Document kDRQ6zq6Bx6eeLe0dB6Xmp9xB

'.il 654 CHAPTER 28 1956 Guide Table 1. Heat Losses from Horizontal Babe Steel Pipes Expressed in Btu per (hour) (linear foot) (Fahrenheit degree difference between the pipe and surrounding still air at 70 F) ---------------------- r \ r Hot Water ? ' Steam f 120 f : - 150 F ' - 180 F 210 F 227.1 F.: 299.7 F (5 psig) (50 psig) Nominal Pipe She , ' '(Inches) i ,. r Temperature Difference--F Deo 337.9 F (100 psig) H H l 1H r .2 2H 3 3*4 r. 4 . . . 5 6 8 10 12 SO 80 0.455 0.555 0.084 0.847 0.958 0.495 0.605 : 0.743 : 0.619 1.041 : 1.180 . 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 6.670 140 157.1 227.7 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 0.612 0.748 0.919 1.138 : 1.288 ' 0.706 0.866 1.065 1.324 1.492 4.578 .1.883 2.260 2.552 2.850 < 1.840 2.190 2.630 2.974 3.320 3.470 4.074 5.210 6.410 ' 7.500 4.050 4.765 . 6.100 7.490 8.800 267.9 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 8.116 9.530 \ Table 2. Heat Loss fbom Horizontal Tarnished Copper Pipe1 Expressed in Btuper (hour) (linear foot) (Fahrenheit degree difference between the pipe ana surrounding still air at 70 F) Nominal Pip* Sib, (Inches) Hot Wateb (Type K Copper Tube) 120 F 150 F 180 F 210 F Steam (Standard Pip Bias Pipe) 227.1 F ` (5 psig) 297.7 F (50 psig) 337.9 F (100 psig) Temperature Difference--F Dbg 50 80 no. 140 157.1 .227.7. 267.9 H H \ Hi m 0.250 0.340 0.440 0.500 0.580 , 6.287 0.381 0.475 0.559 0.656 0.300 0.409 0.509 0.618 0.710 0.321 0.429 0.536 0.622 0.750 0.433 0.533 0.636 . 0.764 . 0.904 - 0.500 0.543 0.746 0.878 1.053 0.530 0.654 0.803 0.934 1.120 2 2h 3 3*4 4 0.730 0.880 1.040 1.180 1.460 01..802050 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 1.364 1.605 1.940 2.170 2.430 4*4 5 6 8 . 1.600 1.840 2.400 i.kii 2.125 2.685 L980 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 Pipe Size (Inches) H * 1 1H Subface Abea (So Ft) 0.22 0.275 0.344 0.435 0.498 Nominal Pipe She (Inches) 2 2H 3 3*4 4 Surface Abba (Sq Ft) 0.622 0.753 0.917 1.047 1.178 Nominal Pipe Sibe (Inches) 5 6 8. 10 12 Subpace Abba (SqFt) 1.4sT 1.734 2.257 2.817 3.338 Pipe and Industrial Insulation 655 Table 4. External Surface per Linear Foot of Copper Tubing Outside diameter J^j in. greater than nominal size Tubs Size (Inches) H H 1 1 *4 m Surface Abba (Sq Ft) 0.164 0.229 0.295 0.360 0.426 Tube Sue (Inches) 2 m 3 3*4 4 Subface Area (Sq Ft) 0.556 - 0.687 0.818 0.949 1.080 Tube Size (Inches) .5g. 8 ' Surface Area (Sq Ft) 1.342, ' 1.604 2.128 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 S: 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 iri the previous example. If 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) -f- [13,000 (Btu) X 2000 0b) 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 on 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 or 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 She (Inches) Flanged Coupling 90 Deg Ell Standard Extra Heavy Standard Extra Heavy Long Radius Ell Standard Extra Heavy Tee ` Standard Extra Heavy Cboss Standard Extra Heavy 1 0.320 0.438 0.795 1.015 0.892 1.0S3 1;235 1.575 1.622 .2.07 IK 0.383 0.510 0.957 1.098 1.084 1.340 1.481 1.925 1.943 2.53 i*a 0.477 0.727 1.174 1.332 1.337 1.874 1.815 2.68 2.38 ,3.54 0.672 0.848, 1.65 2.01 1.84 2.16 2.54 3.09 3.32 . 4.06 2*4 0.841 1.107 2.09 2.57 2.32 2.76 3.21 4.05 4.19 6.17 3 3*4 4 0.945 1.122 1.344 1.484 1.644 1.914 2.38 2.98 3.53 3.49 3.96 4.64 2.68 3.28 3.96 3.74 4.28 4.99 3.66 - 4.48 5.41 5.33 4.77 6.04 5.83 . 7.07 7.03 6.95 ,7.89- 9.24 4*4 5 1.474 2.04 3.95 5.02 4.43 5.46 6.07 7.72 7.87 10.07 1.622 2.18 4.44 5.47 5.00 6.02 6.81 8.52 8.82 10.97 6 8 1.82 2.78 2.41 3.77 5.13 6.98 6.99 9.76. 5.99 8.56 7.76 11.09 7.84 10.55 10.64 14.74 10.08 13.44 13.75 18.97 3.43 5.20 10.18 13.58 12.35 15.60 15.41 20.41 19.58 26.26 4.41 6.71 13.08 17.73 16.35 18.76 19.67 26.65 24.87 34.11 * Including areas of accompanying flanges bolted to the fitting.