Corrosive Effect On Steel example essay topic

MIC Products and machines made of steel have long been considered to be solid, strong, and very durable. The effects of general corrosion, "rust", were considered to be the only factor limiting a steel product's ability to last forever. It is thought that the general corrosion of steel is recognizable and its effects are easily limited by the application of various coatings and paints. Only in more recent years have the destructive effects of Microbiological Influenced Corrosion, "MIC" been discovered. Today MIC, whether it is on the bottom of a barge, in a water pipe, or in a nuclear power plant's cooling tower, has evolved into a billion dollar problem. To cure this problem, I have created a device that cleans MIC out of the bilges of barges operated on the Mississippi River system.

The bilges or confined void spaces have never been able to be cleaned due to the extremely tight or inaccessible area in which you would have to work. I found that most barges have a coating on the steel which provides a food source that the MIC bacteria absorbs (eats) and the bacteria's resulting acid actually can penetrate the steel barge. Businesses that clean these barges to rid them of the MIC and the organic coating can charge as much as $10,000 to do just the ends of the barges, which is an area less than a tenth of the entire barge. The inner bottom void spaces which take up the remainder of the barge's area are only 15" high, 27" wide, and 28' long. Some barges have as many as 90 of these confined spaces, and none of them have been cleaned because their limited size makes them inaccessible. With the completion of my product it will be the first time the inner bottom void spaces of a barge can be cleaned.

This will mean the MIC and its food source, the organic coating; will be completely removed from the barge for the first time since its original construction at the ship yard. For many years, MIC was incorrectly identified as the corrosive effects of saltwater on steel in ocean going vessels. Although salt certainly does have a corrosive effect on steel, it was not until more recent years that the term MIC was originated, and its effects are only starting to be discovered. MIC is responsible for the accelerated corrosion in ocean going ships, water storage tanks, fire protection sprinkler systems, commercial and military aircraft, and most recently discovered affecting the inland river barge fleet. MIC is a type of corrosion which is identified by single celled micro-organisms such as algae, fungi and most commonly bacteria (Smart 57). The presence of bacteria in low oxygen or even anaerobic conditions with the most fundamental nutrient source can allow for the colonization of bacteria and result in MIC.

"The water environment can be free flowing, stagnant, fresh, brackish or salt" (Jeffery 1). "Contrary to general corrosion, MIC corrosion is highly localized and the rate of corrosion can be extremely rapid, resulting in the 100% penetration of heavy gauge steel pipes or plates in just a few months" (Smart 60). Bacteria live synergistically, assisting each other, and when consuming the nutrient source the bacteria excrete acids which are highly corrosive and can destroy certain components of the steel (Chem tex 2). This results in the degradation of the steel. Prohibiting or limiting the destructive effects of MIC, requires a very thorough understanding of the various organic chemical reactions, all occurring within an area visible only through a microscope.

It is said that there are about thirty five thousand barges in the US. The average barge comes out to be close to three hundred and fifty thousand dollars for the purchase price. Multiply those together and that is the value of the barge assets in the US. That staggering amount is over twelve billion dollars. MIC is most commonly found in the wing tanks of the barges. Although it takes awhile for the MIC to eat through the 5/16"-1/2" steel, the affects are the same in that it eats holes though the steel.

Pits in a ballast tank of a ship have reached six inches in diameter (Smart 3). If a boat is taking on water it is an extremely expensive ordeal for the vessel owners. Repairs must be done in a dry dock where the barge is lifted out of the water. Just storage costs at dry docks can be about a thousand dollars a day. On top of that cost is that actual repair of the barge which can be very time consuming considering that a barge is two hundred feet long and thirty five feet wide. The actual repair process takes a very long time and making sure that the welds are water tight is a very intricate skill that only a few shipyards are capable of doing.

For a barge to be done right, it can take many days or weeks to return a barge back into proper working order. In many cases in which large sections of the bottom are in need of workmanship the process is so expensive that the company will purchase a new barge. Though this does not seem ethical, it is not cost effective to pay more than half the price of a new vessel to fix an old. The ocean going ship which encounters salt water magnifies the MIC and process constantly and has to deal with this problem. The largest ocean going boat is over one thousand and five hundred feet long.

It is one of thousands of large ocean going ships that can be affected by MIC. The amount of affected vessels is multiplied by the cost of the vessel; ocean going boats can range from less than a million up to hundreds of millions of dollars. These boats are much larger than barges and since they cost much more money than a barge, the ships are not expendable like the barges and repairs must be made. Since the problem with MIC has occurred, dry docks have been over burdened with ships that need patching. In certain industrial applications, the affects of Microbiological Influenced Corrosion have been known for many years. It has only been in the recent past that Microbiological Influenced Corrosion has been found in non salt water applications, such as the inland river barge industry.

If left unaddressed, MIC could dramatically shorten the remaining life of hundreds of billions of dollars worth of steel pipes, structures, and vessels. Through this paper and resulting research, investors and owners of steel related assets will be made aware of how vulnerable and fragile their investments could be without proper treatment against MIC.

Bibliography

Jeffrey, Wood Marine LTD. 2 Oct. 2002 web.
Smart, John. "An Introduction to Microbiological Influenced Corrosion in the Marine Industry". Journal of Protective Coating& Linings. Feb 1997.
4 Oct. 2003.
Sulfate Reducing Bacteria (SRB). 15 Nov. 2002.