80 



Bulletin 86 



cure the pipe in steam chambers, which accelerates the hardening 

 process. 



The thickness of the pipe recommended is given in Table I. The 

 thickness of the drain tile is about one-twelfth of the diameter of 

 the pipe, of the sewer pipe one-tenth of the diameter, and the thick- 

 ness of the irrigation pipe is intermediate between the other two. 

 If the irrigation pipe is to be subjected to considerable heads, it 

 should be "one-tenth pipe.'' 



TABLE I. THICKNESS AND WEIGHT PER FOOT OE MACHINE-MADE PIPE 



The capacity of the McCracken machine per hour for irrigation 

 pipe is about 300 feet of 6-inch pipe, 200 feet of 12-inch pipe, 120 

 feet of 16-inch pipe, and 80 feet of 24-inch pipe. Straight tile are 

 turned out somewhat faster. The older machines make pipe of 24 

 inches length, but the most recent models make the tile or pipe 30 

 inches in length. The range of sizes for the No. 2 machine is from 

 4 inches to 24 inches in diameter. 



A complete outfit consists of the machine, an engine or motor of 

 25 horsepower, a concrete mixer, and two-wheeled carriers ; jackets, 

 pallets, and packer-heads for each size of pipe which it is desired 

 to make ; and two sizes of elevator buckets. 



The proportions for the mortar should be 1 cement to 3 sand, 

 except for city sewer pipe and irrigation pipe under high head, for 

 which the proportions may be 1 to 2^ or 1 to 2^. In many cases 

 pipe have been made of leaner mixtures,l:4 or 1:5, but failures 

 have resulted sometimes, and the leaner mixtures require better 

 conditions of curing. 



The force of men required to make pipe, as exemplified at Con- 

 tinental, is as follows : At first there were three skilled laborers, — 

 the foreman, the machine operator, and the stripper ; and five un- 



•For very deep trenches, heavier pipe should be used. 



