Corrosion control environmental

Approximately 5% of the U.S. consumption of is in agriculture. Boron is a necessary trace nutrient for plants and is added in small quantities to a number of fertilizers. Borates are also used in crop sprays for fast rehef of boron deficiency. Borates, when apphed at relatively high concentration, act as nonselective herbicides. Small quantities of borates are used in the manufacture of alloys and refractories (qv). Molten borates readily dissolve other metal oxides usage as a flux in metallurgy is an important apphcation. Other important small volume apphcations for borates are in fire retardants for both plastics and ceUulosic materials, in hydrocarbon fuels for fungus control, and in automotive antifreeze for corrosion control (see Corrosion and corrosion inhibitors). Borates are used as neutron absorbers in nuclear reactors. Several borates, which are registered with the Environmental Protection Agency (EPA) can be used for insecticidal purposes, eg, TIM-BOR. 

The industrial economy depends heavily on electrochemical processes. Electrochemical systems have inherent advantages such as ambient temperature operation, easily controlled reaction rates, and minimal environmental impact (qv). Electrosynthesis is used in a number of commercial processes. Batteries and fuel cells, used for the interconversion and storage of energy, are not limited by the Carnot efficiency of thermal devices. Corrosion, another electrochemical process, is estimated to cost hundreds of millions of dollars aimuaUy in the United States alone (see Corrosion and CORROSION control). Electrochemical systems can be described using the fundamental principles of thermodynamics, kinetics, and transport phenomena. 

Contents v. 1. Metal/environmental reactions - v. 2. Corrosion control. 

Whilst careful design and informed forethought can often minimise or even prevent corrosion at little extra cost where the environmental conditions or the conditions of service are severe (as in most forms of marine and offshore engineering) reliable, secure and cost-effective corrosion control cannot be effectively achieved without considerable expense, although even in these circumstances good design can help to significantly reduce this. In... 

Paints are one of the most important methods of corrosion control, but it is well known that many cases of failure result from inadequate surface preparation of the metal and careless application of the paint system procedures that are often carried out under adverse or unsuitable environmental conditions by labour that is relatively unskilled. A great deal of research and... 

USEPA (1985), Odor and corrosion control in sanitary sewerage systems and treatment plants, US Environmental Protection Agency, EPA 625/1-85/018, Washington DC. 

Shipilov, S.A., Catastrophic Failures Due to Environment-Assisted Cracking of Metals Case Histories, in Proceedings of the International Symposium on Environmental Degradation of Materials and Corrosion Control in Metals, M. Elboujdaini, E. Ghali (eds.), The Conference of Metallurgists, COM, METSOC, pp. 225-242, 1999. 

The corrosion engineer can play a major role in system design, material selection, process or environmental control, and remediation. The focus of these efforts should not necessarily be the complete elimination or avoidance of corrosion, but rather the selection of the most cost-effective means of corrosion control and abatement. 

The spray formulation appears to be nontoxic because both fish and algae grow readily in the ponds. The pH level of the water in the ponds has remained constant, which indicates that bacteria are not converting sulfur to sulfuric acid. Samples of the formulation were exposed to bacterial attack in a controlled environmental chamber maintained at a high moisture level to accelerate the rate of attack. No evidence of bacterial attack on the samples has been detected after 1 yr of exposure under aerobic conditions. Initial corrosion tests showed that samples of the formulation did not lose weight after exposure in 1 and 5% sulfuric acid solutions for 4 months. 

Protection of cooling system metals involves complex interrelated problems of scale and deposit prevention, control of microbiological growths and other fouling sources, in addition to corrosion mitigation by inhibitors. Corrosion control programs may be expected to vary considerably between systems, since each installation presents different environmental factors and operating problems which affect response. 

The petroleum refining industry is undergoing intense scrutiny in the United States of America from regulatory agencies and environmental groups. The total cost of corrosion control in refineries is estimated at 3,692 billion. The costs associated with corrosion control in refineries include both processing and water handling. 

Significant maintenance costs for pipeline operation are associated with corrosion control and integrity management. The driving forces for the expenditure of maintenance dollars are to preserve the asset of pipeline, which is equal to 93.3 billion in book value and 541 billion in replacement value and to ensure safe operation without failures that jeopardize public safety, result in lost product and throughput, and cause property and environmental damage that is estimated at 470-870 million/year. 

Periodic reviews are necessary to determine if the current corrosion control methods are adequate. Coatings on equipment may deteriorate and need to be replaced. Inhibitor dosage has to be adjusted depending on environmental or process changes. 

Sometimes the need to be environmentally acceptable may lead to new problems. For instance, ozone was suggested to replace biocides with no data available on the performance in the chlorination of water (60). Corrosion control techniques can have both favorable as well as ill effects and hence one has to exert balanced judgment before embarking on a corrosion prevention method. Organotin antifouling coatings on ships were effective, but they polluted the seawater and hence were banned from further use. The use of cadmium as a sacrificial anode is restricted because of its toxicity. Large amounts of zinc are used to protect steel platforms in the sheltered and shallow waters of the sea, and the effects of zinc on the contamination of waters are not known. 

Environmental and Corrosion Control Effects of Hydrogen Sulfide Scavengers in Oil and Gas Exploration... 

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