Lec 17 Gas Flame and Arc Welding Processes

Questions and Answers

What is oxyfuel-gas welding?

A group of welding processes that use the flame produced by the combustion of a fuel gas and oxygen as the source of heat

Oxyacetylene welding is a type of arc welding process.

False

What is the purpose of preheating the metal in oxyacetylene welding?

To provide shielding from oxidation

The maximum temperature is at the _______________________.

inner cone Signup and view all the answers

Match the following welding processes with their descriptions:

Oxyfuel-gas welding = Uses the flame produced by the combustion of a fuel gas and oxygen as the source of heat Arc welding = Uses an electric arc to melt and join metals Flame straightening = Uses a flame to straighten bent or warped metal Thermal cutting = Uses a high-temperature flame to cut metals Signup and view all the answers

What is the name of the device used to control the flame in oxyacetylene welding?

Oxyacetylene torch Signup and view all the answers

Oxyfuel-gas welding is a type of thermal cutting process.

False Signup and view all the answers

What is the purpose of the oxyacetylene flame in welding?

To provide heat to melt and join metals Signup and view all the answers

What is the primary advantage of plasma arc welding?

Narrow welds with deep penetration Signup and view all the answers

Plasma arc cutting is a slower process compared to other thermal cutting methods.

False Signup and view all the answers

What is the name of the gas flow that transfers heat to the workpiece and melts the metal in plasma arc torches?

Orifice gas Signup and view all the answers

What is the temperature of an oxidizing flame?

3600°C Signup and view all the answers

Plasma arc cutting produces the highest temperatures available from any practical _______________.

source Signup and view all the answers

Oxyhydrogen-gas welding can be used to weld ferrous metals.

False Signup and view all the answers

What is the main difference between GTAW and plasma arc welding?

Constricted arc Signup and view all the answers

Plasma arc welding can be used to weld all metals and alloys.

True Signup and view all the answers

Flame straightening uses controlled, localized _______________ as a means of straightening warped or buckled material.

upsetting Signup and view all the answers

What is the most common thermal cutting process?

Oxy-fuel gas cutting Signup and view all the answers

What is the advantage of plasma arc welding in terms of distortion?

Reduced distortion Signup and view all the answers

Arc welding uses an oxyfuel-gas torch.

False Signup and view all the answers

What is the name of the process that uses an oxyfuel-gas torch to cut materials underwater?

Underwater cutting torch Signup and view all the answers

Which of the following welding processes is best used for welding ferrous metals?

Shielded Metal Arc Welding (SMAW) Signup and view all the answers

Flux-Cored Arc Welding (FCAW) equipment costs less than SMAW.

False Signup and view all the answers

What is the purpose of the flux in Shielded Metal Arc Welding (SMAW)?

To provide a gas shield around the arc, remove impurities, add alloying elements, and provide additional filler metal. Signup and view all the answers

In Gas Metal Arc Welding (GMAW), the supplemental shielding gas flows through the _______________________.

torch Signup and view all the answers

Match the welding processes with their characteristics:

SMAW = Best used for welding ferrous metals FCAW = Equipment cost greater than SMAW GMAW = Supplemental shielding gas flows through the torch SAW = Granular flux is deposited just ahead of the consumable electrode Signup and view all the answers

Submerged Arc Welding (SAW) uses a shielding gas.

False Signup and view all the answers

What is the primary purpose of Stud Welding?

To attach studs, screw, pins or other fasteners to a metal surface. Signup and view all the answers

Which welding process is best suited for making butt or fillet welds in low-carbon steels?

SAW Signup and view all the answers

What is the primary function of helium in Gas Tungsten Arc Welding (GTAW)?

To increase heat input for higher welding speeds and deeper penetration Signup and view all the answers

GTAW welded materials are always thicker than ¼ in.

False Signup and view all the answers

What is the most widely used gas in Gas Tungsten Arc Welding (GTAW)?

