Oxy Acetylene Welding: Carburising Flame and Types of Flames Quiz

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Questions and Answers

What is the primary fuel gas used in gas welding?

Acetylene (correct)

Hydrogen

Producer gas

Natural gas

What is the purpose of flux in gas welding?

To apply pressure to the joint

To add additional material to the weld zone

To increase the temperature of the flame

To remove contaminants from the surface (correct)

What is the typical form of filler metal used in gas welding?

Wire or rod (correct)

Paste

Liquid

Powder

What is the purpose of oxygen in gas welding?

To support combustion at high temperatures Signup and view all the answers

What is the typical joint preparation in gas welding?

A slight gap between the workpieces Signup and view all the answers

What is the primary way to heat the joint in gas welding?

By heating with a flame Signup and view all the answers

What is the purpose of the oxyacetylene flame in gas welding?

To heat the joint to a state of fusion Signup and view all the answers

What is the common characteristic of fluxes used in gas welding?

Made of sodium, potassium, Lithium and borax Signup and view all the answers

What is the characteristic of the oxidizing flame in fusion welding of brass and bronze?

The cone becomes darker and more pointed Signup and view all the answers

What is the typical temperature of the carburizing flame?

30000°C Signup and view all the answers

What is an advantage of oxyacetylene welding?

The equipment is portable and inexpensive Signup and view all the answers

What is a disadvantage of oxyacetylene welding?

Gas welding is slower than electric arc welding Signup and view all the answers

What is a safety precaution when handling gas cylinders in oxyacetylene welding?

Handle them carefully Signup and view all the answers

What is the effect of prolonged heating of the joint in gas welding?

It increases distortion and reduces corrosion resistance Signup and view all the answers

What is the typical melting temperature of the filler metal used in soldering?

Below 450°C Signup and view all the answers

What is the importance of removing flux residues after soldering?

To avoid corrosion Signup and view all the answers

What is the primary function of the regulators in the oxyacetylene welding equipment?

To reduce the cylinder pressure to the required working pressure Signup and view all the answers

What is the working pressure of oxygen in the oxyacetylene welding equipment?

1 kgf/cm2 Signup and view all the answers

What is the characteristic of the outer envelope flame in a neutral flame?

It is only faintly luminous and slightly bluish in color Signup and view all the answers

What is the maximum temperature obtained at the tip of the luminous cone in a neutral flame?

3300°C to 3500°C Signup and view all the answers

What is the undesirable effect of using an oxidizing flame for welding steels?

It oxidizes the steel Signup and view all the answers

What is the function of the check valve in the oxyacetylene welding equipment?

To prevent the backflow of gas Signup and view all the answers

What is the primary component of the oxyacetylene welding equipment that mixes the oxygen and acetylene gases?

Welding torch Signup and view all the answers

What determines the working pressure of the oxyacetylene welding equipment?

The thickness of the workpiece being welded Signup and view all the answers

Study Notes

Resistance Welding

Employs the principle of both pressure and fusion welding methods
Heating is accomplished by the passage of a heavy localized electric current
Temperature at the joint increases due to high resistance
External pressure is applied at the joint to result in a forge weld
Used for fastening thin metal sheets and wires

Gas Welding

Combustion is obtained by mixing oxygen with a fuel gas (e.g. acetylene)
Oxyacetylene weld is produced by heating with a flame obtained from combustion
Filler metal is used to supply additional material to the weld zone
Fluxes are used to clean the surfaces to be joined and promote a better bond

Types of Flames

Oxidising flame: desirable for fusion welding of brass and bronze, obtained by adding more oxygen
Carburising or Reducing flame: used to weld Monel metal, nickel, and nonferrous materials, obtained by turning on oxygen

Advantages and Disadvantages of Oxyacetylene Welding

Advantages:
- Portable and inexpensive equipment
- Can be used for cutting
- Can weld practically all metals
Disadvantages:
- Slower than electric arc welding
- Not suitable for heavy sections
- Gas cylinders are highly explosive and require careful handling
- Prolonged heating of the joint results in distortion and loss of corrosion resistance

Soldering

Process of joining two metal pieces by adding filler metal with a melting temperature below 450°C
Filler metal is usually solder, an alloy of tin and lead
Fluxes used include resin, zinc chloride, and ammonium chloride
Strength of the soldered joint is relatively low

Gas Welding Equipment

Gas cylinders: oxygen (125 kgf/cm2) and acetylene (16 kgf/cm2)
Regulators: reduce cylinder pressure to working pressure and produce a steady flow of gas
Pressure gauges: monitor pressure
Hoses: connect regulators to welding torch
Welding torch: mixes oxygen and acetylene and ignites the mixture
Check valve and non-return valve: used in gas welding equipment