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48IS LOGISTICS48IS LOGISTICS48IS LOGISTICS48IS LOGISTICS

CORROSIONCORROSIONCONTROL TRAININGCONTROL TRAINING

OVERVIEWOVERVIEW

1. Theory and Causes of Corrosion2. Corrosion Prevention3. Corrosion Identification4. Corrosion Removal5. Corrosion Treatment6. Local Corrosion Threats

THE FOLLOWING SUBJECTS WILL BE COVERED DURING THIS TRAINING SESSION

THEORY AND CAUSES OF THEORY AND CAUSES OF CORROSIONCORROSION

• Concept and Objective of CPCP

• Corrosion Control Technical Publications

• Electrochemical Theory of Corrosion

• Biochemical Theory of Corrosion

• Environmental Factors and Corrosion

OBJECTIVE OF THE CPCPOBJECTIVE OF THE CPCP

The purpose of the Corrosion Prevention and Control Program (CPCP) is to prolong the life of all USAF systems and equipment through corrosion prevention and proper treatment. Success of the CPCP depends upon you and every maintenance technician becoming properly trained and practicing proper corrosion prevention and treatment techniques.

CORROSION CONTROL CORROSION CONTROL Technical PublicationsTechnical Publications

• TO 00-25-234 GENERAL SHOP PRACTICE REQUIREMENTS - A wealth of information on electric and electronic workmanship standards, soldering, printed circuit board repair, cable and connector fabrication, and many other related subject areas. It addresses cleaning procedures, corrosion prevention treatments, and protective coatings to be used during maintenance and repair actions.

• TO 1-1-8 APPLICATION OF ORGANIC COATINGS, AEROSPACE EQUIPMENT - In-depth guidance for application of protective coatings on all types of Air Force equipment. Selection of the proper coatings, and knowing exactly how to apply them is critical in corrosion prevention.

• TO 1-1-689 AVIONICS CLEANING AND CORROSION PREVENTION-CONTROL - Although written for Air Force and Navy avionics systems, this TO provides valuable information on corrosion theory, preventive maintenance, corrosion treatment and repair, corrosion control procedures for electrical bonding and grounding, and equipment cleaning procedures.

• TO 1-1-691 AIRCRAFT WEAPONS SYSTEMS CLEANING AND CORROSION CONTROL - A joint Air Force, Army, and Navy aircraft oriented publication that contains in-depth corrosion theory, prevention, and treatment information. It also contains many informative charts and tables.

• TO 31Z-10-37 CORROSION PREVENTION AND PROTECTION (TELECOMMUNICATIONS ENGINEERING) - Written specifically for ground C-E facilities. This TO covers corrosion theory, prevention, and treatment information and guidance in the ground communications environment during installation, operation, and maintenance.

All of these technical orders are available for reference in Maintenance Support, except for TO 1-1-691. This tech order can be found on P:\common\Tech Orders\. You can also find TO 00-25-234 and TO 1-1-8 on the P: drive.

TO00-25-234

ELECTROCHEMICAL THEORY OF ELECTROCHEMICAL THEORY OF CORROSIONCORROSION

Corrosion is the deterioration of a material caused by a reaction with the environment. The reaction is usually electrochemical but it can also be caused by biochemical factors. In each case, corrosion usually begins on the material surface and, if allowed to progress, works its way into the material core as shown below.

Some types of corrosion originate within the material core, but most corrosion starts on the surface where it can be prevented or properly treated in its early stages.

ELECTROCHEMICAL CELLS - The electrochemical process is similar to the current flow in a common dry cell battery. Corrosion by-products are formed when one part of a metal acts as a negative element (cathode) and another part acts as a positive element (anode). When an electrolyte is present, an electrochemical cell is formed and current flows between the two charged elements. The electrolyte may be an acid, alkali, or just plain moisture. The current flow destroys some of the anode material and forms by-products that appear as corrosion.

ELEMENTS OF AN ELECTROCHEMICAL CELL

To form an electrochemical cell, four elements are required:

1. Anode 2. Cathode 3. Electrolyte

4. Metallic contact between the anode and cathode

The following figure depicts the electrochemical process.

In the following figure, one of the four elements, the electrolyte, has been removed by using a protective coating.

