214 THE APPLICATION OF ELECTRIC WELDING 



This disposition, to be conversant of and associated with the many paths of re- 

 search in the shipbuilding and marine engineering field, however, must not be con- 

 fused with its primary function, namely, its responsibility to the shipowners, under- 

 writers and merchants who look to it with implicit faith for technical guidance in the 

 conduct of their business. 



When, therefore, the development of electric arc welding had reached a stage at 

 which its application to the main structure of a vessel, with all the attendant possi- 

 bilities, appeared a feasible proposition, the Technical Committee of Lloyd's Register 

 of Shipping, quite in accord with its traditions, immediately embarked upon an ex- 

 haustive investigation in order to determine at first hand the suitability of electri- 

 cally welded joints for such work. 



A series of experimental tests was devised and carried out under the direction 

 of the Society's Technical Staff in England, extending over a period of many 

 months. A brief description of these tests and summary of the results have already 

 been prepared and circulated by the committee, but they are of so important and 

 practical a nature that it is not considered out of place to refer to them rather more 



fully here. 



It is commonly accepted that the tests imposed on manufactured material do not 

 in any way represent the strains which may be experienced in practice. Such tests 

 are rather based on simple means for determining the average reliability of the 

 material. Thus, also, in this case no one particular test is likely to determine 

 whether the welding process under trial is sufficient for the work it will probably 

 have to perform. 



It is therefore necessary to approach the problem rather on the basis of circum- 

 stantial evidence and to decide from a number of different types of experiments 

 whether, on the whole, the performance is satisfactory. 



The investigations were undertaken to determine the possibilities of the appli- 

 cation of electric arc welding to shipbuilding and, as it was desired to obtain as much 

 knowledge as possible of the physical properties of the combination of rolled and 

 welded material, highly skilled operators were employed. 



Thus it should be realized that the results of the experiments which have been 

 made represent skilled practice, and that in general such performance can only be 

 equalled with good workmanship and efficient supervision. 



The quasi arc process of electric arc welding was used throughout the experi- 

 ments. 



Nature and Description of Experiments. 



The general scope of the experiments included : — 



(o) Determination of modulus of elasticity and approximate elastic limit. 

 (&) Determination of ultimate strength and ultimate elongation, 

 (c) Application of alternating stresses with (i) rotating specimens, (2) sta- 

 tionary test pieces. 



