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CORROSION CONTROL

Every member of the crew is expected to maintain his otherliving spaces. Therefore, besides the technical maintenance details on your gear, you will also be responsible for cleaning, painting, and similar housekeeping work. It is the duty of the division officer to supervise the maintenance, the preservation, and the cleanliness of all spaces and equipment assigned to the division, but the actual tasks are usually assigned by the division LPO (this maybe a PO3 or PO2). That means you have to know how to do the work and be able to teach others. Basic Military Requirements, NAVEDTRA 12043, chapter 17, describes general housekeeping preservation, procedures, and requirements.

As a GM, most of your cleaning and preserving work will be done on metal surfaces, principally steel. The preservatives must protect the metal against rust and corrosion; the cleaning materials must clean the surface before the preservative is applied.

Rust is caused by the slow burning (oxidation) of iron. When iron or steel rusts, it combines slowly with the oxygen in the air.

Technically, corrosion is not exactly the same as rust since its meaning includes metal being eaten away by acid or by the action of salt water or other substances. Rust and corrosion are dangerous and destructive saboteurs that attack unguarded metal at the slightest opportunity.

The way to protect metal from rust and corrosion is to protect it from the air. Paint is a good protective, but many metal surfaces, such as moving parts, cannot be painted.

The lubricants used on moving parts serve as rust preventives to some extent, but often this protection is not enough. These are temporary preservatives for protecting metal from water and weather. Light oils and greases are applied to exposed gun parts and mounts as temporary protection against corrosion. Bright steelwork, such as exposed cam and linkage surfaces, should have such protection. Slushing oils, available in several grades, are provided for this purpose. All old oil and dirt should be cleaned from the part and the surface thoroughly dried before new oil is applied.

Authorized Cleaning and Preserving Materials

Some lubricants (preservative lubricating oil for use in small arms and light machine guns) have preservative additives (rust inhibitors) and can serve for short-term preservation, but no preservative is intended for use as a lubricant.

When lubrication is not desired, there are special preservatives (permanent type) that may be brushed or sprayed on the surface to be protected. Small parts of a mechanism may be dipped. After treatment, the preserved mechanism can be stowed for a long period. (The length of time depends on the characteristics of the preservative, the kind of stowage, and so forth.)

A rust preventive that can be used either to protect exterior surfaces or (as when pumped through a hydraulic system) for preserving interior surfaces, tubes, and so on, is the thin-film compound, MIL-C-16173, that is available in several grades. A hard-film compound is available for metal exterior surfaces only.

Rust preventives are not lubricants and should not be used instead of lubricants. Before treating metal surfaces with rust preventives, be sure to remove all traces of rust and corrosion and all the old lubricant.

Be sure to remove all of the rust preventive before adding lubricant to ordnance equipment that has been stowed with rust-preventive compound coating. OP 1208, Instructions for Inactivation, Maintenance and Activation of Ordnance in Vessels in Inactive Status,

gives step-by-step instructions for removing preservatives from gun mounts and other ordnance equipment. Chapter 5 of OD 3000, Lubrication of Ordnance Equipment, deals with cleaners and preservatives. It contains a chart of all of the cleaning and preserving materials authorized for use on ordnance materials. This chart gives the specification number, characteristics, applications, national stock number, container size, and substitutes, while the text elaborates on the use of each item. Some of the materials will be described very briefly in the following pages.

Dry-cleaning solvent P-D-680 (Varsol or Stoddard solvent) is useful for cleaning away old grease, oil, and rust preventives. However, it is hard on rubber (use soap and water on that). Because of its irritating, flammable fumes, it should be used only where there is plenty of ventilation and where there are fire extinguishers handy.

Diesel fuel or kerosene can also be used for the same purposes as dry-cleaning solvent. The correct solvent must be used since some solvents leave a residue or cause corrosion. Therefore, always check the OP for the equipment.

Spraying or splashing of the solvent must be avoided during cleaning. If the solvent were to fall upon a bearing surface, it would cut or render the lubricant less effective, causing excessive wear. After the solvent has been used, the parts must always be wiped dry with a clean, lint-free cloth.

Removing Rust

When using abrasives to remove rust, be careful to select the proper type (see OD 3000) and use it sparingly.

Never use abrasives without permission from the proper authority. Only experienced personnel may use abrasives or wire brushing. Carelessly used abrasives can do more damage than rust. A few strokes of even a fine abrasive could destroy the accuracy of many close-fitting parts that are machined to close tolerances and could lead to costly replacements. Always be extremely careful to keep grit from getting into bearings or between sliding surfaces.

After the rust has been removed, the parts must be thoroughly cleaned and dried. Avoid leaving your fingerprints on the metal. Cleaned surfaces should not be touched by bare hands before the rust preventive is finally applied. When the surface is clean and dry, you are ready to start applying paint or a preservative.

Painting Pointers

Painting is one of your important maintenance jobs. Instructions for using the chipping hammer in preparing metal surfaces for painting are outlined in Use and Care of Hand Tools and Measuring Tools, NAVEDTRA 12085.

Except for special applications like camouflage, the primary purpose of painting in the Navy is for preservation, rather than decoration. You do not paint just for the sake of appearance nor as a substitute for cleaning. When you do paint, you should do a thorough and neat job. "Thorough means that you cover every square inch of the surface to be painted, and "neat" means that you keep paint off places where it does not belong. You have learned from past experience that it is much better and easier to keep the paint off the places where it should not be than to clean it off later. Always keep paint off gaskets, brightwork, grease fittings, rubber parts and rubber-covered wires, electrical leads and contacts not protected by armor or conduits, instruction or data plates, and working parts of surfaces that are normally supposed to be protected by a coat of lubricant.

The first thing to do when you are given a painting job is to remove the old paint, which you have been taught to do properly. The paint stripping solution

recommended in OD 3000 is 8 ounces of sodium hydroxide (O-S-598 Type 1) in 1 gallon of near-boiling water. Rinse it with clean, hot water after the paint is removed. O-S-598 should not be used on aluminum, zinc, tin, terneplate, or lead.

Before applying paint, be sure the surface is clean and dry. Paint will not adhere to damp or oily surfaces or to surfaces covered with dirt, rust, or solvent. Galvanized surfaces must be wiped with ammonia, vinegar, or a special priming solution called wash primer before the paint will adhere. Brush the solution on, allow it to dry, and then wipe it off. Never use an abrasive on galvanized surfaces.

Soap and water are one answer to the problem of removing all dirt and traces of old oil or grease from metal surfaces to be treated with rust preventives, paint, or other preservatives. Wash away all soap, then see that the surfaces are dry; and, finally, apply rust preventives (or paint) without delay. It is sometimes hard to get at pockets or cavities where water collects; be sure they are not neglected.

The standard finish for United States naval ship superstructures is a gray paint; the exact color and composition are prescribed by NAVSEA. You will also use gray paint for the exterior of gun mounts.

A prescribed gray-blue paint is used for exterior steel decks. Interior bulkheads and overheads are painted with a white paint prescribed by NAVSEA, and interior steel decks are usually finished with gray deck paint, although white is prescribed for decks in ammunition spaces. These are the general rules for painting; you will receive details on painting jobs from your leading GM.



 


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