Operation Manual
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A7 TIG Orbital System 300© Kemppi Oy 2016 1615
OPERATING MANUAL
3.1.7 Shield gas effects
100 % argon is normally used for TIG welding. In certain
cases it may be a good idea to use a mixed gas, such as
95 % argon and 5 % hydrogen.
• Use mixed gas for better control of the weld
puddle and lower heat input.
• Add hydrogen or helium to increase the arc
voltage and create a "stier" more focused arc
column.
• Recommended for single-pass welds only
(stainless steel), mixed gases increase the chance
of cold cracking on multi-pass welds.
To reduce the possibility of cold cracking, use a mixture
of argon/helium (65/35 %) for stainless steels and even
higher amounts of helium for carbon steel. Increasing
amounts of helium in the mixture will degrade arc starting.
3.2 Preparing the work piece
3.2.1 Groove preparation
Precise groove preparation is essential to achieve perfect
welds. There are special tools available for creating
precisely shaped grooves.
It is recommended to use a J-shaped groove with the
geometry presented in the picture. Auto programming uses
this groove as the default.
A
B
C
D
A. Extension: 0.8 mm ±0.1 mm
B. Radius: 2.4 mm ±0.4 mm
C. Root face: 1.5 mm +0.26 mm – - 0.13 mm
D. Bevel angle: 20° ±0.5°
If using counterbore, a 2 mm root face thickness is al-
lowed.
3.2.2 Joint design and fit-up tolerance
Automatic welding requires repeatable t-up within
reasonable tolerances and consistent pipe end
preparation. Mismatch should not exceed 1.5 mm. When
pipe is out-of-round greater than 1.5 mm, you may need
a counterbore. Use recommended joint design "J-Prep".
See recommended J-groove geometry above.
Fit-up is much more critical than welding on a J-Prep.
Hybrid bevel geometries can provide a solution when
welding factory-beveled fittings to pipe ("J" with
2.5 mm land extension matched to “V” with 37.5° and with a
1.6 mm land).