Good Term Paper On Economic Impact Of Corrosion
What is corrosion?
Corrosion is the degradation of materials properties because of the interactions with their environments. The corrosion of most metals and many other materials for that matter is inevitable. While corrosion is associated primarily with metallic materials, all types of materials are susceptible to degradation. Like taxes and death, corrosion is something we anticipate to avoid; however, it is something that we should learn to deal with. The driving force or the fundamental cause for all corrosion is lowering Gibbs energy of the system. The production of all metals and the engineering components made of metals involves addition of energy to the system. As a result of this thermodynamic uphill struggle, metals have a driving force of returning to its native state of low energy oxide. The return to the native oxide state is what is referred to as corrosion, though it is inevitable, corrosion control methods can be utilized to slow down the process towards the equilibrium state (Barbara & Robert, 2014). Our daily lives effect of corrosion are both direct and indirect, in that in indirect effect, it affects our possessions useful service lives, in indirect effect, producers and suppliers of services and goods incur corrosion costs, which can be passed on to the customers.
Forms of corrosion
Corrosion takes place in many different forms. Classification is based in any of the three factors:
Nature of the corrodent. Corrosion can be classified as “dry” or “wet.” Moisture or a liquid is necessary for former, dry corrosions involve reaction with gases with high temperatures.
Corrosion mechanism. It involves either direct chemical or electrochemical reactions.
Appearance of corroded metal. Corrosion is either localized, in this case small areas are affected, or uniform, where the metal corrodes over the entire surface uniformly.
Classification by appearance which is useful particularly in failure analysis is relied on when identifying corrosion forms by visual observation with magnification or naked eye. Attack morphology is the basis for classification. The following eight forms of wet corrosion can be identified basing on the appearance of corroded metal. Namely: general or uniform corrosion, pitting corrosion, galvanic corrosion, erosion-corrosion such as fretting corrosion and cavitation corrosion, intergranular corrosion such as exfoliation and sensitization, de-alloying such as graphic and dezincification corrosion, and environmentally assisted cracking such as corrosion fatigue, stress-corrosion cracking and hydrogen damage(ASM International, 2000).
Most of the dangerous corrosions occur in industrial plants such as chemical processing plants or electrical power plants. Plant shutdowns can occur due to corrosion. This is one of the many indirect and direct consequences. Some of the consequences are economic and can cause the following:
Preventive maintenance such as painting
Overdesign to allow for corrosion
Replacement of corroded equipment
Equipment shutdown because of corrosion failure
Loss of valuable product, for instance, from a container that is corroded.
Loss of efficiency, for instance when corrosion and overdesign products decrease the rate of heat transfer in heat exchangers.
Inability to use desirable materials otherwise
Damage of equipments adjacent to ones in which corrosion failure occurs.
Economic impact of corrosion
Although the cost of erosion varies significantly from industry to industry, in general, several elements combine to make up the total cost of corrosion in an industry. Some elements are readily recognized while others are not easy to recognize. Corrosion costs in manufacturing are incurred in several ways in the product development cycle, beginning with the materials, labor, technical expertise, and energy required to produce a product. For instance, a product may require painting to protect it from corrosion. A metal that is resistant to corrosion can be chosen instead of plain carbon steel, technical services may be needed to design and install in the product cathodic protection. Additional heat treatment may also be needed to relieve stresses to protect against stress corrosion cracking. Corrosion also affects other operating costs. Corrosion inhibitors, for instance must be added to water treatment systems (ASM International, 2000).
Portions of repair and maintenance costs can be attributed to corrosion, and often corrosion specialists are employed in order to implement corrosion control programs. Because of corrosion, capital costs are also incurred. Corrosion decreases the manufacturing equipment useful life. For an operation anticipated to continuously run, excess capacity is needed to allow scheduled downtime and the related corrosion maintenance. In some cases, redundant equipment is installed so as to allow maintenance on one unit while in other units processing continues.
For the consumer or the end user, corrosion costs are incurred for purchases of control products and corrosion prevention, repair and maintenance, and procurement replacement. According to NIST study, the following are the elements of the cost of corrosion; loss of product, replacement of equipment, repair and maintenance, excess capacity, redundant equipment, technical support, corrosion control, design, insurance, and equipment and parts inventory.
Repair and maintenance, loss of product, and replacement are fairly straightforward elements. Excess capacity is a corrosion cost if plants downtime scheduled for continuous operation can be reduced when corrosion is not a factor. The excess capacity element accounts for the extra capital stock (plant capacity) maintenance due to corrosion. The redundant equipment element accounts for the additional capital stock (plant equipment) needed due to corrosion. Specific components like large pumps and funs are backed up by items that are identical to enable processing to continue when maintenance for corrosion control is done.
