Operation Manual

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A7 TIG Orbital System 300© Kemppi Oy 2016 1615
OPERATING MANUAL
3.3.6 300-head guide ring speed factors
1. Use torch rotation speeds of 6 to 9 cm/min for most
welding applications.
2. Select torch rotation speed as the rst parameter.
Carriage speed refers to the speed at which the
weld head moves around the guide ring.
The weld head rotates on the guide ring, not the pipe
surface, and the tungsten electrode is extended inward to
the pipe surface.
3. Actual tungsten electrode speed is slower than
carriage speed. Correct this dierence with the
guide ring factor that can you can calculate when
the guide ring and pipe are set, or you can take the
factor from the table below.
Correction factor = diameter ratio between tractor rotation
diameter and tungsten electrode tip rotation diameter.
The weld head rotates on the guide ring OD, not the
pipe OD. Although this error is small on large pipes, it can
become signicant with small diameters when modifying a
pre-established weld procedure to a new pipe size.
4. For heavy wall pipe welding, correct for the change
in diameter as the weld bevel is progressively lled
and the tungsten is retracted outward (closer to the
guide ring diameter).
This correction factor is 17 mm* + Groove depth for given
pass.
*This value is the radial height of the guide ring.
5. To determine actual tungsten electrode speed from
carriage speed:
Electrode Speed (E.S.) =
T.S. mm/min × Pipe OD mm
Pipe OD mm + 17 mm
• T.S. = Carriage speed (speed that the tractor
has to move for the desired tungsten speed)
• E.S. = Desired tungsten electrode speed
6. Rotation speed can be continuous, or you can
select Step mode. In Step mode, two levels of
rotation speed are synchronized with pulsed
current. Rotation speed during high current pulse is
set as a percentage (0–99 %) of low pulse rotation
speed.
The Travel Step is often used for root pass welding on
materials with poor thermal conductivity, as the torch
can be momentarily stopped during high pulse current,
increasing the arc force available to penetrate the bevel
"land". This feature is also useful when welding thin wall
material that can be welded in a single pass.
The guide ring factor is marked on the face of each
guide ring.
Table: Guide ring factors
Guide ring
size
Pipe/tube nom. OD Guide ring
factor
1 ¾” Tube 1.750“ (44.5 mm) 7.5
1 ½” Pipe 1.900” (48.3 mm) 8.0
2” Tube 2.000” (50.4 mm) 8.5
2 1/8” Tube 2.125” (54.0 mm) 9.0
2” Pipe 2.375” (60.3 mm) 9.5
2 ½” Tube 2.500” (63.5 mm) 10.0
2 ½” Pipe 2.875” (73.0 mm) 11.0
3” Tube 3.000” (76.2 mm) 11.5
3 ¼” Special 3.250” (82.6 mm) 12.5
3” Pipe 3.500” (88.9 mm) 13.0
3 ½” Pipe 4.000” (101.6 mm) 14.5
4” Pipe 4.500” (114.3 mm) 16.0
4 ½” Pipe 5.000” (127.0 mm) 18.0
5” Pipe 5.563” (141.3 mm) 19.5
6” Pipe 6.625” (168.3 mm) 23.0
7 5/8” Tube 7.625” (193.7 mm) 26.5
8” Pipe 8.625” (219.1 mm) 29.5
10” Pipe 10.750” (273.1 mm) 36.0
12” Pipe 12.750” (323.9 mm) 42.5
14” Pipe 14.000” (355.6 mm) 46.5
See calculation of guide ring factor.