The basis of your corrosion control program is ensuring the integrity of all protective barriers and removing all electrolytes. This is due to the fact that the electrolyte is the only element you can easily control.

BIOCHEMICAL THEORY OF CORROSIONBIOCHEMICAL THEORY OF CORROSION

Although not as common, you need to be aware of biochemical corrosion. Biochemical corrosion is caused by fungi and waste products from animals and insects.

FUNGI - Mold, mildew, smut and bacteria draw oxygen from the air and hold moisture against the material to which they are attached. An acid-based waste product is produced causing surface corrosion. Moisture contained in the fungi can also cause intermittent equipment problems that are very hard to isolate.

ANIMALS AND INSECTS - Waste products normally include salts and acids which corrode metallic surfaces. They may also eat insulation, paint, or other protective coatings which exposes the surface to electrochemical corrosive attacks.

ENVIRONMENTAL FACTORS AND ENVIRONMENTAL FACTORS AND CORROSIONCORROSION

Moisture is the single most important environmental factor causing corrosion. Moisture present in the air often contains contaminants such as chlorides, sulfates, nitrates and other chemicals which accelerate corrosion. Sealed compartments can expand and contract with temperature variations, allowing moisture to enter. Temperature variations also cause condensation on equipment. Accumulations of dirt and debris can hold moisture against equipment, accelerating the corrosion process.

California does not hold many records for rainfall, but it is still a consideration.

The bottom line is:Keeping equipment clean and properly painted will greatly decrease the threat of corrosion by moisture.

CORROSION PREVENTIONCORROSION PREVENTION

• Air Force Corrosion Prevention Policy

• Air Force Corrosion Prevention Philosophy

• General Work Practices

• Cleaning Equipment

• Storage, Protection, And Handling Of Equipment

AIR FORCE CORROSION AIR FORCE CORROSION PREVENTION POLICYPREVENTION POLICY

AF Instruction 32-1054 establishes Air Force policy on corrosion prevention and control. It requires effective corrosion prevention programs for all maintenance activities to enhance safety, extend service life, reduce maintenance costs and repair man-hours, and minimize equipment downtime. All maintenance technicians must have an awareness of the causes of corrosion and practice corrective preventive techniques.

AIR FORCE CORROSION AIR FORCE CORROSION PREVENTION PHILOSOPHYPREVENTION PHILOSOPHY

Important elements of corrosion prevention include:• INSPECT for corrosion on a SCHEDULED basis• TRAIN technicians in corrosion PREVENTION and RECOGNITION• Thoroughly CLEAN, PRESERVE, and LUBRICATE equipment at

prescribed intervals• Use APPROVED MATERIALS, EQUIPMENT, and TECHNICAL

PUBLICATIONS• Keep accurate RECORDS and report MATERIEL and DESIGN

DEFICIENCIES that promote corrosion

**Refer to TO 1-1-689, Chapter 3 for more detailed information**

Reporting corrosion problems:

Let’s dwell here for a moment. Reporting corrosion is one of the most overlooked steps of the entire process. Every time you find and treat corrosion, you should enter the correct information in CAMS.

HOW-MAL CODES:170 - Corroded (or) 667 - Corroded, Severe

ACTION TAKEN CODE:“Z” - Corrosion Repair (ALWAYS)

Do not forget to enter this in the Automated History when closing the write-up.

If you suspect corrosion is somehow related to the manufacturing process, it is important that you submit a deficiency report through the USAF Deficiency Reporting System IAW TO 00-35D-54. Maintenance Support will assist you in this process.

All corrosion problems with real property (buildings, and large antenna structures, manholes) need to be referred to the Unit Corrosion Control Monitor for coordination with the Base Civil Engineering Office.

Corrosion on all vehicles should be documented on the form 1800s for each vehicle and brought to the attention of the Unit Vehicle Control Officer.

GENERAL WORK PRACTICESGENERAL WORK PRACTICES

AFQTP 2EXXX-201C (Corrosion Prevention and Control), TO 00-25-234 and the 31-10 series of TOs (Engineering-Installation Standards) covers general practices and corrosion prevention techniques.

