450 ANNU^y:^ report Smithsonian institution, 1935 



by a 300,000-volt portable iniichiiie, the lilm examine*.!, all fla^YS 

 chipped out aiiel rephioed wkh new metal, and the weld X-rayed 

 again. The pipe was then taken by one or more 75-ton traveling 

 eranes to tlie normalizing fnrnaee where it was heated to a tempera- 

 ture of IjloO*^ F., held at this temperature for several hours, and 

 slowly cooled to relieve the stresses set up by rolling and welding. 

 From the furnace, the section traveled to a facing lathe eiiuipped 

 with a 35-foot arm, where the pipe emls were machined, anil the 

 section then taken to the storage yard for cleaning, painting, and 

 the drilling of holes for erection pins. Fabrication of all pipes 

 is expected to be completed in 1935. Items of interest, relating to 

 the work, are that there will be approximat-ely 76 miles of weld- 

 ing and the X-ray tilm used will be "29 miles in length. 



Transportation of sections from plant to canyon rim was by train 

 for the 13-foot diameter pipes and smaller ones, and by a 200-ton 

 trailer pulled and controlled by two 60-horsepower caterpillar trac- 

 tors for the heavier sections. The i20t>-ton Government cableway 

 transferred the pipe from canyon rim to a "' car-on-a-car " at the 

 portals of one of the construction adits from where it traveled on 

 the double carriage through the adit to a penstock header tunnel and 

 was pulled to its approximate final position on the top single car- 

 riage by suitably located winches. 



If the pipe section was intended for a position in one of the raises 

 to the intake towers, the car left the tunnel rails at the base of the 

 raise and traveled on the concrete lining to its place under impetus 

 of three hoists, each of 75 horsepower rating, located on a platform 

 at the tow'er base. 



The procedure of erection was to install spiders in each adjacent 

 pipe section and by means of jaclcs in the ends of the two spider 

 arms form the pipes in round sections. The butt strap was then 

 heated with a gas ring (using butane gas), one pipe was pulled 

 into the other with winches or a specially devised spider, steel 

 pins were inserted and pressed into place from inside the pipe, a 

 rim was cut into the pipe around the outer end of the pin and this 

 rim calked inward beneath a projecting rim on the pin. The outer 

 end of the butt strap was also calked into the pipe it enclosed. The 

 pins for the largest 30-foot sections w^ere S^V inches in diameter, 

 and the diameter of the drilled hole, into which they were pressed, 

 was three-thousandths of an inch less than that of the pin. 



All pipe sections were pinned, excepting the 8V2-foot outlet con- 

 duits, which were hot-riveted, and a few miscellaneous sections that 

 were welded. In the latter case, the weld and pipe near it were 

 stress relieved by heating with gas rings. 



