across the long axis of the ellipse above and below the
center point. Sketch in the remainder of the ellipse. You
now have a useable layout for a pipe to pass through a
deck or bulkhead at an angle.
MAKING TEMPLATES AND TARGETS
Frequently, the section of pipe to be replaced will
have a bend in it. The replacement section will have to
be exactly like the portion that is removed. You can get
an exact fit by using templates and targets.
Templates are made from wood, wire, or small
tubing. You will find them valuable in preparing new
installations, as well as in repair work When properly
made and correctly used, they provide an exact guide
for bends and flange positions. The method of making
and using a template is illustrated in figure 16-10.
A wood template is formed by securing blank
wooden disks to the flanges of the fixed-position pipes.
This is shown in view A of figure 16-10. Insert gaskets
of the proper thickness between the wooden disks and
the fixed flanges. This will provide the proper clearance
for the permanent gasket installation. Next cut a 2 by 4
to fit snugly between the flanges. Secure the 2 by 4 by
nailing triangular wood braces to the wood flanges and
to the 2 by 4. The template can now be taken to the shop.
Figure 16-9.--Finding the length of an elliptical hole.
A target (or reverse template, as it is sometimes called)
can now be made. (See fig. 16-10, view B.)
Targets can be made of wood, but metal is the
or bulkhead. The method used is shown in figure 16-9
preferred material (fig. 16-10, view C) due to its
and described in the following paragraphs.
durability, strength, and flame resistance. The targets
Draw a line to represent the deck or bulkhead that
are constructed of ordinary or blank flanges welded to
the pipe will pass through. Use a protractor to lay out
angle iron or pipe. The target is then welded a minimum
and draw a line at the angle that the pipe will pass
of 12 inches off of a target deck (a large metal slab) to
through the deck or bulkhead. Draw this line as the
make it easier to work on the new section of pipe. The
centerline (A) to represent the center of the pipe. Then
target is then braced to prevent movement while
working with the target. Remember, the target is your
draw a parallel line on each side of the centerline. The
permanent pattern by which you are working off of and
distance between the parallel lines and the centerline is
any movement, however so slight, will cause mis-
equal to one-half the outside diameter of the pipe or
alignment in your finished product. Only after the
tube. This measurement must be made perpendicular
piping assembly has been manufactured, tested, and
from the pipe centerline. Measure the distance from B
installed may you remove the target from the target
to C on the bulkhead line. This distance is the long axis
deck. The target deck can then be used over again for
of the elliptical hole.
Locate the halfway point between the two points
In repair work, the target is usually made directly
marked B and C. This is the center point of the hole to
from the section being repaired. The pipe section then
be cut. Through this point, draw a horizontal line at right
serves as the template. This procedure is illustrated in
angles to the line representing the bulkhead. With a pair
view D of figure 16-10.
of dividers, scribe a circle equal to the outside diameter
of the pipe. Then set the dividers at a radius equal to
A centerline template is made to conform to the
one-half the distance from B to C. Now scribe an arc
bend, or bends, of the pipe to be made. It is used to lay