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Product category: Materials and components
News Release from: Birchwood Casey | Subject: Intercept
Edited by the Engineeringtalk Editorial Team on 11 May 2007

Corrosion - a new way to combat it in a
new era

Mark Ruhland looks at the science of corrosion and why there is such an aversion to it.

Corrosion, as we knew it growing up, was the rust we saw on our bicycle handlebars after we left the bike outside overnight We couldn't quite explain it

But we knew it when we saw it and it was bad.

It is no different today except the problem is much larger.

Corrosion is an ever present threat affecting virtually every manufactured product used in the power generation and turbine industry.

The Department of Commerce estimates that annual monetary losses attributable to corrosion are in the range of billions of dollars, with most of the cost passed on to the end-users of the products.

That number is growing as industry depends more on precision manufactured components incorporated into everything from gas turbines and wind generators to propulsion engines and stationary power systems.

The very essence of our manufacturing base - energy production and manufacturing machinery - is subject to corrosion at increasingly higher levels because there are more of these systems and they are subjected to more corrosive elements throughout their lifecycle.

Our world is getting smaller every day, as global trade plays an increasing role in commerce worldwide.

Although there are many positive aspects to increased global trade, there are also negative aspects that are only now being recognised.

One is the fact that manufactured equipment is being subjected to more and more corrosive conditions as they travel from one country to another.

As a result of population growth and greater industrialisation, there has been a frightening deterioration in air quality, which creates a more hostile environment in which corrosion grows.

Clean, dry air is not by itself a corrosive substance, and unfortunately it doesn't exist in most places.

The air at ground level where we live and work is not clean and not dry.

We may not notice it, but air is laden with corrosive gases and contaminants - everything from humidity, salt, corrosive sulphides, ozone, smog and organic compounds.

In some areas, the air quality is so poor that manufactured components corrode at a measurably higher rate.

Even in the most controlled environments, corrosion has a way of developing.

With its increased emphasis on high quality, modern industry has essentially imposed a zero tolerance policy when it comes to corrosion - in industrial products and with consumer products.

In manufacturing, with modern statistical quality control, one corroded component will often cause an entire lot to be rejected.

The same is true for retail products where one corroded product will result in a mass merchant returning an entire product shipment to the manufacturer.

The point is that corrosion is an unacceptable condition for any newly delivered product, be it a wind turbine or small components to be assembled into a wind turbine system.

Traditional methods of corrosion protection depend on passive surface coatings that act as a physical barrier against corrosion.

Most passive coatings are based on oil, electroplating or paint.

These barrier coatings work by blocking atmospheric humidity and corrosive gases from coming into contact with the metal surface underneath.

If the part itself can tolerate the dimensional change associated with barrier coatings, these materials can work well, as long as the coatings are not damaged or breached in some way.

If the surface is damaged or a breach does occur, the underlying metal is immediately susceptible to corrosion.

In many cases, this corrosion will quickly degrade the quality and/or function of the article in question and perhaps render it unusable, thereby removing its value.

In some applications, the topcoat itself becomes the outer and critical surface.

For appearance and utility reasons, this surface must be protected from both corrosion and excessive wear.

In many cases, once a system is delivered to the customer and put into service, corrosion is no longer an issue because the component is being lubricated or is in contact with other materials as part of its job.

It is difficult for the manufacturer to guarantee long-term corrosion resistance because the component or system is no longer under his control.

Consequently, the time between initial factory shipment and receipt by the customer is the critical period during which corrosion does the most damage in terms of compromising and/or destroying system or component value.

During this period of shipment and storage, high value equipment and components may require extra protection in order to ensure that they arrive at the customer's use site in perfect condition.

Extra protection for high value systems isn't always the answer.

Ironically, while the chemical industry has developed very effective coating chemistries, environmental regulations have forced industry to revert to safer, but less effective, alternatives.

Stringent regulations have removed many very effective coating options from the marketplace in the interests of worker safety.

As a result, working conditions have improved, but manufactured systems and components often have less corrosion resistance than they might have had 20 or 30 years ago.

