SAFETY INFORMATION
6
Changing Electrodes
The electrode holder should be isolated when
changing the electrode, where a work piece is
earthed. If the electrode is changed without
isolating the electrode holder, the welder is
relying on the insulation properties of the glove
to avert shock from the OCV (Open Circuit
Voltage) which can be 80V between the
electrode and earth. If the glove is wet, the
electrode a bad insulator or the welder in
contact with a conductive surface, one or more
of these layers of insulation may be ineffective.
Safety Devices
Safety devices such as interlocks and circuit
breakers should not be disconnected or shunted
out. Before installation, inspection, or service of
equipment, shut OFF all power and remove line
fuses (or lock or red-tag switches) to prevent
accidental turning ON of power. Do not open
power circuit or change polarity while welding. If,
in an emergency, it must be disconnected,
guard against shock burns, or flash from switch
arcing.
Always shut OFF and disconnect all power to
equipment. Power disconnect switch must be
available near the welding power source.
Checking the Equipment
Check that the equipment is suitable for the
operation and connected in accordance with the
manufacturer's recommendations. The welder is
responsible for checking the equipment (cable,
electrode holder and coupling devices) daily for
damage and defects. All external connections
should be clean and tight and checked each
time a reconnection is made. The welding return
clamp should be connected directly to the work
piece, as close as possible to the point of
welding or to the metal work bench on which
the work piece is placed. Any damaged or
defective parts must be replaced before
continuing the welding operation.
Fumes And Gases
The welding process vapourises
metals, and anything that is resting
on the surface. This gives rise to
fumes, which is condensed fine
particulate material. The fume is
mostly oxides of the metals, including any
alloying elements, but it also contains gases
produced in the arc, such as ozone or oxides of
nitrogen, and decomposition products from any
paint or coating which was on the metal
surface. The nature and quantity of this fume
depends critically upon the welding process, the
materials and the welding parameters.
Severe discomfort, illness or death can result
from fumes, vapours, heat, or oxygen
enrichment or depletion that welding (or cutting)
may produce. Prevent them with adequate
ventilation. NEVER ventilate with oxygen. Lead,
cadmium, zinc, mercury and beryllium, bearing
materials, when welded (or cut) may produce
harmful concentrations of toxic fumes. Adequate
local exhaust ventilation must be used, or each
person in the area as well as the operator must
wear an airsupplied respirator. For beryllium,
both must be used. Metals coated with or
containing materials that emit toxic fumes
should not be heated unless coating is removed
from the work surface, the area is well
ventilated, or the operator wears an air-supplied
respirator. Work in a confined space only while it
is being ventilated and, if necessary, while
wearing an air-supplied respirator. Vapours from
chlorinated solvents can be decomposed by the
heat of the arc (or flame) to form PHOSGENE, a
highly toxic gas, and other lung and eye
irritating products. The ultraviolet (radiant)
energy of the arc can also decompose
trichloroethylene and perchloroethylene vapours
to form phosgene. DO NOT WELD or cut where
solvent vapours can be drawn into the welding
or cutting atmosphere or where the radiant
energy can penetrate to atmospheres containing
even minute amounts of trichloroethylene or
perchloroethylene.
1.
Keep your head out of the fumes. Do not
breath the fumes.
2.
If inside, ventilate the area and/or use
exhaust at the arc to remove welding fumes
and gases.
3.
If ventilation is poor, use an approved air-
supplied respirator.
4.
Read the Material Safety Data Sheets
(MSDSs) and the manufacturer’s instruction
for metals, consumables, coatings, and
cleaners.