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610 CHAPTER 27 1954 Guide mg in establishing the factor c which influences'the working pressure, is that after nominal use the pipe may not be as sturdy as it \yas at the time, of manufacture. Note that the joint factor, c, is not included for plain end non-ferrous pipe as listed in Table 2. In addition to IPS copper pipe, several varieties of copper tubing are in use with either flared or compression couplings or soldered joints. Dimen sions of copper water tubing intended for plumbing, underground water service, fuel-oil lines, gas lines','etc'., have been standardized by the U. S. 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. 4. 100 pi*Table Thermal Expansion op Pipe in Inches per (For superheated steam and other fluids refer to -temperature column) 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.1 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 posable are desired as iii fuel-oil lines, the soft temper is commonly used. In new or exposed work copper pipe of a hard temper is generally used. All three claSsstaesndaarerdexdtiemnesnivseiolynsu,sewdewigihthts,soaldnedreddiafmitteintegrs.and wall-thickness toler ances for these classes of copper tubing.aire obtainable from Table 2. Cop peIrnpirpeefriigsearlastoioanvlailiileasb,leuswedithindciomnennesciotinosn owfitshteaeilrpciopne.ditioning equipment. Pipe, Fittings, Welding 611 copper tube is used extensively. For refrigeration use where tubing abso lutely free from scale and dirt is ' required;- bright annealed copper tubing that has been deoxidized 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 oper ating steam or water temperature 100 deg,or more above room tempera ture, 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 tem perature 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) in herent 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 ex pansion, but generally only for'low pressures or where the inherent flexi- bility of the pipe cannot readily be used as in underground steam or hot water distribution lines. Swivel joints are used to some extent in low-pressure steam and hotwater 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 js relatively complicated.1 The following approximate method, however, has been found to give reasonably good results and is deemed to be suf ficiently accurate for most heating installations. 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 fiends may be computed from Equation 1. where L = 6.16 \f~Da (1) b = length of pipe, feet. = outside diameter of the pipe used, inches. ^ = the amount of expansion to be taken up, inches. Fills formula, based on the use of mild-steel pipe with wall thicknesses