Always consult the appropriate Technical Orders prior to using a particular type of material or mechanical procedure

• DO NOT mark on any metal surface with a graphite pencil or sharp object

• DO NOT use graphite as a lubricant (it acts as a cathode to all structural metals)

• DO NOT polish metal surfaces purely for cosmetic purposes (yes, it promotes corrosion)

• Place protective covers over equipment when drilling, grinding or sanding

• Replace rusted screws, bolts and washers• Reapply worn or damaged protective coatings (yes, paint is a

protective coating)• Keep equipment and work areas free of chips, grit, dirt, dust

and foreign materials• Clean spills of any type thoroughly and as soon as they occur• Handle components and circuit boards carefully (salt and oil

from on your fingers are highly corrosive)• Remove flux residue after soldering (when flux is combined

with an electrolyte - you guessed it - it is corrosive)

• Perform detailed corrosion inspections in conjunction with equipment PMIs (all PMI workcards should require this). Check for the following:

• Signs of corrosion by-products and equipment damage

– Potential water traps

– Presence of bacteria and fungi

– Areas of dissimilar metal contact that may create corrosion

– Presence of dirt, lint, and other contaminates

– Adequacy of protective coatings

– Failure of filter systems

– Signs of moisture or fluids and evidence of faulty seals and gaskets that could allow moisture intrusion

• Train personnel in the recognition of corrosion inducing conditions, detection, preservation, treatment and lubrication

• Report severe corrosion problems through command channels to the appropriate item manager

Even under ideal circumstances, corrosion can’t be completely eliminated. Using the above practices will keep corrosion to a minimum.

CLEANING EQUIPMENTCLEANING EQUIPMENT

An adequate cleaning program is essential to preventing corrosion. Equipment should be cleaned frequently using approved materials and prescribed procedures. Detailed information on correct cleaning procedure and various types of cleaning agents can be found in Chapter 4 of TO 1-1-689 and Chapter 3 of TO 1-1-691. Don’t overlook the specific equipment technical data when doing your research.

NOTEDo not use commercial cleaners unless authorized by the appropriate TO.

GENERALPURPOSE CLEANER

Good maintenance practices dictate using the mildest cleaning method to remove all contaminants. Reference the applicable technical order for the correct cleaning solution.

There are numerous types of cleaners available. For most purposes, detergent and water are sufficient to remove dust, dirt and other soils.

Cleaning Procedures:• Disconnect power and remove covers• Ensure all drain holes are open• Lubricated parts and natural entrapment areas need protection

against damage from cleaning agents. Mask and protect these surfaces, areas, accessories and components

• Use only authorized cleaning compounds• Apply the cleaning solution - never spray into electronic

components• When complete, examine the area to ensure all contaminants

have been removed• Check for signs of corrosion

STORAGE, PROTECTION AND STORAGE, PROTECTION AND HANDLING OF EQUIPMENTHANDLING OF EQUIPMENT

Okay, now you know all about taking care of equipment. Something is missing from the picture. Your responsibility does not stop with mission equipment. Bench stock items, supply point materials, repair cycle assets, tools, TMDE, items awaiting parts and equipment in storage all must be protected and checked for signs of corrosion.

All unused or inactive equipment must be protected from moisture by the use of dust caps and proper packaging techniques. Even the slightest amount of moisture can cause corrosion so equipment should be stored in a dry location.

Spare parts and equipment should be stored in hermetically sealed containers or bags whenever possible. If this is not possible, use plastic sheeting and carefully seal the equipment with desiccant. Desiccant is a drying agent, but the chemicals used in desiccant are corrosive in nature, so ensure the desiccant bag is free from rips. It is also a good idea to tape the desiccant to the container to avoid contact with the equipment.

Use of humidity indicators is also a good idea. If the area used for storage is in question, a humidity indicator will let you know if the are is suitable for storage.

Handling of equipment: Most items come in some type of reusable container. Whenever storing or transporting equipment or TMDE, use the appropriate container. If one is not available, use sufficient padding to prevent scratches, dents and paint chips (ideal places for corrosion to start).

Electrostatic Discharge Sensitive (ESDS) Components: All ESDS items will be handled, packaged and transported IAW TO 00-25-234.