Argon Signup and view all the answers

In GTAW, the weld nugget begins to form at the surface where the _______________ makes contact.

gun Signup and view all the answers

Match the following components with their functions in GTAW:

Argon = Produces a smoother arc Helium = Increases heat input for higher welding speeds and deeper penetration Nozzle = Pressed firmly against the material Tungsten = Electrode that produces the arc Signup and view all the answers

What is the primary advantage of using helium in GTAW?

Higher welding speeds and deeper penetration Signup and view all the answers

Oxyfuel-gas welding is a type of arc welding process.

False Signup and view all the answers

What is the purpose of the vented nozzle on the modified TIG gun in GTAW?

improved gas coverage, reduced turbulence, and potentially better visibility Signup and view all the answers

Oxyacetylene welding uses a combination of oxygen and ______ gases to produce a high-temperature flame for welding and cutting metals.

acetylene Signup and view all the answers

The ______ contains valves for oxygen and acetylene flow control.

torch handle (oxygen control unit, fuel gas control valve) Signup and view all the answers

The ______ is where oxygen and acetylene gases mix.

mixing chamber Signup and view all the answers

A ______ flame is a balanced mixture of oxygen and acetylene; ideal for welding.

neutral Signup and view all the answers

To light the torch, open the ______ valve slightly.

oxygen Signup and view all the answers

Increasing oxygen flow increases ______ temperature and velocity.

flame Signup and view all the answers

Study Notes

Plasma Arc Torches

Emerging gas transfers its heat to the workpiece and melts the metal, called the orifice gas flow.
Characteristics of plasma arc welding: fast welding speed, narrow welds with deep penetration, narrow heat affected zone, reduced distortion, and can be used to weld all metals and alloys.

Arc Cutting

Types of arc cutting: carbon arc and shielded metal arc cutting, air carbon arc cutting, oxygen arc cutting, gas metal arc cutting, and plasma arc cutting.
Plasma arc cutting produces the highest temperatures available, is more economical, more versatile, and much faster.

Oxyfuel-Gas Welding Process

Uses oxyfuel gas flame as the source of heat.
Types of flames: neutral flame, oxidizing flame, and carburizing flame.
Alternative fuel gases: propane, propylene, butane, natural gas, and hydrogen.

Oxyfuel-Gas Cutting

Oxy-fuel gas cutting (flame cutting) is the most common thermal cutting process.
Metal is melted by the flame of the oxyfuel gas torch.

Arc Welding

Types of arc welding: shielded metal arc welding (SMAW), flux-cored arc welding (FCAW), gas metal arc welding (GMAW), and submerged arc welding (SAW).
Shielded metal arc welding (SMAW):
- Most widely used process due to versatility and low-cost equipment.
- Best used for welding ferrous metals (carbon steels, alloy steels, stainless steels, and cast iron).
Flux-cored arc welding (FCAW):
- Best used for welding steels.
- Equipment cost greater than SMAW.
- Needs good ventilation to remove fumes generated by the vaporizing flux.
Gas metal arc welding (GMAW):
- Formerly known as metal inert-gas welding or MIG.
- Supplemental shielding gas flows through the torch.
- Consumable electrode: continuous, solid, uncoated wire or a continuous hollow tube with powdered alloy additions as consumable electrode.
Submerged arc welding (SAW):
- Granular flux is deposited just ahead of bare-wire consumable electrode, and the arc is maintained beneath the blanket of flux.
- No shielding gas used.
- Most suitable for making butt or fillet welds in low-carbon steels.

Other Processes

Stud welding: used to attach studs, screw, pins or other fasteners to a metal surface.
Flame straightening: uses controlled, localized upsetting as a means of straightening warped or buckled material.

Oxyacetylene Welding Torch

Principle

Oxyacetylene welding uses a combination of oxygen and acetylene gases to produce a high-temperature flame for welding and cutting metals.

