Tig Welding - Praxair MICROTIG AC/DC 202 PULSE Guide De L'utilisateur

2. TIG WELDING (Tungsten inert gas)
It is a process of arc welding under shield gas, using a torch
with infusible tungsten electrode and which can be run with
or without filler metal in an inert gas atmosphere such as argon
and mixtures thereof. Through this process the arc become
more stable without spatter which guarantees a strong
mechanical resistance of the welding joint.
This Tig process replaces with many advantages the
oxyacetylene on steel, stainless steel, copper, brass DC welding,
the aluminum on AC welding and, in several cases, the MMA and
Mig welding especially when the welding seam remains visible.
Electrode chemical composition
Code
WP
WT4
WT10
WT20
WT30
WT40
WZ3
WZ8
WL10
WC20
∅ Electrode
(mm)
1,6 mm
2,0 mm
2,5 mm
3,2 mm
4,0 mm
5,0 mm
Shield gas: The shield gas is used to:
- Involve the welding arc on an ionizable atmosphere.
- Avoid the seam contamination by the oxygen of the atmosphere.
- Provide the cooling of the electrode.
Argon (Ar) – Is the most common gas used with a purity grade of 99,9%.
Helium (He) – For the copper welding mixed with the argon under percentages between 10% and 75%.
Hydrogen (H) – Inert gas at environment temperature especially for the use on copper welding. Inadvisable for
welding on closed places; it mixes with the atmosphere oxygen and changes the air unbreathable.
Composition
Pure tungsten
0,35-0,55% thorium
0,80-1,20% thorium
1,7-2,3% thorium
2,7-3,3% thorium
3,8-4,3% thorium
0,15-0,50%
zirconium
0,70-0,10%
zirconium
1,0-1,2%
lanthanum
1,9-2,3% cerium
Chart of electrode diameter and current
Amp. DC
Negative (-)
40-130 A
75-180 A
130-230 A
160-310 A
275-450 A
400-625 A
Type Color
W Green AC – Aluminum, Magnesium
Blue
DC
Yellow
Steel, Stainless steel, Titanium,
Red
Copper
Th
Violet
Orange
Brown
Stainless steel, Nickel, Non-ferric
Zr
metals
White
La Black All TIG applications
Ce Grey All TIG applications
Positive (+)
10-20 A
15-25 A
17-30 A
20-35 A
35-50 A
50-70 A
MICROTIG AC/DC 202 PULSE
Welding
Amp. AC
45-90 A
65-125 A
80-140 A
150-190 A
180-260 A
240-350 A
7