GTAW on Mild Steel

Question 1

How should you lay the beads when surface welding for buildup work?
a) Space them so that they are 3.2 mm (1⁄8”) apart.
b) Blend them together so they form a solid layer of weld metal.
c) Space them so that they are 6.4 mm (1/4”) apart.
d) The toe of one bead should meet the toe of the next bead.

Answer 1

b) Blend them together so they form a solid layer of weld metal.

Question 2

Is it necessary (yes or no) to remove the following from the mild steel base metal
before welding with GTAW?
a) mill scale
b) loose rust
c) oil
d) varnish
e) soapstone markings

Answer 2

a) mill scale = Yes
b) loose rust = Yes
c) oil= Yes
d) varnish= Yes
e) soapstone markings=No

Question 3

Identify the following for GTAW on mild steel.
a) most common electrode type:
b) electrode preparation shape:
c) current type:

Answer 3

a) most common electrode type: EWTh-2
b) electrode preparation shape: Conical
c) current type: Direct Current Straight Polarity

Question 4

What shielding gas is most often used for GTAW on mild steel?

Answer 4

Argon

Question 5

What size of gas nozzle is recommended for any GTAW application?

Answer 5

-The Smallest nozzle

-whose lip does not melt in the heat of the arc,

-yet allows good visibility and adequate gas shielding

Question 6

An appropriate electrode stickout for GTAW:
a) prevents good visibility in all positions.
b) allows you to maintain a long arc.
c) causes atmospheric contamination of the electrode.
d) maintains a gas shield around the electrode and molten weld metal.

Answer 6

d) maintains a gas shield around the electrode and molten weld metal.

Question 7

Using the GTAW process, complete Table 15 with one advantage and one disadvantage for each method of striking the arc.
Start Method-Advantage– Disadvantage

Touch start

High frequency start

Lift start

Answer 7

Start Method- Advantage -Disadvantage

Touch start-
-Dc Without High Frequency(AD)
-May contaminate electrode(Dis)

High frequency start -
-Start without contamination(AD)
- Ceramic nozzle must be used(DIS)

Lift start-
-No high frequency required (AD)
-Machine design must be compatible (DIS)

Question 8

Name two (2) techniques used for adding filler rod with GTAW.
a)
b)

Answer 8

a)Dip Feed Technique
b) Continuous Feed Technique

Question 9

Changing the inclination of the electrode holder in relation to the direction of travel:
a) changes the depth of penetration of the weld.
b) has no effect on the weld.
c) causes the filler rod to freeze in the puddle.
d) causes the filler rod to melt prematurely.

Answer 9

a) changes the depth of penetration of the weld.

Question 10

In what position(s) can you do surface welding with GTAW?
a) vertical position only
b) flat and horizontal positions only
c) all positions except vertical
d) all positions

Answer 10

d) all positions

Question 11

Describe the purpose of tailing out prior to breaking the arc.

Answer 11

to prevent cracking in the weld crater.

Question 12

How is the work positioned for a 1F Tee joint?
a) 90° and 0° relative to the horizontal plane
b) 180° and 360° relative to the horizontal plane
c) 120° and 60° to the horizontal plane
d) each member at 45° to the horizontal plane

Answer 12

d) each member at 45° to the horizontal plane

Question 13

Given the choice, what position should you use for the most productive fillet welding?
a) 4F
b) 3F
c) 1F
d) 6F

Answer 13

c) 1F

Question 14

What is the recommended electrode angle for a 2F weld on 10 gauge material?
a) 90° to the vertical plane
b) 90° to the horizontal plane
c) 45° to the vertical and horizontal planes
d) 270° to the welder’s initial position prior to arc ignition

Answer 14

c) 45° to the vertical and horizontal planes

Question 15

What is the likely weld progression for a single pass 3F weld on 10 gauge material with GTAW?
a) uphill
b) downhill
c) saw tooth weave
d) back step

Answer 15

a) uphill

Question 16

As a general rule, at what thickness of material should joint preparation be considered for full penetration groove welds when using GTAW?
a) 2.5 mm (3/32”)
b) 4.8 mm (3/16”)
c) 6.4 mm (1/4”)
d) 9.6 mm (3/8”)

Answer 16

b) 4.8 mm (3/16”)

