ARTICLE

RUST BUSTERS

Written by Peter Buxbaum
Source: MLF 2013 Volume: 7 Issue: 2 (March)

Corrosion impacts the U.S. military on multiple fronts. Maintenance is affected by the increased costs over the life cycle of an asset. It impacts readiness when an asset is not in condition to meet a required mission. Safety is impacted when deterioration resulting from corrosion brings the asset to a condition where it is no longer safe to use.

Corrosion also has a profound impact on defense budgets. One study showed that the Navy spends one-quarter of its maintenance budget, around $7 billion per year, on corrosion. A 2010 report showed that the Department of Defense as a whole spent $23.2 billion, or 23 percent of its maintenance dollars, on corrosion. The ongoing redeployment of equipment from Southwest Asia casts a bright spotlight on the necessity to take measures to prevent corrosion.

"Corrosion is ubiquitous," said Edward Lemieux, director of the Center for Corrosion Science and Engineering at the Naval Research Laboratory. "It affects operations, the expected service life of equipment, and can also cause service failures."

"Anything that can be done to protect corrosion provides more beans and bullets," said Mark Schultz, a project development manager at Sherwin Williams. "Doing things properly the first time provides equipment with greater longevity and saves DoD money. The goal is to reduce total ownership costs for a piece of equipment."

"With the ongoing redeployment, more equipment is headed for long-term storage and corrosion prevention plans are required," said Steve Hanna, president of Protective Packaging Corp. "The key is that you have to be flexible. It is impossible to develop one system to do everything for everybody."

The U.S. Marine Corps has a formal Corrosion Prevention and Control (CPAC) program that is charged with the prevention of corrosion on all ground assets through a three-pronged approach. The first involves support to new acquisition platforms. "Here, corrosion prevention is emphasized from the design phase to ensure proper materials, manufacturing techniques and maintenance processes are used to minimize deterioration," said Matthew Koch, the CPAC program manager.

The second involves sustainment operations. "Corrosion prevention is emphasized as a maintenance and storage philosophy," said Koch, "including the application of corrosion prevention compounds, dehumidified warehousing for long-term storage of equipment, and applying protective covers."

The third is applied research and testing to identify corrosion prevention technologies and methodologies for vehicles. "This is a comprehensive program where fleet issues are evaluated against solutions from industry, academia and the military labs to maximize the benefits to the Marines while considering costs and other impacts," said Koch.

The Marine Corps operates corrosion repair facilities where corrosion repair and vehicle repainting are performed. There are also numerous dehumidified temporary shelters and existing warehouses that are used for long-term storage of equipment. The Marine Corps also fields corrosion service teams that use mobile trucks to apply corrosion prevention compounds and do touch-up painting.

The Navy also makes strenuous efforts at corrosion prevention. "The best time to effect material selection is during the design phase," said Lemieux. "After that the program is usually married to the materials selected and it is hard to change them."

Cathodic methods are a common way to prevent corrosion. "Passive cathodic protection involves allowing one level of metal to corrode and sacrifice itself for the protected metal," Lemieux explained. "Active cathodic methods involve placing electrodes and delivering an electric current to the protected surface." Since the 1980s, almost all Navy ships have had active cathodic systems protecting their outer hulls.

Development and selection of advanced paints and coatings is another part of the Navy effort. "These prevent not just corrosion but also the buildup of barnacles and organisms on the hull," said Lemieux. "The use of ultra-high solid coatings on the topside prevents corrosion as well as UV degradation."

Oshkosh Defense, which provides the U.S. Army with trucks, has long delivered the vehicles with a triple layer of coating designed to prevent corrosion. "We have traditionally applied by spray a zinc-rich primer followed by an epoxy coating followed by a top coat," said Mike Ivy, vice president and general manager for Army Programs at Oshkosh Defense. "When we won the FMTV contract in 2009 there was a new requirement that corrosion prevention measures had to last 22 years."

