GTAW Equipment Maintenance and Troubleshooting

Question 1

When installing electrical powered welding machines, the installation must comply with:
a) Workplace Health and Safety regulations.
b) applicable local electrical codes.
c) American Welding Society regulations.
d) welding shop installation procedures.

Answer 1

b) applicable local electrical codes.

Question 2

Badly discoloured cable lugs indicate that the connection has:
a) overheated during use.
b) been in service for too long.
c) been exposed to a corrosive atmosphere.
d) lost its protective coating.

Answer 2

a) overheated during use.

Question 3

Continuous high frequency current may be required with GTAW when:
a) thoriated tungsten electrodes are used.
b) the electrode is ground to a sharp point.
c) it is necessary to increase penetration.
d) you are using alternating current.

Answer 3

d) you are using alternating current.

Question 4

What current type produces good penetration and oxide removal when using GTAW on aluminum?
a) DC electrode positive
b) AC electrode negative
c) AC with continuous high frequency current
d) AC rectified current

Answer 4

c) AC with continuous high frequency current

Question 5

Using direct current reverse polarity with GTAW:
a) requires the use of larger electrodes.
b) only works with high frequency current.
c) fails to remove oxides from aluminum.
d) requires a zirconiated tungsten electrode.

Answer 5

a) requires the use of larger electrodes.

Question 6

With the machine running, what is most likely to be the problem when you are unable to start an arc?

Answer 6

The work lead is not attached or the lead to work connection is faulty.

Question 7

Why must metal components be grounded when high frequency current is used?

Answer 7

High frequency current radiation must be controlled to prevent radio and television interference.

Question 8

High frequency current leakage can be prevented by:
a) keeping the welding cables as short and straight as possible.
b) wrapping cables around your neck when welding.
c) keeping the cables coiled together.
d) using a long, large diameter torch cable.

Answer 8

a) keeping the welding cables as short and straight as possible.

Question 9

What can happen if the torch body or handle becomes cracked?

Answer 9

A possible shock hazard from the high frequency current (when used) can occur.

Question 10

Water pressure on a GTAW torch should NOT exceed:
a) city supplied water pressure.
b) the CSA ratings for the hose fittings.
c) the pressure required for circulation.
d) the manufacturer’s recommendations.

Answer 10

d) the manufacturer’s recommendations.

Question 11

The end of the gas nozzle must be kept clean and uniform in order to avoid:
a) deep penetration.
b) uneven gas coverage.
c) arc wandering across the puddle.
d) undercutting at the bead edges.

Answer 11

b) uneven gas coverage.

Question 12

Metal particles sticking to the inside of the ceramic nozzle may:
a) cause the tungsten electrode to overheat.
b) cause a short-circuit between the tungsten electrode and the nozzle.
c) cause gas turbulence and possible atmospheric contamination.
d) impede the flow of electrons from the tungsten electrode.

Answer 12

c) cause gas turbulence and possible atmospheric contamination.

Question 13

Why must collets be kept clean?

Answer 13

Keeping collets clean ensures that

• the best electrical contact can be obtained between the electrode and

-the collet to reduce heating of the electrode and the torch body.

Question 14

A GTAW electrode that discolours when the arc is broken is an indication that:
a) excessive current was used.
b) low amperage was used.
c) post flow time is too long.
d) the electrode has atmospheric contamination.

Answer 14

d) the electrode has atmospheric contamination.

Question 15

What are the symptoms of creep on a shielding gas regulator?

Answer 15

Creep is identified

• when the working pressure gauge shows an increase in pressure after the cylinder is opened while the adjustment screw is disengaged.

Question 16

If you strike an arc and immediately experience atmospheric contamination, what part of the equipment may not be properly adjusted?

Answer 16

the flowmeter

Question 17

Why should the gas and coolant hoses be encased in a protective cover?

Answer 17

To prevent damage to the hoses that lead to gas and water leaks, resulting in weld metal porosity.

Question 18

What may occur if the gas hose fittings are not tightly secured?

Answer 18

Atmospheric air can be drawn into the shielding gas or a loss of shielding can contaminate the weld and/or the electrode.

Question 19

What is the likely cause of porosity in a GTAW weld?
a) inadequate electrode extension
b) excessive back purge pressure
c) inadequate gas shielding
d) improper joint fit up

Answer 19

c) inadequate gas shielding

Question 20

Excessive shielding gas flow may result in:
a) contamination of the weld puddle.
b) a stable arc at low welding currents.
c) contamination of the tungsten.
d) wider heat-affected zones.

Answer 20

a) contamination of the weld puddle.

Question 21

What shielding gas is the best choice to aid in oxide removal on aluminum? Why?

Answer 21

-Argon because the molecular weight of argon is ten times that of helium,
&
-the cleaning action is much better due to ionic bombardment during welding.

Question 22

Contaminated shielding gas generally causes:
a) porosity.
b) cracks.
c) lack of fusion.
d) undercut.

Answer 22

a) porosity.

Question 23

Why is argon-hydrogen shielding not recommended for carbon steels?

Answer 23

Hydrogen becomes dissolved in carbon steels and causes hydrogen embrittlement that may lead to cracking.

Question 24

GTAW troubleshooting can be grouped into one of which three (3) categories?
a)
b)
c)

Answer 24

a) process
b) mechanical
c) electrical

Question 25

One reason for a crack in the weld is:
a) oxidation of the electrode from improper shielding.
b) the wrong combination of filler metal to base metal.
c) poor operator manipulation.
d) travel speed that is too fast.

Answer 25

b) the wrong combination of filler to base metal.

Question 26

One reason for crater cracks occurring at the end of the weld is:
a) improper manipulation of the torch.
b) improper positioning of the filler metal.
c) current setting that is too high.
d) an improper arc length.

Answer 26

a) improper manipulation of the torch.

Question 27

What is the purpose of tailing out prior to breaking the arc?

Answer 27

to reduce the size of the weld puddle to prevent crater cracking

Question 28

Incomplete penetration could be caused by:
a) shielding gas that is set too high.
b) arc length that is too long.
c) contaminated plate surfaces.
d) oxidization of the electrode.

Answer 28

b) arc length that is too long.

Question 29

What is a likely cause of lack of fusion?
a) shielding gas that is set too high
b) excessive electrode extension
c) arc length that is too long
d) arc length that is too short

Answer 29

c) arc length that is too long

Question 30

Root pass suck back is the result of:
a) welding current that is set too low.
b) arc length that is too long.
c) arc length that is too short.
d) improper position of filler metal addition.

Answer 30

d) improper position of filler metal addition.

Question 31

Tungsten inclusions in the weld zone are most often caused by:
a) exceeding the current limit of the electrode.
b) inadequate electrode extension.
c) improper joint design.
d) improper technique for the weld position.

Answer 31

a) exceeding the current limit of the electrode.

Question 32

A reason for undercut in a GTAW weld is:
a) welding current that is set too high.
b) poor preparation and fit up.
c) too much restraint applied to the joint.
d) greasy, wet or dirty plate edges.

Answer 32

a) welding current that is set too high.