Question 17

How long should the tack welds be for the plate weld projects in this module?
a) 2.5 mm - 3.2 mm (3/32” - 1/8”)
b) 3.2 mm - 4 mm (1/8” - 5⁄32”)
c) 6.4 mm - 9.6 mm (1/4” - 3⁄8”)
d) 12.8 mm - 19 mm (1/2” - 3⁄4”)

Answer 17

c) 6.4 mm - 9.6 mm (1/4” - 3⁄8”)

Question 18

What is the recommended electrode inclination for the 1G weld?
a) 0° - 15° forehand
b) 0° - 15° backhand
c) 20° - 30° forehand
d) 20° - 30° backhand

Answer 18

a) 0° - 15° forehand

Question 19

Describe the dip technique of adding filler rod

Answer 19

In the dip technique
- the filler rod is added at the leading edge of the puddle until the desire fill is attained
-then removed from the puddle to progress forward

Question 20

What is fall-through?
a) a technique for adding filler rod in the root bead
b) a low crater at the end of the weld
c) a localized area of excessive penetration
d) crater cracking as the result of failing to tail out

Answer 20

c) a localized area of excessive penetration

Question 21

What is the maximum electrode extension used for GTAW? Why?

Answer 21

Do not extend the electrode beyond 6.4mm (1/4”) because this may result in inadequate gas coverage.

Question 22

What is likely to happen if a keyhole forms in the 1G position?
a) full fusion and penetration
b) lack of fusion
c) the electrode melts off into the puddle
d) fall-through

Answer 22

d) fall-through

Question 23

What is meant by suck-back and how may it occur?

Answer 23

-Suck-back refers to an area of root bead that has been drawn into the groove leaving the root side concave in contour.

-This generally caused by overheating the root pass during the second pass application.

-Suck-Back during welding of the root pass is caused by:
*Travel speed too slow
*high current setting for overhead position
*excessive arc length
*Failure to add filler rod deep enough into the backside of the groove

Question 24

State three (3) actions that may be used to increase root bead penetration.
a)
b)
c)

Answer 24

Any of this (3)

a) Change the Electrode inclination
b) Slow the travel speed
c) Shorten the arc length
d) Increase Amperage Settings
e) Add filler metal closer to the back of the groove preparation.
f) Change the configuration of the land and gap

Question 25

In multi-pass welds, which pass is more susceptible to cracking?
a) the first filler pass
b) the cap pass
c) the second filler pass
d) the root pass

Answer 25

d) the root pass

Question 26

A procedure used to help prevent weld bead crater cracking is:
a) tailing out prior to breaking the arc.
b) using a shorter arc.
c) increasing the electrode angle.
d) breaking the arc and removing the filler rod as quickly as possible.

Answer 26

a) tailing out prior to breaking the arc.

Question 27

What is the purpose of pre-setting the 2G weld on plate?
a) It makes them easier to tack.
b) It compensates for the shrinkage caused by stringer bead multi-pass welding.
c) It makes the groove wider for better penetration.
d) The weld edges can be seen more clearly.

Answer 27

b) It compensates for the shrinkage caused by stringer bead multi-pass welding.

Question 28

What is the recommended bevel angle range for a single Vee groove weld preparation on pipe?
a) 10° - 15°
b) 15° - 22.5°
c) 30° - 37.5°
d) 60° - 75°

Answer 28

c) 30° - 37.5°

Question 29

How many tacks are recommended for joining 150 mm (6”) nominal pipe size?
a) 2
b) 3
c) 4
d) 6

Answer 29

c) 4

Question 30

If the gap is unequal after the first two tacks have been placed on a pipe joint, you should:
a) cut the joint apart and start the joint preparation all over again.
b) place the third tack on the tight side to even out the gap.
c) place the third tack at the widest location to even out the gap.
d) use a sledge hammer to even out the gap.

Answer 30

c) place the third tack at the widest location to even out the gap.

Question 31

Which of the following would be most effective in reducing accidents caused by portable grinders kicking back?
a) Keep both hands on the grinder and clamp the work.
b) Keep the grinder in contact with the work from start to stop.
c) Place the grinder on a flat surface until it stops rotating.
d) Keep one hand on the grinder while holding onto the work with the other

Answer 31

a) Keep both hands on the grinder and clamp the work.