Hastelloy C-22 has found major applications in the chemical, petrochemical processing, pollution control, power production, marine systems, pulp and paper processing and waste industries. The alloy actively resists oxidation, carburization and sulfidation at high temperatures. It prevents high temperature corrosion by halides such as chlorides and halides. This super alloy is used to secure steel tubes and various other components in the coal- fired and waste to energy boilers. General corrosion prevention Hastelloy C22 prevents attack in reducing and oxidizing acids like sulfuric acid and hydrofluoric acids. It has extreme resistance against oxidizing acid chlorides, damped chlorine, formic and acetic acids, ferric and cupric chlorides, marine water, brines and contaminated chemical media including organic and inorganic solutions. High temperature services Alloy C22 is commonly used for offering outstanding service in the aqueous media, it also performs adequately in the high temperature service media about 1250oF for example Hastelloy C-22 wire is specifically found useful in the security of boilers, waterwalls and other parts in the coal fired electric generation boilers. The alloy has also offered supreme service in squat NOx boilers. The alloy prevents corrosion at the high temperatures by halides and sulfur that are usually seen in grades of coal used for power production. Hastelloy C22 also provides supreme resistance to severe corrosion by metal chloride and sulfate salts discovered in power production boilers involved in municipal solid waste incineration. Grade C22 is used to overlay the steel components through welding. The welds made from Hastelloy C22 prevent segregation as seen in Nickel – chromium – molybdenum – niobium alloys. To handle the severe emission limits, the fossil fuel and waste fired power production boilers are designed to add burners to limit the development of oxides of nitrogen. Enhanced security of boiler tubes and waterwalls for service in the severe environments is needed. Inconel 625 weld overlays have been utilized for a long time for the security of these boiler parts however the recent analysis shown that such overlays can experience circumferential cracking because of stress caused by sulfidation of the dendrite centers of the weld overlays within 18 months. Hastelloy C22 is developed fo-r applications that demand corrosion resistance in the severe service media. It is an increasing safeguard product that offers several benefits including enhanced life cycle cost service, higher reliability, nominal maintenance and decreased downtime cost. Alloy C22 has PREN (Pitting resistance equivalent number) 75 that is above 40 stating that it is extremely resistant to crevice attack in the marine water. Although in the very tight crevice media, for example in marine water cooled plate heat exchangers that receive tight crevices, use of Hastelloy C22 is recommended. The maximum attack depth by crevice attack after interaction with natural marine water at 29oC for 6 months is in reference of PREN. In the hot seawater at 60oC that is observed for two months, alloy C22 showed complete prevention of crevice signs. It was observed in offshore oil and gas plant seawater systems. Overall Hastelloy C22 offers the supreme service in the severe application media varying from seawater to chemical plants. |
26 Comments
Nichrome a primarily used resistance wire is ideally suited as heating material for its good electric resistivity, large melting point and potential to withstand the high temperature oxidation. The production of a chromium oxide security layer makes nichrome very stable in the high temperature air. Nichrome was patented in 1906 and far now it has become popular for use as coils and heating elements in the electric equipments such as toasters, oven, kilns, electric fires additionally, it is also used in the various other applications for example: Explosives, fireworks, where nichrome is used as electric ignition to develop a connection, hot nichrome 80 wire is used in the cutting applications, positive electrode in thermocouples, normally nichrome is used to supervise temperatures about 1110oC. Nichrome is used as a support structure for clay products that are fired. Nowadays nichrome is popularly used in electronic cigarettes and vaporizer. The excellent characteristics of high electric resistivity and oxidation resistance at the elevated temperatures make Nichrome fit for use in electric ovens, irons and hair dryers. In the industrial applications, nichrome is used as different heating elements for ovens of various sizes and systems that need to supply heat straight to the surfaces for example for sealing plastic packages. In the medical units, nichrome wire loops of spoon size are used in handling samples as they withstand quick and periodic sterilization and then cool quickly. In the industrial application, fine nichrome meshes are used as filters for handling high temperature liquids. As the wire heats up fast by supplying the nominal current, it is safe for igniters to light to activate the fireworks and model rockets. A part of nichrome wire of 1.5 inch length linked to a lead wire to safely allow the operator to detonate the system from some distance keeping only a battery and switch. The fireworks experts utilize nichrome igniters with specific times at big screens. Nichrome thin layers are commonly used in various applications in microelectronics like thin film resistors, filaments and humidity sensors as of their high resistivity, high oxidation resistance and small temperature coefficient of resistance. Nichrome provides good resistance to oxidation and corrosion and has adequate mechanical strength. Nichrome films are used in for strain gauge applications due to their good resistivity, low temperature resistance coefficient, easy availability and small temperature dependence of gauge factor. Benefits of Nichrome
|
AuthorHeanjia Super Metals Co ltd - one of the best metals and alloys provider in industry. Archives
March 2017
Categories |