Welding Flashcards
What are the 3 harmful rays from cutting?
Visible light rays
Ultraviolet light rays
Infrared light rays
What is the best protective clothing for welding?
Leather is best
Wool
Denim
Cotton
What is the most suitable lens for heating and cutting?
4-5 green lens
What three elements are used in the fire triangle?
Heat, fuel, oxygen
What are the 4 classes of fire
A-wood and paper
B-flammable liquids
C-electrical
D-combustible metals
How long does spark watch need to stay after hot work is complete?
30min
When cutting galvanized what is needed?
Approved air line respirator
What is the percentage of oxygen used for cutting?
99.5 percent
What happens when you introduce grease to oxygen?
Explosion or fire
A new oxygen cylinder is fully charged to what PSI?
2200 psi
Mark all empty bottles with what symbol?
M/T
What thread is oxygen components?
Right hand thread
How much is the oxygen cylinder opened when in use?
All the way
What and where is the rupture disc on the oxygen cylinder?
Disc mounted on the rear of the cylinder valve and is a safety to blow off at 3200 psi. This will slowly release oxygen instead of exploding.
What are the physical properties of oxygen?
Colourless, odorless and tasteless
What are the properties of acetylene
Colourless, strong pungent odour
What is the critical point of acetylene at 70 F/21C
28 psi
What is max safe working pressure for acetylene?
15psi
What is in acetylene bottles to absorb acetylene ?
40 percent acetone
What is draw limit of an acetylene bottle?
The maximum amount of acetylene that can be drawn before acetone is drawn out.
What is a fusible plug?
Safety valve when dangerous temperatures are present. The melting temp is 212f/100C
Where are the fusible plug located?
Bottom of cylinder, collar or neck ring and shoulder of the cylinder
What hand thread are the acetylene opponents?
Left hand
What are the hose colours?
Acetylene is red
Oxygen is green
How much do you open acetylene bottle?
1 1/2 to 2 turns for knob
1 - 1 1/2 for key type
What are regulators for?
Reduce cylinder pressure to a usable working pressure.
What do flash back arrestors do?
Prevent flames from travelling back to the bottle
What are the uses of a rosebud?
Bending, straightening, preheating, shrink fitting, hardsurfacing large areas.
What oxygen pressure and acetylene pressure for rosebud?
Equal pressure. Number of holes in tip = PSI
What is a backfire? What is the cause?
The flame backs up into the tip.
Often caused by unequal pressure and to little gas flow.
What is a flash back? What causes it?
One of the gases backs up into the other line forming an explosive mixture.
The cause is grossly unequal pressure, faulty seats, or faulty manipulation of valves.
What is burn back? What causes it?
Combustion takes place in the tip and mixer. Black smoke, red sparks and screeching sound emit from the tip.
Hot tip
Tip orifices enlarged
Faulty mixer or torch body seats
What metals are suitable for torch cutting?
Typically ferrous metals, with exceptions
What materials are not suitable for cutting?
Non ferrous metals such as copper, brass, bronze, aluminum and their alloys.
When cutting a beveled edge where do you line up you preheat holes?
Equally divided on either side of the cut line.
When cutting a straight line where do the pre heat holes line up?
The lead hole is inline with the cut line.
What are the two different hole cutting methods?
Travelling torch method - quicker method
Still torch method - best for small diameter holes.
What are the 3 types of flame?
Carbonizing - adds carbon to weld
Neutral - adds nothing to weld deposit
Oxidizing - attacks the carbon
What is brazing suitable for?
Joining smaller assemblies and complex shapes, where different kinds of metals need to be joined.
What are typical filler rods made of?
Alloys
How can you tell when brazing temperature is reached?
Flux is clear, active and looks watery and the metal surface is visible underneath.
Liquid propane expands to what?
270 times the volume.
