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3 Corrosion Disasters of the Far East

Bhopal Accident - India

On the night of the 2-3 December 1984 water inadvertently entered the MIC storage tank, where over 40 metric tons of MIC were being stored. The addition of water to the tank caused a runaway chemical reaction, resulting in a rapid rise in pressure and temperature. The heat generated by the reaction, the presence of higher than normal concentrations of chloroform, and the presence of an iron catalyst , produced by the corrosion of the stainless steel tank wall, resulted in a reaction of such momentum, that gases formed could not be contained by safety systems.

As a result, MIC and other reaction products, in liquid and vapor form, escaped from the plant into the surrounding areas. There was no warning for people surrounding the plant as the emergency sirens had been switched off. The effect on the people living in the shanty settlements just over the fence was immediate and devastating. Many died in their beds, others staggered from their homes, blinded and choking, to die in the street.

It is been estimated that at least 3000 people died as a result of this accident, while figures for the number of people injured currently range from 200,000 to 600,000, with an estimated 500,000 typically quoted.

Sinopec Gas Pipeline Explosion - China

On Friday, November 22, 2013, the Donghuang II oil pipeline suddenly exploded in Qingdao in eastern China, ripping roads and sidewalks apart, turning cars over and sending thick black smoke over the city. The blast killed 62 people and injured 136 —China's deadliest spill since the benzene oil spill in the Songhua River in 2005.

 In January 2014, Sinopec published a statement on the explosion that blames worker error and corrosion for the accident; Huang Yi, a spokesman for the State Administration of Work Safety, said that the initial oil leak at the pipeline wasn’t properly inspected and that both the pipeline’s operator and local government departments bore responsibility for the explosions. The direct cause of the explosion was the ignition of vapors produced from oil leaking from a corroded under-ground pipeline when workers used a hydraulic hammer that wasn't explosion-proof, resulting in sparks that triggered the blasts. 

Fukushima Nuclear Plant Tank Leak - Japan

On March 11, 2011, a 9.0 magnitude earthquake took place 231 miles northeast of Tokyo, Japan, causing a tsunami with 30 foot waves. The earthquake and tsunami caused a full meltdown of the Fukushima nuclear plant. At the start of 2014, three miles from the plant the roads are still closed, and radiation levels are 100 times higher than normal. All four reactors are still emitting radiation. Tokyo Electric Power Co. (Tepco), the company that owns the plant, injects hundreds of tons of water daily into the highly radioactive reactors to keep them cool, but groundwater is pouring into the damaged reactors and has to be pumped out and stored. The steel tanks that are used to store the contaminated water can’t be built fast enough--400 tons of contaminated water needs to be stored every day.

In August 2013, 300 metric tons of contaminated water leaked from a storage tank. The leak, first detected on August 19, was described by Japan's nuclear regulator as the worst accident at Fukushima since the earthquake and tsunami of 2011 caused reactors to melt.

Tepco concluded that the tank leak was probably caused by corrosion around faulty seals. The Fukushima plant has more than 1,000 tanks holding in excess of 380,000 tons of water irradiated from contact with reactor fuel. About 300 of the tanks are of the same bolted variety as the leaking tank. Tepco had rushed to build the tanks out of steel, but with the salt and all the radiation, they corroded quickly. At the time of the leak, only two inspectors were checking 900 tanks at any one time, so this highly radioactive leak went unnoticed for a month.

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The protection of assets from corrosion is a key commercial, safety and environmental issue.

Deterioration of concrete structures can become a challenge for the owners of structures such as bridges, walkways, high rise buildings, etc. It is important to identify these defects on time and plan appropriate repair strategies. Concrete deterioration can occur through scaling, disintegration, erosion, corrosion of reinforcement, delamination, spalling, alkali-aggregate reactions, and cracking of concrete. Moreover, corrosion of reinforced steel is the main cause in modern concretes.

Successful contractors understand the importance of adding value to their clients' assets/structures. One of the best ways to do this is to offer additional services that provide a cost-effective benefit to the client. Contractors can provide value added service to their clients through the application of cathodic protection. Cathodic protection system stops the corrosion cycle in concrete by utilizing an electrical current. It can be an add-on service for the concrete contractor and a cost-effective benefit to the client.

How does cathodic protection work?

In the simplest terms, a small DC electrical current is discharged off of an anode and flows through the concrete to the reinforcing steel. This protective current prevents corrosion from occurring. A small power supply unit converts AC power available at the site to DC power to provide the negative charge, which is used to arrest the natural corrosion process. Typically these systems use very little power -- not much more than a conventional 120 Watt electric light bulb. The contractor has a wide range of decorative top coats available to finish the process while meeting the aesthetic requirements of the project. For more than 20 years, this proven technology has been employed successfully on numerous installations in coastal environments.

Contractors should be encouraging their clients to consider cathodic protection when major repair projects are undertaken. The first reason is the most important -- quite simply, cathodic protection stops the repair cycle by preventing further corrosion. When the client/owner completes a major concrete repair only to find that more corrosion is occurring just a few years later, there is an unhappy client eager to blame the initial repair contractor. Cathodic protection stops future corrosion which in turn stops the vicious restoration cycle.