Introduction to the GTAW Process

Question 1

Define the term GTAW.
Gas tungsten arc welding (____), often referred to by its non-preferred term TIG, is a process in which fusion welding is accomplished by the heat of an electric arc drawn between a non-consumable tungsten electrode and the work. The electrode, arc, weld puddle and the adjacent heated area of the workpiece are protected from atmospheric contamination by an externally applied gaseous shield. Filler rod may or may not be added.

Answer 1

Gas tungsten arc welding (GTAW), often referred to by its non-preferred term TIG, is a process in which fusion welding is accomplished by the heat of an electric arc drawn between a non-consumable tungsten electrode and the work. The electrode, arc, weld puddle and the adjacent heated area of the workpiece are protected from atmospheric contamination by an externally applied gaseous shield. Filler rod may or may not be added.

Question 2

With GTAW, the heat of the arc is transferred to the work through a nonconsumable:
a) titanium electrode.
b) carbon electrode.
c) tungsten electrode.
d) ceramic electrode.

Answer 2

c) tungsten electrode.

Question 3

GTAW requires an inert gas to:
a) shield the weld puddle.
b) cool the ceramic cup.
c) cool the base metal.
d) reduce current resistance across the arc.

Answer 3

a) shield the weld puddle.

Question 4

GTAW is used primarily when:
a) high deposition rates are required.
b) high heat input is desirable.
c) welding on thick materials.
d) high quality welds are mandatory.

Answer 4

d) high quality welds are mandatory.

Question 5

For what application would hot wire GTAW be used?
a) where high production welds are required
b) for square butt joints on thin wall tubing
c) for the joining of precision parts
d) where weld quality is of no concern

Answer 5

a) where high production welds are required

Question 6

State the major difference between hot wire GTAW and cold wire GTAW.

Answer 6

=Hot wire GTAW has the wire preheated with an auxiliary AC current prior to the
wire entering the weld pool,
-whereas the cold wire process feeds wire that is at ambient temperature and without an auxiliary power source attached

Question 7

In what positions can the GTAW process be used?
a) flat only
b) flat and horizontal only
c) vertical only
d) all positions

Answer 7

d) all positions

Question 8

Which metal requires a full preheat when welded with the GTAW process?
a) aluminum
b) carbon steel
c) magnesium
d) cast iron

Answer 8

d) cast iron

Question 9

GTAW has an advantage over SMAW because it:
a) reduces the overall cost of welding.
b) can eliminate the need to use a flux.
c) does not require a skilled operator.
d) uses inexpensive welding equipment.

Answer 9

b) can eliminate the need to use a flux.

Question 10

Electrical shock can be a hazard with GTAW if:
a) electrical connections are not insulated.
b) cable lugs have soldered connections.
c) cables are not coiled up on insulated hangers.
d) AC current is used for welding aluminium.

Answer 10

a) electrical connections are not insulated.

Question 11

The intensity of the ultraviolet light produced by the GTAW process is similar to _______ metal arc welding, but is much greater than that produced by the __________ metal arc welding process.

Answer 11

___gas____ metal arc welding, but is much greater than that produced by the ____stick_____ metal arc welding process.

Question 12

When welding with GTAW, you should wear:
a) dark-coloured, tightly woven clothing.
b) light-coloured, open mesh clothing.
c) light-coloured, heavy weight clothing.
d) dark-coloured, synthetic fabric clothing.

Answer 12

a) dark-coloured, tightly woven clothing

Question 13

When using GTAW, good ventilation is required in order to prevent:
a) gamma radiation poisoning.
b) an oxygen deficiency.
c) smoke inhalation.
d) explosive gas mixtures.

Answer 13

b) an oxygen deficiency.

Question 14

When working in a confined space, GTAW presents a hazard in that the shielding
gas:
a) is highly toxic.
b) is extremely noxious.
c) can become explosive.
d) can asphyxiate you.

Answer 14

d) can asphyxiate you.

Question 15

The arc radiation from GTAW reacts with elements in atmospheric air to form:
a) CO (carbon monoxide).
b) CO2 (carbon dioxide).
c) O3 (ozone).
d) SO2 (sulphur dioxide).

Answer 15

c) O3 (ozone).

Question 16

Ultraviolet radiation from GTAW can react with chlorinated degreasing solvents to produce:
a) phosgene gas.
b) sulphur dioxide gas.
c) ammonia gas.
d) ozone gas.

Answer 16

a) phosgene gas.

Question 17

List five (5) basic components of a GTAW set-up.

Answer 17

a) power source
b) torch body assembly
c) connecting work leads
d) electrodes
e) gas supply, gas control equipment
f) filler metals
g) safety equipment
h) ventilation

Question 18

Pulsing the arc with GTAW is an advantage when:
a) a wide heat-affected zone is required.
b) penetration on thin metals must be controlled.
c) maximum bead width is preferred.
d) high current settings must be used.

Answer 18

b) penetration on thin metals must be controlled.

