Document 82RYx9b3R5oro2MZpDdG27vG5

HEATINC VENTILATING AIR CONDITIONING GUIDE 1941 first cost is said to be justified on the basis of longer life expectancy. Wrought-iron pipe may be identified by the spiral line marked into each length, either knurled into the metal or painted on it in red or other bright color. Otherwise, there is little difference in the appearance of wrought iron and steel pipe, although microscopic examination of polished and etched specimens will readily disclose the difference. Cast Ferrous Pipe. There are now available several types of castferrous metal pipe made of a good grade of cast-iron with or without additions of nickel, chromium, or other alloy. This pipe is available in sizes from 1 Yi in- to 6 in., and in standard lengths of 5 or 6 ft with external and internal diameters closely approximating those of extra strong wrought pipe. Cast ferrous pipe may be obtained coupled, beveled for welding, or with ends plain or grooved for the several types of couplings. It is easily cut and threaded as well as welded. The fact that it is readily welded enables the manufacturers to supply the pipe in any lengths practicable for handling. Alloy Metal Pipe. Steel pipe bearing a small alloy of copper or other alloying element and iron pipe bearing a small alloy of copper and molyb denum have been claimed to possess more resistance to corrosion than, plain steel pipe and they are advertised and sold under various trade names. Copper Pipe and Fittings. Owing to its inherent resistance to cor rosion, copper and brass pipe have always been used in heating, venti lating, and water supply installations, but the cost with standard dimen sions for threaded connections has been high. The recent introduction of fittings which permit erection by soldering or sweating allows the use of pipe with thinner walls than are possible with threaded connections, thereby reducing the cost of installations. The initial cost of brass and copper pipe installations generally runs higher than the corresponding job with steel pipe and screwed connections in spite of the use of thin wall pipe, but the corrosive nature of the fluid conveyed or the inaccessibility of some of the piping may warrant use of a more expensive material than plain steel. The advantages of corrosionresisting pipe and fittings should be weighed against the correspondingly higher initial cost. COMMERCIAL PIPE DIMENSIONS The IPS dimensions of commercial pipe universally used at the present time conform to the recommendations made by a Committee of the A.S.M.E. in 1886. Pipe up to 12' in. in diameter is made in certain definite sizes designated by nominal internal diameter which is somewhat different from the actual internal diameter, depending on the wall thick ness required. There are three weights of wrought iron and steel pipe commonly used, known as standard-weight, extra-strong, and double extra strong. Because of the necessity of maintaining the same external dia meter in all three weights for the same nominal size, the added wall thickness is obtained by decreasing the internal diameter. The term full-weight, when applied to sizes below 8 in., means that the pipe is up to the nominal weight per foot. When applied to sizes between 8 and 12 in., inclusive, it often indicates that the pipe has the heaviest of several wall 324 CHAPTER 17. PIPE. FITTINGS, WELDINC thicknesses listed. In sizes 14 in. and upward, pipe is designated by its outside diameter (O.D.) and the wall thickness is specified. While the demands for pipe for the heating and ventilating industry are reasonably well served by the standard-weight and extra-strong pipe, demands for pipe for higher pressures and temperatures in industry resulted in the use of a multiplicity of wall thicknesses for all sizes. Even in heating installations, the erection of piping by welding was deemed to Table 1. Dimensions of Welded and Seamless Steel Pipe Nominal Pipe Size %/Q v> 1/ 1 \y. 2m 2li 3 3^i 4 5 6 8 10 12 14 O. D. 16 O. D. 18 O. D. 200. D. 24 0. D. 30 0. D. Nominal Wall Thicknesses pob Schedule Numbers Outsids Duk. Schedule Schedule Schedule Schedule Schedule Schedule Schedule Schedule Schedule Schedule 10 20 30 40 60 80 100 120 140 160 0.405 0.068* 0.095* 0.540 0.088* 0.119* 0.675 0.091* 0.126* 6.840 0.109* 0.147* 1.050 0.113* 0.154* 1.315 0.133* 0.179* 1.660 1.900 0.140* 0.145* 0.191* 0.200* ____ 7.375 0 154* 0.218* 2.875 0.203* 0.276* 3.500 0.216* 0.300* 4.000 0.226* 0.318* 4.500 0.237* 0.337* 0.437 5.563 0.258* 0.375* 0.500 6.675 0.280* 0.432* 0.562 8.625 0.250 0.277* 0.322* 0.406 0.500* 0.593 0.718 0.812 10.75 0.250 0.307* 0.365* 0.500* 0.593 0.718 0.843 1.000 12.75 0.250 0.330* 0.406f 0.562f 0.687 0.843 1.000 1.125 14.0 0.250 0.312 0.375 0.437' 0.593 0.750 0.937 1.062 1.250 16.0 0.250 0.312 0.375 0.500 0.656 0.843 1.031 1.218 1.437 18.0 0.250 0.312 0.437 0.562 0.718 0.937 1.156 1.343 1.562 20.0 0.250 0.375 0.500 0.593 0.812 1.031 1.250 1.500 1.750 24.0 0.250 0.375 0.562 0.687 0.937 1.218 1.500 1.750 2.062 30.0 0.312 0.500 0.625 0.187 0.218 0.250 0.250 0.281 0.343 0.375 0.437 0.531 0.625 0.718 0.906 1.125 1.312 1.406 1.562 1.750 1.937 2.312 All dimensions are given in inches. The decimal thir:lrnsq listed for the respective pipe sizes represent their nominal or average wall dimensions. For tolerances on wall thicknesses, see appropriate material specification. Thicknesses marked with asterisk in Schedules 30 and 40 are identical with thicknesses for standardweight pipe in former lists; those in Schedules 60 and 80 are identical with thicknesses for extra-strong pipe in former lists. The Schedule Numbers indicate approximate values of the expression 1000 x P/S. tOwing to a necessary departure from the old standard-weight and extra-strong thicknesses in these two sizes, the new thicknesses are not as yet stocked by all manufacturers and jobbers, thence, where agreeable to the purchaser and suitable for the service conditions, the old standard-weight 0.375 in. wall pipe corre sponding to a 1000 P/S value of 37.7 is still available and can be substituted for the 0.406 in. wall, and the old extra-strong 0.500 in. wall pipe corresponding to a 1000 P/S value of 55 can be substituted for the 0.562 in. wall. warrant the use of pipe lighter than standard weight. For these reasons, a Sectional Committee on Standardization of Wrought Iron and Wrought Steel Pipe and Tubing functioning under the procedure of the American Standards Association, was appointed to standardize the dimensions and materials of pipe. The proposed pipe standard recommended by that sectional committee has set up several schedules of pipe including standard-weight and extra strong thicknesses which are now included in Schedules 40 and 80, re-