Mitigation corrosion

Miller, M. C., Portable Testing Instruments for Corrosion Mitigation Testing , Proceedings Appalachian Underground Short Course, W. Virginia University, USA (1959)... 

The large pores (ranging from 0.01 pm to 0.1 pm) are sealed by the continuous polymer film formed in the comatrix of LMM and LMC. Consequently, they show reduced water absorption, water permeability and water vapor transmission over ordinary cement mortar and concrete and this effect increases with an increase in polymer content and polymer-cement ratio (Fig. 6.15). The improved water permeability also improves the resistance to chloride ion entry and hence corrosion mitigation [87]. 

CORROSION MITIGATION IN REPAIR CONCRETE MIXES (ACCELERATED SETTING IN CONCRETES CONTAINING CALCIUM NITRITE AND... 

The definitions of the terms encountered in discounted cash-flow calculations are taken from the literature.1 3 Discounted cash flow is concerned with the analysis of the value of money as a function of time. The money available at a future date has less value at the present and should be discounted by the interest to present worth (PW). P is the notation for the present sum of money, which should be used in such a manner that it produces a future income more than other forms of investment, irrespective of whether it is used for new equipment or the corrosion mitigation process. Let F be the amount of money available in the future when an investment of P is made. The relation between P and F may be written as ... 

Corrosion mitigation of steel rebar in concrete can be achieved by ... 

The first mode of corrosion mitigation involves selection of material such as stainless steel rebar and the merits and demerits of this mode are detailed below. 

When a chemically stable oxide (or salt) film is present on the surface of a metal (see the iron oxide stable regions of Figure 4), that metal may be free of subsequent corrosion. The conditions for this form of corrosion mitigation are that the underlying film is adherent, coherent and pore-free. In essence, these conditions merely stipulate that the film must be an effective barrier between the metal and the environment. This condition is called passivity and is characterized by measured electrode potentials in the regions where the film.is stable. Iron and its alloys have been shown to exhibit passive behavior (i6). ... 

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. 

For gas distribution piping, corrosion mitigation is primarily sacrificial CP. ILI is not feasible for the relatively complex network of distribution mains and services. This makes integrity assessment of the piping somewhat difficult. 

External corrosion of water systems may be caused by general corrosion, stray current corrosion MIC, and/or galvanic corrosion. Corrosion mitigation techniques include the application of protective coatings, wrapping pipe in a plastic cover, and the application of CP. The areas of major external corrosion impact are generally those where localized attack may take place, such as in the proximity of other systems like galvanic corrosion or in areas where stray currents may occur. 

To address this type of corrosion mitigation problem, a specialized CP system was developed that can minimize the drying effect at the anode/concrete interface without direet water exposure. By creating a low-resistance anode interface using a semicon-ductive layer the effect of electrochemical osmosis at the anode/concrete interface can be minimized, so that the CP system is not dependent on water or moisture from the outside environment and can also operate at low voltage. In addition, the semicon-ductive layer would minimize acid generation if the anode comes into direct contact with saltwater present because of new water leakages. 

Because of the high cost of failure and inability to rehabilitate facilities in deep water, offshore production in deep water requires the use of high alloy steels and more exotic corrosion control measures. A similar need for advanced corrosion control measures is encountered when dealing with high-pressure and high-temperature offshore oil and gas fields where conventional corrosion mitigation is not applicable. Typical costs for various expenses for one large oilfield area are listed in Table 4.41. 

Corrosion in oil and gas production varies from one location to another location. Corrosion can be internal corrosion caused by the produced fluids and gases, external corrosion because of exposure to groundwater or seawater, and atmospheric corrosion caused by salt spray and weathering offshore. Of these, internal corrosion mitigation is the most difficult and expensive to mitigate and inspect periodically. 

It is usefiil to consider the case of an installation of a subsea gathering system for a natural gas production field. The pipeline design for a new gas production facility consisted of 20 cm diameter subsea gathering lines (flow lines) emptying into a 19 km, 50 cm diameter subsea transmission gas pipeline. The pipeline was to bring wet gas from an offshore producing area to a dehydration facility on shore. The internal corrosion was estimated to be 300-400 mpy. The corrosion mitigation options considered were (i) carbon steel treated with a corrosion inhibitor (ii) internally coated carbon steel with a supplemental corrosion inhibitor (iii) 22% Cr duplex stainless steel (iv) 625 corrosion-resistant alloy (CRA). The chance for success was estimated from known field histories of each technique, as well as the analysis of the corrosivity of the system and the level of sophistication required for successful implementation (Table 4.42). 

The Australian study was patterned after the Battelle-NBS study. An lO model of the Australian national economy was constmcted to first represent the real world and secondly to represent the world of optimum corrosion mitigation technology. Differences between the two scenarios were used as estimates of avoidable costs of corrosion and to indicate areas of potential savings. 

Houghton CJ, Westermark RV. Downhole corrosion mitigation in Ekofisk (North Sea) field. In CO2 Corrosion in Oil and Gas Production, Selected Papers, Abstracts, and References. Houston NACE Task Group T-1-3,1984. 

In NACE 2003, this author presented an algorithm that later became the basis of a software package to predict corrosion of a buried pipeline and especially predict the possibility of MIC. The software was also capable of comparing the changes and modifications applied in the system to see how efficient corrosion mitigation strategies had been. 

However, in today s harsh oil/gas production environments where facilities and equipment are becoming old, with attendant increases in maintenance costs, the use of inhibitors as opposed to the use of other expensive corrosion mitigation methods becomes an obvious choice as cost-saving solutions to extend the life of assets and infrastructures. Researchers have now focused on the use of volatile inhibitors mixed with oil and water-soluble inhibitors for use in mitigating corrosion in multiphase systems such as in the control of internal corrosion of pipelines and corrosion of... 

NeviUe, A., Wang, C. 2009. Erosion-corrosion mitigation by corrosion inhibitors— An assessment of mechanisms. Wear 267 (1-4), pp. 195-203. 

This book covers a wide spectrum of corrosion topics with rich illustrations, an easy to understand writing style, and the presentation of review articles, providing state-of-the-art corrosion-mitigation techniques useful for practicing engineers, technologists, and field technicians. It also provides a basic understanding of corrosion mechanisms, which will be equally beneficial to people who are not directly involved in the corrosion field to assist them in their related tasks. Based on its content and presentation of scientific and technical issues, this... 

Mitton, D.B. et al. (1998) Corrosion mitigation in SCWO systems for hazardous waste disposal, in Symposium on Corrosion in Supercritical Fluids, Corrosion 98, San Diego. 

Sun J, Howlett PC, MacFarlane DR, Lin J, Forsyth M (2008) Synthesis and physical property characterisation of phosphonium ionic liquids based on P(0)2(0R)2— and P(0)2(R)2— anions with potential application for corrosion mitigation of magnesium alloys. Electrochim Acta 54 (2) 254-260. doi 10.1016/j.electacta.2008.08.020... 

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