assemblies are constructed of rubber or Teflon .
A casual inspection of a badly scaled zinc
Each of these materials has its own distinct
anode, especially while it is still wet, may lead
advantages or disadvantages, depending upon its
personnel to believe that the metal is exposed
application.
instead of the scale. The anode, even though it
Steel piping and tubing are relatively in-
appears to be in good condition, should be cleaned
with a chipping hammer to learn the true
expensive, have a high tensile strength, are suitable
condition of the metal. Whenever zincs are
for bending and flanging, and are very adaptable
to high pressures and temperatures. Its chief
inspected or cleaned, check the condition of the
disadvantage is a comparatively low resistance to
metallic contact between the anode and its
support.
corrosion.
Copper and brass piping and tubing have a
high resistance to corrosion and are easily drawn
PIPING
or bent. Pipe or tubing made from these materials
is unsuitable for systems with high temperatures,
The control and application of fluid power
stress, or vibration because they have a tendency
would be impossible without a suitable means of
to harden and break.
conveying the fluid from the power source to the
Aluminum has many characteristics and
point of application. Fluid lines used for this
qualities required for fluid systems. It has a high
purpose are called piping. They must be designed
resistance to corrosion, is lightweight, is easily
and installed with the same care applicable to
drawn or bent, and (when combined with certain
other components of the system. To obtain this
alloys) will withstand high pressures and
desired result, attention must be given to the
temperatures.
various types, materials, and sizes of lines
Stainless steel piping or tubing is relatively
available for the fluid power system. The different
lightweight and is used in a system that will be
types of lines and their application to fluid power
exposed to abrasion, high pressure, and intense
systems are described in the first part of this
heat. Its main disadvantage is high cost.
section. The last part of this section is devoted
to the various connectors applicable to the
FLEXIBLE HOSE ASSEMBLIES
different types of fluid lines.
The flexible hose assembly is a specific type
IDENTIFICATION OF PIPING
of flexible device that uses reinforced rubber hose
The three most common lines used in fluid
power systems are pipe, tubing, and flexible hose.
They are sometimes referred to as rigid (pipe),
semirigid (tubing), and flexible piping. In
commercial usage, there is no clear distinction
between piping and tubing, since the correct
designation for each product is established by the
manufacturer. If the manufacturer calls its
product pipe, it is pipe; if the manufacturer calls it
tubing, it is tubing.
In the Navy, however, a distinction is made
between pipe and tubing. The distinction is based
on the method used to determine the size of the
product. There are three important dimensions
of any tubular product-outside diameter (OD),
inside diameter (ID), and wall thickness. The
product is called tubing if its size is identified by
actual measured outside diameter and by actual
wall thickness. The product is called pipe if its
size is identified by a nominal dimension and wall
thickness.
PIPING MATERIALS
The pipe and tubing used in fluid systems
today are commonly made from steel, copper,
brass, aluminum, and stainless steel. The hose
Figure 6-36.--90 and 180 flexible hose configurations.
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