Orbetz Bridge Restoration

Rust Bullet Bridge Restoration Coating Application

Witness the Orbetz Bridge Restoration with Rust Bullet being applied on an airless spray system using 517 tip at 3200 PSI.

Corrosion protection has become an important area of concern that should be dealt with immediately. Stop rust for safety and longevity of a public structure by applying in your bridge restoration projects the proven results of Rust Bullet products.

Rust Bullet has been awarded an unprecedented Two Patents from the United States Patent & Trademark Office. Never before has the U.S.P.T.O. issued Two Patents for Two New Technologies to One Rust/Corrosion Control Product.

Rust Bullet is a unique single component high solids industrial coating, unparalleled in the coatings industry. Rust Bullet is an advanced coating, which provides far more than just rust protection especially applicable for Bridge Restoration tasks.

Orbetz Bridge Restoration is a post from: PPC Online - Rust Bullet Australia

Rust Bullet Rust Protection & Corrosion Control

The Rust Bullet Advantage

Testing Rust Bullet against the market leaders using independent laboratories and numerous real life environmental situations. Rust Bullet does not only claim to be the best, but had already proven it.

Rust Bullet’s Superior Patented Technology has been awarded an Unprecedented Two United States Patents from the United States Patent & Trademark Office. Never before has the U.S.P.T.O. issued Two Patents for Two New Technologies to One Rust/Corrosion Control Product.

Why Choose Rust Bullet is a post from: PPC Online - Rust Bullet Australia

Cost and Maintenance of Corrosion-Damaged Infrastructures

All infrastructures are affected by corrosion; it can shorten the life of train and rail systems, highway bridges, buildings and pipeline systems. Corrosion can result in serious public and industrial safety issues.

In USA, corrosion is costing approximately $300 billion per year, for metallic corrosion (about 4% of GNP or >$1000 per person). More than one third of costs considered avoidable using existing know-how and technology. (Batelle news release, 1996.)

This is Part I of the History Channel documentaries reporting bit by bit the causes, impact, and ways on how to prevent corrosion using modern protective applications, science, and technology.

Corrosion & Decomposition (1 of 5) is a post from: PPC Online - Rust Bullet Australia

Custom Automotive Hot Rod Restoration

Rust Bullet Black Shell and Automotive Hot Rod Restoration

Custom Hot Rod Restoration of a 20 yr-old 1965 Mustang Fastback using Rust Bullet products Black Shell and Automotive administered by Mike Haley, an award winning master builder/restorer at H & H Custom Hot Rods, Inc.

Rust Bullet is a two-application product that penetrates the porous rust and reaches the metal underneath, producing chemical activity. In this hot rod restoration, the rust becomes intertwined in the resin matrix of Rust Bullet and remains a permanent part of the coating. The second coat of Rust Bullet fills any pinholes in the first coat and forms a nearly impenetrable coating that protects the metal.

Rust Bullet Automotive contains more metal than Rust Bullet Standard Formula, providing the smooth finish desired for automotive projects. While Rust Bullet BlackShell provides outstanding protection when used as protective topcoat for Rust Bullet Automotive as well as a stand alone coating especially for this hot rod restoration.

Custom Hot Rod Restoration is a post from: PPC Online - Rust Bullet Australia

Rust Bullet Application

Rust Bullet Guidelines and Preparation Works

Rust Bullet can be applied directly over rusted and clean metal surfaces with little or no surface preparation. To ensure you achieve the best possible results, it is extremely important that Rust Bullet Application Guidelines should be read thoroughly before use.

Rust Bullet protects various metals, as well as, other substrates including concrete, wood, and fiberglass making it the ideal coating for everything from metal roofs to concrete floors. Its versatility provides exceptional protection from the damaging effects of extreme weather conditions, abrasive objects, harsh chemicals, and other destructive elements.

Rust Bullet products are available in Standard, Automotive, BlackShell, Rapid Fire, and Metal Blast.

Applications of Rust Bullet is a post from: PPC Online - Rust Bullet Australia

Coating Application Methods Non-Spray

Roll

Roll (direct and reverse)

In direct roll coating, the applicator roll rotates in the same direction as the substrate moves. In reverse roll coating, metal feed stock is fed between the rolls as a continuous coil. The applicator roll rotates in the opposite direction of the substrate.

Dip

Dip refers to immersing a piece into a tank containing the coating material, removing the piece from the tank, and allowing it to drain. The coated piece can then be dried by force-drying or baking.

Dipping is extremely dependent on the viscosity of the coating, is very messy, and may be highly hazardous. The viscosity of the paint in a dip tank must remain practically constant if the deposited film quality is to remain high.

Flow

In flow, the part is suspended, and the coating is poured over it. The excess material drips off and is collected for reuse.

Flow is usually used for large or oddly shaped parts that are difficult or impossible to dip coat. Coatings applied by flow coating have only a poor to fair appearance unless the parts are rotated while dripping.

Dip-Spin

In dip-spin, a wire basket containing up to 50 pounds of parts is immersed in a reservoir of paint. The basket is raised, the parts are allowed to drain, the basket is spun to remove excess paint, and the parts are dumped onto a mesh conveyer belt, then moved through a bake oven. The entire process is automatic. The main advantage is the extremely high production rate.

Dip-spin coaters are designed to paint large-quantity batch loads of small parts, such as hairpins, clips, and fasteners.

