Document v14DoJmM4RYZMLJbVkabLzQ2q

582 CHAPTER 28 1049 Guide Table 5. Area or Flanged Fittings, Square Feet* Nominal Pips Size (Inches) Flanged Coupling Standard Extra Heavy 90 Deg Ell Standard Extra Heavy Long Radius Ell Standard Extra Heavy Tee Standard Extra Heavy Cross Standard Extra Heavy 1 ltf 2 2M 3 3K 4 . 4M <.-.5 6 8 30 1 12 0.320 0.383 0.477 0.672 0.841 0.945 1.122 1.344 1.474 1.622 1.82 2.41 3.43 4.41 0.438 0.795 0.510 0.957 0.727 1.174 0.848 1.65 1.107 2.09 1.484 . 2.38 1.644 . 2.98 * 1.914; .. 3.53 . 2.04 3.95 2.18 : 4.44 2.78 ! 5.13 3.77 6.98 . 5.20 10.18 6.711 ` 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 1.235 1.340 1.481 1.874 . 1.815 2.16 2.54 2.76 3.21 3.74 3.G6 . 4.28 .. : ` 4.48 ' 4.99 . 5.41 5.46 6.07 6.02 6.81 7.76 !7.84 11.09 10.55 15.60 15.41 18.76 19.67 1.575 1.622 1.925 1.943 2.63 2.38 3.09 3.32 4.05 4.19 5.33 4.77 . 6.04 5.83 7.07 7.03 7.72' 7.87 ' * 8.52 , . 8.82 10.64 10.08 14.74 13.44 20.41 19.58 26.65 24.87 2.07 2.53 3.54 4.06 5.17 6.95 . 7.89 9.24 10.0710.97 . 13.75 . 18.97 ' 26.26 34.11 * Including areas of accompanying flanges bolted to the fitting. Standard thicknesses of 85 per . cent 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 Conductivity (k) op Various Type Pipe Insulations fob'Medium and Hiou Temperature Pipe* Expressed in Btu per (hour) (square foot) (Fahrenheit degree temperature difference per inch) Types of Insulating Materials Density Lb/CuFt Temp. Range of Accepted ; - . -Use. ' __ Mean Temperature, F Deg ioo' 200 300 400 500 85% Magnesia--Type_____ Corrugated Asbestos--Type 4 Ply per 1 iii ............... 6 Ply per 1' in- . _____ 8 Ply per 1 in ............. ___ LaminatedAsbestos--Type................. (35-40 laminations per. 1 in.) ............ Mineral Wool--Type.____ ____ ___ Diatomaceous Silica--Type;..... ........ Brown Asbestos Fiber--Type.---.... ........ 13-^15 11t13 ` 15-17 18-20 30-35 10-15 : 25-30 13^15 : * . Up to 600 F 0.41 Up to 300 F Up to. 300 F Up to 300 F 0.57 0.51 0.49 Up to 700 F, . 0.39 Up to 800 F 0.40 Up to 1900 F * 0.63 Up to ^200 F. 0.34 0.45 0.48 0.52 0.68 0.80 0.59 0:69 0.57 0.65 0.44 0.49 0.54 0.45 0.50 0.55 0.66 0.69 0.72 0.39 0.44 0.49 0.75 0.54 * Average values from'various laboratories tor insulating ranteriala of various manufacturera. Table 7., Pipe Covebinq Factors Types of Insualting Materials Corrugated Asbestos--Type 6 Ply per 1 in.................. 8'Ply per 1 In.__ > ... ,, Laminated Asbestos--Type....................... Mineral Wool--Type.___ ; .............. Diatomaceous Silica--Type. Brown Asbestos Fiber--Type______ _ Temperature Difference, Pipe to Air. F Deg 100 200 300 400 500 1.30 1.19 . 1.15 0.96 0.98 1.37 Q.86 1.36 . 1.23 1.19 0.98 1.00 .1.36 0.88 1.27 1.23 1.00 1.02 1.35 0.91 -- 1.02 1.05 1.35 0.93 -- 1.04 1.07 - 1.34 0.96 . Pipe lnsuiation '-' 583 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 Fig. 1. Heat Loss Through 1 In. Thick 85 peb cent Magnesia. Type Covebinq 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. ` ; In the case of a single thickness of pipe covering, the quantity,of heat