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*Aluminum-jacketed calcium silicate insulation with an emissivity factor of 0.05. To convert inches to millimeters, multiply by 25.4; to convert miles per hour to kilometers per hour, multiply by 1.609; and to convert dollars per 1 million British thermal units to dollars per 1 million kilojoules, multiply by 0.948; °C = 5/9 (°F - 32).

*Aluminum-jacketed calcium silicate insulation with an emissivity factor of 0.05. To convert inches to millimeters, multiply by 25.4; to convert miles per hour to kilometers per hour, multiply by 1.609; and to convert dollars per 1 million British thermal units to dollars per 1 million kilojoules, multiply by 0.948; °C = 5/9 (°F - 32).

The tables were based upon the cost of energy at the end of the first year, a 10 percent inflation rate on energy costs, a 15 percent interest cost, and a present-worth pretax profit of 40 percent per annum on the last increment of insulation thickness. Dual-layer insulation was used for 3a-in and greater thicknesses. The tables and a full explanation of their derivation appear in a paper by F. L. Rubin (op. cit.). Alternatively, the selected thicknesses have a payback period on the last nomin -in increment of 1.44 years as presented in a later paper by Rubin ["Can You Justify More Piping Insulation?" Hydrocarbon Process., 152-155 (July 1982)].

Example 1 For 24-in pipe at 371°C (700°F) with an energy cost of \$4/million Btu, select 2-in thickness for indoor and 2a-in for outdoor locations. [A 2a-in thickness would be chosen at 399°C (750°F) indoors and 3a-in outdoors.]

Example 2 For 16-in pipe at 343°C (650°F) with energy valued at \$5/mil-lion Btu, select 2a-in insulation indoors [use 3-in thickness at 371°C (700°F)]. Outdoors choose 3-in insulation [use 3a-in dual-layer insulation at 538°C (1000°F)].

Example 3 For 12-in pipe at 593°C (1100°F) with an energy cost of \$6/million Btu, select 3a-in thickness for an indoor installation and 4a-in thickness for an outdoor installation.

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