Some of the painted parts dumped on the conveyer may stick together in the oven, leaving paint voids when they are separated. These parts may be run through the process a second time to eliminate the defects.

Coating Application Methods Spray

Airless Spray

Airless paint sprayers are designed to cover large surfaces quickly. The tip size used in the spray gun determines the type of coating possible. Tip and motor size will dictate speed of coverage.

It can deliver twice the amount of material as a compressed air system. This allows airless guns to be used advantageously on high-speed production lines or where surface areas are large.

Transfer efficiency is higher than conventional spray because of reduced fog and overspray. The absence of blow air associated with the gun simplifies application.

Airless Spray Awareness

• Overspray and bounce back reduced
• Higher film build up
• Faster production rates
• Compress air not used for atomization
• Air, gas powered, electric units.
• No control over fan size which regulated by tip size
• On or Off no feathering possible
• Difficult to coat small intricate parts
• Tips wear out relatively fast

Spray Do and Don’t

Spray Distance –> 10″-16″

Conventional Spray

Conventional air spray is the oldest spray process. It offers the best control of spray patterns and degree of atomization. This system produces the finest atomization and, therefore, the finest finishes. Conventional spray will also spray the widest range of coating materials of the four techniques.

In conventional or air atomized spraying, the coating is supplied to a spray gun by siphon, gravity, or pressure feed. When the gun trigger is pulled, the coating flows through the nozzle as a fluid stream. Compressed air from the center of the nozzle surrounds the fluid with a hollow cone as it leaves the nozzle, breaking the coating into small droplets and transferring velocity to it. Additional jets of compressed air from the nozzle break up the droplets further and form an elliptical pattern.

Conventional Spray Awareness

The spray pattern is easily adjusted to any fan width. Thus, it produces high quality finishes. Moreover, spray cause more material loss and turbulence caused by atomization air. Usually, this requires solvent reduction resulting to less DFT per coat.

Spray Do and Don’t

High Volume Low Pressure Spray (HVLP)

HVLP is a type of air atomized spraying. HVLP guns operate at pressures of 0.1 to 10 psi at the air nozzle and use 15 to 30 cfm of air. However, there are many factors that affect overspray, most important of which is the manner in which the painter sets the air and fluid pressures, fan width, and gun-target distance.

The low atomizing air pressure of an HVLP gun minimizes the amount of bounce-back paint fog and reduces the amount of atomized paint that is blown past a part as overspray. The higher transfer efficiency helps hold down operating costs by reducing paint waste.

HVLP has a higher transfer efficiency than conventional air spray, up to 65 to 75%. This results in lower material use (reduces costs), less spray booth maintenance and cleanup, and less hazardous waste.

The droplet size is not as fine as conventional air atomization. To achieve good finish quality on some applications, additional polishing or coating reformulation may be necessary. However, if surface preparation is done properly, spray application should have good adhesion.

HVLP

High Volume Low Pressure spray systems use high volumes of air delivered at low pressure to atomize the fluid into a soft low velocity system, thus, you get:

• Better controlled spray pattern
• Reduce bounce back
• Reduce overspray
• Reduced VOC
• Better transfer efficiency
• Less hazardous waste

Surface Preparation before Applying RustBullet

The surface must be dry and in sound condition. Remove mildew, oil, dust, dirt, loose rust, peeling paint or other contamination to ensure good adhesion.

No exterior painting should be done immediately after a rain, during foggy weather, when rain is predicted, or when the temperature is below the recommended temperature.

Inspection (Suggested)

Inspection should be carried out at the following critical stages:

• Inspection of steel to be used
• Inspection of applied shop primer
• Inspection of steel work (welding, cutting of edges)
• Inspection of surface preparation
• Inspection before and during application
• Inspection after application

Inspection Of Steel Work
This involves:

• Rounding of sharp edges
• Smoothing of rough welding seams
• Removal/grinding of weld spatter and beads
• Cracks and pittings
• Surface faults like laminations, etc.

Inspection of Surface Preparation

Inspection of surface preparation should undergo the following:

• Cleanliness; solvent cleaning to remove salt, oil, grease, and dust/dirt
• Evaluation of present condition (rust grade)
• Evaluation of surface (preparation grade and roughness)
• Is the remaining contamination acceptable?

Inspection Before and During Application

Inspection during application should include the following activities:

• Climatic conditions
• Technical Data Sheet must be available and followed
• Ensure correct mixing and thinning (extremely important)
• Measuring the wet film thickness (WFT)
• Number of coats as given in the specification
• Cleanliness between coats (salts, dust, oil etc.)
• Drying time between coats, minimum and maximum
• The workmanship
• Controlling the equipment and methods used

Inspection After Application

Another critical stage that needs to be followed up is when the application has been finished. Inspection after completion of the application consists the:

• Dry film thickness (DFT)
• Curing/drying
• Adhesion
• Holiday detection

Coating Failures Common Causes and Types Of Failures

The following are the common causes for Coating Failures:

• Improper stirring
• Not enough or excessive millage
• Surface contamination
• Contamination in lines
• Out of Shelf life
• Improper Air pressure
• Hose or line too long
• Too long between surface preparation and prime
• Wrong product for service
• Poor applicator training
• Poor quality control
• Lack of facilities to adjust environment
• Improper surface preparation
• Specification non-compliance
• Recoat too quickly
• Too long between coats
• Improper storage

Types of Failures

Coating failures may appear during application, at the stage of curing or after a certain period of service life.

