Service copper

Trade Service, Copper Pricing 2006, http //www.tradeservice.com/ copper pricing/index.htm, accessed September 20, 2006. 

Iron, steel, stainless steel, Monel, and some plastics have proven satisfactory in methy-lamine service. Copper, copper alloys (including brass and bronze), zinc (together with zinc alloys and galvanized surfaces), and aluminum are corroded by the methylamines and should not be used in direct contact with them. Mercury and the methylamines can explode on contact, and instruments containing mercury must never be used with the methylamines. Among gasket and packing materials satisfactory for use with them are compressed asbestos, polyethylene, Teflon, and carbon steel or stainless steel wound asbestos. 

Iron, steel, stainless steel. Monel, and some plastics have proven satisfactory in methylamine service. Copper, copper alloys (including brass and bronze), zinc (together... 

For most applications, 316 s.s. is used for seal strips as flexibility and corrosion resistance are required. In noncorrosive services, copper alloy seal strips are used. 

Copper, with its high heat conductivity, resists frictional heat during service and is readily moldable. It is generally used as a base metal, at 60—75 wt %, whereas tin or zinc powders are present at 5—10 wt %. Tin and zinc are soluble in the copper, and strengthen the matrix through the formation of a soHd solution during sintering. 

Ammonia is corrosive to akoys of copper and zinc and these materials must not be used in ammonia service. Iron or steel should usuaky be the only metal in ammonia storage tanks, piping, and fittings. It is recommended that ammonia should contain at least 0.2% water to prevent steel stress corrosion. Mercury thermometers should be avoided. 

Greater amounts of copper increase the proportion of needles or stars of Cu Sn in the microstmcture. Increase in antimony above 7.5% results in antimony—tin cubes. Hardness and tensile strength increase with copper and antimony content ductiUty decreases. Low percentages of antimony (3—7%) and copper (2—4%) provide maximum resistance to fatigue cracking in service. Since these low alloy compositions are relatively soft and weak, compromise between fatigue resistance and compressive strength is often necessary. 

A. Sutulov, Copper Porphyries University of Utah Printing Services, Salt Lake City, Utah, 1974. 

D. H. Davidson, R. E. Weeks, and J. P. Edwards, Generic In Situ Copper Mine Design Manual, 5 vols., available from National Technical Information Service, Springfield, Va., 1988. 

Stress Relaxation. Copper alloys are used extensively in appHcations where they are subjected to moderately elevated temperatures while under load. An important example is the spring member for contacts in electrical and electronic coimectors. Critical to rehable performance is the maintenance of adequate contact force, or stabiUty, while in service. Excessive decrease in this force to below a minimum threshold value because of losses in spring property can lead to premature open-circuit failure (see Electrical connectors). 

Fatigue properties in bending are most appropriate for copper aHoys as these are often used as spring contact components in beUows and electrical switches and coimectors. These articles are usuaHy designed for acceptable service Hves at a moderate to high number of stress cycles. 

Heat for soldering is usually obtained from torches. The high conductivity of copper makes it necessary to use large flames for the larger sizes, and for this reason the location in which the joint will be made must be carefully considered. Soldered joints are most widely used in sizes 2 in and smaller for which heat requirements are less burdensome. Soldered joints should not be used in areas where plant fires are hkely because exposure to fires resiilts in rapid and complete failure of the joints. Properly made, the joints are completely impervious. The code permits the use of soldered joints only for Category D fluid service and then only if the system is not subject to severe cychc condions. 

TABLE 10-32 Copper Outside-Diameter Tubing for Refrigeration Field Service and Automotive and General Service (ASTM B280) ... 

Copper-silicon alloys are not always suitable when exposed to certain media and liigh temperature, particularly above lOO C (212 F). Users should satisfy tliemselves that the alloy selected is satisfactory for the service for wliich it is to be used. 

The U-tube exchanger with copper tubes, cast-iron header, and other parts of carbon steel is used for water and steam services in office buildings, schools, hospitals, hotels, etc. Nonferrous tube sheets and admiralty or 90-10 copper-nickel tubes are the most frequently used substitute materials. These standard exchangers are available from a number of manufacturers at costs far below those of custom-built process-industry equipment. 

Clad tube eets in service with carbon steel backer material include stainless-steel types 304, 304L, 316, 316L, and 317, Monel, Inconel, nickel, naval rolled brass, copper, admiralty, silicon bronze, and titanium. Naval rolled brass and Monel clad on stainless steel are also in service. 

Many shell-and-tube condensers use copper alloy tubes, such as admiralty brasses (those containing small concentrations of arsenic, phosphorus, or antimony are called inhibited grades), aluminum brasses, and cupronickel austenitic stainless steel and titanium are also often used. Utility surface condensers have used and continue to use these alloys routinely. Titanium is gaining wider acceptance for use in sea water and severe service environments but often is rejected based on perceived economic disadvantages. 

Polymer cable anodes are made of a conducting, stabilized and modified plastic in which graphite is incorporated as the conducting material. A copper cable core serves as the means of current lead. The anode formed by the cable is flexible, mechanically resistant and chemically stable. The cable anodes have an external diameter of 12.7 mm. The cross-section of the internal copper cable is 11.4 mm and its resistance per unit length R is consequently 2 mQ m l The maximum current delivery per meter of cable is about 20 mA for a service life of 10 years. This corresponds to a current density of about 0.7 A m. Using petroleum coke as a backfill material allows a higher current density of up to a factor of four. 

The copolymers have been used in the manufacture of extruded pipe, moulded fittings and for other items of chemical plant. They are, however, rarely used in Europe for this purpose because of cost and the low maximum service temperature. Processing conditions are adjusted to give a high amount of crystallinity, for example by the use of moulds at about 90°C. Heated parts of injection cylinders and extruder barrels which come into contact with the molten polymer should be made of special materials which do not cause decomposition of the polymer. Iron, steel and copper must be avoided. The danger of thermal decomposition may be reduced by streamlining the interior of the cylinder or barrel to avoid dead-spots and by careful temperature control. Steam heating is frequently employed. 

On acetylene service, use only approved fittings and regulators. Avoid any possibility of it coming into contact with copper, copper-rich alloys or silver-rich alloys. (In the UK use at a pressure greater than 600 mbar g must be notified to HM Explosives Inspectorate for advice on appropriate standards.)... 

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