MetFab - Welding Fume Handbook - Flipbook - Page 34
9 Effect of shielding gas: ozone
9.3 Aluminium alloy welding
MIG
The shielding gases commonly used for MIG welding
aluminium and its alloys are argon, argon/helium mixtures
or argon with small additions of nitric oxide.
Figure 27 shows the effect of these gases on exposure to
ozone, and again demonstrates that argon/helium mixtures
can reduce ozone levels.
0.20
I
0.15
I
0.26
0.25
I
0.24
0.12
0.10
I
0.05
I
Average exposure to ozone ppm
I
0.30
0.09
0
Argon
Argon/NO
Alumaxx®Plus
25%Ar/75%Helium
shielding gas
Figure 27: The effect of shielding gas on ozone during MIG welding
of Al/5%Mg alloy (33% duty cycle) with spray transfer
TIG
The common shielding gases for TIG welding of aluminium
are pure argon, pure helium, argon/helium mixtures and
argon with a small addition of nitric oxide.
The ozone-reducing effects of argon/helium mixtures
compared to pure argon and pure helium are similar to
those observed for stainless steel welding with similar
formulations.
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