Statistics show that as much as 95% of all coating failures is a result of poor surface preparation and application.

Below you will find some examples of common coating failures and the reason why they occur. Please note that there may be many reasons for a coating failure and in some cases it requires a lot of experience to find the exact cause.

Sagging

Sagging occurs when:

• Coating is applied in excess of the DFT specified
• Too much thinner has been added to the paint
• The gun is held too close to the surface.

Sags are recognized as “curtains” on the painted surfaces. If the wet film thickness is too high, excessive sagging can result in pools of paints forming on horizontal surfaces or in corners. After curing, the paint may crack all the way to the substrate in such areas and reveal unprotected steel.

If sagging is noticed at the spraying stage, it should be brushed out while the paint film is still wet. Repairs after drying consists of abrasion (sanding) and re-coating.
Pinholes and Pores

Using the wrong spraying technique, such as excessive air pressure, excessive film thickness, strong wind (too good ventilation) and too long application distance may cause craters, pinholes and pores. If noticeable on the paint film, check the spraying equipment to ensure that the air pressure and nozzle size is correct. Pinholes in a paint film can also result from overspray.

On excessive film thickness air will be entrapped in the paint. The escaping air will create pinholes. The consequence being that pinpoint rusting occurs, followed by undercutting of the coating around the pinholes.

Repairs consist of grinding and re-coating the area using appropriate coats to seal the defects and build up the coating to the correct DFT. If the coating is still uncured, brush out and apply the additional coat.

Blistering

This is one of the most common types of failure related to the adhesion of the paint. Sometimes the blisters are dry and sometimes filled with liquid. The blisters can be both large and small, often shaped as hemispheres. The size usually depends on the degree of adhesion to the substrate, or between the coats, and the internal pressure of the gas or the liquid inside the blister.

Blistering can be caused by a number of different conditions:

1. Poor or inadequate solvent release from the coating. Entrapped solvents can increase the water absorption and moisture vapour transmission of the coating and lead to blistering. Solvent odour is usually connected with retained solvents. If the blistering is widespread on a construction: reblast and wash before a new system is applied. For local areas: blast or carry out other mechanical cleaning before recoating.
2. Soluble salts contaminating the substrate or contaminating the surface between coats. No coatings are 100% water proof. The moisture vapour passing through the coating can dissolve salt into a concentrated solution. Pressure in the high concentration liquid will cause blisters. This phenomen is called osmosis.
3. Contamination of the surface (e.g. oils, waxes, dust, etc.) will not allow proper adhesion of the coating. The moisture vapour tends to be concentrated in these areas of low adhesion. In this case, the blisters are so-called “dry” blisters.

Lifting

Lifting is a raising of the undercoat. It is caused by a stronger solvent in the topcoat attacking the previously applied film. The result is a wrinkled surface.

A typical example is a topcoat containing xylene, on top of an alkyd-based primer containing white spirit. The xylene in the topcoat will dissolve the primer.

Blast cleaning and reapplication of the paint is necessary to repair the damaged surface.

Delamination/Peeling

Loss of adhesion to the substrate or between coats of paint is delamination or peeling.

The causes are:

• Unsatisfactory surface preparation
• Incompatible primer or undercoat
• Substrate or intercoat contamination
• Excessive cure time between coats

The way to repair the surface, is to remove paint down to sound paint or to the substrate, and recoat.

Orange Peel

Finely pebbled or dimpled surface texture with an appearance similar to the skin of an orange.

Caused by:

• Improper atomization due to excessive low air pressure
• Spraying too close to the surface
• Rapid solvent evaporation

Orange peel is mainly a cosmetic defect; sand down to smooth surface and repaint if necessary.

Coating Failure In Marine Application

Through Film Breakdown

Through film breakdown most commonly occurs in the hullage space at the top of ballast tanks and tends to be common the under deck plating. In the picture, the coating breakdown shown is in the later stages of development, where the rust spots have grown due the warm and humid conditions found in these areas.

Through film breakdown usually occurs first on the upper surfaces of longitudinal stiffeners (1st picture above) and on stringer decks (2nd picture), where residual water remains on both surfaces for longer periods after the tank is first emptied.

Blistering
Blisters often take the form of clusters of liquid filled, hemispherical bubbles at the paint/metal interface, although blisters can form between layers of paint, these are less common.

Typical blister rashes are shown in pictures at left.

Edge Breakdown

One of the areas to exhibit early coating breakdown is the edge of stiffeners (1st picture at right) and around cut outs (2nd picture), which frequently fail through edge breakdown mechanisms.

Often, special care is taken with the coating process in these areas. Edges can be ground smooth and stripe coats of paint applied by hand. Surface tension effects in the wet film, high coating velocity during spraying and poor local surface preparation are common caused of edge breakdown.

Weld Corrosion
Welds are susceptible to enhanced localized coating breakdown in the same manner as edges.  Commonly, two types of weld corrosion occur.  The first is illustrated in the 1st picture at left, where corrosion initiates on either side of the weld bead in the area associated with oxide build up from the welding process.

The second type of weld coating failure occurs much closer to the weld and is associated with poor surface cleanliness prior to coating.  An example is visible at the 2nd picture above.

Over thickness at the edges of the weld bead is also a contributing factor to weld corrosion.  Weld spatter, (which takes the form of small beads of metal close to the weld) can cause micro-blistering if overcoated.

