wedging action of the tapered thread may cause the
fittings to split. Usually there are two or three unused
threads on a pipe that is threaded properly. If you
follow the above steps and the threads are made
properly, the joints will be tight for pressures several
times the 150-psi working pressure of the fittings.
Cement-asbestos pipe is corrosion-resistant and
does not rust or rot. It has a smooth interior surface that
is a favorable friction factor. This pipe comes in sizes
from 3 to 36 inches in diameter for pressures of 50 to
200 psi and in lengths of 5, 10, and 13 feet. Light in
weight, cement-asbestos pipe is easy to handle. It is
made with beveled ends, and adapters are available for
connecting to pipe made of other materials.
FITTINGS. In the absence of cement-asbestos
fittings, you can use double-bell, cast-iron fittings and
make them up as you would with cast-iron pipe, using
sulfur compounds or lead.
CUTTING.Cement-asbestos pipe can be cut to
any length or angle with a carpenters saw or a transite
pipe cutter. Or, it can be tapped for threaded service
connections by using a water main self-tapping
machine. With this machine, the pipe can be tapped,
threaded, and a corporation stop installed while the
pipe is under water pressure.
Because of the health and environmental hazards
associated with cement-asbestos pipe, special cutting
and handling kits have been procured by the Navy and
Figure 3-62.Pipe- and bolt-threading machine.
are available through the naval supply system.
Whenever cement-asbestos pipe is encountered, the
base or unit environmental officer should be contacted.
Also, the newest and most up-to-date instructions
should be obtained and followed. Since safety
procedures governing asbestos-related equipment
change, an attempt to outline all the pertinent
procedures for working with asbestos are not included
in this manual; however, there are two important
factors you should keep in mind. First, always wear a
breathing filter or mask. Second, use water while
cutting to keep the dust from becoming airborne, or use
a vacuum to pull dust from the area of the cutting tool.
JOINING.Joints in cement-asbestos pipe are
made with a special coupling with three rubber sealing
rings. Three rings are fixed in grooves at the factory,
ready for assembly.
Figure 3-63 shows a cutaway view of a completed
joint with the three rings in proper position. As each
pipe moves into position during assembly, the rubber
Figure 3-63.Cutaway view of a cement-asbestos pipe joint.