MetFab - Welding Fume Handbook - Flipbook - Page 32


0.10
I
0.09
I
0.08
I
0.07
I
0.06
I
0.05
I
0.04
I
0.03
I
0.02
I
0.01
I
Ozone concentration ppm
9 Effect of shielding gas: ozone
0.017
0.011
0.005
0.007
0.004
0
Argon
Alumaxx®Plus
50% Ar/50% He
25% Ar/75% He
Helium
shielding gas
Figure 23: The effect of percentage helium in argon on
ozone level during TIG welding of stainless steel
0.10
I
0.09
I
0.08
I
0.07
I
0.06
I
0.05
I
0.04
I
0.03
I
0.02
I
Ozone concentration ppm
Figure 24 also relates to autogenous TIG welding of stainless steel,
and shows the beneficial effect of hydrogen in the shielding gas.
0.013
I
0.01
0.006
0
Argon
Alumaxx®Plus
0.001
50% Ar/50% He
shielding gas
Figure 24: The effect of percentage hydrogen in argon on ozone
emissions during TIG welding of austenitic stainless steel
Argon-based shielding gases containing nitrogen are
increasingly used in MIG and TIG welding of duplex stainless
steels, but the nitrogen produces a significant increase in
ozone emissions. Figure 25 shows how the addition of helium
to an argon-based shielding gas can reduce exposure to
ozone.
32

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