Calcareous Deposit Induced Coating Failures

When the cathodic protection system is working well, the volume of the deposits is just sufficient to fill any cracks in the damaged area (1st picture at right).

When the anodes are overworked, then the voluminous deposits forming beneath the coating can lever it off the steel, as shown in (2nd picture).

The presence of sacrificial anodes in ballast tanks induces the formation of hydroxyl ions at the coating/metal interface – which has the result of inhibiting or preventing corrosion from occurring beneath the coating.  A side effect is that a white, chalky material (called calcareous deposit) forms beneath the coating.

The calcareous deposit originates partially from the reaction of carbon dioxide with the hydroxyl ions and partly as the result of semi-soluble carbonates being deposited from the sea water.

Poor Surface Preparation

The most common cause of coating failure is poor surface preparation. When the film is in good condition at thicknesses of greater than 250mm, micro-blistering results.

However, when the coating is either poorly applied or too thin, then failures of the type shown in picture at left tend to occur.  This is typically extensive corrosion breakthrough occurring in localized, clustered areas.

Reverse Impact Damage

A typical example is shown in the first picture at the right, which illustrates the shatter patterns that result from the coating failing in a brittle manner.

Reverse impact damage is also common in the shell plating, especially around tug contact areas and in the forepeak tank as a result of collisions with floating objects (2nd picture).  This type of reverse impact damage are usually slower and result in distortion of the coating, which in turn leads to through film corrosion at the damaged site.

Mud Cracking

Cracks in a typical pattern extend down from the surface of the coating and can reach the coating/metal interface.  Mud cracking is generally a result of either a very high build up of coating or can be due to excessive thinning in conjunction with thick films.  Often the interface with the steel is weakened and corrosion quickly initiates in the cracks.

Stress Related Coating Failures

Corrosion can initiate at heavily stressed areas within tanks.  Stress related coating failures can be recognized by their location or by the presence of the repetition of the same failure in the same place along the length of a structure.

Often stress related failures can initiate at cut outs as shown in the first picture  at right or at the toes of welds as shown in the second picture.

Both stress and strain are causes of the coating failure.  Stress concentrations can cause local anodic areas to develop, which then concentrates corrosion at that location.  Strain can lead to cracking and disbonding of the coating, due to differences in mechanical properties between the coating and the underlying steel.

Basic Finishing Rules for Avoiding Common Products Finishing Problems

1. Be sure the material you are using is adequate for the purpose intended. Proper testing of finished samples or pilot lots will offset future complaints.
2. Make routine inspection of material for working properties before throwing on production line. This prevents shutdowns.
3. Keep equipment in working order. Daily inspections should be made. Dip tanks should be checked for viscosity, gravity, performance; spray lines should be kept clear, etc.
4. Be sure that the product surface is properly cleaned and in suitable condition for painting.
5. Reduce paint in accordance with manufacturer’s instructions. Strain reduced material into spray tank or other production line equipment.
6. Practice routine inspection. Faulty production should be apprehended quickly to prevent accumulating rejects.
7. Use good housekeeping measures. A clean shop produces clean work, and reduces lost time caused by accidents, fire, etc.
8. Be aware that changes in weather often require adjustments in handling procedure, such as change of reducer, drying time before packing, etc.
9. Check on stock rotation. Use lots in order received, to prevent leaving extremely old materials in stock.
10. In refilling leftover material, strain into clean containers, fill containers to the top, and close tightly so that there will be no air leakage into the package. Label and date.

Rust Bullet Application Methods, Coating Failures & Preparation Rules is a post from: PPC Online - Rust Bullet Australia

Before the 1950′s, automobile owners reported no evidence of corrosion related problems. The first signs of automobile corrosion appeared on the year 1955. As the years pass by, localized corrosion of 430 stainless steel (1960), Galvanic corrosion (1965), Body perforation (1970), Corrosion of anodized aluminum (1980), and reports of 434 stainless steel marginal performance (1985) were all gradually recorded. By the year 1990′s, regular reports of body perforation has already evolved to become a major problem in the automobile industry.

Vehicle Coating

Many of the coatings used to prevent or slow corrosion can have specific vulnerabilities.

The existence of anodic and cathodic sites on the surface of vehicle body implies that differences in electrical potential are found on the surface. These potential differences have a number of causes.

One important mechanism is oxygen concentration cell corrosion, in which the oxygen concentration in the electrolyte varies from place to place.

Common Corroded Areas

Trunk, Tailgate and Rear Valance

Front Wheel Arches and Wells

Rear Wheel Arches and Wells

Window Edge

Corrosion of Car Doors

Corrosion of Wings and Fenders

Sills, Rockers, Door Step and Jacking Points

Others of Body

Chassis I

Chassis II

Rust Bullet LLC
300 Brinkby Avenue, Suite 200
Reno, Nevada 89509 USA
800-245-1600
www.RustBullet.com

Introduction To Vehicle Corrosion is a post from: PPC Online - Rust Bullet Australia

Corrosion is the deterioration of materials by chemical interaction with their environment.

Most metals corrode on contact with water (and moisture in the air), acids, bases, salts, oils, aggressive metal polishes, and other solid and liquid chemicals.Metals will also corrode when exposed to gaseous materials like acid vapors, formaldehyde gas, ammonia gas, and sulfur containing gases.

The term corrosion is sometimes also applied to the degradation of plastics, concrete and wood, but generally refers to metals.

How does Corrosion happen?

