Cupro-Nickels

Table 21. Conductivity and H04 (Hard) Temper Tensile Properties of Cupro—Nickel Alloys...

Cupro-nickel Not for oxidizing conditions (test if in doubt) concentration and temperature slightly limited... 

The cupro-nickel alloys (5-30% of nickel) are perhaps the best of all for strength and resistance to corrosion. Table 3.20 gives typical properties. 

Table 3.20. Mechanical Properties of Annealed Cupro-Nickel Alloys [30]...

Mechanical properties of aimealed cupro-nickel alloys. 83... 

The non-ferrous alloys include the misleadingly named nickel silver (or German silver) which contains 10-30% Ni, 55-65% Cu and the rest Zn when electroplated with silver (electroplated nickel silver) it is familiar as EPNS tableware. Monel (68% Ni, 32% Cu, traces of Mn and Fe) is used in apparatus for handling corrosive materials such as F2 cupro-nickels (up to 80% Cu) are used for silver coinage Nichrome (60% Ni, 40% Cr), which has a very small temperature coefficient of electrical resistance, and Invar, which has a very small coefficient of expansion are other well-known Ni alloys. Electroplated nickel is an ideal undercoat for electroplated chromium, and smaller amounts of nickel are used as catalysts in the hydrogenation of unsaturated vegetable oils and in storage batteries such as the Ni/Fe batteries. 

Plain tubes (either as solid wall or duplex) are available in carbon steel, carbon alloy steels, stainless steels, copper, brass and alloys, cupro-nickel, nickel, monel, tantalum, carbon, glass, and other special materials. Usually there is no great problem in selecting an available tube material. However, when its assembly into the tubesheet along with the resulting fabrication problems are considered, the selection of the tube alone is only part of a coordinated design. Plain-tube mechanical data and dimensions are given in Tables 10-3 and 10-4. 

More than 100 material combinations exist for these tubes. A few materials suitable for the inside or outside of the tube include copper, steel, cupro-nickel, aluminum, lead,... 

The I.D. of this plain surface duplex tube is determined hy deducting the gage thickness from the O.D. = 0.804 in. I.D. of cupro-nickel. 

Duplex tubes 1-in. O.D. X 16 ft, 0 in. long, 16 BWG steel outside, 16 BWG cupro-nickel inside No. = 578,1 V4 -in. triangular pitch Shell 36-in. O.D., 4 tube pass Film coefficients ... 

Where an under-slung condenser has been specified, the provision of a basement to the engine room offers the attraction of compactness at the expense of enhanced civil works, while alternatively, the specification of pannier condensers can obviate the need for a basement and will simplify the foundation design, but will considerably increase the floor area requirements. The condensing plant itself consists essentially of banks of tubes through which cooling water flows and around which exhausted steam from the turbine is condensed to form a vacuum. Such tubes have traditionally been made of brass, but where severe corrosion conditions exist, cupro-nickel is sometimes used. 

Fig. 1.94 Effect of chromium additions on the erosion corrosion of 70/30 cupro nickel in...

The results of tests on copper alloys have been given by Tracy , Thompson , Mattsson and Holm and Scholes and Jacob , the first two of these investigations being made under the aegis of the American Society for Testing and Materials. The tests of Tracy, and Scholes and Jacob were both for periods up to 20 years in those of Thompson, and Mattsson and Holm specimens have been removed after 2 years and 7 years and further specimens remain exposed for removal after 20 years. The numbers of materials tested are given in Table 4.11 they included brasses, nickel silvers, cupro-nickels, beryllium coppers and various bronzes. Mattsson and Holm tested 14 alloys in the form of rod in addition to the sheet materials, the results for which are given in Table 4.11. 

In addition to nickel alloys, nickel also forms an important alloying element in stainless steels and in cast irons, in both of which it confers additional corrosion resistance and improved mechanical and engineering properties, and in Fe-Ni alloys for obtaining controlled physical and magnetic properties (see Chapter 3). With non-ferrous metals nickel also forms important types of alloys, especially with copper, i.e. cupro-nickels and nickel silvers these are dealt with in Section 4.2. 

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