Informal surveys of stationary power systems and like type machinery and components indicate that most surfaces are protected by paint, black oxide, phosphate or some other protective barrier coating.

All these protective materials work by blocking atmospheric humidity and corrosive gases from coming into contact with the metallic surface underneath.

They can work well in many instances, unless they are damaged or breached in some way or if the part itself cannot tolerate the dimensional buildup of a protective topcoat.

In some cases, the topcoat itself is the critical surface, for sales appeal and aesthetic reasons, requiring protection from the elements.

These materials offer a partial solution to the challenge but fall short of meeting the entire goal.

Because of the growing worldwide emphasis on safety and environmental factors, the solution to the problem lies with the wrap and packaging of the finished product - ideally one that provides high quality protection at low cost without using hazardous chemicals.

Although there are many different types of specialty wraps and packaging materials available to manufacturers, there are really only four primary types of packaging materials in common use to protect critical surfaces: wooden pallets, crates and corrugated cartons; traditional plastic wrap, such as plastic bags/shrink wrap; plastic wrap containing an active volatile corrosion inhibitor; and protective film infused with environmentally friendly elements that neutralises corrosion before it starts.

Wrapping systems and components in plastic wrap, crates, cardboard cartons and plastic bubbles often does little to protect product contents from corrosion.

More often than not, these types of packages trap moisture and contaminants inside the package and exacerbate the problem.

These traditional methods of packaging finished systems and components are often inadequate and require additional passive corrosive protection.

Even with this added protection, corrosion protected storage life for the product may be limited.

The result is uncertain protection over time once increased atmospheric hazards are increased.

Volatile corrosion inhibitor (VCI) packaging/wrap has been used for several years as an improvement over the previous two methods of protection described above.

VCI packaging consists of a plastic film, infused with a volatile organic chemical amine that off-gasses, or evaporates, to form a protective cloud of alkaline vapours around parts.

The problem with the chemical amine is that it is not always safe to use.

Amine products can cause skin and eye irritation for the workers using them.

Additionally, amine products can stain and produce hazy films on the surfaces of components being wrapped in it.

This is especially true of precision machined or ground surface finishes.

With VCI wrap, if the package is less than airtight or is opened, the protective gases dissipate into the atmosphere and protection is lost.

With today's emphasis on worker safety, VCI packaging products are problematic because they become a potential corporate liability.

The corrosion problem therefore becomes secondary to the worker safety issue.

Additionally, VCI products have no capability to inhibit bio-hazards such as bacteriological residues.

Following many years of research and development, an exacting combination of environmentally friendly natural elements have been imbedded into a patented film that provides the ultimate in corrosion protection known as the Intercept Technology.

This material consists of a special polyethylene film infused with metallic copper particles and activated carbon.

Without the use of harmful amines or other chemicals, this film when configured into wrap and packaging material creates a protective, corrosion-free zone around metal parts that are contained inside the packaging wrap.

The Intercept packaging wrap material itself has the unique ability to neutralise and remove corrosive elements in the air around the stored part.

Completely nonhazardous, these materials aggressively neutralise and absorb corrosive elements inside the package through sacrificial galvanic action and absorption.

When examined in detail, each component serves a different function: the copper particles neutralise and absorb corrosive elements, such as sulphides, ozone, salt air etc.

Meanwhile, the activated charcoal absorbs any organic chemicals in the air, such as fumes from engine exhaust or other industrial chemical residues.

In addition, the metallic copper has long been regarded as an effective natural biocide that kills any surface bacteria and prevents their growth.

By removing these corrosive elements from the air inside the packaging wrap, the Intercept film effectively generates a benign, protective zone around the system and components stored within without the use of chemicals.

The protective zone, while benign in nature, encapsulates the contents so that it is impervious to corrosion and the system and components are fully protected.

The Intercept technology neutralises the corrosive gases that exist inside a wrap package and any atmospheric gases which may permeate through the film during time of storage.

The corrosive gases that cause corrosion are permanently bound with the particles.

All parts contained within are equally protected, including parts made from iron/steel, brass, zinc, aluminium, even plated parts.