Corrosion is an electrochemical reaction. The reaction require four prerequisites:

• An anode
• A cathode
• An electron pathway
• An electrolyte (ionic pathway)

Electrochemistry of Corrosion

The corrosion process (anodic reaction) of the metal dissolving as ions generates some electrons, as shown here, that are consumed by a secondary process (cathodic reaction).

These two processes have to balance their charges.

The sites hosting these two processes can be located close to each other on the metal’s surface, or far apart depending on the circumstances.

The electrons (e- in this figure) produced by the corrosion reaction will need to be consumed by a cathodic reaction in close proximity to the corrosion reaction itself.

Iron in a deaerated neutral solution

Anodic reaction

• surface area = 1 cm2
• Fe –> Fe2+ + 2 e-
• E0 = -0.44 V vs. SHE
• for a corroding metal one can assume that Eeq = E0 · i0 = 10-6 A cm-2
• I0 = 1×10-6 A
• ba = 0.120 V decade-1

Cathodic reaction

• surface area = 1 cm2
• [H+] = 10-5 (pH = 5)
• 2 H+ + 2 e- –> H2
• Eeq = E0 + 0.059 log10 [H+] = 0.0 – 0.059x(-5) = -0.295 V vs. SHE
• i0 = 10-6 A cm-2
• I0 = 1×10-6 A
• bc = -0.120 V decade-1

Sequence of Corrosion (Pitting)

Types of Corrosion

The types of corrosion is divided into three major groups. Group 1 are those that are readily identifiable by ordinary visual examination. Group 2 are specific conditions that may require supplementary means of examination. Finally, Group 3 undergoes verification and is usually required by microscopy (optical, electron microscopy etc.) This also highlights the Atmospheric Corrosion and High Temperature Corrosion.

Group 1 are types of corrosion readily identifiable by ordinary visual examination. This includes Uniform corrosion, Pitting, Crevice corrosion (under which are: crevice model, filiform corrosion, and pack rust), Galvanic corrosion, Lamellar corrosion.

The Group 2 types may generally require supplementary means of examination. Erosion corrosion, Cavitation, Fretting corrosion, Intergranular corrosion, Exfoliation, and Dealloying (selective leaching or Selective Attack) are what specifies the depth of a certain corrosion in this category.

Group 3 is where the corrosion undergoes verification and is usually required by microscopy (optical, electron microscopy etc.) The specific types may fall under Environmental Cracking, Stress Corrosion Cracking (SCC), Corrosion fatigue, and Hydrogen embrittlement.

Uniform Corrosion
This type of corrosion occurs over the majority of the surface of a metal at a steady and often predictable rate.  As the most common form of corrosion, this is normally characterized by a chemical or electrochemical reaction, which proceeds uniformly over the entire exposed surface or over a large area.

Pitting Corrosion

Pitting Corrosion occurs in materials that have a protective film such as a corrosion product or when a coating breaks down. This is a localized form of corrosion by which cavities or “holes” are produced in the material.

Trough Pits

Sideway Pits

Crevice Corrosion

Crevice corrosion is a localized form of corrosion usually associated with a stagnant solution on the micro-environmental level.

Crevice corrosion is initiated by changes in local chemistry within the crevice:

• Depletion of inhibitor in the crevice
• Depletion of oxygen in the crevice
• A shift to acid conditions in the crevice
• Build-up of aggressive ion species (e.g. chloride) in the crevice

Filiform Corrosion

A special form of crevice corrosion in which the aggressive chemistry build-up occurs under a protective film that has been breached.

Normally starts at small, sometimes microscopic, defects in the coating. Lacquers and “quick-dry” paints are most susceptible to the problem. Their use should be avoided unless absence of an adverse effect has been proven by field experience. Where a coating is required, it should exhibit low water vapor transmission characteristics and excellent adhesion. Zinc-rich coatings should also be considered for coating carbon steel because of their cathodic protection quality.

Pack Rust

Pack rust is a form a localized corrosion typical of steel components that develop a crevice into an open atmospheric environment. This expression is often used in relation to bridge inspection to describe built-up members of steel bridges which are showing signs of rust packing between steel plates.

Galvanic Corrosion

This occurs when two different metals are placed in contact with each other and is caused by the greater willingness of one to give up electrons than the other.

This is one of the most common forms of corrosion as well as one of the most destructive. Here’s a classic example of galvanic corrosion; a stainless screw in contact with a cadmium plated steel washer.

The Statue of Liberty Case

The galvanic reaction between iron and copper was originally mitigated by insulating copper from the iron framework using an asbestos cloth soaked in shellac. However, the integrity and sealing property of this improvised insulator broke down over the many years of exposure to high levels of humidity normal in a marine environment.

Lamellar Corrosion or Exfoliation

Exfoliation corrosion is a particular form of intergranular corrosion associated with high strength aluminum alloys. Alloys that have been extruded or otherwise worked heavily, with a microstructure of elongated, flattened grains, are particularly prone to this damage.

In ferrous alloys, exfoliation is characterized by excessive internal growth of oxide, which has a volume some seven times that of the steel. Excessive internal growth of oxide can elevate temperature and the exfoliated material damage turbines. Exfoliation occurs in ferritic materials when multilayer growth occurs.

Stresses are induced by temperature cycles and by the difference in thermal expansion between the scale and tube. Exfoliation can also occur in austenitic stainless steels, again because of the difference in thermal expansion between the metal and the oxide.