Oshkosh's response was to invest in a 150,000-square-foot facility to perform a new method called electrode deposition, or e-coating. After an initial zinc phosphate coat, all components are 100 percent immersed in a paint solution. After that, the coatings are strengthened through a heat curing process before given the top coat.

"E-coating is fairly standard in the auto industry but it is not common in the defense industry," said Ivy. "The FMTV vehicles are backed by a 22-year warranty that they will not fail due to corrosion."

E-coating allows all of the nooks and crannies of truck components to be coated, a condition that cannot be assured with a manual application of coating. "Once the investment is made in the e-coating facility, e-coating is probably less expensive than other ways of applying corrosion prohibiter," said Ivy.

"CPAC maintains that the best time to consider corrosion control is during the material development and design phases," said Koch. "Emphasizing the importance of corrosion control early helps manufacturers weigh corrosion prevention against other functional characteristics, allowing for informed tradeoff decisions. We work closely with program managers, to assist them as corrosion control subject matter experts as they develop contractual language with regard to corrosion control, evaluating design recommendations from manufacturers, testing those designs and identifying areas needing redesign or additional consideration for maintenance activities."

CPAC also works with OEMs on corrosion prevention in the manufacturing process. "Included in this support is a full vehicle corrosion test where the system is operated under typical conditions, while subjected to various corrosive environments," said Koch. "This is a yearlong test where conditions representative of up to 20 years of service can be simulated. The results are used to improve the design or change the frequency or type of maintenance performed. Systems where CPAC has been involved since the start of the acquisition program have been much more corrosion resistant than their predecessors."

The Marine Corps also acquires specific products and services for corrosion treatment or prevention. "For sustainment activities we utilize products that have been demonstrated to provide increased service life and reduced deterioration on ground equipment as well as the authorized chemical agent resistant coating paint systems developed by Army Research Lab," said Koch. "For new acquisitions we evaluate the proposed materials of manufacture to ensure that they will meet the desired performance, in terms of length of service and operating environments, of the system and that they are compatible with the CARC system."

Protective Packaging Corp. designs covers for specific types of equipment. "The design depends on whether it is to be short- or longterm protection and whether the equipment is to be stored outdoors or indoors," said Hanna. "Do they want to park the equipment somewhere and forget about it until the next war? It also depends on whether the equipment is to be protected from corrosion or also mold, mildew or static electricity. We gather a whole host of information from our customer and then develop the cover that meets those specifications. When we put a protective flexible cover over the equipment with the right amount of desiccant, we can guarantee there won't be any corrosion." Desiccant is a moisture-absorbing mineral or compound.

Protective Packaging provided a packaging solution to a defense contractor for the preservation of the JDAM precision guided weapons system. The company was able to provide packaging that protected the equipment against any damage caused by corrosion or electrostatic discharge and also provided a 20-year warranty to that effect.

The protective covers provided by companies like Protective Packaging Corp. and Shield Technologies Corporation are strong yet breathable so that they don't capture moisture inside them. "Vinyl traps moisture and is rapidly broken down by grease and oils," said Bob Ward, Shield's chief executive officer. "It also deteriorates rapidly from the UV radiation of sunlight."

Shield Technologies' product, Envelop Protective Covers, is waterproof, yet allows moisture to escape. The Envelop material contains a vapor corrosion inhibitor, which floods the covered space, bonds to metals and prevents oxygen from initiating corrosion.

Shield Technologies developed and provided a set of Envelop Protective Covers for the U.S. Army's Patriot missile system. In December 2012, the company delivered two protective covers for a U.S. submarine's vertical launch platform designed to protect the weapons from heat and humidity while stationed at the Polaris Point Naval Submarine Base in Guam. The company also recently began to design covers for the F-16 Block 30, and introduced its Magnum product line last year. "We listened to our customers, who told us they wanted lighterweight covers," said Ward. "The lighter Magnum material also goes on quicker. It takes a soldier just minutes to cover vehicles like the Bradley or Stryker."

