Figure 2-7.Side-cutting chisel.
After removing the main part of the tube from the
boiler, use a safety ripping chisel of the type shown in
figure 2-8 to make a cut on the inside of the remaining
portion of the tube. The safety ripping chisel is
designed so it cannot cut entirely through the tube;
therefore, it cannot score the tube sheet.
After cutting the tube approximately three fourths
of the way along the tube sheet, crimp the edges of the
tube and drive out the stub with a blunt chisel. If the
tube is a large one, you may have to make two cuts with
the safety ripping chisel instead of one; the cuts should
be about an inch apart.
If a safety ripping chisel is not available, you can
remove the tube by the following method:
1. Split the ends of the tube with a flat chisel, from
the end of the tube to the drum or header, at two
places about three fourths of an inch apart.
2. Force the 3/4-inch piece upward with a bar until
it has been raised off its seat and has curled into
3. Split the tube to a point beyond the other side of
the tube seat with a tool ground to conform to the tube
hole. Be careful not to damage the tube hole.
4. Break in the ends of the tube with a crimping
tool, and then drive out the stub.
Arc welding equipment can be used as an aid to the
tube removal on some boilers. This procedure requires
running two beads, three fourths of an inch apart,
through the entire tube sheet, quenching with water,
and then using a backing-out tool. Do NOT use this
method of tube removal if the drums or headers are
made of 4-6 chromium steel.
Replacement tubes must be thoroughly cleaned to
remove all scale, dirt, and preservatives. One way of
cleaning a tube is to push a kerosene-soaked rag
through it and wipe the outside of the tube with a
similar rag. Diesel oil may also be used. If a large
enough tank is available, boiler tubes may be cleaned
by immersing them in an approved cleaning solution,
such as a saturated solution of boiler compound in hot
water, to which a small amount of kerosene has been
added. Boiler tubes may also be cleaned with steam
Figure 2-8.Safety ripping chisel.