ground wire of an electrical device such as an electrically powered
Several techniques are used to
methods is usually used to cut down on corrosion as much as possible.
Soil studies are made and the planners try to avoid high acidic areas
such as swamps and high alkaline areas such as clay deposits.
Protective coverings. Pipe sections are coated at the factory or at
the construction site with coal tar enamel.
Protective wrappings are
put around the pipeline before it is buried. The enamel and wrappings
are waterproof. They act as a barrier between the pipeline and
surrounding ground and atmosphere, and they prevent current from
leaving the pipeline. When a pipeline is repaired it is important
that these protective coverings be restored to their original
Sacrificial anodes. Another way to protect the pipeline is to use
sacrificial anodes. One type of sacrificial anode is magnesium. Bars
of magnesium are buried in ground beds that are located away from the
pipeline. The anodes are connected to the pipeline with insulated
copper wires. In this way, the pipeline becomes the cathode and the
magnesium anode is sacrificed to protect the pipeline. Corrosion is
not stopped; it is only directed to a less important surface.
Mitigation bonds. Mitigation bonds are used to protect the pipeline
from stray electrical current. These bonds are insulated grounding
cables that serve as paths of least resistance to stray electrical
currents. Stray current will tend to flow through these cables
instead of the pipeline.
PART B - PIPELINE TESTING
A new coupled or welded pipeline should be tested before it is accepted
for service by the using organization. Testing is done to locate leaks,
blockages in the line, and flaws in construction. Testing may be done
with water, fuel, or compressed air.
Although testing with water is safer than testing with fuel,
there are disadvantages to using water.
Water may be scarce in some
area. It may not be practical or possible to pack the line with water.
Water expands as it freezes. It should not be used to test a line if
there is any chance of the temperature falling low enough to freeze the
line. All water should be removed or displaced entirely form the line
before it is packed with fuel. In a combat situation this process could
use valuable time.
Since there are problems testing with water testing is usually
done with fuel. Several conditions should be met when fuel is used.
The test section should be outside of a city or heavily populated