipping hammer
 Goggles
 Wire brush
 Spark light

6. Fusion Welding
Some of the important properties of a weld include:
• Strength – the ability to withstand an applied load
• Ductility – the ability to deform/ stretch without failing
• Hardness – the ability to resist indention
• Toughness – the ability to absorb energy
• Soundness – freedom from imperfection
• Fatigue Strength – resistance to failure under repeated loads
Fusion Welding Principles
• Base metal is melted
• Filter metal may be added
• Heat is supplied by various means
• Oxyacetylene gas
Electric Arc
Plasma Arc
Laser
Fusion Welding

7. Welding Torches
A welding torch is used in an automatic welding system to direct the welding electrode
into the arc, to conduct welding power to the electrode, and to provide shielding
of the arc area. There are many types of welding torches, and the choice depends on the
welding process, the welding process variation, welding current, electrode size and
shielding medium.
A torch can be described according to whether it is a straight torch or has a bend in its
barrel. A torch with a bend is often used for robotic arc welding applications to provide
access for the weld.
The major function of the torch is to deliver the welding
current to the electrode. For consumable electrode process
this means transferring the current to the electrode as the
electrode moves through the torch.