Document ymnxOD864Mep6D7jpxjvw4q1n

592 CHAPTER 27 1951 Guide Table 6. Area op Flanged Fittings, Square Feet* Nominal Pipe Size (Inches) IX 12 Flanced Coupling Standard Extra Heavy 0.438 0.510 0.727 0.84S 1.107 1.644 4.41 2.18 2 78 3.77 6.71 90 Deg Ell Standard Extra Heavy 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 Long Radius Ell Standard Extra Heavy 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 3.74 4.28 4.99 5.46 6.02 7.76 11.09 15.60 18.76 Tee Standard Extra Heavy 1.235 1.481 1.815 2.54 3.21 3.66 4.48 5.41 6.07 6.81 7.84 10.55 15.41 19.67 1.575 1.925 2.68 3.09 4.05 5.33 6.04 . 7.07 7.72 8.52 10.64 14.74 20.41 26.65 Cross Standard Extra Heavy 1.622 1.943 2.07 *3.54 4.06 6.95 7.89 7.87 8.82 10.03 13.44 19.58 24.87 10.97 m.ib 18.97 34.11 * Tn*1nH?ng areas of accompanying flanges bolted to the fitting. Standard thicknesses of 85 percent magnesia pipe covering_ are not exactly 1 in. However, the loss through any given thickness of insulation can be obtained by interpolation. Also, the losses through any of the insulations given in Table 6 can be obtained by multiplying the losses obtained from Figs. 1, 2, or 3 by the factors given in Table 7. Pipes operating at high temperatures are frequently insulated to the Table 6. Thermal Conductivitt (ft) op Various Ttpb Pipe Insulations for Medium and High Temperature Pipe* Expreseed in Btu per (hour) (square foot) (Fahrenheit degree temperature difference per inch) Types op Insulating Matbbxaib Density Lb/Cu Ft Temp. Range Ubb Mean Tbmpbbatubb, F Dbg 100 200 300 400 600 Corrugated Aabeetoa--Type y.wminwtM Asbestos--Type Brown Asbestos Fiber--Type..................... 11-14 11-13 15-17 18-20 30-35 10-15 25-30 13rl5 Up to 000 F Up to 800 F Up to 300 F Up to 800 F Up to 1900 F Up to 1200 F 0.39 0.45 0.61 .0.57 0.68 0.80 0.51 0.59 0.69 0.49 0.57 0.65 0.39 0.44 0.49 0.64 0.40 0.45 0.50 0.55 0.63 0.66 0.75 0.34 0.89 0.44 0.49 0.54 * Average values from laboratories lor insulating materials of various manufacturers. Table 7. Pipe Covering Factors Types op Insulating Materials FTempebatube Dippebencb. Pipe to Aib, Deg 100 200 300 400 500 Corrugated Asbestos--Type 1.30 1.30 1.42 1.19 1.23 1.27 1.15 1.19 1.23 0.96 0.98' 0.98 1.00 1.00 1.02 1.02 1.05 i.04 1.07 1.37 1.36 1.35 1.35 0 eft 0.88 0.91 0.93 0.96 Pipe Insulation 593 best advantage by combining a high temperature insulation near the pipe with a moderate or low temperature insulation around it as an outer layer. By this method an efficient material may be used for each of the two temperature ranges encountered. In calculating the heat loss 1.3 '40 80 120 160. 200 240 280 TEMP DIFF FROM PIPE TO ROOM, F DEG Fig. 1. Heat Loss Through 1 In, Thick 85 percent Magnesia Ttpb Covering through such a combination the mean temperature of each layer must be determined along with the thickness of each. This is readily' done in three or four calculations performed as a series of approximations,' in which assumptions of thickness and mean temperature are adjusted as indicated_in. the. discussion which follows. . . ..u. .... . In the case of a single thickness of pipe covering, the quantity-pf heat