234 THE APPUCATION OF ELECTRIC WELDING 



rivets in multiple, and another heats four in series. This work is done very successfully and 

 replaces the usual forge. 



■Another adaptation of electrical energy is in the heating of rivets inserted in plates. For 

 this method is claimed. not only rapidity of operation but also annealing of the plate in the 

 vicinity of the hole, due to the heating in place. 



Mr. Cox refers only slightly to the use of the carbon arc, and that is probably because he 

 has considered here, again, welding of the ship structure proper. On the lighter work that 

 goes into a ship (the sheet metal work) there is a vast field for the carbon arc, and this is 

 particularly true of the carbon arc mechanically driven. 



Although the hand-operated carbon and metal electrodes have been used exclusively up 

 to the present time, the development of the mechanically driven electrode is now making rapid 

 strides, it is doing practical work of a high order, and there is every reason to believe that 

 it will supplant hand welding in many places. Mr. Hobert's remarks on the advantages of 

 high-current densities and high-current values will tend to accelerate that progress. 



In shipbuilding, considering the structure as a whole, the metallic electrode will, of course, 

 be the principal means used, whether bare, coated, covered, or composite. By composite I 

 mean a steel electrode with some form of core. The Research Sub-Committee of the main 

 Welding Committee is now engaged on the development of steel electrode wires with cores 

 applied somewhat after the fashion of electric light carbons. 



A reference is made in the paper to the tests of larger sized models. I did not arrive in 

 time to see the moving pictures, but I believe a picture was shown of Mr. Wagner's 12-foot 

 cubical tank at Pittsfield, which has been welded and tested with repeated bending tests. At 

 Norfolk there is a similar tank almost finished, which is to be subjected to similar tests. The 

 welds in the Norfolk tank are different, but its design is practically the same, though it is of 

 somewhat smaller size. 



We are also building at Norfolk a battle-towing target, the design of which some of you 

 may know, but for the benefit of the others I will say it is a target carrying a large screen, 

 towed behind battleships, and used in their gunnery practice at sea. Among other parts it has 

 a steel vertical box keel 100 feet long by 16 feet deep, made up of half -inch plate. The 

 two vertical sides are braced 4 feet apart, with cross frames or floors. The welding of this 

 target is under way and we would be glad to have any one interested call and see it. 



Two days ago we had one of the first chilly days at Norfolk, and a little after 7 o'clock 

 the first gang got out and began chipping out a bad spot in a weld. Suddenly a whole butt be- 

 tween two of these plates went ofif like a gun. The cause of the break was the contraction 

 of an improperly welded strapped butt joint. The welders had first welded the fillet on each 

 edge of the strap and then filled in the bevel between the plates being joined. They had thus 

 introduced some molecular strains in the filler metal, so that the cold weather, coupled with 

 the hammering in the vicinity, caused the seam 6 feet long to let go. It was, nevertheless, a 

 very useful lesson and we were not surprised at the break. We now understand how to weld 

 strapped butts. 



When the Jupiter was put into use, there were two questions often asked : First, whether 

 there was not some danger from the voltage (2,300 volts) ; and, second, whether dampness 

 would not affect the integrity of the insulation. I was questioned many times about the Jupi- 

 ter and these were the two principal questions which were put. Similarly in arc welding, the 

 questions generally asked are the ability of the arc weld to resist vibration, its ductility in case 

 of collision, and its ability to resist corrosion. 



