120101i Oxyfuel Cutting

Question 1

Describe the oxyfuel cutting process.

Answer 1

Oxyfuel cutting is a controlled process of rapid oxidation in which steel is heated to its kindling temperature and a high-pressure jet of pure oxygen is directed to the heated area. Metal exposed to the oxygen oxidizes and is blown away by the oxygen jet stream.

Question 2

What two (2) ferrous-based metals cannot be cut satisfactorily with an oxyfuel cutting torch?

Answer 2

cast irons and stainless steels

Question 3

When a piece of metal is cut, it creates a cut gap called the:
a) groove.
b) bead.
c) kerf.
d) crater.

Answer 3

c) kerf.

Question 4

On a combination cutting torch, the oxygen valve on the torch handle must be:
a) closed tightly.
b) partially open.
c) fully open.
d) used to adjust to a neutral flame.

Answer 4

c) fully open.

Question 5

The rivet cutting tip is designed to:
a) make suitable holes for riveted construction.
b) facilitate right angle square hole cutting.
c) facilitate cutting in confined spaces.
d) cut off rivet and bolt heads without disturbing the parent metal.

Answer 5

d) cut off rivet and bolt heads without disturbing the parent metal.

Question 6

Which cutting tip has the preheat orifices in a smaller pitch circle around the cutting orifice?
a) standard cutting tip
b) high-speed cutting tip
c) gouging tip
d) rivet cutting tip

Answer 6

b) high-speed cutting tip

Question 7

The larger the orifices of a cutting tip the:
a) less gas you bum.
b) greater the heat loss.
c) faster you cut.
d) thicker the plate that you can cut.

Answer 7

d) thicker the plate that you can cut.

Question 8

Which metals can you cut easily using the oxyfuel cutting process?
a) cast irons
b) mild steels
c) stainless steels
d) nickel alloys

Answer 8

b) mild steels

Question 9

Which oxyfuel torch design has the mixer chamber inside one of the tubes leading to
the torch head?
a) tip mixing
b) high speed
c) premixing
d) oxygen lance

Answer 9

c) premixing

Question 10

Explain why you cannot cut non-ferrous metals using an oxyfuel torch

Answer 10

Unlike steel, non-ferrous metals will not oxidize or bum progressively.

Question 11

List three (3) methods used for starting a cut on round stock.

Answer 11

a) Use a chisel to nick the surface.
b) Drill into the surface.
c) Apply a bead of arc weld.

Question 12

List three (3) types of control systems used for mechanized oxy fuel cutting

Answer 12

a) machine tracer-guided.
b) magnetic tracer-guided.
c) electronic tracer-guided.

Question 13

Templates for magnetic tracers are made of:
a) steel.
b) non-ferrous metal.
c) plastic.
d) paper cut-outs.

Answer 13

a) steel.

Question 14

Photoelectric cells and computer controls are used with _____________________
tracer-guided cutting machines.

Answer 14

Photoelectric cells and computer controls are used with electronic tracer-guided
cutting machines.

Question 15

When preheating for flame cutting, the metal should be heated until it reaches its:
a) liquid state.
b) bright yellow colour.
c) kindling point.
d) transition temperature.

Answer 15

c) kindling point.

Question 16

When the cut is rough and slag accumulates on the bottom edge, the likely cause is:
a) using propane fuel gas.
b) using oxygen that is only 99.5% pure.
c) using a dirty tip.
d) using a cutting attachment type torch.

Answer 16

c) using a dirty tip.

Question 17

When piercing holes in a plate you should:
a) press the cutting lever sharply to start the cut.
b) allow the preheat cones to touch the material surface.
c) raise the oxygen pressure by 25%.
d) raise the tip when the cutting lever is depressed.

Answer 17

d) raise the tip when the cutting lever is depressed.

Question 18

What is likely to happen if the cutting travel speed is too fast?
a) Productivity increases and your employer is very impressed.
b) Slag bubbles to the surface and the cutting action eventually stops.
c) The tip overheats and begins to backfire.
d) A clean, slag-free cut is produced.

Answer 18

b) Slag bubbles to the surface and the cutting action eventually stops.

Question 19

What is the likely problem if the kerf edges are melting back together behind the cut?
a) The tip is too large for the material thickness.
b) Impurities are in the fuel gas.
c) The steel has too high a carbon content.
d) You are running low on fuel gas.

Answer 19

a) The tip is too large for the material thickness.

Question 20

If a shop were to switch from acetylene to propane gas for cutting, it would be necessary to:
a) purchase all new cutting torches.
b) install special fuel gas regulators.
c) check with the manufacturer to determine if the equipment is compatible.
d) change to larger size hoses.

Answer 20

c) check with the manufacturer to determine if the equipment is compatible.

Question 21

You can determine a good quality cut by:
a) inspecting the kerf lines.
b) asking the foreman.
c) the amount of welding experience the operator has.
d) the amount of oxygen and acetylene consumed.

Answer 21

a) inspecting the kerf lines.

Question 22

Kerf draglines on a properly performed shape cut should be:
a) irregular in profile.
b) curved to match the shape.
c) perpendicular to the plate surface.
d) horizontally inclined.

Answer 22

c) perpendicular to the plate surface.

Question 23

If you notice the preheat flames changing from neutral to carbonizing during the cutting process, the most likely cause would be that the:
a) oxygen cylinder is nearly empty.
b) acetylene consumption is too high.
c) acetylene cylinder is nearly empty.
d) tip is dirty and requires cleaning.

Answer 23

a) oxygen cylinder is nearly empty.

Question 24

What tools can you use to lay out a structural shape?
a) contour marker
b) hammer and center punch
c) square and level
d) combination square
e) all of the above

Answer 24

e) all of the above

Question 25

A skid unit requires two S shapes to be welded together to create a 90° angle. How can you cut the S shapes to create the required fit up?
a) butt the flanges together and weld the gaps
b) cope one beam to fit inside the other
c) cut an angle of 45° on each shape and fit together
d) both b and c
e) all of the above

Answer 25

d) both b and c

Question 26

When cutting structural shapes, it is important to remember to watch your torch angle. A torch angle that is off can cause a structural shape to be cut incorrectly, which could result in a scrapped piece.
a) true
b) false

Answer 26

a) true