Section II. PRESERVATIVE MATERIALS AND THEIR APPLICATION

TM 38-260

Residue from cleaning will not affect these solvent-cutback preservatives but might harm other types.

(b) This method is not intended for use when contact preservatives are not required. Prior approval of this

draining procedure shall be obtained by the owning command for conditions other than these specified in (a) above.

Section II. PRESERVATIVE MATERIALS AND THEIR APPLICATION

2-4.

Deterioration Data

a. Complexity of IPE. Corrosion and deterioration are always threats to the useful life of IPE. This type of

equipment usually contains a complex assortment of many different kinds of material. Rubber, textiles, paper, plastic,

metals, and other organic materials are used extensively. Typical of the metals and alloys that can be found in a single

unit of IPE are steel, iron, magnesium, chromium, bronze, brass, copper, nickel, and silver. When such a variety of

metals is consolidated in a single unit, the deterioration problem is intensified.

b. Basic reason for deterioration. The reason why most equipment and materials are in a constant battle against

deterioration by their environments is that they are not in their natural form. For example, pure metals are seldom found

in nature. They exist in nature in the combined state, that is in combination with other substances.

c. Metallic corrosion. Metallic corrosion is chemical destruction of metal by its environment. The oxidation

process is chemical, in that some substances are converted into new substances such as iron into rust. It is

electrochemical in that the chemical action either causes or is caused by electric current. Corrosion is distinguished from

erosion which is mechanical wearing away of a metal. Corrosion usually occurs at the surface of a metal since that is the

place where the metal comes into contact with the corrosives in the environment. The agents of corrosion, which are

various solids, liquids, and gases in the environment, react or combine with the metal to form the corrosion product such

as rust and verdigris.

d. Other forms of deterioration. The absorption of water, by wire and cable insulations and by other component

parts, can produce swelling, warping, or cracking. In addition, the presence of moisture engenders the growth of fungi

which contributes to corrosion, in that it tends to hold moisture against exposed surfaces.

2-5.

Selecting the Proper Preservatives

a. Control of environment. If the agents of deterioration which occur in the equipment's environment are not

controlled, they will eventually render equipment unusable. This can be prevented by the application of proper

preservatives to the most exposed surface areas of IPE. When selecting the type of preservation to be used,

consideration must be given to the environment in which the equipment will be stored. Instructions for selecting the

correct type of preservative for the type of storage condition to be used is outlined in more detail in chapters 3

2-12