Corrosion resistance, stainless

S00001-S99999 Heat- and corrosion-resistant (stainless) steels... 

TABLE 28-14 Standard Cast Corrosion-Resistant Stainless Steels ... 

Truman, J. E., An Austenitic Stainless Steel of Improved Strength and Corrosion Resistance , Stainless Steel Industry, 6, 21-32 (1978)... 

The design of equipment for use in controlled environment areas follows similar principles, whether for general injectable manufacturing or for the manufacturer of sterile ophthalmic pharmaceuticals. All tanks, valves, pumps, and piping must be of the best available grade of corrosion-resistant stainless steel. In general, stainless steel type 304 or 316 is preferable. 

Washing machines currently on the market are constructed almost exclusively with drums and laundry tubs of corrosion-resistant stainless steel or with an enameled finish that is inert to alkaline wash liquors. Nevertheless, various machine components are made of less detergent resistant metals or alloys. To prevent corrosion of these parts, modern detergents contain corrosion inhibitors in the form of sodium silicate. The colloidal silicate that is present, deposits as a thin, inert layer on metallic surfaces, thereby protecting them from attack by alkali. 

Acidic must use corrosion-resistant (stainless steel) vessels. 

Modification of the metal itself, by alloying for corrosion resistance, or substitution of a more corrosion-resistant metal, is often worth the increased capital cost. Titanium has excellent corrosion resistance, even when not alloyed, because of its tough natural oxide film, but it is presently rather expensive for routine use (e.g., in chemical process equipment), unless the increased capital cost is a secondary consideration. Iron is almost twice as dense as titanium, which may influence the choice of metal on structural grounds, but it can be alloyed with 11% or more chromium for corrosion resistance (stainless steels, Section 16.8) or, for resistance to acid attack, with an element such as silicon or molybdenum that will give a film of an acidic oxide (SiC>2 and M0O3, the anhydrides of silicic and molybdic acids) on the metal surface. Silicon, however, tends to make steel brittle. Nevertheless, the proprietary alloys Duriron (14.5% Si, 0.95% C) and Durichlor (14.5% Si, 3% Mo) are very serviceable for chemical engineering operations involving acids. Molybdenum also confers special acid and chloride resistant properties on type 316 stainless steel. Metals that rely on oxide films for corrosion resistance should, of course, be used only in Eh conditions under which passivity can be maintained. 

The column, pumps, and piping in contact with the hot fatty add are made from corrosion-resistant stainless steel. The column is a hollow vessel, containing no baffles, trays, or packing material of any kind The quality of the hydrolyzing operation is determined by the degree of split obtained on the fat. lbe fatty acid stream contains very little free glycerin, if any. 

It is stored in isolated corrosion resistant stainless steel tanks. The spent acids from various sources (e.g. alkylation catalyst, jet fuel catalyst) are stored separately. This avoids unanticipated reactions between their different organic components. 

The corrosion resistance of steel is significantly improved by alloying with other metals. Highly corrosion-resistant stainless steel is an alloy containing about 15% Cr by mass. 

ACI. Alloy Castings Institute produced a system for corrosion resistant and heat resistant castings. The letter C indicates the corrosion series and the letter H indicates the heat series. For example, CF-8 is a corrosion resistant stainless steel and HK-40 is a heat resistant stainless steel. 

Figure 4-4. Martensitic stainless steels are the least corrosion resistant stainless steel family. 

Stabilizing is done on certain corrosion resistant stainless steels and nickel alloys containing titanium, niobium or tantalum to enhance corrosion resistance. They are heated to specific temperatures so that these elements combine preferentially with carbon, preventing any detrimental loss of... 

Yearly inspection or twice in a year inspection of stainless steel components especially load bearing components is desirable. Where staining or corrosion is found, corrosion products may be removed and the loss of cross section and integrity assessed. Load bearing or other safely components should be tested for SCC. When necessary, components should be more corrosion-resistant stainless steel parts. 

Aberle D., Agarwal D. (2008), High Performance Corrosion Resistant Stainless Steels and Nickel Alloys for Oil and Gas Apphcations (Paper No. 08085), Houston, TX NACE International. 

Aberle, D., Agarwal, DC. 2008. High performance corrosion resistant stainless steels and nickel alloys for oil and gas applications. NACE—International Corrosion Conference Series, Corrosion 2008 New Orleans, LO March 16-20, 2008 Code 77054, pp. 080851-0808517. 

Some materials are more susceptible to crevice corrosion than others. These materials depend on an oxide film to achieve corrosion resistance. Stainless steel and titanium are prime examples. In addition to improving the design to minimize crevices and to maintain a clean surface on certain materials, alloying of particular materials can be used to improve their resistance to corrosion. 

Material of Constmction of Float shall be corrosion-resistant Stainless Steel 316 or carbon steel coated with Teflon or glazed ceramic. 

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