Document mpm1EMM84GkdQYa7vmx033zQd

646 CHAPTER 28 1955 Guide Table 1. Heat Losses from Horizontal Bare Steel Pipes Expressed in Btu per (hour) (linear foot) (Fahrenheit degree difference between the pipe and surrounding still air at 70 F) Hot Water Steam Nominal Pipe Size (Inches) .. 120 F 150 F 180 F 210 F 227.1 F (5 psia) 299.7 F 337.9 F (50 psia) (100 psia) Temperature Difference--F Deo H H IK IK 2 2H 3K 4 10 12 50 80 0.455 0.555 0.684 0.847 0.958 . 0.495 0.605 0.743 0.919 1.041 1.180 i 1.400 1.680 1.900 2.118 1.281 1.532 1.825 2.064 2.302, 2.580 3.036 3.880 4.760 5.590 2.804 3.294 . 4.215 5.180 6.070 110 0.546 0.666 0.819 1.014 1.148 1.412 1.683 2.010 2.221 2.534 3.084 3.626 4.638 5.680 6.670 140 0.584 0.715 0.877 1.086 1.230 1.512 1.796 2.153 2.433 2.717 3.303 3.886;' 4.960 6.090 7.145 157.1 0.612 0.748 0.919 1.138 1.288 1.578 1.883 2.260 2.552 2.850. 3.470 4.074 5.210 6.410 7.500 227.7 ' 267.9 0.706 0.866 1.065 1.324 1.492 . 1.840 2.190 2.630 2.974 3.320 4.050 4.765 6.100 7.490 8.800 0.760 0.933 1.147 1.425 1.633 1.987 2.363 2.840 3.215 3.590 4.385 5.160 6.610 8.115 9.530 Table 2. Heat Loss from Horizontal Tarnished Copper Pipe1 Expressed in Btu per (hour) (linear foot) (Fahrenheit degree difference between the pipe and surrounding still air at 70 F) ____ Nominal Pipe Size (Inches) Hot Water (Type K Copper Tube) 120 F .150 F 180 F 210 F Steam (Standard Pipe Size Pipe) (5 psia) 297.7 F 337.8 F (50 psia) (100 psia) Temperature Difference--F Deg 50 80 110 140 ' 157.1 227.7 267.9 H H 0^250 0.340 0.440 0.287 0.381 0.475 0.300 0.409 0.509 0.321 0.429 0.536 0.433 0.533 0.636 0.500 0.543 0.746 0.530 0.654 IK 0.500 0.580 0.559 0.656 0.818 0.710 0.622 0.750 0.764 0.904 0.878 1.053 1.120 2K 3K 4 0.730 0.880 1.040 1.180 1.460 0.825 1.000 1.175 1.350 1.500 0.890 1.091 1.272 1.454 1.635 . 0.957 1.143 1.343 1.535 1.715 1.101 1.305 = 1.560 1.750 1.941 . 1.273 1.490 1.800 2.020 2.240 3.364 1.605 1.940 2.170 2.430 4H 8 1.600 1.840 2.400 1.812 2.125 2.685 1.980 2.270 2.910 2.071 2.430 3.110 2.131 2.387 2.740 3.310 2.465 2.770 3.210 4.050 2.650 2.990 3.440 4.370 Table 3. External Surface per Linear Foot of Pipe Nominal Pips Size (Inch sb) K K 1 lK IK Surface Area (So Ft) 0.22 0.275 0.344 0.435 0.498 Nominal Pipe Size (Inches) 2 2K 3 3H 4 Surface Area (So Ft) 0.622 0.753 0.917 1.047 1.178 Nominal Pipe Size (Inches) . 5 6 8 10 12 Surface Abba (So Ft) 1.456 1.734 2.257 2.817 3.33S Pipe and Industrial Insulation 647 Table 4. External Surface per Linear Foot of Copper Tubing Outside diameter /g in. greater than nominal size Tube Size (Inches) HK 1 IK w Surface Area (So Ft) 0.164 0.229 0.295 0.360 0.428 Tube Size (Inches) 2 2H 3 3K 4 Surface Area (So Ft). 