CORROSIONCORROSIONIDENTIFICATIONIDENTIFICATION

• Uniform Surface Corrosion• Pitting Corrosion• Galvanic Corrosion• Filiform Corrosion• Concentration Cell Corrosion• Intergranular Corrosion• Exfoliation• Stress & Fatigue Corrosion• Visual Appearance Of Corrosion By-products On

Common Metals

UNIFORM SURFACE CORROSIONUNIFORM SURFACE CORROSION

This is the most common type of corrosion. Uniform corrosion takes place when oxygen, water, ozone, salt or other materials attack a metal surface. It is a localized chemical attack which occurs consistently and uniformly over the entire metal surface. It causes dulling of the surface initially and may progress until the surface has a rough texture or frosted appearance. Rusted iron, tarnished silver and frosted nickel are examples.

PITTING CORROSIONPITTING CORROSION

This is a common and more severe form of localized corrosion. Pitting corrosion occurs between grains of an alloy. It produces various shades of gray or white powder that form in blotches on the surface of the metal. When the deposits are removed, tiny pits or holes can be seen. Aluminum, magnesium and their alloys are very susceptible to this type of corrosion.

GALVANIC CORROSIONGALVANIC CORROSION

This type of corrosion occurs when two types of dissimilar metal are joined together. The mating of different types of metals and alloys promotes electrochemical cell formation and rapid material deterioration. Whenever you notice surface dulling, tarnish, powdery deposits or rust near joints, cowlings, rivets and mated surfaces, you should suspect galvanic corrosion. Note in the figure below, corrosion takes place on the anodic material.

To avoid galvanic corrosion, you must consider the properties of the metals you are using. Metals in Group I corrode the fastest. Metals in group IV are the most resistant to corrosion. If you must mix metals, try to use metals from the same group. If this is not possible, select the metal with the smallest area from the lower activity group (III & IV). Example: If aluminum fasteners from group II are not available to install on aluminum sheet, use fasteners from Group III or IV. If the TO allows, use sealants or primers to isolate the metals.

GROUP METALS

I

III

IV

II

MAGNESIUM/MAGNESIUM ALLOYS; ALUMINUM/ALUMINUM ALLOYS; TIN

ALUMINUM; ZINC; CADMIUM; TIN; TIN-LEAD

ZINC; CADMIUM; STEEL; LEAD; TIN; NICKEL/NICKEL ALLOYS; TIN-LEAD; TITANIUM

COPPER/COPPER ALLOYS; NICKEL/NICKEL ALLOYS; CHROMIUM; STAINLESS STEEL;GOLD; SILVER; TITANIUM

COMPATIBLE GROUPING OF METALSCOMPATIBLE GROUPING OF METALS

FILIFORM CORROSIONFILIFORM CORROSION

Not as common as the previous types of corrosion, this type is fairly easy to recognize and treat in its early stages. Filiform corrosion occurs on metal surfaces with organic coatings, such as petroleum oils and greases. It normally occurs when the relative humidity is between 78 and 90% and the surface is slightly acidic. It starts at breaks in the coating (scratches or nicks). Filiform corrosion has the appearance of worm like traces underneath the protective coating.

CONCENTRATION CELL CORROSIONCONCENTRATION CELL CORROSION

Concentration cell corrosion usually forms in cracks and crevices, metal-to-metal joints, behind or under gaskets, sealants, electrical tape or other foreign material affixed to metallic surfaces. The cause of this type corrosion is an imbalance of oxygen and ions in electrolytes that tend to concentrate under the surface of the joint or foreign material. If not detected and corrected early, pitting corrosion usually results.

The following types of corrosion are hard to detect until significant damage has occurred. When discovered, it is usually beyond your capability to repair.

INTERGRANULAR CORROSIONINTERGRANULAR CORROSION

This type of corrosion occurs inside the grain of metals when dissimilar alloys exist side-by-side in the same metal. One alloy acts as the cathode and the other allot acts as the anode. Many times intergranular corrosion is the result of improper heat treatment during manufacture. Because intergranular corrosion begins internally, it is very difficult to prevent and detect.

EXFOLIATIONEXFOLIATION

Exfoliation corrosion is the physical evidence of advanced intergranular corrosion. The metal surface is forced up by the expanding corrosion products below the surface. It can be identified by metal surface flaking, bumps and blisters, and metal peeling in layers near edges and joints. When exfoliation is detected, the only recourse is to replace the material.

