120202a GTAW Process (Q&A) Flashcards
Define the term GTAW.
- 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.
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.
c) tungsten electrode.
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) shield the weld puddle.
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.
d) high quality welds are mandatory.
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) where high production welds are required
State the major difference between hot wire GTAW and cold wire GTAW.
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.
In what positions can the GTAW process be used?
a) flat only
b) flat and horizontal only
c) vertical only
d) all positions
d) all positions
Which metal requires a full preheat when welded with the GTAW process?
a) aluminum
b) carbon steel
c) magnesium
d) cast iron
d) cast iron
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.
b) can eliminate the need to use a flux.
The intensity of the ultraviolet light produced by the GTAW process is like ____________ metal arc welding, but is much greater than that produced by the ____________ metal arc welding process.
The intensity’ of the ultraviolet light produced by the GTAW process is like gas metal arc welding, but is much greater than that produced by the shielded metal arc welding process.
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) dark-coloured, tightly woven clothing.
When using GTAW, good ventilation is required to prevent:
a) gamma radiation poisoning.
b) an oxygen deficiency.
c) smoke inhalation.
d) explosive gas mixtures.
b) an oxygen deficiency.
The arc radiation from GTAW reacts with elements in atmospheric air to form:
a) CO (carbon monoxide).
b) CO? (carbon dioxide).
c) O3 (ozone).
d) SO? (sulphur dioxide).
c) O3 (ozone).
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) phosgene gas.
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.
b) penetration on thin metals must be controlled.
Welding machines designed for GTAW are:
a) constant voltage (CV).
b) rising voltage (RV).
c) constant potential (CP).
d) constant current (CC).
d) constant current (CC).
Which statement is true with respect to orbital GTAW?
a) Filler wires must always be added.
b) It can be done without filler wires.
c) The pipe turns while the arc is fixed.
d) It is less productive than manual welding.
b) It can be done without filler wires.
Which of the following machines would be best suited for GTAW?
a) AC transformer
b) DC generator
c) AC/DC rectifier
d) AC alternator
c) AC/DC rectifier
Power sources recommended for GTAW have a _________________
volt-amp curve.
Power sources recommended for GTAW have a steep drooping volt-amp curve.
A post-purge control is designed to:
a) keep gas flowing for a pre-set time after the arc is extinguished.
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) keep gas flowing for a pre-set time after the arc is extinguished.
What is the recommended size of electrode when using 125 amperes on:
a) AC current
b) DCEN
c) DCEP
a) 2.5 mm (3/32”)
b) 1.6 mm (1/16”)
c) 6.4 mm (1/4”)
What is the recommended current type for welding stainless steel?
DC electrode negative
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 cunent electrode positive
d) direct current electrode negative
d) direct current electrode negative
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) during the positive half of the AC cycle.
AC high frequency is most suited forGTAW on:
a) aluminum and carbon steel.
b) stainless steel and nickel alloys.
c) aluminum and magnesium.
d) cast iron and copper.
c) aluminum and magnesium.
Continuous high frequency current is required when:
a) DCSR 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.
c) a stabilized AC current is needed.
Which statement is true with respect to square waves?
a) The EP portion is always greater.
b) The EN portion is always greater.
c) The EP and EN portions must be equal.
d) The EP and EN portions can be adjusted.
d) The EP and EN portions can be adjusted.
Why should the torch cables be kept as short as possible when using GTAW?
To help prevent the loss of high frequency current as it travels from the machine to the electrode.
A GTAW torch that is too small for the current setting overheats the __________.
A GTAW torch that is too small for the current used overheats the torch body.
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.
b) protects the electrode from accidental arc strikes.
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.
d) positions the electrode and transfers current.
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.
b) the size of the puddle and the electrode.
To use continuous high frequency current, the nozzle must be constructed of:
a) copper.
b) brass.
c) stainless steel.
d) ceramic.
d) ceramic.
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) to reduce supply pressure to a safe working pressure
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.
b) litres per minute or cubic feet per hour.
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
b) to meter the flow of shielding gas
A floating ball type flowmeter must be used in the __________ position.
A floating ball type flowmeter must be used in the vertical position.
What type of hose is recommended when using helium shielding gas?
plastic
What are the five advantages of using orbital GTAW?
a) increased productivity compared to manual welding,
b) superior weld quality and consistency to that of manual welding,
c) once a certified welder has set up the parameters, someone else can operate it,
d) may be the only solution where pipe cannot be rolled and
e) well-suited for applications where physical access is limited.
