116 Bulletin 86 



should be given a three hours' dip in in irrigation ditch or in a vat 

 shortly before laying.; or water should be run down the trench on 

 top of a shallow backfill at the same time that water is admitted into 

 the line. This is easily accomplished by leaving the riser valves 

 open. 



At Continental there has been no failure of pipe smaller than 20- 

 inches in diameter, though several gate pits were crushed by the 

 longitudinal expansion of dry 12 and 16-inch pipe lines. Expansion 

 joints placed near gate pits relieve the pressure against these struc- 

 tures and would be useful on curves. Accuracy in alignment is ad- 

 visable. In hot weather the pipe making should be slowed down to 

 the same rate as pipe laying, so that the pipe can be laid within a 

 few days after its curing period. Cement pipe plants should not 

 carry a large stock of pipe out of doors through the summer. 



Accidents and failures are likely to occur on all pipe lines, 

 whether clay or cement, when they are new. The pipe layer should 

 stay on the work while the pipe is being tested and proven. Almost 

 never does an accident occur on an old line. 



