APPARATUS REPAIRS
(=50=) Occasionally in setting up a welding apparatus, a leak may be
noticed along the lines, some time after the plant is in operation.
Leaks on either the oxygen or acetylene lines are to be considered
dangerous as well as costly and therefore to be avoided at all times.
When the cylinder valves are closed on the drums containing the gases,
and the hands on the low-pressure gauges of each regulator are seen
to drop or reduce their pressure when the torch valves are shut off
and allowed to remain so, this is an indication that there is a leak
between the regulator and the torch. It is not desirable to use a match
or a flame of any kind in testing for leaks. There are various methods
employed by the cautious welder, but about the best of these is a soapy
solution of water, which is kept in a can at all times and is applied
with a paint brush. If this solution is applied to any leaky part,
bubbles will form immediately and the leak will be located.
(=51=) At times, when working in isolated places, where repairs cannot
be had, and no means have previously presented themselves for testing
out the cylinders or the apparatus as a whole, it may be found that the
threads or ground seat on the cylinder valve of the regulator which
is connected will be in such a condition that a leak is in evidence.
Or it may be that the threads will not permit the seat being drawn up
sufficiently to make it airtight. In cases of this kind, the welder
must find some means of proceeding with his work, and while it will be
impossible for him to use white lead or any oily substance with safety,
he may stop the leak with litharge or lead oxide mixed with a small
quantity of glycerine. A string soaked in this solution may be wound
around the main connection and the swivel nut screwed up to the seat as
far as it will go. If allowed to harden for a short time, the litharge
will set and a very satisfactory temporary repair will be effected.
[Illustration: FIG. 32.--Method of Attaching Hose to Connection so it
cannot Pull or Blow off.]
(=52=) The method shown in Fig. 32 of attaching connections to hoses so
that they will not blow off when pressure is applied is a very simple
and effective means of overcoming this difficulty. Undoubtedly it will
assist some operators in solving the trouble that has been occasioned
by the ordinary hose clamps, especially when doing cutting or heavy
welding work where the gas pressure is considerably higher than usual.
The wire used should be large enough to prevent cutting the fabric in
the hose.
(=53=) An injured hose which may leak should never be used after the
leak is noticed unless some means are taken to repair it. The use of
tape in trying to repair hose on an oxy-acetylene welding outfit should
never be permitted. The most efficient way of overcoming an injury of
this kind is to cut the hose at this part and insert a piece of pipe.
The ends of the hose are then wired to this pipe and a union is thereby
effected which will generally outlast the life of the hose. Special
connections for this purpose are put out by most welding companies, so
that a supply may be on hand if hose trouble is expected.
(=54=) When transporting welding apparatus, occasionally the
“cross-bar” on the regulator is lost and many times the operators do
not know what is to be done. The purpose of the “cross-bar,” as we have
already seen, is only to apply pressure on the diaphragm springs, so
that if a set screw of the same diameter and same thread as those of
the “cross-bar” can be found and screwed into its place with a wrench,
a section of filler-rod can be welded across the top of it and the use
of the regulator will not be impaired. If a special thread is used by
any particular company, a piece of brass or iron can be turned down in
a lathe to fit.
[Illustration:
(_Courtesy of the Bastian-Blessing Co._)
FIG. 33.--Various Types of Adaptors Used to Connect Regulators to
Cylinders having Different Connection.]
(=55=) The manufacturers of practically all regulators use the
quarter-inch tapered pipe thread in attaching the cylinder connections
to the regulator and do not depend upon the threads being gas-tight, so
they solder them in. There are various types of cylinder connections
put out by different manufacturers of the gases and occasionally it
may be necessary to use a cylinder of gas which contains a different
connection than is supplied on the regulator. Various adapters, such
as shown in Fig. 33, are supplied to overcome this difficulty, but at
times the operator is confronted with the very embarrassing situation,
of having a cylinder of gas and his regulator of different connections,
but no adapter suitable. This predicament is usually found when some
very important work is to be done and sometimes far from a supply
depot. At times the operator may have an adapter which will fit the
cylinder but not the regulator. If this is the case, his difficulty
can be very easily overcome, for generally all adapters are made of
two parts, “sweated” together, and have the same quarter-inch tapered
thread as used in the cylinder connections on the regulator. The
adapter can be separated, the tank connection removed and the correct
connection “sweated” into the regulator.
[Illustration:
(_Courtesy of the U.S. Gauge Co._)
FIG. 34.--Showing Solid-front and Hinged-back Features of a
“Safety-first” High-pressure Oxygen Gauge.]
(=56=) Most gauges used in the oxy-acetylene industry to indicate gas
pressure are of the Bourbon type. The most recent types of the oxygen
high-pressure gauges are constructed with a hinged back and a solid
front, which means that should an oil or foreign matter enter the gauge
from any source whatsoever and tend to burst it, the back would be
blown off and there would be no glass that could possibly fly around.
This is a safety device which has been welcomed with much enthusiasm on
the part of the oxy-acetylene industry. When leaks occur in gauges,
it is always best to remove the gauge from the regulator, stopping
the hole temporarily with a pipe plug and return the gauge to the
manufacturers for repair. These gauges are very delicately constructed
and can be rendered useless if handled by the inexperienced. A great
many times after the case of the gauge has been jarred or loosened,
the screws connecting this case to the inside working mechanism are
tightened up, breaking the soldered connection holding the spring
tube on the inside of the gauge. This causes a leak which can be
repaired quite easily if the operator is able to solder it. It must be
remembered, however, that if the flame is brought in contact with any
of the springs that their tension will be lost and that the gauge may
not operate correctly after this repair is made unless great care is
exercised.
[Illustration: FIG. 35.--A 3000-pound High-pressure Oxygen Gauge.]
(=57=) Undoubtedly there are many welders who in beginning to operate
their welding apparatus conclude that their gauges must be at fault
when they show a reading after apparently all pressure has been
released in closing down the apparatus. It is to avoid the impression
that the gauge is at fault that time is here taken to show that
even though the cylinder valve is closed and the “cross-bar” on the
regulator screwed out that when the torch valves are opened to drain
the lines there will still be a reading on the high-pressure gauge
if the regulator seat is in good working order. It is simply a case
of gas being trapped between the regulator and the cylinder valve. To
reduce this reading it is only necessary to screw in the “cross-bar,”
thus opening the regulator seat. This could be avoided if the cylinder
valve were closed first and the torch valves opened while the regulator
“cross-bar” were still screwed in, then as soon as the gas had left
the line, the torch valves could be closed and the “cross-bar” on the
regulator could be screwed out until free.