The U.S. Navy turned to Sherwin Williams when it found that corrosion- inhibiting coatings on vessel ballast tanks typically failed at the edges. This, in turn, led to the failure of the remainder of the coating in the tanks. "The thought was that if we could arrest the corrosion on the edges we could make the entire system last longer," said Schultz. "Our research found that ultra-high solid coatings are superior to their traditional counterparts in protecting the edges." Those solids are also low in volatile organic compounds.

"As a result of this innovation," said Schultz, "the service life of the ballast tanks went from five to 10 years to 15 to 20 years. NAVSEA came to the conclusion that this product saves 20 percent in costs and 50 percent in scheduled maintenance time." Sherwin Williams has also, in recent years, provided the Navy with a new vessel topside coating that provides higher levels of corrosion resistance.

The NRL has itself developed a new topside coating that is skidresistant and more durable to environmental conditions. The new polysiloxane coating has several attributes that contribute to corrosion resistance as well as lower maintenance costs for the Navy.

"The first is that it does not require mixing of components," said Lemieux. "It goes on quicker and reduces costs. It provides better performance in that it is skid-resistant, provides better color retention, and does not easily degrade when exposed to ultraviolet light. Older coatings tended to crack and delaminate quicker. When that happens, moisture and contaminants seep in and corrosion begins to occur." The new product is currently in a demonstration phase. Lemieux expects it to be available to the fleet next year.

Koch foresees that the Marine Corps will place more of an emphasis on tracking and understanding the condition and benefits of technologies being used to mitigate corrosion. "All of this will help support efforts to extend the useful service life of materiel," he said. "Corrosion prevention and control will become a large part of the consideration for new acquisitions as well as of service life extension programs to minimize its effect on maintenance costs, readiness and safety."

The NRL is also working in software designed to aid in the prediction of material corrosion rates so that the Navy can better select materials and plan maintenance activities. "This will help in design and material selection," said Lemieux. "We would like to be able to assess the materials going into components and systems.

"That is not a capability we have today," Lemieux added. "Currently we rely on subject matter experts, our knowledge base, and the available literature. But we don't have a tool to predict quantitative performance. That is a goal we are working toward at the research level."

NAVAIR's PMA-261 (manages the family of H-53 helicopters) is participating in a small business technology transfer solicitation that seeks to use peridynamics theory to predict corrosion fatigue across length and time scales in naval aircraft.

The difficulties in accurate prediction of corrosion damage point to the fact that corrosion fatigue is inherently a multi-scale process in both length and time. Although qualitative effects from three basic sources of corrosion, i.e., design, environment and maintenance, are well understood, prediction of corrosion fatigue damage in service has been a quite a challenge despite several decades of research.

Peridynamic theory is a nonlocal extension of classical continuum mechanics that is based on integral equations, in contrast with the classical theory of continuum mechanics, which is based on partial differential equations, and has the capability to handle multi-scale modeling for both length and time, and address discontinuities and non-linearity. The peridynamic theory has the potential to serve as a basic model across all scales avoiding the difficulties inherent in multimodel coupling in addition to the ability to efficiently link with many microscale models, including molecular dynamics.

For more information about Envelop, its markets and technology, the research, or to schedule a demonstration of Envelop covers, click here to contact us.

About ENVELOP® Protective Covers
Envelop Protective Covers are the next generation of environmental and operational covers, replacing ineffective vinyl tarps and corrosion-inhibiting chemicals that contaminate the environment. Envelop covers were originally developed to protect military weapons and other assets from water, salt, humidity, sand and other sources of environmental degradation. Validated in the Navy's ocean-going environment, Envelop covers have proven to dramatically reduce maintenance time for military assets, and they are the only soft covers approved by the U.S. Navy for topside weapons and equipment. More than 14,000 Envelop covers are now used by the U.S. Navy, U.S. Army, U.S. Marine Corps, U.S. Coast Guard, and allied navies. They are also available for consumer and industrial applications such as oil and gas machinery, commercial shipping, amusement parks, airplanes, gun cases and cruise ships. Shield Technologies Corporation is headquartered in Chicago, Ill., with operations in the Twin Cities suburb of Eagan, Minn.