Y68 NEW YORK STATE MUSEUM 



Manufacture of sewer pipe 



If a sliale or very hard clay is used the material is first ground 

 in a dry pan, after which, or directly, if soft clay is used, the 

 material is put into the wet pan, or chaser mill, either of which in 

 a few minutes tempers a charge of clay in a thorough manner. This 

 method of tempering is far more thorough and quicker than the 

 work of a pug mill, though requiring more power. 



The tempered clay is usually conveyed to the upper floor of the 

 factory by means of bucket elevators, where it is delivered to the 

 sewer j)ipe press. This press consists of two cylinders, an upper 

 steam cylinder and a lower clay cylinder, the ratio of their diam- 

 eters being most often as 3 to 1. The steam cylinder has a diameter 

 of about 40 inches; the piston of the steam cylinder is moved both 

 upward and downward. 



The clay cylinder is filled with clay; and the piston then forced 

 downward by the piston of the steam cyhnder above, the pis- 

 ton rod of the two being continuous. This forces the clay out 

 through a specially constructed die at the lower end of the clay 

 cylinder. Inside of the cylinder at its lower end is the bell, which 

 regulates the internal dimension of the pipe. The clay pipe issues 

 from the press till of sufiicient length, when the machine is stopped, 

 and the pipe cut off, and removed to the drying floor. The cutting 

 off of the clay pipe takes place close to the mouth of the die either 

 by means of a wire or an automatic knife edge set within the die. 



The drying of the pipe is often done on slatted floors, or at other 

 times on solid ones, in steam-heated rooms. The small diameter 

 pipe can be dried comparatively fast, but the large ones must be 

 dried very slowly. 



Sewer pipe are usually burned in down-draft kilns, from 16 tc 

 25 feet in diameter, (pi. 97) The pipes are set on one another, 

 and when they are of several sizes can be nested. 

 , Sewer pipe should be free from blisters, cracks and other defects, 

 and should be straight. 