STRESS CORROSIONSTRESS CORROSION

Stress corrosion occurs when opposing or alternating pressure is applied to a metal surface or structure. This pressure produces cracks in the grains of the metal allowing moisture to penetrate. Electrochemical action sets in, minute cracks appear, split open, and lengthen until they become visible to the eye. Transportable shelters, antenna support structures and other types of equipment exposed to alternating pressure may experience stress corrosion. Look for minute cracks, incorrectly sized hardware, and indications of corrosion near joints, corners, and support bases.

FATIGUE CORROSIONFATIGUE CORROSION

Fatigue is the end result of other types of corrosion. When metal is subjected to repeated mechanical stress and chemical attack, it becomes fatigued and separates. Severe pitting, cracking, and separation along stress lines are evidence of fatigue corrosion.

VISUAL APPEARANCE OF CORROSION VISUAL APPEARANCE OF CORROSION BY-PRODUCTS ON COMMON METALSBY-PRODUCTS ON COMMON METALS

Recognizing corrosion is the key to an effectiveCorrosion Prevention and Control Program.

The table on the next slide shows different metal susceptibilities and what corrosion by-productswill look like.

ALLOY TYPE OF ATTACK APPEARANCEAluminum Alloy Surface, pitting and intergranular. White or gray powder

Titanium Alloy Highly corrosion resistant. Extended or repeated contact with chlorinated solvents may result in embrittlement. Cadmium plated tools can cause embrittlement of titanium.

No visible corrosion products

Magnesium Alloy Highly susceptible to pitting. White powder snow-like mounds and white spots on surface

Carbon and Low AlloySteel (100-800 series)

Surface oxidation and pitting, surface and intergranular. Reddish-brown oxide (rust)

Stainless Steel (300-400series)

Intergranular corrosion. Some tendency to pitting inmarine environment (300 series more resistant than 400 series).

Corrosion evidences by rough surface; sometimes by red, brown or black stain

Nickel-Base Alloy Generally has good corrosion resistant qualities. Sometimessusceptible to pitting.

Green powdery deposit

Copper-Base Alloy Surface and intergranular corrosion. Blue or blue-green powdery deposit

Cadmium (used as aprotective plating)

Good corrosion resistance. Will cause embrittlement if notproperly applied.

White to brown or blackmottling on the surface

Chromium (used as awear-resistant plating)

Subject to pitting in the presence of sulfur. Is cathodic to steel, does not corrode, promotes rusting of steel where pits occur

Silver Will tarnish in the presence of sulfur. Brown to black film

Gold Highly corrosive resistant. Deposits cause darkening of reflective surfaces

Tin Subject to whisker growth. Whisker-like deposits

CORROSION REMOVALCORROSION REMOVAL

• Safety

• Corrosion Removal Tools And Materials

• Corrosion Removal Procedures

SAFETYSAFETY

Safety is the first consideration when performing corrosion removal. Common sense and use of proper protective equipment is a key player here. We will cover four hazards that require special attention.

1. HIGH VOLTAGE

2. RADIATION

3. FUMES

4. CHEMICALS

HIGH VOLTAGEHIGH VOLTAGE

If there is even a remote chance of coming into contact with high voltages when removing corrosion, postpone the job until another time. Never endanger yourself! A second consideration is doing damage to the equipment. Take necessary precautions to protect the equipment from corrosion residue, metal chips and shavings. Always have a safety observer and post “DANGER - DO NOT ENERGIZE” signs on all applicable circuit breakers.

Schedule the down time you need to perform the job correctly.

RADIATIONRADIATION

The same basic precautions taken around high voltage also applies to radiation hazards. Most radiation hazards are encountered by radar and antenna personnel. Corrosion control actions (or any maintenance) should not be performed on hot antennas. Again, schedule the down time that you need. Always post a safety observer and “DANGER - DO NOT ENERGIZE” signs where necessary.

