250+ TOP MCQs on Oxygen Cutting and Answers

Welding online quiz on “Oxygen Cutting”.

1. Which gas is used for the removal of oxygen layer formed on molten iron?
a) Hydrogen
b) Oxygen
c) Carbon dioxide
d) Chlorine
Answer: b
Clarification: In oxygen cutting method, under considerable amount of pressure, when a jet of oxygen gas is made to blow on the particles of molten iron oxide, the oxygen layer present on the molten iron gets removed.

2. Up to what amount of carbon content in steels, can they be treated by oxygen cutting?
a) 0.3%
b) 0.2%
c) 0.7%
d) 0.4%
Answer: c
Clarification: For a steel to be treated by oxygen cutting process, the carbon content that should be available in terms of percentage composition is around 0.7%, that is, the steel that can be treated by this process is a high alloy steel.

3. Up to what temperatures are high alloy steels heated before treating them by oxygen cutting?
a) 675°C
b) 725°C
c) 775°C
d) 825°C
Answer: a
Clarification: In oxygen cutting process, not all steels can be treated by this method. Only high alloy steels can be treated by this method. These steels need to be preheated before oxygen cutting. The temperature range up to which these steels are preheated is about 650°C to 700°C.

4. What are the number of opening available in the cutting torch used in oxygen cutting process?
a) 4
b) 5
c) 6
d) 7
Answer: d
Clarification: Just like any other gas welding equipment, the welding torch gets substituted by a cutting torch in oxygen cutting process. The total number of openings available in the torch are six, with a large opening at the center, making the count to seven.

5. What is the maximum oxygen pressure that can be applied to steel?
a) 13 atm
b) 14 atm
c) 15 atm
d) 16 atm
Answer: b
Clarification: None.

6. What is the minimum oxygen pressure that can be applied to steel?
a) 3 atm
b) 4 atm
c) 5 atm
d) 6 atm
Answer: a
Clarification: In oxygen cutting process, not all steels can be treated by this method. Only high alloy steels can be treated by this method. The pressure supply of oxygen should not be low, as it may lead to the formation of slag on the bottom of the cut. The minimum oxygen pressure that can be applied to steels is 3 atmospheres or 300 kN/m².

7. What is the initial oxygen pressure provided through the lance?
a) 1 atm to 2 atm
b) 2 atm to 3 atm
c) 3 atm to 4 atm
d) 4 atm to 5 atm
Answer: a
Clarification: In oxygen lance cutting, jet of oxygen is passed through steel pipes, and by doing this, holes are produced. For doing this, the jet of oxygen is passed through the lancer under the pressure of 1 atm to 2 atm.

8. What should the outer diameter of a thick-welled lance be, for having good results?
a) 13 mm to 15 mm
b) 15 mm to 17 mm
c) 17 mm to 19 mm
d) 19 mm to 21 mm
Answer: c
Clarification: In oxygen lance cutting, when the lance is made up of a thick wall, with its outer diameter of 17 mm to 19 mm, and possessing an inner diameter of 8 mm to 6 mm, respectively, then good results can be obtained.

9. Cast irons are best treated using oxygen cutting process.
a) True
b) False
Answer: b
Clarification: Cast irons cannot be treated using oxygen cutting process. The reason being that the melting point of cast irons is a lot lower than its ignition temperature. The same cannot be said for high alloy steels.

10. Oxygen cutting process can be applied to metals having a melting point higher than their oxidization temperature.
a) True
b) False
Answer: b
Clarification: It can be counted among one of the drawbacks of oxygen cutting process, that the metal which is to be treated must have its oxidizing temperature higher than its melting temperature, otherwise the metal would get melted before getting oxidized.

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