Erosion Corrosion

Erosion corrosion is an acceleration in the rate of corrosion attack in metal due to the relative motion of a corrosive fluid and a metal surface.

The increased turbulence caused by pitting on the internal surfaces of a tube can result in rapidly increasing erosion rates and eventually a leak.

Erosion corrosion can also be aggravated by faulty workmanship.

Cavitation Erosion

Cavitation occurs when a fluid’s operational pressure drops below it’s vapor pressure causing gas pockets and bubbles to form and collapse.

This form of corrosion will eat out the volutes and impellers of centrifugal pumps with ultra pure water as the fluid will eat valve seats.

It will contribute to other forms of erosion corrosion, such as found in elbows and tees.

Fretting Corrosion

Fretting corrosion refers to corrosion damage at the asperities of contact surfaces.

This damage is induced under load and in the presence of repeated relative surface motion, as induced for example by vibration.

Pits or grooves and oxide debris characterize this damage, typically found in machinery, bolted assemblies and ball or roller bearings.

Intergranular Corrosion

Intergranular corrosion is localized attack along the grain boundaries, or immediately adjacent to grain boundaries, while the bulk of the grains remain largely unaffected.

Dealloying (selective leaching) Selected Attack

This occurs in alloys such as brass when one component or phase is more susceptible to attack than another and corrodes preferentially leaving a porous material that crumbles.

Dealloying or selective leaching refers to the selective removal of one element from an alloy by corrosion processes.

Environmental Cracking

Environmental cracking refers to a corrosion cracking caused by a combination of conditions that can specifically result in one of the following form of corrosion damage:

• Stress Corrosion Cracking
• Corrosion fatigue
• Hydrogen Embrittlement

Stress Corrosion Cracking

(SCC) is the cracking induced from the combined influence of tensile stress and a corrosive environment.

Corrosion Fatigue

Corrosion-fatigue is the result of the combined action of an alternating or cycling stresses and a corrosive environment.

The fatigue process is thought to cause rupture of the protective passive film, upon which corrosion is accelerated.

If the metal is simultaneously exposed to a corrosive environment, the failure can take place at even lower loads and after shorter time.

Hydrogen Embrittlement

It involves the ingress of hydrogen into a component, an event that can seriously reduce the ductility and load-bearing capacity, cause cracking and catastrophic brittle failures at stresses below the yield stress of susceptible materials.

Atmospheric Corrosion

Metals can corrode when exposed to the outdoor atmosphere as a consequence of wet and dry cycles induced by rainfall and condensation.

Corrosion is more significant when pollutants such as sulphur dioxide or chloride are present in the atmosphere.

Factors conducive to atmospheric corrosion

• Sensible moisture
• High RH (above 70-80%)
• Salt mist
• Surface contaminants (dust, sweat residues, soldering fluxes, etc)
• Atmospheric contaminants (SO2, HCl, organic acids)
• High temperature

High Temperature Corrosion

This is a form of corrosion that does not require the presence of a liquid electrolyte.  This type of damage is called “dry corrosion” or “scaling”. The oxidation of metal/Alloy has resulted from exposing to high temperature.

Corrosive High Temperature Environments

• Corrosive gases
• Ash
• Molten salts
• Molten metals

Consequences of Corrosion

• Reduction of metal thickness leading to loss of mechanical strength and structural failure or breakdown. When the metal is lost in localized zones so as to give a crack like structure, very considerable weakening may result from quite a small amount of metal loss.
• Hazards or injuries to people arising from structural failure or breakdown (e.g. bridges, cars, aircraft)
• Loss of time in availability of profile-making industrial equipment.
• Reduced value of goods due to deterioration of appearance.
• Contamination of fluids in vessels and pipes (e.g. beer goes cloudy when small quantities of heavy metals are released by corrosion)
• Perforation of vessels and pipes allowing escape of their contents and possible harm to the surroundings. For example a leaky domestic radiator can cause expensive damage to carpets and decorations, while corrosive seawater may enter the boilers of a power station if the condenser tubes perforate.

Other Factors that accelerate Corrosions

• Acid Rain
• Coastal Factor
• De-icing Agents – i.e Road salt, MgCl
• Green House Effect

Acid Rain Impact on Paint Surface

Corrosion rates for ingot iron (Coast Distance and Salt Content)

Green House Effect

75 Deg F + 75% Humidity = Corrosion Acceleration

Introduction to Corrosion and Process is a post from: PPC Online - Rust Bullet Australia

Generally, corrosion problem is measured or rated at 4 stages. The corrosion rating is on a scale of 0 to 4. One must establish a consistency of assessing material corrosion conditions. This Stage/Scale system is designed to assist common folks in understanding of corrosion problems and establish corrective action required.

Stage/Scale 0

• The painted surface has shown no sign of cracking, bubbly or paint bubbles.
• There is no pitting, no etching and the surface shows no rust stain or trace of rust.
• Surface Coating is not comprised.

Examples of Stage 0

Corrective Measures

At Stage/Scale 0, there are no corrective measures required.

• Preventive measures are:
• Maintain a clean surface.
• Remove corrosive agents such road salt.
• Remove contaminated agents such as dirt, grease, solvent and contaminated water etc.

Stage/Scale 1

• The painted surface is bubbly or the paint bubbles have broken to reveal rusty red, black, or white corrosion deposits on the metal surface. This may be accompanied by minor etching or pitting of the metal.
• No scale is present but the metal may have loose, powdery, or small granular deposits on the surface, base metal is sound.
• No direct visual evidence of pitting,
• Surface coating has been comprised.