Components

Torch Handle: contains valves for oxygen and acetylene flow control
Mixing Chamber: where oxygen and acetylene gases mix
Nozzle: where the flame is produced
Hoses: supply oxygen and acetylene gases to the torch

Operation

Lighting the Torch: open oxygen valve slightly, light the torch with a spark or flame, and adjust oxygen flow to achieve a neutral flame (feather-edged, blue-colored)
Adjusting the Flame:
- Increasing oxygen flow increases flame temperature and velocity
- Increasing acetylene flow increases flame size and reduces temperature

Types of Flames

Neutral Flame: balanced mixture of oxygen and acetylene; ideal for welding
Oxidizing Flame: excess oxygen; used for cutting and heavy welding
Carburizing Flame: excess acetylene; used for bronze welding and brazing

Safety Precautions

Wear protective gear (gloves, goggles, apron)
Ensure good ventilation
Keep the torch and hoses away from heat sources and sparks

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Lec 17 Gas Flame and Arc Welding Processes

Questions and Answers

What is oxyfuel-gas welding?

Oxyacetylene welding is a type of arc welding process.

What is the purpose of preheating the metal in oxyacetylene welding?

The maximum temperature is at the _______________________.

Match the following welding processes with their descriptions:

What is the name of the device used to control the flame in oxyacetylene welding?

Oxyfuel-gas welding is a type of thermal cutting process.

What is the purpose of the oxyacetylene flame in welding?

What is the primary advantage of plasma arc welding?

Plasma arc cutting is a slower process compared to other thermal cutting methods.

What is the name of the gas flow that transfers heat to the workpiece and melts the metal in plasma arc torches?

What is the temperature of an oxidizing flame?

Plasma arc cutting produces the highest temperatures available from any practical _______________.

Oxyhydrogen-gas welding can be used to weld ferrous metals.

What is the main difference between GTAW and plasma arc welding?

Plasma arc welding can be used to weld all metals and alloys.

Flame straightening uses controlled, localized _______________ as a means of straightening warped or buckled material.

What is the most common thermal cutting process?

What is the advantage of plasma arc welding in terms of distortion?

Arc welding uses an oxyfuel-gas torch.

What is the name of the process that uses an oxyfuel-gas torch to cut materials underwater?

Which of the following welding processes is best used for welding ferrous metals?

Flux-Cored Arc Welding (FCAW) equipment costs less than SMAW.

What is the purpose of the flux in Shielded Metal Arc Welding (SMAW)?

In Gas Metal Arc Welding (GMAW), the supplemental shielding gas flows through the _______________________.

Match the welding processes with their characteristics:

Submerged Arc Welding (SAW) uses a shielding gas.

What is the primary purpose of Stud Welding?

Which welding process is best suited for making butt or fillet welds in low-carbon steels?

What is the primary function of helium in Gas Tungsten Arc Welding (GTAW)?

GTAW welded materials are always thicker than ¼ in.

What is the most widely used gas in Gas Tungsten Arc Welding (GTAW)?

In GTAW, the weld nugget begins to form at the surface where the _______________ makes contact.

Match the following components with their functions in GTAW:

What is the primary advantage of using helium in GTAW?

Oxyfuel-gas welding is a type of arc welding process.

What is the purpose of the vented nozzle on the modified TIG gun in GTAW?

Oxyacetylene welding uses a combination of oxygen and ______ gases to produce a high-temperature flame for welding and cutting metals.

The ______ contains valves for oxygen and acetylene flow control.

The ______ is where oxygen and acetylene gases mix.

A ______ flame is a balanced mixture of oxygen and acetylene; ideal for welding.

To light the torch, open the ______ valve slightly.

Increasing oxygen flow increases ______ temperature and velocity.

Study Notes

Plasma Arc Torches

Arc Cutting

Oxyfuel-Gas Welding Process

Oxyfuel-Gas Cutting

Arc Welding

Other Processes

Oxyacetylene Welding Torch

Principle

Components

Operation

Types of Flames

Safety Precautions

Studying That Suits You

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