THE FLOW OF WATER IN CONCRETE PIPE. 
OPINIONS OF ENGINEERS REGARDING THE CARRYING CAPACITY OF 
CONCRETE PIPE. 
Experiments upon the flow of water in concrete pipes have been 
so few in number that there has been developed no clearly defined 
trend in thought, as was the case with the capacity of wood-stave pipes. 
In his discussion of tunnels, Finkle 1 advocates applying a one- 
fourth inch coat of cement and sand in a 1 to 2 mixture to give a 
smooth surface and prevent percolation through the main concrete 
walls. "By means of this construction/' he adds, "the coefficient 
of roughness in the Kutter formula has been reduced as low as 0.010 
and in other cases it has been as high as 0.012. If the work is very 
poorly done it might run to 0.013." 
Schuyler states 2 that the conduit supplying Mexico City was 
designed with a value of n equal to 0.017, but upon examination after 
construction he remarks, "The interior of the conduit is very smooth, 
and answers to Kutter' s rating of 0.011." 
In his conclusions concerning the use of small cement-lined iron 
pipe, Metcalf has this to say of the carrying capacity: 3 
Satisfactory data are lacking upon the carrying capacity of cement-lined pipes. It 
is believed that under favorable conditions the coefficient of discharge to be used in 
the Hazen and Williams formula is about C w =120, but under actual conditions this 
coefficient has been found, in several carefully observed cases, to lie between 95 and 
110. Unless the conditions are definitely known, therefore, the use of a coefficient 
not exceeding C w =100 to C w =110 in the Hazen and Williams formula is to be 
recommended. 
Jorgensen used a value of n of 0.012 in the design of a 6-foot rein- 
forced concrete flow line. 4 
Conway 5 says that n was taken as 0.013 in the design of some 
lines in Mexico. The pipe units were 61 cm. (practically 2 feet) long, 
made with a u dry mix" and afterwards coated "with a Portland 
cement grout to which a little freshly slaked lime was added." 
Table 1. — Friction factors used in designing concrete pipes of United States Reclamation 
- Service. 
Project. 
Line. 
Type. 
Size. 
Kutter's 
used. 
Length. 
Salt River 
Continuous 
. . .do 
Indies. 
63. 
63 
6 to 30 
54 
30| 
12 to 47 
70 
64 
30J 
30J 
36 
0.012 
0.012 
0.013 
Feet. 
2 130 
Do 
500 
Tieton 
Various 
255, 689 
3,100 
Sunnyside 
Mabton * 
...do 
Do 
do. . 
0.013 
3,088 
61, 728 
3,565 
Umatilla 
do 
Belle Fourche 
Belle Fourche 
Continuous 
do 
0.012 
0.014 
0.013 
0. 013 
0.013 
Milk River 
Willow Creek 
1,479 
Boise 
Chance 
4,770 
3,546 
Do 
. .do 
Do 
do. . 
8,575 
1 The Most Economic Type of Hydraulic Power Conduits. F. C Finkle, Eng. Rec, vol. 52, Sept. 2, 
1905, p. '263. 
2 The New Water-Works and Reinforced Concrete Conduit for Mexico City. J. D. Schuyler, Eng. News 
vol. 55, Apr. 19, 1906, p. 435. 
» Wrought-Iron Cement Lined Water Pipe. Leonard Metcalf, Eng. News, vol. 61, p. 2, Jan. 7, 1909. 
4 Eng. News, vol. 62, Aug. 5, 1909, p. 146. 
5 The Water Works and Sewerage of Monterev, Mexico, by G. R. G. Conway: Trans. Amer. Soc. Civil 
Engin., vol. 72, 1911, p. 497. 