Examples of Stage/Scale 1

Corrective Measures

• Painted Surfaces: This condition does not require immediate corrective action; however. The surface should be cleaned and apply a corrosion control coating for preventing further corrosion.
• Interior Machine Surface (Both Functional and Non-Functional): This condition does not require immediate action other than re- processing as necessary.
• Exterior Machine Surface (Both Functional and Non-Functional): This condition does not require immediate corrective action other than re- processing as necessary. However, a corrosion control coating is recommended to control further corrosion.
• Notes: If the component is critical, replacement is needed. If surface is covered with dirt, grease, soil, mud or dust, cleaning.

Stage/Scale 2

• Powered granular or scaled condition exits on the surface metal.
• Rusty red, black or white corrosion deposits are present.
• Metal surface may be etched or pitted.
• Metal beneath the corroded area is still relatively sound.

Examples of Stage/Scale 2

Corrective Measures

• Painted Surfaces: Clean the surface by any applicable process. Apply Corrosion Control coating. Touch up with paint as originally applied.
• Interior Machine Surface (Both Functional and Non-Functional): Clean, exercise, and reprocess.
• Exterior Machine Surface (Both Functional and Non-Functional): Clean, exercise, and reprocess. Apply corrosion control coating wherever required.
• Remarks: For machine or equipment where critical thickness is essential, apply a suitable corrosion control coating is a must. For electronic equipment and instruments, clean the surface by an applicable process and coat the surface with a suitable corrosion control coating that will not interfere the operation.

Stage/Scale 3

• Surface conditions and corrosion deposits present are similar to Stage 2 except that metal in corroded area is unsound and small pin holes may be present.
• Rust, black or white corrosion accompanied singularly or in – combination with etching, pitting, or – more extensive surface damage.
• Loose or granular condition.

Examples of Stage/Scale 3

Corrective Measures

• Painted Surfaces: Corrective action is required immediately. Clean the surface by any applicable process. Repair the damaged surface. It may require to replace the damaged parts. Apply a suitable corrosion control coating to cover the entire surface . Top coat with paint as originally applied.
• Interior Machine Surface (Both Functional and Non-Functional): Clean, exercise, and reprocess. Apply a proper oil based corrosion control product to prevent further corrosion.
• Exterior Machine Surface (Both Functional and Non-Functional): Clean, exercise, and reprocess. Apply corrosion control coating wherever required.
• Remarks: At this stage the function or fitness of the equipment will be affected. Immediately corrective action is required. Remove the rust, clean the surface properly and apply a suitable corrosion control coating. For machine or equipment where critical thickness is essential apply a suitable corrosion control coating is a must.

Stage/Scale 4

• Corrosion has advanced to the point where the metal has been penetrated throughout.
• No metal remains at the point of the most severe corrosion.
• There are holes in the surface area or metal is completely missing along the edges.

Examples of Stage/Scale 4

Corrective Measures

• Painted Surfaces: Corrective action is required immediately. Clean the surface by any applicable process. Replace the damaged surface. Apply a suitable corrosion control coating to cover the entire surface . Top coat with paint as originally applied.
• Interior Machine Surface (Both Functional and Non-Functional): Clean, exercise, and reprocess. Apply a proper oil based corrosion control product to prevent further corrosion.
• Exterior Machine Surface (Both Functional and Non-Functional): Clean, exercise, and reprocess. Apply corrosion control coating wherever required.
• Remarks: At this stage the function or fitness of the equipment will be comprised or greatly affected. Safety of the operator is at risk. For machine or equipment where critical thickness is essential apply a suitable corrosion control coating is a must.
• Replacing the parts or components are generally recommended.

Painted Aluminum Surface

Power Connector

Steel Panel

Painted Door Panel

Stainless Steel

Stage/Scale 0: The stainless steel is in good condition, no pits and the protective Cr film is intact. Preservation and passivation is required to maintain the protective Cr film.

Stage/Scale 1: The stainless steel has shown sign of early stage of pitting corrosion problem. The protective Cr film has been comprised. Flash Rust stain is also easily seen.  The metal is sound. Protective Cr film is comprised.

Stage/Scale 2: The stainless steel has advance to Stage 2 of corrosion. Small pits are developed on more than 60% of the surface and flash rust stains are easily seen. The metal is still sound. The protective Cr film is comprised and flaking is spreading but still visible.

Stage/Scale 3: The stainless steel has suffered a severe pitting corrosion problem. Because the pits are closed together, a uniform corrosion will likely develop and core diameter is severely reduced. It can be up to 30% reduction. Depending on the purpose of the stainless steel, the strength of the stainless steel may have reached a critical stage where further investigation is required. The protective Cr film is nearly disappeared.

Stage/Scale 4: The stainless steel has suffered severe pitting corrosion problem. Although the general surface area appeared to be better than it shows in picture B, the severe side pitting corrosion problems are hidden beneath the surface. (a poor repair job was done after Stage 3 was observed).

Stages/Scales: 4 --------- 0 --------- 3 --------- 2 --------- 1

Corrosion Stages/Scale is a post from: PPC Online - Rust Bullet Australia

Pigment

Two different types of pigment go into a can of paint. First are “prime” pigments. These provide color and hide. Second are low-cost “extender” pigments. By comparison, they add bulk to the product, but have little value as it relates to color.

