Chemical process industry crevice corrosion

The Materials Technology Institute of the Chemical Process Industry (MTI) has identified five corrosion tests for iron- and nickel-based alloys, out of which two concern the resistance to crevice corrosion. The method MTI-2, originating from ASTM G48, involves the use of 6% ferric chloride solution for determining the relative resistance of alloys to crevice corrosion in oxidizing chloride environment. The method MTI-4 uses an increase in neutral bulk Cl- concentration at eight levels, ranging from 0.1 to 3% NaCl, to establish the minimum critical Cl concentration that produces crevice corrosion at room temperature (20-24°C).43,44... 

The Ni-Cr-Mo alloys are widely used within the chemical process industry. These alloys are resistant to both oxidizing and reducing environments. They resist chloride-induced pitting, crevice corrosion, and S.C.C. In addition, they are easily formed and are weldable. 

To overcome these limitations. Method D measures the critical crevice corrosion temperature, using a multiple crevice assembly (MCA). The test solution is 6 wt. percent FeCl3 acidified with 1 wt. percent HCl. This test method is also referenced in ASTM G 157 for evaluating the corrosion properties of wrought iron- and nickel-based corrosion resistant alloys for the chemical process industries. 

MaterialsTechnology Institute of the Chemical Process industries. Inc. Crevice corrosion, but reoorted as average corrosion rate... 

There are large numbers of reported case histories of MIC on stainless steel in water and aqueous waste systems. They are related to different industrial applications such as freshwater storage and circulation systems in nuclear power plants [103, 113,116,142] and cooling water systems in chemical process industries [117,118]. There are basically three cases (a) crevice corrosion under unexpected deposits, (b) sensitivity of pitting and crevice corrosion to trace of H2S, and (c) crevice corrosion in natural seawater. Most of these reports are not well documented concerning the microorganisms involved in the process. However, some general features are... 

Type 317 stainless steel contains greater amounts of molybdenum, chromium, and nickel than type 316. The chemical composition is shown in Table 10.1. As a result of the increased alloying elements, these alloys offer higher resistance to pitting and crevice corrosion than type 316 in various process enviromnents encoimtered in the process industry. However, they may still be subject to chloride stress corrosion cracking. The alloy is... 

The corrosion resistant properties of alloy A1-6XN show exceptional resistance to pitting, crevice attack, and stress cracking in high chloride concentrations and general resistance in various acid, alkaline, and salt solutions found in chemical processing and other industrial environments. 

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