FUMESFUMES

Numerous electronic facilities use battery banks for back-up power or starting devices. Liquid cell batteries emit toxic and combustible fumes. The electrolyte used in batteries is highly corrosive, creating the need for continuous corrosion control measures. Exercise extreme caution to avoid inhaling fumes or creating sparks that could cause an explosion. Always wear goggles, rubber gloves and a rubber apron when performing corrosion control on batteries. Ensure eye wash is available. Avoid skin contact with the electrolyte. Never use power tools around batteries. Always use a safety observer.

CHEMICALSCHEMICALS

Many corrosion preventives, cleaners, paint strippers, sealers and solvents are hazardous to the skin, eyes and respiratory tract. Observe all cautions and warnings listed on the manufacturers labels and Material Safety Data Sheets (MSDSs).

One final word on safety, keep your work area clean and free from clutter. This will greatly reduce the chance of mishap while performing corrosion removal.

CORROSION REMOVAL TOOLS AND CORROSION REMOVAL TOOLS AND MATERIALSMATERIALS

• Common Materials And Hand Tools

• Power Tools

• Alternate Removal Methods

COMMON MATERIALS AND HAND TOOLSCOMMON MATERIALS AND HAND TOOLS

Materials and hand tools are classified as abrasive mat/cloth/paper, metallic wools, wire brushes and scrapers.

ABRASIVES & SANDPAPERS: The selection and use of any abrasive is determined by the type of metal and degree of corrosion damage.

Flint - used due to low cost, dulls and wears out quickly, normally a tan color

• Emery - mainly used for final polishing of metal due to it’s fine mineral face

• Aluminum Oxide - used on metal surfaces, fast and last longer than flint

• Silicon Carbide - sharp abrasive for wet or dry sanding on paint and metal

Aluminum oxide works better on softer metals such as aluminum and magnesium. Silicon is more effective on harder metals like ferrous alloys. These materials should be used primarily to remove mild to moderate corrosion and for surface polishing after corrosion removal.

Don’t overlook the common pencil eraser. It can be used to remove light corrosion from electrical contacts and printed circuit boards.

METALLIC WOOLS - Used to remove corrosion that is not tightly adhered to a metal surface.

TYPE USEGRADE

Very FineFine

Medium

Medium Coarse

Coarse

000

1

0

2

3

Final Smoothing

Most Commonly Used

General Purpose

Rough Work

Restoration

There are four major types of metallic wools:

Aluminum

Copper

Steel

Stainless Steel

Selecting the proper metallic wool looks easy at first glance. There is another consideration that comes into play here. You must know what type of metals you are working on. Steel wool is used on ferrous metals; aluminum wool on aluminum, aluminum alloys, magnesium and magnesium alloys; copper wool on copper, bronze and brass; and stainless steel wool on stainless steel. DO NOT use metallic wools which are not galvanically compatible with the metal surface being treated. Remember the chart on compatible metals? Using the incorrect metallic wool will only cause the corrosion to return in the near future.

When using metallic wool, always wear gloves and exercise caution - wool fibers are sharp!

WIRE BRUSHES - Come in a variety of sizes, shapes and are composed of different types of metal. The same rule applies to wire brushes and metallic wool - use a metal brush that is compatible with the metal you are treating. Wire brushes are used to remove heavy corrosion deposits. Thick, short bristles are used for rapid removal of heavy deposits, finer brushes for lighter jobs. NEVER use a brush with a bristle diameter greater than 0.010 inch because it can damage the metal you are treating.

Never brush sideways across another brush mark, this can cause unnecessary damage to the metal. After brushing a soft metal, polish the surface with a fine abrasive paper to remove brush marks.

SCRAPERS - Used primarily to remove heavy corrosion deposits in corners and crevices that cannot be reached. Due to gouges made by scrapers, the area will require further finishing.

FILES - Same as scrapers.

POWER TOOLS - Remove watches, rings, button shirt sleeves, tuck in loose clothing and always wear eye protection. Ensure work area is properly ventilated and wear a respirator. Be careful not to generate too much heat on the metal surface. It can change the bonding of metals making them vulnerable to intergranular corrosion. Remember to protect nearby equipment and clean up the entire area after work has been completed.

WARNINGCorrosion products of copper are highly toxic. Proper safety precautions

must be taken to avoid inhalation or ingestion during corrosion removal. Personnel should wash hands before eating or smoking.