0.556 0.687 0.818 0.949 1.080 Tube Size (Inches) 5 6 8 Surface Area (So Ft) 1.342 1.604 perature difference of 169.4 F is found to be 1.624 Btu per (hr) (linear ft) (Fdeg). The total annual heat loss from the entire line = 1.624 X 169.4 X 165 (linear ft) X 4000 (hr) = 181,600 Mb. (Mb = 1000 Btu.) Example 2: Coal costing $11.50 per ton and having a calorific value of 13,000 Btu per pound is being burned in the furnace supplying steam to the pipe line given in the previous example. H the system is operating at an overall efficiency of 55 percent, determine the monetary value of the annual heat loss from the line. Solution: The cost of heat per 1000 Mb supplied to the system = 1,000,000 X 11 5 (dollars) -p [13,000 (Btu) X 2000 (lb) X 0.55 (efficiency)] = $0,804. The total cost of heat lost per year = 0.804 X 181.6 (thousand Mb) = $146.00. INDUSTRIAL AND PIPE INSULATIONS Insulating materials are made of various substances and are supplied in a number of different forms. Preformed insulations are made in the form of blocks for flat surfaces, segmental pieces for small cylindrical vessels and large pipes, and sectional insulation for smaller pipes. Preformed pipe insulation is regularly supplied in sectional form up to about 12-inch pipe size. Certain types up to 20-inch pipe size are available in sectional form. Sections are either split in half longitudinally or cut through oh one side and scored on the inner surface of the other .to facilitate applica tion to the pipe. Blanket insulations are used to insulate flat dr curved surfaces or large pipes.. Pipe fittings and bends are commonly insulated with portions of standard preformed insulations, or, when irregular in contour, with blankets or plastic insulating cements. Insulation is secured to pipes, flat surfaces, and large vessels in a variety of ways depending on the contour of the surface and the form of the in- Table 5. Area of Flanged Fittings, Square Feet* . Nominal Pipe Size (Inches) Flan GED Coup]UNO 90 Deg Ell Standard Extra Heavy Standard Extra Heavy Long Radius Ell Standard Extra Heavy Tee Standard Extra Heavy Cross Standard Extra Heavy 1 2K 3 6 12 0.320 0.438 0.510 0.727 0.848 1.107 0.945 1.4/4 1.622 1.484 1.644 1.914 2.04 2.18 i.82 : 2.78 ` 3.77 3.43 5.20 6.71 0.795 0.957 1.174 1.65 2.09 2.38 2.98 3.53 3.95 4.44 5.13 6/98 10.18 13.08 1.015 1.098 1.332 2.01 2.57 3.49 3.96 4.64 5.02 5.47 6.99 9.76 . 13.58 17.73 0.892 1.084 1.337 1.84 2.32 2.68 3.28 3.96 4.43 5.00 5.99 . 8.56 12.35 16.35 1.083 1.340 1.874 2.16 2.76 1.235 1.481 1.815 2.54 3.21 1.575 1.925 2.68 3.09 4.05 3.74 4.28 4.99 5.46 6.02 3.66 4.48 5.41 6.07 6.81 5.33 6.04 7.07 . 7.72 8.52 .7.76 ":7.84 . 11.09 . 10.55 15.60 15.41 18.76 19.67 : 10.64 14.74 20.41 26.65 1.622 1.943 2.38 3.32 4.19 4.77 5.83 7.03 7.87 8.82 10.08 13.44 19.58 24.87 2.07 2.53 3.54 4.06 5.17 6.95 7.89 9.24 10.07 10.97 13.75 18.97 26.26 34:11 Including areas of accompanying flanges bolted to the fitting.