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 (3) At all tee, cross, or Y branches of systems.
(4) At all valves.
(5) At any point which will clarify a complicated system. Piping system markings may be omitted for
those locations where another marking on the same system is clearly visible from the specified location.
Thus a straight run through a relatively small compartment need be marked only once and not at both
bulkheads. Nonpotable fresh water line outlets shall be labeled as being unfit for drinking.
NOTE
Fittings will not be painted.
(6) Storage tanks shall be stenciled with the name of its contents. Lettering shall be color coded and
applied to the manhole cover or other visible location. Lubrication fittings shall be marked by the color-
coded letter '"L" applied adjacent to the fitting.
j. Marking the Anchor Chain. For the safety of every ship, the ship's officers and the boatswain must
know at all times how much anchor chain has been paid out. To make this information quickly available, a
system of chain markings shall be used as illustrated in figure C-1 of Appendix C.
k. Obliteration of Watercraft's Markings. On watercraft to be disposed of, all exterior Army Designations
such as '"US ARMY," watercraft's name and/or number, etc., shall be removed. Name boards shall be
removed from the watercraft as well. To provide for future identification, builder's nameplates and other
designative markings located within the interior of the watercraft shall not be obliterated. When markings
are painted on, they shall be completely obliterated; where welded onto the hull or other structural
member, markings shall be removed by grinding off the weld.
a. Cathodic Protection. Although coatings are used as the principal corrosion prevention measure on
metal surfaces, a supplemental method of protection is needed for the underwater hull and appendages
of ships to safeguard against premature paint failures, e.g., porosities, cracking, poor adhesion, abrasion,
aging, and erosion. Cathodic protection (an electrochemical technique) can successfully arrest or control
the corrosion of metals in a marine environment.
b. Cathodic Protection System. The type of cathodic protection system used is as follows: Sacrificial
(galvanic) Anode System.
c. Sacrificial Anodes System. A system based upon the theory that a less noble metal when connected
to a more noble metal in a corrosive environment will generate a current of sufficient magnitude to protect
the more noble metal. In so doing, it in turn is sacrificed. Such is the case, when magnesium, aluminum
or zinc anodes, attached to a ship's hull slowly dissolve generating a current to protect the hull and its
appendages against corrosion by eliminating local anodes and cathodes on the hull. The disadvantage
with this type of protective system is that periodic replacements of the anodes are required.
(1) Sacrificial anode systems require maintenance on a continual basis. The system specified herein
is designed to last 3 or 4 years to conform to normal overhaul periods. The actual service life is
dependent upon a combination of many factors.
(2) During Dry-dock Overhaul (3-year schedule), the ship shall be inspected to determine the need
for anode replacement. All anodes shall be replaced when 3 years or more have elapsed since the last
dry-docking involving anode replacement. Normally, stern anodes deteriorate more rapidly than those
installed midships. However, this may not be the case where large bare metal areas may exist in the
forward area due to beaching operations. In addition, the leading and trailing anodes usually deteriorate
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