CORROSION PREVENTION AND CONTROL (CPC) - Continued
prevent the problem in future items. The term "corrosion" means the deterioration of a material or its properties
due to a reaction of that material with its chemical environment. An example is the rusting of iron. Corrosion
damage in metals can be seen, depending on the metal, as tarnishing, pitting, fogging, surface residue, and/or
cracking. Plastics, composites, and rubbers can also degrade (also considered to be corrosion based on the
above definition of corrosion). Degradation is caused by thermal (heat), oxidation (oxygen), solvation (solvents),
or photolytic (light, typically ultraviolet) processes. The most common exposures are excessive heat or light.
Damage from these processes will appear as cracking, softening, swelling, and/or breaking. The US Army has
defined the following nine (9) forms of corrosion used to evaluate the deterioration of metals. These shall be used
UNIFORM (or general attack): Affects a large area of exposed metal surface, like rust on steel or tarnish on silver.
It gradually reduces the thickness of the metal until it fails.
CREVICE: Occurs in crevices created by rubber seals, gaskets, bolt heads, lap joints, dirt or other surface
deposits. It will develop anywhere moisture or other corrosive agents are trapped and unable to drain or
SELECTIVE LEACHING: One element, usually the anodic element of an alloy, corrodes away, leaving the
cathodic element. This can create holes in metal.
INTERGRANULAR: Metal deterioration caused by corrosion on the bonds between or across the grain
boundaries of the metal. The metal will appear to be peeling off in sheets, flaking, or being pushed apart by
layers. A particular type of intergranular corrosion is exfoliation.
PITTING: This can result from conditions similar to those for crevice corrosion. Pits can develop on various
materials due to their composition. Rifle boxes are big victims of pitting.
EROSION: Results when a moving fluid (liquid or gas) flows across a metal surface, particularly when solid
particles are present in the fluid. Corrosion actually occurs on the surface of the metal, but the moving fluid
washes away the corrosion and exposes a new metal surface, which also corrodes.
FRETTING: Occurs as a result of small, repetitive movements (e.g., vibration) between two surfaces in contact
with each other. It's usually identified by a black powder corrosion product or pits on the surface.
GALVANIC: Occurs when two different types of metal come in contact with each other, like steel bolts on
aluminum, for example. This is a common problem on aircraft because of their mix of metals.
STRESS: Term used to describe corrosion cracking and corrosion fatigue.
Where an item is not ready/available due to one of these forms of corrosion, it shall be recorded as a corrosion
failure in the inspection record and the appropriate code (170) for corrosion shall be used when requesting/
SF Form 368, Product Quality Deficiency Report should be submitted to the address specified in DA PAM 750-8,
The Army Maintenance Management System (TAMMS) Users Manual.
ARMY OIL ANALYSIS PROGRAM (AOAP)
The dump body is not enrolled in the Army Oil Analysis Program. HARDTIME INTERVALS APPLY.
Leakage Definitions for PMCS
Leakage indicated by wetness or discoloration, but not great enough to form
Leakage great enough to form drops, but not enough to cause drops to drip
from the item being checked/inspected.
Leakage great enough to form drops that fall from the item being checked/