WOOD PIPE FOE CONVEYING IRRIGATION WATER. 21 



crossed it is usually best to carry the pipe line over the stream rather 

 than under it. This facilitates draining the pipe, and repairs can 

 be more easily made. 



CONSTRUCTION OF CONTINUOUS STAVE PIPE. 



Where the pipe is to be built in a trench, the excavation is made 

 from 1 to 2 feet wider than the diameter of the pipe. Then the 

 staves of the lower half of the pipe are set up in a U-shaped form 

 made usually of l|-inch gas pipe bent on a curve equal to the outside 

 diameter of the pipe. Another piece of gas pipe bent into a circle, 

 of diameter slightly less than that of the wood pipe, with the ends 

 overlapped and spread so that it will stand alone, is set on the lower 

 staves already placed, and serves as a form for the upper part. If 

 wooden cradles are used and two-piece bands, the lower section of the 

 band, set in a cradle, is sometimes used as the bottom form instead of 

 the gas pipe. A few bands sufficient to hold the staves in place are 

 then slipped on, and the final banding is completed by other men, 

 the spacing of each section being marked along the pipe according to 

 tables or profiles in the hands of the foreman. During the progress 

 of lining up and partially tightening the bands, the pipe is rounded 

 out evenly and the staves are driven up to make the butt joints tight. 

 Wooden mallets are used for the " coopering," and in driving home 

 the staves iron-bound hardwood blocks are used with sledge hammers. 



The end driving must usually be done repeatedly as the bands are 

 tightened, care being exercised not to bruise or injure the staves. 

 The final cinching may be delayed somewhat and should be done 

 with careful judgment, particularly where the spacing is close, in 

 order to avoid crushing the wood or shearing quarter-sawed staves. 

 Special braces or wrenches with long shanks and short leverage are 

 generally used for this work, each builder, as a rule, designing his 

 own tools. Curves are made by crowding or pulling the partially 

 banded pipe to the desired position with jackscrews or blocks and 

 tackle. 



A pipe-laying gang usually consists of from 8 to 16 men, the num- 

 ber depending on the closeness of banding, etc. The speed of con- 

 struction depends upon the size of the pipe, spacing of bands, curva- 

 ture, etc. On a 48-inch pipe built at Clarkston, Wash., in 1906, 250 

 feet was the most that was laid in 10 itours, and the amount ran 

 down to as low as 50 feet where work was difficult. 



According to J. D. Schuyler, 1 150 to 300 feet of 34-inch pipe 

 was made per day by a crew at Denver, Colo., the number of bands 

 placed ranging from TOO to 1,000, while on 44-inch pipe 500 bands 

 were placed per day. In 1910 a 48-inch pipe, 10 miles long under a 



1 Trans. Amer. Soe. Civ. Engin., 31 (1894), p. 135. 