And only one packaging material is needed for all applications.

Salt-fog test comparison by the US Army Tank Command (TACOM) verifies three different polyethylene barrier materials including the new Intercept material for their effectiveness.

It should be noted that in the test on all materials, the Intercept technology provided significantly better corrosion protection than the other two tested materials including the foil/polyethylene material specified by the US Army.

The added days of protection for zinc ranged from 20% more days of protection to nearly double that for steel.

VCI polyethylene film was the least effective form of protection in the test with the Intercept technology providing from two to four times added days of protection.

The most dramatic difference in corrosion protection was for steel where the Intercept technology offered two or more times the number of days of corrosion protection.

Originally developed, patented and proven by Bell Labs during the 1990s, the Intercept packaging and wrap design provides ten years of protection per mil (0.001in) of Intercept thickness.

It is the most ideal packaging solution to date because it actively combats corrosion and biohazards without the use of chemicals.

It is therefore safe for workers exposed to it and will not leave a residue on the protected part surface.

Numerous short and long term studies of costs show the Intercept wrap and packaging to be very competitive with all other classes of materials.

Taking into account added corrosion protected storage life, reduced handling time and reduced product losses due to corrosion, the Intercept material came out on top in every study.

In fact, quality conscious companies such as BMW have made the Intercept technology their sole choice for long term storage protection.

Indirect benefits also accrue heavily in favour of Intercept wrap and packaging.

These include the fact that Intercept film meets the new European RoHS and other end-of-life product directives, and it is completely recyclable, safe, and effective for virtually all metals.

In some market segments, the supply chain is so efficient that finished systems and components are manufactured and shipped within a day or two of the purchase order.

Customers receive their order in a few days.

This quick response lowers the likelihood of rust occurring during transit, and for components of modest value, the rusting issue may not be critical at all.

For high value systems, rust becomes a major issue.

These products are of higher value, take longer to make, are shipped by ocean freight and/or must wait in storage for extended periods before going into service.

These factors can greatly increase the likelihood of rusting and also increase the monetary costs if rusting does occur.

Oilfield equipment is a good example.

This industry requires complex, expensive parts and critical assembly operations.

These parts and assemblies are typically shipped in wooden crates to the drill site by ocean freight, to all parts of the world, where they are stored under minimal or no shelter for extended periods.

Several months can elapse before these components actually go into service.

However, the components must be rust-free when they come out of the crate.

These components can benefit greatly from flat Intercept rollstock used as a liner for the wooden crates in which the components are shipped.

The Intercept film is laid into the crate around the components, then closed and taped within the crate enclosure for maximum protection at minimal cost.

Other examples include large systems and machinery where the outside housing is painted, but the critical working parts, such as gears, ways and fixturing are precision machined steel and are highly susceptible to rust, even with heavy oil coating the surfaces.

These systems have high value and require longer time frames to manufacture, ship and install.

More often than not, this equipment is weeks or more old before the customer receives it.

Although the painted surfaces are not likely to rust, the oiled steel surfaces often do rust and often they are the components that represent the largest proportion of the system's value.

Consequently, they require specialised wrapping and packaging in order to ensure that the equipment arrives at the customer's use site in satisfactory, rust-free condition.

On equipment like this, the Intercept stretch film can offer a very economical option that provides superior protection for long periods.

Other smaller systems including parts and assemblies also benefit from packing in Intercept wrap or presized bags.

For example, screw machine parts or stampings are often shipped in tote bins for assembly in another location - sometimes on a flatbed truck open to the weather.

The individual piece parts usually have a relatively low value - until the entire bin turns rusty.

In these instances, the large-size Intercept gusset bags can be used as tote-bin liners to protect these shipments at minimal cost.

Often the bags can be re-used once the bin has been emptied, so the protection is very economical.

To summarise, this new era for corrosion protection requires products that do a better job of providing corrosion protection while satisfying environmental and worker safety issues.

With today's ever tightening regulatory environment, manufacturers are under greater pressure to modify and improve their systems and equipment so that they do comply.

Intercept technology provides these opportunities.

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