welding-arc-fumes-9.html
AGA CW Handbook A4_32130-UK
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10 the work environment the effect of different factors on
fume
generation and the work environment. affecting factor effect mma
welding
more
fume
s
than in mig/mag and tig
welding
mig/mag
welding
the amount of
fume
s
depends on the
welding
parameters and the shielding gas tig
welding
low amount of
fume
s
filler material largest cause of
fume
s
. affects the amount and composition. solid wires generate less
fume
s
than cored wires. most
fume
s
are generated from wire without shielding gas.
welding
parameters short arc = low amount of
fume
s
globular arc = more
fume
s
pulse arc = less
fume
s
spray arc = less
fume
s
shielding gas more spatter = more
fume
s
shielding gas has low co 2 or o 2 content = less
fume
s
shielding gas has high co 2 or o 2 content = more
fume
s
3.4
fume
composition
fume
composition depends on, for example, how easily the additives mainly contained in the filler material tend to vaporise and oxidise. the following is a short description of the most typical
fume
components and their harmful effects. chromium, cr when chromium alloy steels are welded, chromium iii and chromium vi compounds are generated, the latter of which are more harmful as they are water-soluble. the
fume
s
cause irritation of the mucous membranes and metal
fume
fever, and they also affect the respiratory tract and lungs. chromium is considered to be carcinogenic. copper, cu copper can be contained in the base material or the filler material. most filler material wires for unalloyed and low-alloy steels are copper- coated. breathing copper
fume
s
may cause metal
fume
fever and lung deformation. iron, fe ferrous oxides are present in
welding
fume
s
when ferrous metals are welded. long-term of breathing ferrous oxides may cause iron dust lung. it is condition somewhat similar to silicosis but not as dangerous. manganese, mn manganese is used as an alloy component in steel and filler materials. manganese oxide is poisonous in large quantities. the symptoms of a manganese poisoning are irritation of the mucous membranes, tremors, stiffness in the muscles and overall weakness. it can also affect the nervous system and the respiratory tract. manganese may also cause metal
fume
fever. nickel, ni nickel is a common alloy material in stainless steels together with chro- mium. the nickel oxides in the
welding
fume
s
may cause metal
fume
fever. nickel is among the substances suspected to be carcinogenic. zinc, zn zinc oxide
fume
s
are generated when galvanised sheet metal is welded. breathing zinc
fume
s
causes metal
fume
fever. 3.5 gases generated during
welding
gases generated during
welding
have a significant impact on the welder’s work environment. the following section contains information on the main gases, their origin and effects. in gas arc
welding
, the very high temperature and the uv radiation of the arc are the main causes of the generated gases. the gases examined in the following are toxic and/or suffocating. 3.5.1 ozone, o 3 ozone is a colourless, highly toxic gas. in particular, ozone affects the mucous membranes in the respiratory tract. overexposure to ozone causes irritation or a burning feel in the throat, cough, chest pains and wheezing breath. ozone’s htp 8h value in finland is only 0.05 ppm o 3 (htp values, 2009) 1. the
welding
arc generates uv radiation 2. the uv radiation collides with the oxygen molecules in the air, splitting it and forming two separate oxygen atoms (o 2 -> o+o) 3. an oxygen atom meets a new oxygen molecule, forming an ozone molecule (o+o 2 -> o 3 ) 4. most of the ozone is formed at a distance of 10–15 cm of the arc. the ozone rises up with the hot air column and enters the welder’s breathing zone 1 2 3 4
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