142
Gas Tungsten Arc Welding Handbook
Procedure:
1. Prepare and clean the materials.
2. Tack weld the plates with 3/32″ (2.4 mm) or 1/8″
(3.2 mm) spacing, depending on the fi ller metal
used. Mount the joint in the horizontal position.
3. Weld the root pass with 3/32″ (2.4 mm) or 1/8″
(3.2 mm) diameter welding rod.
A. Add the welding rod to the upper part of the
weld pool. Use the work and travel angles
shown in Figure 8-15.
4. Wire brush the weld to remove the oxide fi lm (both
passes).
5. Realign the torch and weld a second pass. Use a
3/32″ (2.4 mm) or 1/8″ (3.2 mm) diameter welding
rod.
A. Do not oscillate the torch. The weld should be
approximately 1/16″ (1.6 mm) wider than the
groove, and the weld crown should not be over
1/16″ (1.6 mm) high.
Problem Areas and Corrections:
1. Undercut.
Possible cause: Sagging due to gravity.
Solution: Add welding rod at the top of the weld
pool.
Possible cause: Weld bead is excessively large.
Solution: Hold the torch and welding rod at the
proper angles.
Solution: Do not oscillate the torch. Keep the weld
pool small.
Possible cause: Excessive amperage.
Solution: Use a lower amperage range and add
fi ller metal more often.
Possible cause: Heat buildup in the weld pool.
Solution: Allow the plates to cool between passes.
2. Uneven bead width.
Possible cause: Variation in the size and shape of
the weld pool.
Solution: Determine the size of each pass before
starting.
Solution: Determine the location of each pass
before starting.
Solution: Maintain the same pass dimensions for
the full length of the joint.
Welding Procedure Number 8-8
Weld joint type: Square-groove butt
Position: Vertical uphill
Material type: Cold-rolled steel
Thickness: 11 gauge
Filler metal: ER70S-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. Tack weld the plates with 3/32″ (2.4 mm) or 1/8″
(3.2 mm) spacing depending on the fi ller metal
used. Mount the joint in the vertical position.
3. Weld the root pass with 3/32″ (2.4 mm) or 1/8″
(3.2 mm) diameter welding rod. Use the same
travel and work angles shown in Figure 8-16.
A. Add the welding rod to the top of the weld pool.
B. Add the welding rod directly on the pool
centerline.
C. Keep the electrode centered over the molten
pool.
4. Wire brush the weld to remove the oxide fi lm (all
passes).
5. Realign the torch and weld the second pass
using a 3/32″ (2.4 mm) or 1/8″ (3.2 mm) diameter
welding rod.
A. Use a slight oscillation for a wider bead.
B. Add welding rod at the edge of the weld pool
and always wait for a moment before dipping
the fi ller into the weld pool. Keep the weld pool
in a fl uid state.
Problem Areas and Corrections:
1. Undercut.
Possible cause: Sagging due to gravity.
Solution: Add welding rod at the top of the weld
pool.
Possible cause: Weld bead is excessively large.
Solution: Hold the torch and welding rod at the
proper angles.
Solution: Do not oscillate the torch. Keep the weld
pool small.
Possible cause: Excessive amperage.
Solution: Use a lower amperage range and add
fi ller metal more often.