Alloys costs

TABLE 9-58 Typical Factors for Converting Carbon Steel Cost to Equivalent-Alloy Costs... 

Tantalum-Titanium Bishop examined the corrosion resistance of this alloy system in hydrochloric, sulphuric, phosphoric and oxalic acids and found that alloys containing up to about 50% titanium retained much of the superlative corrosion resistance of tantalum. Under more severe conditions, a titanium content of below 30% appears advisable from the standpoint of both corrosion resistance and hydrogen embrittlement, although contacting or alloying the material with noble metals greatly decreases the latter type of attack. Tantalum-titanium alloys cost less than tantalum because titanium is much cheaper than tantalum, and because the alloys are appreciably lower in density. These alloys are amenable to hot and cold work and appear to have sufficient ductility to allow fabrication. 

How much does the chain of the last problem cost if the gold alloy costs 450/ounce (1 ounce = 28.35g) Ans. 

The velocity on the tube side can be modified by changing the single-pass design to a multiple-pass configuration. In this case Ft = 1 in Equation (b). From formulas in McCabe, Ft depends on t2 (or At2), hence the necessary conditions derived previously would have to be changed. The fluids could be switched (shell vs. tube side) if constraints are violated, but there may well be practical limitations such as one fluid being quite dirty or corrosive so that the fluid must flow in the tube side (to facilitate cleaning or to reduce alloy costs). 

REM Alloy Costs. For a typical North American sulfur specifics tion"Tfo7oT5 laax., a minimum retained REM content of O.OhS is required to insure full MnS substitution, i.e. a RE J/S ratio of minimum 3/1. Using the delayed mold addition practice with at least 75% recovery and mischmetal 5.30/lb the current cost of a typical treatment is ... 

Zinc—Cobalt. Alloys of Zn—Co usually contain 0.3—0.8% cobalt. Higher cobalt alloys, from 4—8%, have shown better salt spray resistance (156), but the commonly plated alloy is 0.3—0.8%. One automotive company specifies 0.3—1.0%. Cobalt is expensive, and economics favor the lower alloys. Costs have been quoted for zinc—cobalt at 1.2 times the cost of chloride zinc, with zinc—nickel alloys at 1.5—1.6 times the chloride zinc. Deposits can be very bright, but the improved corrosion resistance advantage requires yellow or bronze chromates. Alkaline baths give fewer problems in plating components with lapped, spot-welded seams. 

DCS FOB, hardware including computer = 5000 (CE = 1000)/point FOB field instrumentation c/s equipment = 1800 (CE = 1000)/balloon for carbon steel. The alloy cost factors are low alloy x 1.33, high alloy x 1.5. 

In Section 16.3.4.2, the L + m costs were expressed as a fraction of the cited FOB cost (which is usually carbon steel fabrication). If the equipment is made of an alloy, the FOB cost of the equipment is larger, say 70,000 instead of 30,000. However, theL + m costs of concrete, painting, insulation, and other components in the BM remain about the same as they were for the carbon steel equipment. To account for this, we need to multiply the FOB alloy cost by an L + M factor that is smaller than the factor reported for carbon steel. This is counterintuitive, because we inmitively may think alloys = more expense for everything. The amount of reduction in the L + M factor for carbon steel is determined from Figure 16.3. 

Control valves including all materials cost 240000 for the number of main plant items, MPI, = 75 with n = 1.2 for the range 15-400. Alloy cost factor c/s X 1.00 chrome/moly X 2.4 s/s X 4.2. 

Tray/shelf, (batch, conduction) vacuum, indudmg vacuum-tight box, shelves excluding vacuum equipment and trays. FOB 30 000 at shelf area = 30 m with n = 0.56 for the range 1-100. L-rM = 2.2-2.75. L/M = 0.36. Alloy cost factors c/s X 1.00 s/s, X 2.2. Factors excluding vacuum equipment, X 1.00 including vacuum equipment, X 1.5-1.9. 

Rotary dryer, (continuous, indirect convection) atmospheric, steam tube, c/s including shell and flights, motor, drive, intake hopper, discharge. FOB 155000 at heat transfer area = 100 m with n = 0.75 for the range 40-700. L-rM = 2.2-3. L/M = 0.4. Alloy cost factors c/s X 1.00 s/s shell and flights X 1.25. 

Thickener, single compartment, concrete with 3 m walls, overflow weir, launder excluding central rake, excavation, site preparation, piping feed launder, overflow pump. PM cost = 400000 for a surface area = 100 m with n = 0.38 for the range 80-2000. L-i-M = 3.1. L/M = 0.4. Alloy cost factors c/s X 0.7, concrete X 1.0 rubber lined for acid-leach mineral processing X 1.22. 

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