Manufacture of Cement Pipe 



95 



beneath a river should have heavy reinforcement longitudinally. 

 A long section of the city supply pipe was unjoined when a river 

 flood broke into the unfilled trench and floated the pipe line upward. 

 Usually the longitudinal reinforcement is introduced merely for the 

 purpose of holding the horizontal rings in place. 



The circular reinforcement is designed usually to take all of the 

 internal tension, allowing 16,000 pounds i:>er square inch for the 

 unit stress. If the tension is 

 due to internal water pressure, 

 the steel is placed near the out- 

 side of the pipe, but buried in 

 the concrete about an inch to 

 protect it from rust. If the re- 

 inforcement is to resist the 

 weight of backfill, then the 

 steel rings are made elliptical, 

 so that they are near the inside 

 of the pipe at top and bottom 

 and near the outside on the two 

 sides. For pipe over 24 inches 

 in diameter it is practical to al- 

 low higher pressure heads, be- 

 cause the pipe layers can work 

 inside of large pipe and can 

 make better joints; Many con- 

 crete pipe lines with heads be- 

 tween 100 and 200 feet are in 

 successful use. 



The Massey Company make 



reinfnrrpd ronrretp rnlvert nine^'^- 16.— Cage of Triangle Mesh reinforcement 

 remiorcea concrexe cun eri pipe ^j^j^ ^^'iTes properly spliced. 



for railways and highways. For 



small sized pipe they use steel mesh, with steel uprights and bell 

 rings, while in the larger sizes they use a cage of ^-inch Havemeyer 

 bar for vertical bars and all rings, all hand-tied with No. 14 annealed 

 wire. The mix is 1:2:4. 



Reinforced concrete pipe, wet-poured, is also constructed in 

 place in many instances, a local example being the cross-cut col- 

 lecting head of the Tucson Farms Company near the southwest 

 corner of the city. The power conduit at the Roosevelt Reservoir 

 has two inverted siphons constructed in this manner, one of them 

 crossing Cottonwood Canyon at a depth of 75 feet below the grade 

 line of the canal. 



