Document Lp4r9zKELYy0Lvz79G5OXV5RX

HEATING VENTILATING AIR CONDITIONING CUIDE 1942 Table 5. 100Thermal Expansion of Pipe in Inches per ft* (For superheated steam and other fluids refer to temperature column) I - - - -- Saturated Steam Pressure VIanccuhuam of H*. Pounds Tem perature Sgujuv Degrees Inch f Fahren Gage heit Eponqation m Inches pen 100 rr moil -20 F op Saturated Steam CastIron Pipe Steel Pipe Pipe [Pressure Copper Kpe Pounds Per fperatorel Square Inch Gage Degrees Fahren heit Elongation ik Incues red iqq pt peom --20 F up CastIron Pipe Steel ,ym*htJ & 29.39 28.89 27.99 26.48 24.04 20.27 14.63 6.45 2.5 10.3 20.7 34.5 52.3 74.9 103.3 138.3 180.9 232.4 293.7 366.1 451.3 550.3 -20 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 000 0.127 0.145 0.152 0.255 0.293 0.306 0.390 0.430 0.465 0:518 0.593 0.620 649 0.725 0.780 0.787 0.898 0.939 0.926 1.051 1.055 1.209 1.110 1.265 1.200 1.368 1.427 1.345 1.528 1.597 1.495 !1.691 1.778 1.634 1.852 1.936 1.780 2.020 2.110 1.931 2.183 2.279 2.085 2.350 2.465 .233 2.519 2.630 395 2.690 2.800 2.543 2.862 2:988 700 3.029 3.175 .859 3.211 3.350 3.008 3.375 3.521 182 3.566 3.720 345 3.740 3.900 511 3.929 4.096 .683 4.100 4.280 0 | 664. 500 0.2041 795. 520 0.442J 945. 540 0.655 Jlll5.3| 560 0.88811308.,, 580 1.100 (1525.3 600 1.338(1768.3 620 1.570 (2041. ,, 640 1.794(2346.3 660 2.008 (2705 680 2.255 13080 700 2.500 720 2.720 740 2.960 760 3.189 780 3.422 800 3.665 820 3.900 840 4.145 860 4.380 880 4.628 900 4.870 920 5.118 940 5.358 960 5.612 5.855 i 980 1000 3.847 4.020 4.190 4.365 4.541 725 4.896 5.082 5.260 5.442 5.629 5.808 006 6.200 6.389, 6.587 6.779 6.970 7.176 7.375 570 7.795 -. .989 8. .200 8. 8.406 9. 8.617 9. 250 ,464 662 4.477 6.110 4.677 6.352 4.866 6.614 5.057 6.850 5.268 7.123 5.455 7.388 5.660 7.636 5.850 7.893 6.067 8.153 6.260 8.400 6.481 8.676 6.673 8.912 6.899 9.203 7.100 9.460 7.314 9.736 7.508 9.992 7.757 10.272 7.952 10.512 '8.195 10.814' 8.400 II.175 8.639 III. 360 8.867 11.625 9.089 11.911 9.300 12.180 9.547 12.473 9.776 12.747 From Piping Handbook, by Walker and Crocker. This table1gives the expansion from --20 F to the temperature in question. To obtain the amount of expansion between any two temperatures take the difference between the figures in the table for those temperatures. For example, if a steel pipe is installed at a temperature of 00 F and is to operate at 300 F, the expansion would be 2.519 -- 0.593 ** 1.926 in. has been found to give reasonably good results and is deemed to. be sufficiently accurate for most heating work. Fig. 1 shows several types of expansion bends commonly used for taking up thermal expansion. The amount of pipe, L, required in each of these bends may be computed from Equation 2. 6.16 yDt where L = length of pipe, feet. D = outside diameter of the pipe used, inches. AA -- the amount of expansion to be taken up, inches. (2) This formula, based on the use of mild-steel pipe with wall thicknesses not heavier than extra-strong, assumes a maximum safe value of fiber stress of 16,000 lb per square inch. When square type bends are used, the width of the bend should not exceed about two times the height. It i is 348 CHAPTER 18. PIPE, FITTINCS, WELDING further assumed that the corners are made with screwed or flanged elbows or with arcs of circles having radii five to six times the pipe diameter. Use of welding elbows with radii of 1J4 times the pipe diameter will decrease the end thhists somewhat but will raise the fiber stress correspondingly. All risers must be anchored and safeguarded so that the difference in length when hot from the length when cold shall not disarrange the normal and orderly provisions for drainage of the branches. Proper anchoring of piping is especially necessaiy with light-weight radiators, to allow for freedom of expansion in order that no pipe strain will distort the radiators. When expansion strains, from the pipes are Offset U bend Fig. 1. Measurement of L on Various Pipe Bends permitted to reach these light metal heaters they usually emit sounds of distress which are exceedingly troublesome. PIPE THREADS All threaded pipe for heating and ventilating installations uses the American Standard taper pipe thread which is made with a taper of 1 in 16 measured on the diameter of the pipe so as to secure a tight joint. 1 Thre1ads oIf fittingI s are tapped to the same taper. The number of threads per inch varies with the different pipe sizes. All threaded pipe should be made up with a thread paste suitable for the service under which the pipe is to be used. HANGERS AND SUPPORTS Heating system piping requires careful and substantial support. Where changes in temperature of the line are not large, such simple methods of support may be utilized as hanging the line by means of rods or perforated strip from the building structure, or supporting it by brackets or on piers. When fluids are conveyed at temperatures of 150 F or above, however, hangers or supporting equipment must be fabricated and assembled to permit free expansion or contraction of the piping. This can be accom plished by the use of long rod hangers, spring hangers, chains, hangers or supports fitted with rollers, machined blocks, elliptical or circular rings of larger diameter than the pipe giving contact only at the bottom, or trolley hangers. In all cases, allowance should be made for rod clearance to permit swinging without setting up severe bending action in the rods. For pipes of small size, perforated metal strip is often used. For horizontal mains, the rod or strip usually is attached to the joists or steel work of the floor above. For long runs of vertical pipe subject to con siderable thermal expansion, either the hangers should be designed to 349