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1-15. SOLVENTS
Do
not
weld where chlorinated
hydrocarbon
vapors from de
greasing,
cleaning,
or
spraying
may
reach
or
be drawn into air
surrounding
the
welding
operation.
The heat of the
arc
can
decompose
solvent
vapors
to
form
phosgane,
a
highly
toxic
gas and other
irritating
decomposition products.
Do
not
weld where ultraviolet
light
from the electric
arc can
penetrate air
containing
even
minute
amounts
of
vapors
from
~olvents such
as
trichloroethylene
or
perchloroethylene.
Ul
traviolet
light
can
decompose
the vapors
to
form
phosgene,
a
highly
toxic gas and other
irritating products.
1-16. FIRE HAZARDS
electrode
on
the table top
or
in
contact
with
a
grounded
metallic surface.
(Figure
1-7)
When
it
is
not
in
use,
never
place
an
electrode holder
in
contact
with the
tabletop
or
other metallic surface in
contact
with
welding ground.
Provide
an
insulated hook
or
holder for
the electrode holder. A
potential danger
is
that
a
holder in
contact
with the
ground
circuit
provides
a
dead short
circuit
on
the
welding
machine. If the machine should be started
up,
this short circuit would
cause
an
excessive load
on
the
ma
chine and
may
damage
the
insulation.
1-20. FACE PROTECTION
DONT
use
cracked or defective helmets
or
shields.
DONT
weld
near
flammable
or
combustible materials.
Fires
can
be caused
by
the
arc,
by
contact
with the
heated
metal, by
slag,
or
sparks. Keep
combustibles
at
least
35 feet
from the
arc or
suitably protected.
If
welding
must
be done
in
a
particular
area,
move
the combustibles away. If
they
cannot
be
moved,
cover
them
completely
with fire resistive
screens.
Cover cracks
or
openings
in floors
or
walls;
sweep
floor free of combustibles and
wet
down,
if
wood,
being
sure
welder
wears
insulation shoe
coverings.
Avoid
welding
on
par
tition walls in
contact
with combustibles. Heats metal
on
the other side of
partition
wall
being
weded upon
can
ignite
combustibles
in
contact
with the
partition.
Where other than
a
minor fire
might develop,
have
a
fire watcher
stand-by
with
suitable fire
extinguishing equipment
for
at
least one-half
hour after the
welding
is
completed.
1-17.
ELECTRICAL SHOCK-VOLTAGE
OPEN
power
circuits before
checking
machines.
Before
working
on
the
wiring, switches,
controls,
etc., open
the power line disconnect
switch.
In
most
welding shops
the
power
supply
used for
arc
welding
machines is 230
or
460
volts, Open
circuit
voltages
are
usually
less than 100 volts and
welding
or
arc
voltage drops
are
still lower.
However,
all of
these
voltages
are
capable
of
developing
a
harmful
or
fatal
current
to
the
body.
DONT
touch
electrically
hot
parts.
NEVER
touch
any
exposed
or
non-insulated part of the
cables,
cable
connectors,
clamps,
electrode
holders,
elec
trodes,
or
the power
supply equipment
to
prevent harmful
or
fatal electric shock
or
burns.
1-18. ELECTRICAL SHOCK-DAMPNESS
NEVER work in
a
damp
area
without suitable insulation
a
gainst
shock.
Keep hands, feet,
and
clothing dry
at
all times.
To.prevent
harmful
body shocks, keep hands,
feet and
cloth
ing dry.
Never stand
or
lie in
puddles
of water,
damp ground,
or
against grounded
metal when
welding
without suitable in
sulation
against
shock.
Always
find
a
dry
board
or
rubber
mat to
stand
on
when water,
moisture,
or
perspiration
cannot
be avoided.
Dampness
between the
body
and
an
energized
or
grounded
metallic
part
lowers the resistance
to
the passage of
current
to
the
body
which
may
produce
a
harmful
or
fatal
shock. Salt in
perspiration
or
sea
water
dangerously
lowers
contact
resistances.
Figure
1-7, Dont
leave electrode in
contact
with
grounded
metallic surface.
Keep
the
helmet,
hand
shields,
or
face shield in
good
condi
tion. If cracks
occur
in the fibre
material, replace
the
shield,
since the
leakage
of
arc
rays may
cause
serious burns.
1-21. EVE PROTECTION
NEVER
under
any
circumstances,
look
at
an
electric
arc
without eye
protection.
Make
sure
that flash
goggles
are
used under the weld
ing
helmet
at
all
times, particularly
while gas shielded-
arc
welding.
In
some
type of
arc
welding,
such
as
gas shielded-arc
welding,
ultra-violet and infra-red radiation from the
arc
is
particularly
intense and
requires
constant
attention
to
avoid
arc
flashes
to
the welder when
striking
an
arc
and
to
avoid exposure
to
other welders.
NEVER strike
an
arc
without
ascertaining
that
nearby
per
sons
either have the
necessary
protective equipment
or
are
looking
in the
opposite
direction.
For
welding operations
in open
areas,
provide portable,
non-
ref
Iecting
screens
to
shield
persons
nearby
from the
rays
of
the
arc.
Eye
burns from the
arc,
through
not
generally
per
manent
injuries,
are
exceedingly painful.
Such
burns fre
quently
referred
to
as
flashes,
feel like hot sand in the eye.
If the eye is focused
on
the
arc
without
filter-glass
protec
tion,
infra-red radiation
can
cause
retinal
scarring
and im
paired
vision. For eye burns consult
your
first aid station
or
doctor.
NEVER
use
cracked,
ill-fitting,
or
defective
plates.
The filter
glass
plate provided
in the helmets and
shields
must
be of
reputable
manufacture
conforming
to
the latest Ameri
can
National
Standards
Institute,
Standard
Z2.1.
Replace
cracked
or
ill-fitting
filter
plates
promptly.
NEVER
use
filter
plates.without
a
protecting
cover
glass.
Figure
1-8, Use
eye
protection
at
all times
I
I
U
I
1-19. STARTING UNDER LOAD
DONT
leave
an
uninsulated
electrode
holder,
or
a
live
OM-313
Page
3
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