Question 19

Welding machines designed for GTAW, are:
a) constant voltage (CV).
b) rising voltage (RV).
c) constant potential (CP).
d) constant current (CC).

Answer 19

d) constant current (CC).

Question 20

Which of the following machines would be best suited for GTAW?
a) AC transformer
b) DC generator
c) AC/DC rectifier
d) AC generator

Answer 20

c) AC/DC rectifier

Question 21

Power sources recommended for GTAW have a ________ volt-amp curve

Answer 21

Power sources recommended for GTAW have a ___drooping_____ volt-amp curve

Question 22

A post-purge control is designed to:
a) keep gas flowing for a pre-set time after the arc is extinguished.(broken)
b) protect the filler rod from atmospheric contamination.
c) increase the cooling rate of the deposited metal.
d) increase the gas flow when filling the weld crater.

Answer 22

a) keep gas flowing for a pre-set time after the arc is extinguished.(broken)

Question 23

What is the recommended size of electrode when using 125 amperes on:
a) AC current
b) DCEN
c) DCEP

Answer 23

a) AC current (3⁄32”)
b) DCEN (1⁄16”)
c) DCEP (1⁄4”)

Question 24

What is the recommended current type for welding stainless steel?

Answer 24

DC electrode negative

Question 25

Which current type produces the deepest penetration?
a) alternating current with continuous high frequency
b) alternating current with high frequency set on start only
c) direct current electrode positive
d) direct current electrode negative

Answer 25

d) direct current electrode negative

Question 26

Removal of aluminium oxide occurs:
a) during the positive half of the AC cycle.
b) when high frequency current is activated.
c) on the straight polarity setting of a DC machine.
d) with the addition of a fully deoxidized filler metal.

Answer 26

a) during the positive half of the AC cycle.

Question 27

AC high frequency is most suited for GTAW on:
a) aluminum and carbon steel.
b) stainless steel and nickel alloys.
c) aluminum and magnesium.
d) cast iron and copper.

Answer 27

c) aluminum and magnesium.

Question 28

Continuous high frequency current is required when:
a) a thoriated electrode is used.
b) the electrode is ground to a sharp point.
c) a stabilized AC current is required.
d) it is necessary to increase the penetration.

Answer 28

c) a stabilized AC current is required.

Question 29

Why should the torch cables be kept as short as possible when using GTAW?

Answer 29

To help prevent the loss of high frequency current as it travels from the machine to the electrode.

Question 30

A GTAW torch that is too small for the current setting overheats the ________.

Answer 30

GTAW torch that is too small for the current setting overheats the
torch body.

Question 31

A torch cap is the part of a GTAW torch that:
a) reduces amperage loss.
b) protects the electrode from accidental arc strikes.
c) keeps the electrode clean and cool.
d) controls electrode contamination.

Answer 31

b) protects the electrode from accidental arc strikes.

Question 32

The sealing surfaces between the cap and the torch body of a GTAW torch provide:
a) an insulated current seal.
b) a lubricating seal.
c) a shielding gas seal.
d) a watertight seal.

Answer 32

c) a shielding gas seal.

Question 33

What torch part serves the primary purpose of binding the collet onto the electrode?

Answer 33

A torch cap

Question 34

A collet is a device in the GTAW torch that:
a) the ceramic cup attaches to for a gas tight seal.
b) protects the electrode from accidental arcing inside the torch head.
c) allows the shielding gas to pass through the torch head.
d) positions the electrode and transfers current.

Answer 34

d) positions the electrode and transfers current.

Question 35

The diameter of the nozzle is normally determined by:
a) your ability to see the molten puddle.
b) the size of the puddle and the electrode.
c) the shielding gas flowmeter setting.
d) the voltage range and polarity set at the machine

Answer 35

b) the size of the puddle and the electrode.

Question 36

To use continuous high frequency current, the nozzle must be constructed of:
a) copper.
b) brass.
c) stainless steel.
d) ceramic.

Answer 36

d) ceramic.

Question 37

What is the purpose of a regulator when used with GTAW?
a) to reduce supply pressure to a safe working pressure
b) to meter the flow of shielding gas
c) to reduce the flow of shielding gas
d) to reduce the surface pressure at the nozzle

Answer 37

a) to reduce supply pressure to a safe working pressure

Question 38

A flowmeter is calibrated in:
a) litres per hour or cubic inches per hour.
b) litres per minute or cubic feet per hour.
c) litres per minute or cubic feet per minute.
d) litres per minute or cubic inches per hour.

Answer 38

b) litres per minute or cubic feet per hour.

Question 39

What is the purpose of a flowmeter when used with GTAW?
a) to reduce the supply pressure to a safe working pressure
b) to meter the flow of shielding gas
c) to control the post-flow time of shielding gas
d) to reduce the line pressure of the shielding gas

Answer 39

b) to meter the flow of shielding gas

Question 40

A floating ball type flowmeter must be used in the ____ position.

Answer 40

A floating ball type flowmeter must be used in the __vertical___ position.

Question 41

What type of hose is recommended when using helium shielding gas?

Answer 41

Plastic