The corrosion control costs are straightforward; this is because technical support such as testing, engineering, and research and development costs associated with corrosion. The costs of corrosion associated with design are not always obvious. Inventory and insurance elements in specific cases can be significant. In addition to the ten elements, other cost factors that are less quantifiable such as loss of good will or loss of life due to corrosion can have major impact. For instance, in catastrophic failures, corrosion induced leak in oil pipeline resulting in environmental contamination and loss of product can result in costly damage to the company that is difficult to repair or assess and massive legal penalties for the damage.
Facts on cost of corrosion
The cost of meat corrosion in the economy of United States is about 300 billion dollars per year at current prices. Approximately 1/3 of these costs can be reduced by application of materials that are resistant to corrosion and application of best technical practices related to corrosion. These estimates come from a recent update on findings of a study conducted by National Institute of Standards and Technology (NIST) and Battelle Columbus Laboratories in 1995, Economic Effects of Metallic Corrosion in United States. This was based on an elaborate model of more than one hundred and thirty economic factors, corrosion cost US 82 billion dollars, or 4.9 percent of its gross national product. It was found also that 60 percent of that cost could not be avoided. The remaining 40 percent (33 billion dollars) was incurred due to failure to use known best practices (avoid able costs). Price inflation and economic growth over the last two decades have increases gross national product more than four times. Therefore, if nothing else has changed, metallic corrosion costs would have risen to about 350 billion dollars annually, 139 billion dollars of which can be avoided (ASM International, 2000).
However, twenty years of technological change and scientific research have affected these costs. Battelle updated its earlier results by evaluating the two decades of changes related to corrosion judgmentally in industrial practices and scientific knowledge. In the original study, about 40 percent of metallic costs were incurred in use, production, and maintenance of motor vehicles. However, no other sector accounted for more than 4 percent of the total cost, most sectors contributed less than 1percent. For instance, aircraft sector was the second largest contributor and accounted for more than 3 percent. Pipeline sector which corrosion leads to a serious problem accounted for less than 1 percent of the total cost.
The panel also found that automotive sector has made great anti-corrosion efforts. Advances have been made in the use of coated metals, stainless steel, and more protective finishes. Also, several substitutions of materials primarily made for weight reduction reasons have also reduced corrosion. Moreover, the panel estimates that 15 percent of the corrosions costs that could not be avoided before are now classified as avoidable. It is estimated that the industry have eliminated 35 percent of avoidable corrosion through improved practices. In examining ship building, pipeline, and aircraft sectors, the panel reported both gains and losses have occurred, for example, the use of expensive materials in many cases has reduced the need for repairs related to corrosion or repainting. Finally, increased costs of corrosion results from regulations from government that prohibit use of time-honored protection methods because of environmental or safety damage. For instance, in order to reduce smog, elimination of paints with lead on bridges and houses, chromate inhibiting paints on oil based, and aircraft paints throughout industry has severe repercussions.
Methods of corrosion control
There are five methods of controlling corrosion namely; material selection, coatings, inhibitors, cathodic protection, and design (ASM International, 2000).
Coating for protection against corrosion can be categorized into metallic and nonmetallic. Either coating type has the same intent which is to isolate the underlying metal from any corrosive media.
Inorganic coatings include chemical setting silicate cement linings, porcelain enamels, linings and glass coatings, and other ceramics resistant to corrosion. Inorganic coatings like organic coatings serve as barrier coatings.
Some chemical species inhibit corrosion. Organic amines, silicates, and chromates are common inhibitors. For instance, in organic amines, the inhibitor is absorbed on cathodic and anodic sites and stifles corrosion current. Other inhibitors promote formation of protective film on metal surface.
This kind of protection suppresses corrosion current which causes damage in corrosion cell and force current to flow to metal structure to be protected, hence corrosion is prevented.
Rational design principles application can eliminate several corrosion problems and reduce greatly the cost and time associated with corrosion repair and maintenance. Corrosion often occurs in dead crevices and spaces where corrosive medium becomes much more corrosive. These can be minimized or eliminated in the design process.
Barbara, A. & Robert G. Materials - Effects & Economic impact of Corrosion, 2014. 11 April 2015 < http://www.wermac.org/materials/corrosion.html>
ASM International. The Effects and Economic Impact of Corrosion, 2000. 11 April 2015 <http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCMQFjAA&url=http%3A%2F%2Fwww.asminternational.org%2Fdocuments%2F10192%2F1849770%2F06691G_Chapter_1.pdf&ei=FDUpVdW8D8PU7AbV64DoAQ&usg=AFQjCNHU13fNvHygCUHyAk5LIz8MBZyLtg&sig2=WiTDiVmzPUu1Z0Ag3CxAsg&bvm=bv.90491159,d.ZGU>