Introduction to the GTAW Process Flashcards

1
Q

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.

A

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.

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2
Q

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.

A

c) tungsten electrode.

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3
Q

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.

A

a) shield the weld puddle.

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4
Q

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.

A

d) high quality welds are mandatory.

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5
Q

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

A

a) where high production welds are required

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6
Q

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

A

=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

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7
Q

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

A

d) all positions

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8
Q

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

A

d) cast iron

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9
Q

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.

A

b) can eliminate the need to use a flux.

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10
Q

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.

A

a) electrical connections are not insulated.

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11
Q

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.

A

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

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12
Q

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.

A

a) dark-coloured, tightly woven clothing

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13
Q

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.

A

b) an oxygen deficiency.

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14
Q

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.

A

d) can asphyxiate you.

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15
Q

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).

A

c) O3 (ozone).

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16
Q

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.

A

a) phosgene gas.

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17
Q

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

A

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

18
Q

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.

A

b) penetration on thin metals must be controlled.

19
Q

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

A

d) constant current (CC).

20
Q

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

A

c) AC/DC rectifier

21
Q

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

A

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

22
Q

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.

A

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

23
Q

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

A

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

24
Q

What is the recommended current type for welding stainless steel?

A

DC electrode negative

25
Q

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

A

d) direct current electrode negative

26
Q

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.

A

a) during the positive half of the AC cycle.

27
Q

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.

A

c) aluminum and magnesium.

28
Q

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.

A

c) a stabilized AC current is required.

29
Q

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

A

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

30
Q

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

A

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

31
Q

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.

A

b) protects the electrode from accidental arc strikes.

32
Q

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.

A

c) a shielding gas seal.

33
Q

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

A

A torch cap

34
Q

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.

A

d) positions the electrode and transfers current.

35
Q

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

A

b) the size of the puddle and the electrode.

36
Q

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

A

d) ceramic.

37
Q

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

A

a) to reduce supply pressure to a safe working pressure

38
Q

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.

A

b) litres per minute or cubic feet per hour.

39
Q

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

A

b) to meter the flow of shielding gas

40
Q

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

A

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

41
Q

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

A

Plastic