Table of Contents
Advertisement
Figure
1-4.
Vent exhaust gases
1-10. POWER CIRCUIT GROUND
DONT
use
welding
machine without
grounding
frame
or
case.
(Figure
1-5)
Figure
1-5. Ground frame
or
case
Ground
the
ground
cable of every power Circuit
to
prevent
accidental
shock
by
stray
current.
The
potential
danger
is
that
development
of
a
stray
current
may
give
a
fatal shock
should
a
person, for
example, place
one
hand
on
the
welding
machine and the other
on
the switch
box,
or
other
grounded
equipment.
Do
not
ground
to
pipelines carrying
gases
or
flammable
liquids
and conduits
carrying
electrical conduc
tors.
Be
sure
conductors
can
safely
carry
the
ground
current.
When
connecting
the
welding
machine, properly ground
the
machine frame
or
case.
1-11. CONTAINERS WHiCH HELD COMBUSTIBLES
DONT
weld
on
containers which have held combustible
or
flammable
materials
or
materials
which,
when
heated, give
off ftammabte
or
toxic vapors without
proper
cleaning,
purg
ing,
or
inerting.
Welding
containers which have held flammable
or
combust
ible materials may be
extremely dangerous.
To
prevent
a
fire
or
explosion
of the
container,
follow the recommendations
of the American
Welding Society Pamphlet
A6.O
Welding
or
Cutting
Containers Which Have Held Combustibles.
DONT
depend
on
your eyes
or
nose
to
decide
if it is safe
to
weld
on
a
closed container.
Find
Out
what
was
in the container
or use
an
explosimeter.
A
very
small
amount
of residual flammable gas
or
liquid
can
cause
a
serious
explosion.
NEVER
use
oxygen
to
ventilate
a
container.
When you know the container held
a
gas
or
liquid
which will
readily
dissolve in
water:
1.
Flush
out
with
water
several
times and
then
fill
with
water
as
far
as
work
permits,
positioning
container
to
permit
introduction of
as
much
water
as
possible.
2.
Before
welding
be
sure
there is
a
vent
or
opening
to
pro
vide for release of air pressure.
When you know the container held
a
gas
or
liquid
which will
not
readily
dissolve in
water:
1.
Clean
out
thouroughly
with
steam
or
a
cleansing
agent
and purge all air
or
inert with
a
gas
such
as
carbon dioxide
or
nitrogen
before
repairing.
Carbon dioxide is heavier
than air and
will
tend
to
remain in the container if the
opening
is
at
the top.
2.
Use
steam
to
clean
out
light
material,
3.
Use
a
strong
caustic soda solution
to
clean
out
heavy
oils
or
grease.
4.
Be
sure
to
purge all air
or
inert with
a
gas,
such
as
nitro
gen
or
carbon
dioxide,
no
matter
how well
you
have
cleaned. There
may
still be
traces
of
oil,
grease,
or
other
readily
oxidizable material under the
seams.
Be careful
when
cleaning
with
steam
or
caustic soda
wear
goggles
and
gloves.
DONT
clean where there is poor ventilation.
Ventilation is necessary
to
carry away harmful
or
explosive
vapors.
DONT
clean where there
are
open flames.
When
scraping
or
hammering
to
remove
heavy sludge
or
scale,
use
a
spark
resistive tool and
keep
it
wet
to
avoid
sparks.
Keep
your
head and
arms
as
far away from your work
as
possible,
1-12. HOLLOW CASTINGS
DONT
weld
on
hollow (cored)
castings
that have
not
been
properly
vented. The
casting
may
explode. (Figure
1-6)
Figure
1-6. Dont
weld
on
hollow
(cored) castings
1-13. EXPLOSION HAZARDS
NEVER weld
in
or
near
explosive
atmospheres.
Such
atmos
pheres
can
be created
by
flammable gas leaks
or
by
vapors
from flammable
liquids (gasoline,
alcohol, etc.)
or
by
com
bustible dusts.
1.14. VENTILATION
DONT
weld in confined spaces without
adequate
ventilation.
When
welding
in
confined
spaces,
provide
ventilation
in
accordance with United States of American Standard
Z49.1,
1967.
Always provide
adequate
ventilation
by blowers,
air
lines,
or
other
acceptable
means:
Never
use
compressed
ox
ygen. The
depletion
of the oxygen
supply,
the heat
of weld
ing,
and the fumes
given
off may
cause severe
discomfort
or a
serious illness.
When toxic fumes from lead
or
cadmium
bearing
materials
or
any
other substances
are
present in harmful
concentrations,
always
use
an
air
supplied respirator.
-~
______---
S
I
/
Page
2
Hide quick links:
Advertisement
Table of Contents
