The following article is taken from the October, 1911 issue
of American Thresherman column, ‘Asked and
Question of E. E. H.
I want to learn how to cut out flues and repair boilers with
crude or homemade tools. Is there any substance besides lime in
which flues may be annealed?
What kind of homemade tools can be made for cutting out an old
set of flues or a damaged boiler plate?
Can you explain how to put a patch on a boiler and how to take
out old stay bolts or put new ones in?
Answer: It is a pretty big contract to tell you
all about boiler repairing in these columns. The best we can do is
to give you a few ideas and leave the rest to your ingenuity and
common sense. Making extensive repairs on a boiler is a boiler
maker’s job, and we always recommend that a competent man be
engaged when such a condition arises. There is no good reason,
however, why any handy man could not put in a set of flues if he
understands just what the essentials are for a good job. The
putting on of a patch is a more serious undertaking and one that
should be turned over to a boiler maker.
If a whole set of flues is to be taken out it will prove
economical to purchase a flue cutting tool. The one advertised in
this journal will be found easy to use and much more rapid than any
hand tool that can be made at home. After the flues are all cut off
just inside the flue sheet, they may be removed through one of the
hand holes. If only one flue is to be taken out there will be no
trouble in getting it out if in either the top or bottom row,
through one of the hand holes. If it is in the middle of the tube
bank there is only one thing to do and that is to split it at both
ends, pinch the ends together and take it out through the tube
opening. If badly coated with scale, it is next to impossible to
get it out. If copper ferrules are used in the fire box end, the
difficulty is greatly lessened.
In splitting a tube, the tools shown in figure 1 can be used and
in pinching in the ends figure 2 is a handy tool. An ordinary cold
chisel will not do as there is danger of gouging the boiler plate
around the edge of the openings. If this occurs it is, of course,
next to impossible to make a tube tight enough to prevent leaking.
Figure 2 is also used when taking out the ends of flues that have
been cut off. The tool shown in figure 3 may also be used to split
tubes but it is designed especially for cutting out a damaged piece
of plate. In using this tool, it will be found advisable to
lubricate the point occasionally with a little lard oil.
The ends of the tubes must be annealed, that is, softened so
they can be rolled and beaded without danger of their breaking or
splitting. Annealing is a simple process, but one that must be done
carefully if it is to be successful. The ends of the tubes, back
four or five inches from the ends, should be slowly heated to a
cherry red. Be careful not to heat too hot because at the higher
heats a scale forms over the surface of the iron and when it comes
off the surface is left rough. When the proper temperature is
reached, the tubes must be taken out and the heated ends plunged
into a box containing slaked lime, dry ashes, or fine dry sand.
Lime is the best. The tubes must be left to cool off slowly, after
which the opposite ends may be treated in the same way.
In refluxing an old boiler measurements should be taken for each
flue as the tube sheet may be somewhat warped and there may be
considerable variation in the lengths of the different flues. Allow
from an eighth to three-sixteenths of an inch at each end for
beading. If too much is left, it is impossible to do a good job or
fit the tubes so they will not burn off, especially if used in the
flue box end. A small compact bead is essential to success. Another
essential is to have the surface of the tube where it enters the
tube sheet perfectly clean. It should have every bit of rust and
scale removed with a piece of emery cloth or a file. The ends of
the tube should, if it is possible, be trimmed off smooth in a
lathe. Sometimes they have to be put in just as they are received
from a pipe cutter but it is impossible to do as nice a job.
Either the spring expander or the roller expander may be used
and it makes little difference which. Personally we prefer to use
the roller on new work and the spring expander on old boilers on
account of the fact that new holes are round while old ones may be
slightly distorted. In expanding the tube end, it will be necessary
to have a man at the free end with a heavy bar to hold it in
position. After one end is expanded the other end can easily be
taken care of.
Care and judgment should be exercised in expanding tubes. If
they are expanded too much, the adjacent tubes will be loosened and
a poor job will result. The holes will be either enlarged or
distorted. The proper way to proceed is to drive the taper pin of
the expander in lightly and turn it around, drive again and turn
and repeat the operation until it is evident from the way the pin
drives that the tube is tight. Always use oil on the expander
rollers and upon the pin. It will turn much easier and the pin can
be jarred loose easier.
In using the spring expander it should be turned about a fifth
of a turn each time. Drive the pin in until it meets with
considerable resistance, then jar it loose, turn the whole expander
about a fifth of a turn and repeat the operation. In using this
expander, great care must be taken to note if the bead D shown in
figure 4 is inside the tube sheet. If it is not it will be
impossible to do a good job. An inspection of the figure will
convince the reader to do the best work there must be a special
spring expander for every thickness of flue sheet. This is a point
that is frequently overlooked.
It is also an argument in favor of the roller expander, which is
not subject to such limitations. Not only must the spring expander
be designed for the thickness of plate in which the tubes are to be
expanded, but the amount the tubes project outside is limited to
the width of the shoulder outside of the tube sheet. With the
various points intelligently attended to there is no better tool
for the purpose than the spring or Prosser expander as it is
Figure 5 shows the kind of work done by this tool. The
depression B is formed by the bead D of figure 4.
The next operation is to bead the flues and here again care and
intelligence must be exercised. First turn the ends of the tube
over with the ball pene of a machinist’s hammer, then use the
starting tool, figure 6 and finish the job with figure 7. The
finishing tool must have the right radius of curvature at E for the
size of bead that is to be turned. If too deep, the point will
gouge into the edge of the bead. It must be just right.
In using the beading tool, care must be taken that the direction
of every blow be toward the edges of the tube sheet. There is a
tendency, for beginners, to drive the tube inward, resulting in the
kind of job illustrated in figure 8. A tube beaded in this way will
burn off and leak in a very short time.
Many people have trouble with leaky flues and even some boiler
manufacturers have trouble. They can’t keep the tubes from
leaking and the trouble in almost every case can be traced down to
faulty workmanship in putting them in. There are some places where
the water is so bad that it is next to impossible to make the tubes
hold, but even there good workmanship will help wonderfully.
Figure 9 shows a calking tool. This is very necessary as a part
of the equipment of the engineer. It is easy to make and may be
made in a great variety of forms. There is only one thing to bear
in mind and that is never to make one with a sharp edge. Such an
edge will groove the plate and eventually cause a crack to develop
along the seam. Another thing, under no condition calk a seam or
tighten up a union or screw in a plug or attempt any repairs upon a
boiler or a steam pipe under pressure.
Taking out stay bolts is a difficult job. About the only way you
can do this is to drill them out from each end, then tap the hole
out for the next larger size bolt. It is impossible to unscrew a
stay bolt that has been riveted in on both ends. When a bolt
holding a bracket gets loose, the best thing to do is to put in a
new one a sixteenth of an inch larger.
We will not attempt to tell how to patch a boiler at this time
as the story is too long.