ALTERNATE REMOVAL METHODSALTERNATE REMOVAL METHODS

There are several other methods available to remove severe corrosion. Workcenters in the 48IS will not perform these, but I will mention them briefly.

ABRASIVE BLASTING - Corrosion is blasted away using an abrasive driven by air pressure in excess of 125 pounds per square inch. C-E equipment should never be allowed to deteriorate to the point this is required. Steel antenna support structures may require this treatment.

CHEMICAL REMOVAL - Application of acid-based or rust conversion chemical. If left on equipment too long, it may eat into the metal being treated. Should be accomplished only by personnel with the proper training and equipment.

CORROSION REMOVAL PROCEDURESCORROSION REMOVAL PROCEDURES

PREPARATION: • Identify the extent of the corrosion and type of material to be

treated. Then determine if the work can be accomplished at the workcenter level and the type of corrosion removal tools needed.

• Survey the area for safety hazards and take the appropriate precautions.

• Cover up and protect all equipment and facilities that could be damaged in the removal process.

• Gather all materials needed (to include protective equipment and safety observer).

• Consult the applicable TO for correct removal procedures, cautions or restrictions.

• Coordinate the work with Maintenance Control

CORROSION REMOVAL:• Closely inspect your work - 100% of the corrosion must be removed.• Use the appropriate materials to smooth the surface area and prepare it for

the protective coating.

CLEANUP:• Remove all dust, particles and corrosion residue from the treated equipment

and surrounding area.• Remove protective covers from other equipment and inspect for

contamination. Clean as necessary.• Wipe down the area from which the corrosion was removed with isopropyl

alcohol.• Properly dispose of used materials and put away tools.• Return the equipment to operation and complete the correct documentation

in CAMS.

CORROSION TREATMENT CORROSION TREATMENT PROCEDURESPROCEDURES

SAFETY - Many materials used for corrosion treatment are both flammable and toxic. All products obtained through normal supply channels will have a Material Safety Data Sheet (MSDS). It is extremely important for you to follow all safety precautions when using corrosion treatment materials. Wear of respiratory protective devices, rubber gloves, apron and eye protection is a good idea if you are ever in doubt. Always wash hands thoroughly after working with these products and always before eating, drinking or smoking.

X

PROTECTIVE FILMSPROTECTIVE FILMSSEALANTS:

• POLYSULFIDE - Prevents moisture intrusion on equipment exposed to outside elements.

• ZRC AEROSOL SPRAY - General use sealant.

• ROOM TEMPERATURE VULCANIZING (RTV) - One of the most commonly used sealants.

WARNINGDO NOT use an RTV containing Acetic Acid. This RTV

will cause serious corrosion on all metallic surfaces.

CORROSION PREVENTION COMPOUNDS (CPC):

CPCs are effective corrosion inhibitors, but never apply a CPC unless authorized by a TO. Consult Maintenance Support for assistance.

LUBRICANTS: Fill air gaps between moving parts and forms protective barriers against dirt, moisture and foreign materials thus inhibiting corrosion. Use only IAW the applicable TO.

VARNISHES: Provides a thin film that is resistant to moisture and fungus.

CONFORMAL COATINGS: Special protective compounds that conform to the contour of the material it is applied to. Many circuit boards have conformal coatings. Again, check the appropriate TO.

TOPCOATS: Paint. Always use the correct paint specified in your equipment TO.

LACQUERS & ENAMELS: Good for indoor use only.

POLYURETHANE: Perhaps the most effective topcoat made. Requires careful mixing and respiratory protection. (No we’re not talking about the type you buy at the hardware store.)

As you can probably tell, there are many types of protective films. Always check your equipment TOs as well as TO 1-1-689 and 1-1-691. Your Unit Corrosion Control Monitor in Maintenance Support can also offer assistance.

Once you have determined the appropriate protective film to use, always follow manufacturer application instructions and personal protective measures on the MSDS.

Remember corrosion prevention and control is everyone's responsibility. Wherever there is a metal surface, there could be corrosion.

IT’S TIME TO TAKE THE TEST

GO TO:

P:\common\LS\LSK\corrosion training\corrosion test\

Follow the instructions and Good Luck.