satisfactory braze with water in the line. Never try to
5. Insulate all hangers and other supports at their
braze until the line has been drained and completely
point of contact from the pipe or other unit they are
secured. You may want to break the line at a union or
supporting. Otherwise a considerable quantity of heat
flange and slip a piece of sheet metal between the faces.
will be lost through the support via conduction.
This will divert a trickle of water before it reaches the
6. Sheet metal covering should be kept bright and
section on which you are working.
not painted unless the protecting surface has been
bright-bodied and light-colored objects is considerably
less than from rough and dark-colored objects.
7. Once installed, heat insulation requires careful
most of the troubles can be readily fixed. However, you
inspection, upkeep, and repair. When you remove
must know how and where the drain lines run.
lagging and insulation to make repairs, replace it just as
Snakes, suction cups, air pressure, and water
carefully as when it was originally installed. When
pressure are usually used to free lines of obstructions.
replacing insulation, make certain that the replacement
The use of a snake or a suction cup usually involves no
material is the same as the original. Old magnesia
danger. But when you use air or water pressure, you will
blocks and sections broken in removal can be mixed
have to be careful. Make sure that all the other drains
with water and reused in the plastic form for temporary
connected to the line you are working on are closed. If
repairs. Save all old magnesia for this use.
there are outlets in which no closure is installed, you
8. Insulate all flanges with easily removable
will have to drive a wooden plug into the drain. The plug
forms, which can be made up as pads of insulating
may be in a compartment other than the one in which
material wired or bound in place. Cover the whole thing
you are working. If so, have someone watch the plug to
with sheet-metal casings, which are in halves and easily
let you know if it blows out. Otherwise, you may think
that the drain you are repairing is satisfactorily
Lag the main steam, auxiliary steam, auxiliary
to hold in the heat. Lag the circulating drainage, fire,
Locating the exact trouble spot in a clogged line is
simply a matter of knowing what drains run into a
moisture on the outside of the piping.
common discharge line. When you are called to a job,
Inspect pipes, machinery, and allied equipment
you should first check the drain line to see what sanitary
periodically for evidence of broken or loose insulation
facilities drain into it. Then go back along the line to
or lagging materials. The insulating and lagging
determine what is free and running and what is stopped
materials used and the method of installation will vary
according to the service. Guidelines for insulation
Figure 16-46 is a diagram that should help you
requirements, installation, and repairs are covered in
understand how to check back along a drain line to
MIL-STD-769 and in the NSTM, chapter 635.
Most of your trouble will be in flushing and
firemain systems. This section tells you how to locate
trouble spots and how to correct troubles in these
On ships built during and since World War II, these
two systems have been made of copper-nickel pipe and
tubing with bronze fittings. The valves for the most part
are bronze-bodied with Monel seats and disks. These
systems are assembled by brazing with a silver-base
When brazing on these systems, you need to be sure
Figure 16-46.--How to check for the location of trouble spots
that all water is secured. It is impossible to get a
in a drain line.