PRO-POINT ARC 170 Manuel D'utilisation page 34

8611295 ARC 170 DUAL VOLTAGE ARC/TIG WELDER V1.0
the arc. Tungsten has the highest melting point of any metal,
6,170 degree Fahrenheit.
Tungsten electrodes are non-consumable and come in a variety of
sizes, they are made from pure tungsten or an alloy of tungsten
and other rare earth elements. Choosing the correct tungsten
depends on the material being welded, the amount of amps
required and whether you are using AC or DC welding current.
Tungsten electrodes are colour-coded at the end for easy
identification.
THORIATED
(Colour Code: Red)
Thoriated tungsten electrodes (AWS classification EWTh-2)
contain a minimum of 97.30 percent tungsten and 1.70 to 2.20
percent thorium and are called 2 percent thoriated. They are
the most commonly used electrodes today and are preferred
for their longevity and ease of use. Thorium increases the
electron emission qualities of the electrode, which improves arc
starts and allows for a higher current-carrying capacity. This
electrode operates far below its melting temperature, which
results in a considerably lower rate of consumption and
eliminates arc wandering for greater stability. Compared with
other electrodes, thoriated electrodes deposit less tungsten
into the weld puddle, so they cause less weld contamination.
However, thorium is a low-level radioactive hazard and many
users have switched to other alternatives.
Regarding the radioactivity, thorium is an alpha emitter but when it
is enclosed in a tungsten matrix the risks are negligible. Thus holding
a stick of Thoriated tungsten in your hand should not pose a great
threat unless a welder has open cuts on their skin. Thoriated
tungsten should not come in contact with open cuts or wounds. The
more significant danger to welders can occur when thorium oxide
gets into the lungs. This can happen from the exposure to vapours
during welding or from ingestion of material/dust in the grinding of
the tungsten. Follow the manufacturer's warnings, instructions, and
the Safety Data Sheet (SDS) for its use.
34 For technical questions call 1-800-665-8685