378 HYDRAULICS 



in which T is the weight, in tons, and m the length, in miles. 

 In estimating, about 5% may be added to cover breakage, 

 specials, and contingencies. 



EXAMPLE. What is the weight of 17 mi. of pipe 16 in. in 

 diameter and .7 in. thick? 



SOLUTION. Substituting given values in the formula, T 

 = 2SX17X.7X(16+.7) = 5,564 T. Adding 5%, the required 

 weight is 5,564 + 5,564 X. 05 = 5,842 T. 



The following table gives the nominal diameter, thickness, 

 weight per foot and per length of 12 feet with standard 

 sockets, for four different pressures. 



RIVETED STEEL PIPE 



Thickness of Riveted Steel Pipe. The thickness of a riveted 

 steel pipe may be computed by the following formula: 



pd 



l = ~ -- 1- .3 

 20,000 



in which t is the thickness, in inches; d, the diameter of pipe, in 

 inches; p, the pressure, in pounds per square inch, due to 

 static head. 



EXAMPLE. Determine the thickness of a riveted steel pipe 

 36 in. in diameter, to withstand a pressure of 125 Ib. per sq. in. 



SOLUTION. Here, = 125 and d = 36. Substituting these 

 values in the formula, 



125X36 



Flow in Riveted Pipes. On account of their special con- 

 struction, riveted steel pipes offer greater resistance to flow than 

 do cast-iron pipes. Sufficient data are not available from which 

 a satisfactory value for / can be found. The formula most 

 generally used for the velocity in riveted pipes is Chezy's for- 

 mula supplemented by Kutter's formula with a value for n 

 varying between .013 and .015. 



WOODEN-STAVE PIPES 



Wooden-stave pipes are composed of wooden staves held 

 together with round steel rods called bands. They are well 

 adapted for carrying water for long distances and in quantities 

 that necessitate ^rge diameters. Their cheapness in first cost, 



