144
Gas Tungsten Arc Welding Handbook
C. Wire brush the weld to remove the oxide fi lm
(all passes).
D. Weld the second pass. Make sure the weld
pool fuses into the bottom plate and overlaps
the root pass by approximately 50%. See
Figure 8-18.
E. Weld the third pass. Make sure the weld pool
fuses into the top plate and the second pass,
creating a fl at weld in the joint.
Problem Areas and Corrections:
1. Concave weld crown or improper contour.
Possible cause: Insuffi cient fi ller metal.
Solution: Add welding rod more often.
Possible cause: Incorrect torch angle and
improperly placed welds.
2. Leg sizes are not equal.
Possible cause: Incorrect torch angle.
Solution: Reposition the torch to keep the weld
pool even.
Possible cause: Too much fi ller metal. Weld pool
is too heavy.
Solution: Add less fi ller metal.
3. Undercut on top weld.
Possible cause: Weld pool is too hot.
Solution: Add welding rod more often.
Possible cause: Incorrect torch angle.
Solution: Reposition the torch to keep the weld
pool even.
Welding Procedure Number 8-11
Weld joint type: T-joint
Position: Vertical uphill
Material type: Cold-rolled steel
Thickness: 11 gauge
Filler metal: ER70S-2 or 6
Diameter: 3/32″ (2.4 mm) or 1/8″ (3.2 mm)
(welder’s preference)
Machine setup: DCEN high-frequency start
Shielding gas: Argon
CFH: 15–25
Tungsten type: 1%, 1.5%, or 2% lanthanated,
ceriated, or thoriated
Diameter: 3/32″ (2.4 mm) (tapered)
Procedure:
1. Prepare and clean the materials.
2. Align the plates.
3. Tack weld the two plates at approximately right
angles.
4. Weld the joint using the torch and welding rod
angles shown in Figure 8-19.
A. Add the fi ller metal in small amounts.
B. Feed the welding rod directly into the
intersection of the joint.
C. Wire brush the joint to remove the oxide fi lm.
3rd pass
1st pass
(root)
2nd pass
Figure 8-18.
The three passes used to weld a T-joint in
the horizontal position. (Mark Prosser)
Figure 8-19.
Torch and welding rod positions for uphill
welding a T-joint in the vertical position. (Mark Prosser)