224 THE APPLICATION OF ELECTRIC WELDING 



Since her completion the barge has been engaged in cross-channel service and 

 with a full cargo of ammunition has experienced some exceptionally heavy weather, 

 but has so far shown no signs of failure in the electrically welded joints. 



Mr. A. J. Mason''s Experimental Section. — With the object of trying out on full 

 scale several methods of electric welding, Mr. Mason of the United States Shipping 

 Board is having constructed at the Federal Shipbuilding Company's yard, Kearny, 

 New Jersey, a 42-foot length of the full-size middle-body section of one of the stand- 

 ard 9,600-tons deadweight vessels, the drawings for which are shown in Plate 24. 



Owing to the difficulty in securing material, some departure has been made from 

 the regular scantlings, and ordinary tank quality steel is being used. 



It is proposed to employ a variety of different methods of connection, including 

 riveting, in the different parts, and a serious attempt will be made to apply the port- 

 able spot welder, previously referred to, both for clamping and welding. 



In this work Mr. Mason is collaborating with the Welding Committee, and 

 considerable information of a practical nature is anticipated during the erecting 

 and welding of the structure by different systems. 



The section is arranged so that on completion it may be filled with water and 

 subjected to hydraulic and such other tests of a practical or scientific nature which 

 may be suggested. 



Designs for Welded Ships. — Two significant points to bear in mind in design- 

 ing an electrically welded vessel, for the present at any rate, are, first, that our 

 knowledge of the welded joint is still far from complete, and secondly, a welded 

 joint has not yet been produced which is 100 per cent efficient in all respects as com- 

 pared with the parent material united. With reasonable precautions it is compara- 

 tively easy to obtain a tensile strength at least equivalent to the metal united, but 

 tension is only one of the many stresses to which such structures are subjected. It is 

 not so easy to reproduce the same degree of ductility, the resistance to fatigue and 

 to combined stresses of various kinds. 



Another unknown factor which must not be lost sightof is the ability of a riveted 

 vessel to adjust itself to stresses, or, as Kipling puts it, to "find" itself. The joints 

 are made when the ship is on the ways, inanimate. When she gets afloat an entirely 

 different set of conditions is presented, and the unbalanced internal stresses intro- 

 duced during the process of bolting up and riveting are frequently intensified. How- 

 ever, when put into a sea-way, the repeated and alternating stresses cause her to 

 "work," a rivet "gives" a little here, a joint "takes up" a little there, and the stresses 

 are passed from one to the other, until the structure acts as one harmonious whole. 



Just how essential is this property in a ship joint, experience with the first welded 

 ocean-going ship alone can show. 



There is no doubt that these questions will be largely if not wholly answered as 

 a result of further study of the metallurgy and physics of welding, and with a wider 

 practical experience of its application to the main structure of ships. 



Until then, however, and in the absence of any exact method of testing the 