Higher-quality paints have more of the all-important, yet more expensive prime pigments – all the things that in the end give you easier application as well as better durability and color retention.

Pigments are defined as any insoluble solid in coating materials. They are typically the colorant portion of a coating material, but can also perform other functions.

Some pigments provide corrosion protection, stability in ultraviolet (UV) light, or protection from mold, mildew or bacteria. Others can be used for conductive ability, texture, or metallic or pearlescent appearance.

Rust Bullet Pigment

Rust Bullet Products are very unique in that they contain ONE Pigment – That ONE pigment is the PRIME Pigment. We do not add a low-cost extender pigment to our product.

Binders or Resins

Binders primarily function as an adhesive to the substrate. They are polymer resin systems with varying molecular weights.  The molecules in the binder crosslink during the curing stage to improve strength and create the thin film. The type of binder usually gives the paint formulation its name. Common binders are acrylics, epoxies, polyesters, and urethanes.

A variety of binders are used in today’s paints. These are latex and oil paints. Latex paints contain either 100 percent acrylic, styrene-acrylic, or vinyl acrylic binders. Oil paints typically contain linseed oil, soya oil, or modified oils called alkyds.

The type, quality and amount of binder affect everything from stain resistance and gloss to adhesion and crack resistance. Higher quality binders, found in higher quality paints, adhere to surfaces better and provide enhanced film integrity. This makes them more resistant to cracking, blistering and peeling.

The viscosity of the paint is often attributed to the binders contained in the coating formulation. Coating viscosity must be considered when choosing certain application techniques.

Rust Bullet Binders or Resins

Rust Bullet Products are unique in that not only is the one and only Pigment a PRIME Pigment, The Resin, which is a Urethane, is a PREMIER RESIN. The combination of a single Prime Pigment and a Premier Resin provide the most optimum performance provided by any coating available.

Additives

Additives are the ingredients that give paint a specific benefit that it might not otherwise have. Common additives in higher-end paints include:

* Rheology modifiers – provide better hide and durability
* Mildewcides – keep mildew in check
* Dispersing agents – keep pigment evenly distributed
* Preservatives – prevent spoilage

Additives are usually low molecular weight chemicals in coating formulations that allow coatings to perform specific functions but do not contribute to color.  Non-pigment additives include stabilizers to block attacks of ultraviolet light or heat, curing additives to speed up the crosslinking reaction, co-solvents to increase viscosity, or plasticizers to improve uniform coating.

Rust Bullet Additives

Rust Bullet Products are unique in that there is no need for an Additive. Not only is the one and only Pigment a PRIME Pigment, this Prime Pigment is so unique, that it provides the specific benefits of the additive;

- CORROSION CONTROL
- UV PROTECTION
- THERMAL STABILITY
- APPROPRIATE VISCOSITY

Solvents or Liquids

Providing no added performance benefits, liquids are simply the “carrier” that allows you to get the paint from the can to the surface. As you might guess, top quality paints have a greater ratio of solids (pigment and binders) to liquids, while cheaper paints are more “watered down” with liquid.

Four common types of coating materials are;

* Solvent-based coatings
* High-solids coatings
* Waterborne coatings
* Powder coatings

The names are descriptive of the main type of carrier fluid present in the coating. The carrier fluid is typically a liquid such as an organic solvent or water. The carrier fluid allows the coating material to flow and be applied by methods such as spraying and dipping.

This component may be in the coating formulation before application, but evaporates afterwards to allow the solid materials to immobilize and form the thin protective film.

Despite its temporary presence in the coating material, the solvent plays a major role in how well the film will perform.  Powder coatings have no carrier fluid and consist only of the other three components.

While the solids portion adheres to the work piece, the solvent component of coating materials evaporates and causes the most environmental concern.  The solvent materials are mostly volatile organic compounds (VOCS) that contribute to the creation of ozone (smog) in the lower atmosphere and are toxic to human health.  Some solvents may also be classified as  hazardous air pollutants (HAPS).

US Federal environmental statutes now regulate these VOCs and HAPS.  One way organic finishing facilities have responded to these regulations is by creating coatings with lower solvent content.

Rust Bullet Solvents

RUST BULLET MEETS THE HIGHEST STANDARDS SET FOR VOC COMPLIANCE;

* The SMAQMD RULE 442 – Sacramento Metropolitan Air Quality Management District

* The SCAQMD METHOD 318-95 – South Coast Air Quality Management District

Coating Formulations

Coating formulations vary widely, with different types and amounts of pigments, binders, additives, and carrier fluids.

The differences in coating formulations provide film characteristics specifically set for the part and its end-use.

Often, one type of coating cannot be formulated to provide all of the desired properties. Several layers of different coating material may be applied to a surface to form a coating film that will thoroughly protect the part. The first coat is typically called the primer, or undercoat, and the final layers are called topcoats.

Coating Success

Regardless of the coating formulation or number of layers applied, proper surface preparation, application techniques, and curing processes are necessary for the desired coating characteristics to be achieved.

RUST BULLET IS COATING SUCCESS

Rust Bullet Products:

* REQUIRE MINIMAL SURFACE PREPARATION

* EASE OF APPLICATION VIA BRUSH, ROLLER OR SPRAY

* PROVIDE AN ARMOR-TOUGH SURFACE UPON CURING

The 4 Components of Paints & Coatings is a post from: PPC Online - Rust Bullet Australia