Corrosion estimation

Table 12.5 Initiation time for chloride-induced corrosion estimated for different concrete cover thicknesses, utilising apparent diffusion coefficients of chlorides (D,pp) evaluated on specimens submerged in the North Sea for 16 y (concrete of 420 kg/m of Portland cement, OPC, or blast furnace slag cement with 70% GGBS and identical curing procedures) [18]...

M. Pentti, The accuracy of the ex-tent-of-corrosion estimate based on the sampling of carbonation and cover depths of reinforced concrete facade panels , Tampere University of Technology, Publication 274, 1999. 

Corrosion control methods consist of protective coatings, corrosion-resistant metals and alloys, corrosion inhibitors, polymers, anodic and cathode protection, corrosion control services, corrosion research and development, and education and training. The total annual cost of corrosion estimated with this method for the average year of 1998 was 121.41 billion or 1.381% of the 8.79 trillion gross domestic product. Table 4.1 shows the distribution of corrosion control methods and services eosts. 

The total cost of electricity sold in the United States in 1998 was 3.24 million gigawatt hours at a cost to consumers of 218.4 billion. The electricity generation plants use fossil fuel, nuclear, hydroelectric, cogeneration, geothermal, solar, and wind energies. The major players are fossil and nuclear steam supply systems. The two types of nuclear reactors are boiling water and pressurized water reactors. Some relevant data on the costs of corrosion estimated in 1998 are as follows nuclear facilities 1,546 billion fossil fuel sector 1,214 billion transmission and distribution 607 million hydraulic and other power 66 million. The total cost of corrosion in the electrical utilities industry in 1998 is estimated at 6,889 billion/year. 

Equation (5.36) is used to calculate the corrosion rate of a system without knowledge of electrode-kinetic parameters. This approximation may not always result in accurate corrosion estimates. However, this equation provides a basis for rapid corrosion evaluation studies. 

The hydroxide has the highest anion effectiveness to stop pitting corrosion Estimated inhibitor anion effectiveness is Perchlorate < Sulphate [Pg.718]

FIGURE 6.20 Amount of corrosion (estimated by Faraday s law) with progress of accelerated corrosion. (From Mihashi, H. et al., Journal of Advanced Concrete Technology, 9(2) 159-167, 2011. With permission.)... 

The partial current/corr is called the corrosion current and the rate of corrosion estimated from this current and Faraday s law should be the same as that from weight loss experiments where the rate of metal dissolution is determined by weighing a sample of metal before and after standing in the electrolyte for a period. It should be noted that the corrosion potential is a, so-called, mixed potential since it is determined by the kinetics of two electron transfer couples, M/M" and H2O/H2 (cf. the equilibrium potential for a single couple. Chapter 1). 

Post-test analysis porous component stability estimation, electrolyte content measurement, corrosion estimation, and so on. 

In reality, the wet candle method gives an indication of the salinity of the atmosphere rather than the contamination of exposed metal surfaces. The technique is considered to measure the total amount of chloride arriving to a vertical surface and its results may not be truly significant for corrosivity estimates. 

The results obtained during the electrochemical testing of various faces of aluminum sheet material indicated that short-term EIS measurements could provide good predictions of the general and localized corrosion behavior of this material when exposed to seawater. In fact, the prediction of the localized corrosion behavior with the CPE calculated from the EIS data seemed to agree more closely to the long-term test results than the general corrosion estimation. ... 

According to the World Corrosion Or nization, the annual direct cost of corrosion estimated worldwide exceeds 132 trillion, which means approximately between 3 and 4% of the gross domestic product (GDP) of industrialized countries. 

Knowing the form in which free alkali reaches the tube surface is essential for the high temperature corrosion estimation of biomass fuels as KOH can form a molten phase from metal temperatures of 400°C upwards [3], whereas K2CO3 melts at 891°C and even the system (Na,K)Cl-(Na K)2C03-(Na,K)2S04 has a lowest possible melting point of 511°C [7]. 

