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498 CHAPTER 27 1946 Guide - Government and the American Society for Testing Materials. .There are three standard wall-thickness schedules of copper water tubing, classified in accordance with their principal uses as follows: Type K--Designed for underground services and general plumbing service. Type L--Designed for general plumbing purposes. Type M--Designed for use with soldered fittings only. In general, Type K is used where corrosion conditions are severe, and Types L and M where such conditions may be considered normal as, for instance, in heating work. Types K and L are available in both hard and . soft tempers; Type M is available only in hard temper. Where flexibility is essential as in hidden replacement work or where as few joints as possible are desired as in fuel-oil lines, the soft temper is commonly used. New or Table 4. Thermal Expansion of Pipe in Inches per'IOO ft* [For superheated steam and other fluids refer to temperature column) Saturated Steam Elongation in Inches peb 100 it isom --20 F up Saturated Steam Elongation m Inches pee 100 IT FROM -- 20 F UP Tem Vacuum laches Pressure perature Fahren^ of Hg. . .fti* . heit Degrees CastIron - Pipe Steel Pipe Wrooght- Iron Pipe Copper Pipe Tem Pressure Psig perature Fahren heit Degrees Cast-1 Iron Pipe Steel Pipe WroughtIrou Pipe Copper Pipe * 29.39 28.89 27.99 26.48 24.04 20.27 14.63 6.45 -- -20 0 .20 40 60 80 100 120 140 160 180 200 00 0.127 0.145 0.255 0.293 0.390 0.430 0.518 0.593 0.649 0.725 0.787 0.898 0.926 1.055 1.051 1.209 1.200 1.368 1.345 1.528 1.495. 1.691 0 0.152 0.306 0.465 0.620 0.780 0.939 1.110 1.265 1.427 1.597 1.778 o. 0.204 0.442 0.655 0.888 1.100 1.338 1.570 1.794 2:008 2.255 2.500 2.5 10.3 20.7 34.5 52.3 74.9 103.3 138.3 180.9 232.4 293.7 366.1 220 .240 260 280 300 320 340 360 380 400 420 440 1.634 1.780 1.931 2.085 2.233 2.395 2.543 2.700 2.859 3.008 3.182 3.345 1.852 2.020 2.183 2.350 2.519 2.690 2.862 3.029 3.211 3.375 3.566 3.740 1.936 2.110 2.279 2.465 2.630 2.800 2.988 3.175 3.350 3.521 3.720 3.900 2.720 2.960 3.189 3.422 3.665 3.900 4.145 4.380 4.628 4.870 5.118 5.358 From Piping Handbook, by Walker and Crocker. This table gives 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 60 F and is to operate at 300 F, the expansion would be 2.519 -- 0.593 " 1.926 in. exposal work generally employs copper pipe of a hard temper. All three classes are extensively used with soldered fittings. Standard dimensions, weights, and diameter and wall-thickness, tolerances for these classes of copper tubing are given in Table 3: Copper pipe is also available with dimensions of steel pipe. . . Refrigeration lines used in connection with air conditioning equipment also, employ copper tubing extensively. For refrigeration use where, tubing absolutely free from scale and dirt is required, bright annealed copper tubing that has been dgoxidized is used. This tubing is available in a variety of sizes and wall thicknesses. EXPANSION AND FLEXIBILITY The increase in temperature of a pipe from room temperature to an operating steam or water temperature 100 deg or more above room tem perature results in an increase in length of the pipe for which provision must be made. The amount of linear expansion (or contraction in the case of refrigeration lines) per unit length of material per degree change in' Pipe,'Fittings, Welding 499 temperature is termed the- coefficient of .linear expansion, or commonly, the coefficient of expansion. This coefficient varies with the material. The linear expansion of cast-iron, steel, wrought-iron, and copper pipe; the materials most frequently used in heating and ventilating work, can be determined from Table 4. The three methods by which the elongation due to thermal expansion may be taken care of are: (1) Expansion joints; (2) Swivel joints; (3) Inherent flexibility of the pipe itself utilized through pipe bends, right-angle turns, or offsets in the line. Expansion joints of the slip-sleeve, diaphragm, or corrugated types made of copper, rubber, or other gasket material are all used for taking up expansion, but generally only for low. pressures or where the inherent flexibility of the pipe cannot readily be used as in underground steam orhot water distribution lines. Swivel joints are used to some extent in low-pressure steam and hot- water heating systems, and in hot-water supply lines. Since swivel joints permit the expansive movement of the pipe by turning of threaded joints, which may ultimately result in a leak, it is preferable to provide sufficient flexibility without resorting to swiveling in the threads. Probably the most economical method of providing for expansion' of piping in a long run is to take advantage of the directional changes which must necessarily occur in the piping and proportion the offsets so that sufficient flexibility is secured. Ninety-degree bends with long, straight tangents in either a horizontal or a vertical plane are an excellent means for securing adequate flexibility with larger sizes of pipe. When flexi bility cannot'be obtained in this manner, it is necessary to make use of' some type of expansion bend. The exact calculation of the size of ex pansion bends required to take up a given amount of thermal expansion is relatively complicated1. The following approximate method, however, 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 1. L = 6.16 y D A (1) where L = length of pipe, feet. D = outside diameter of'the pipe used, inches. A = the amount of expansion to be taken up, inches. 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