Operation Manual

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A7 TIG Orbital System 300© Kemppi Oy 2016 1615
OPERATING MANUAL
3.13 Shielding gas
Select proper shield gas/gas mix for optimum results.
100% argon is normally used for TIG welding. In certain
cases, you can benet from using a mixed gas, such as 95%
argon, 5% hydrogen. This mixed gas gives better control of
the weld puddle and lower heat input. Adding hydrogen
or helium increases the arc voltage and creates a "stier",
more focused arc column.
Industrial grade inert gas is sucient for most stainless
steel welds. Use a higher purity grade for high quality
welds on easily oxidizable alloys.
The purpose of purging is to replace unwanted air and
other vapor contaminants from the root pass by a gas
that prevents oxidation during welding. Oxidation can
produce a variety of problems, such as root oxidation
(sugar), incomplete fusion, porosity and changes in weld
chemistry, which can aect weld mechanical and corrosion
resistance properties adversely.
Purging is recommended when welding stainless steel,
nickel alloys, and most nonferrous base metals. Argon is
commonly used.
The gas regulator / ow meter should be set for 4 bar
(60 PSI) and a suitable ow rate. Recommended gas ow
rate is 3-5 l/min for backing gas and 5-10 l/min for shielding
gas. Prepurge time is recommended to set so that backing
gas volume is about 10 times the volume to be lled inside
the tube.
You can apply separate backing gas for root
protection. When using backing gas, also use dual ow
meter regulator that allows having two independently
regulated (shielding and backing gas) circuits from one gas
bottle