The Zond VD - 96 is intended for the detection of cracks, precipitates, inclusions etc. and corrosive defects with the preliminary estimation of their depth in various objects of magnetic and non - magnetic steels, non-ferrous and refractory metals and welds including coatings. 

Projection radiography is widely used for pipe inspection and corrosion monitoring. Film digitisation allows a direct access to the local density variations by computer software. Following to a calibration step an interactive estimation of local wall thickness change based on the obtained density variation is possible. The theoretical model is discussed, the limitations of the application range are shown and examples of the practical use are given. The accuracy of this method is compared to results from wall thickness measurements with ultrasonic devices. 

Projection radiography has long been used for pipe inspection and corrosion monitoring. In this traditional tangential wall thickness estimation the distance of border lines of the projected wall shadows of a pipe onto the film is a direct measure for the wall thickness. This method is not considered here, newer developments can be found in / /. 

In fig, 4 local corrosion by erosion is shown in a pipe with a bore of 100 mm behind a welding. In this case only the nominal wall thickness of the pipe is known (6.3 mm). To calibrate the obtained density changes into wall thickness changes a step wedge exposure with a nominal wall thickness of 13 mm (double wall penetration in the pipe exposure) and the same source / film system combination was used. From this a pcff = 1-30 1/cm can be expected which is used for the wall thickness estimation of the pipe image according to equation (4). 

The basic seed processing plant design is based on 70% removal of the sulfur contained in the coal used (Montana Rosebud), which satisfies NSPS requirements. Virtually complete sulfur removal appears to be feasible and can be considered as a design alternative to minimize potential corrosion problems related to sulfur in the gas. The estimated reduction in plant performance for complete removal is on the order of 1/4 percentage point. The size of the seed processing plant would have to be increased by roughly 40% but the corresponding additional cost appears tolerable. The constmction time for the 500 MW plant is estimated to be ca five years. 

Explosion-bonded metals are produced by several manufacturers in the United States, Europe, and Japan. The chemical industry is the principal consumer of explosion-bonded metals which are used in the constmction of clad reaction vessels and heat-exchanger tube sheets for corrosion-resistant service. The primary market segments for explosion-bonded metals are for corrosion-resistant pressure vessels, tube sheets for heat exchangers, electrical transition joints, and stmctural transition joints. Total world markets for explosion-clad metals are estimated to fluctuate between 30 x 10 to 60 x 10 annually. 

S. M. Ah, "An Updated Version of Computer Code CORA II for Estimation of Corrosion Product Mass and Activity Migration ia PWR Primary Circuits and Related Experimental Loops," Eourth International Conference on Water Chemistry of Nuclear Systems, Bournemouth, U.K., Oct. 1986, pp. 107-109. 

Diffusion alurninide and sihcide coatings on external and internal surfaces for high temperature corrosion protection in parts such as gas-turbine blades is estimated at 40 x 10 /yr in North America and about 50 x 10 worldwide. 

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. 

Knowledge of the composition of coal ash is usehil for estimating and predicting coal performance in coke making and, to a hmited extent, the folding and corrosion of heat-exchange surfaces in pidverized-coal-fired furnaces. 

To obtain the corrosion current from Rp, values for the anodic and cathodic slopes must be known or estimated. ASTM G59 provides an experimental procedure for measuring Rp. A discussion or the factors which may lead to errors in the values for Rp, and cases where Rp technique cannot be used, are covered by Mansfeld in Polarization Resistance Measurements—Today s Status, Electrochemical Techniques for Corrosion Engineers (NACE International, 1992). 

Actual lifetime of the plant equipment. Corrosion monitoring provides data, which must then be analyzed with additional input and interpretation. However, only estimates can be made of the lifetime of the equipment of concern. Lifetime predictions are, at best, carefully crafted guesses based on the best available data. 

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