THE POWER-FORGING OF CHAIN CABLES. 
By Navat Constructor Freperic G. Cospurn, U. S. N., MemBer. 
[Read at the twenty-fourth general meeting of the Society of Naval Architects and Marine Engineers, held in 
New York, November 16 and 17, 1916.) 
There has been developed, during the last two years, at the United States Navy 
Yard, Boston, Massachusetts, a power-forging process for the manufacture of chain 
cables which has been highly successful; and on account of its success and of the 
possibilities at present in view this paper has been prepared for the information of 
the members of this Society. It will be remembered that a paper on chain cables 
was read before this Society in December, 1913, by Assistant Naval Constructor 
J. E. Otterson, United States Navy, his paper being a historical review of the manu- 
facture of chain cables by hand and a statement of the efforts made up to that date to 
produce chain by a power process. Those who are interested are referred to Assist- 
ant Naval Constructor Otterson’s paper for a discussion of the relative merits of 
side- and end-welded chain, the function of the stud, breaking and proof stresses, etc. 
This paper will deal with the progress of the yard in power-forging since the neces- 
sity for its development arose. 
No great mechanical difficulty was experienced in the manufacture of chain by 
hand until diameters as great as 234 inches were reached; even that size was fairly 
well handled; but when the 3-inch cables were taken up, serious difficulties were en- 
countered on account of the size of the metal, the mechanical difficulties involved, and 
the very hard labor required of the chainmakers’ helpers. It was not only difficult 
to get chainmakers to make good chain; it was exceedingly difficult to get them to 
attain a satisfactorily high rate of production and regularity of attendance. 
When the Panama Canal Commission went into the market for the guard 
chains for the Panama Canal, which were 3 inches in diameter, the Boston Navy 
Yard was the only plant that could reasonably approach the requirements of the 
Commission. A great part of these cables was made with open links—that is, with- 
out studs—and hence was inherently weaker than stud chain; and as the welds were 
not well made the ultimate breaking stresses obtained were low. Whereas 525,000 
pounds ultimate breaking strength was required for stud-link chain and desired for 
3-inch open-link chain, it was found necessary to reduce the requirement to 500,000 
pounds and subsequently to 450,000. Private chainmakers were given contracts. 
Their chain was not so good as that made by the hand-welders at the Boston Navy 
Yard; it lacked the uniformity in shape and size of link and was not so well welded. 
In the photographs of Panama chain test triplets, to which reference is now invited, 
it will be seen how irregular in shape the hand-welded links were, how they were 
reduced in diameter next to the weld, and how obviously inferior they are to the 
