NOTES ON RIVETS AND SPACING OF RIVETS FOR OIL-TIGHT WORK. 77 
In conclusion, I might remark that undoubtedly these notes of Mr. Frear’s will form 
a valuable addition to the Society’s collection of data for the future. 
CapTaAIN RoBERT STOCKER, C. C., U. S. N., Member (Communicated) :—The paper 
“Notes on Rivets and Spacing of Rivets for Oil-tight Work,” by Mr. Hugo P. Frear, has 
been read with a great deal of interest, especially as the Bureau of Construction and Repair 
has given considerable thought and attention to this subject during the past four years; 
also as the types of naval construction for capital ships now make it particularly desirable 
to use wider spacing for oil-tight riveting. It is thought that some notes on the activities 
of the bureau in regard to oil-tight riveting may be of interest to the Society. The 
notes relate to oil-tight riveting, use of double versus single butt straps, painting of 
faying surfaces and oil stops. 
The bureau’s standard practice for spacing of rivets in oil-tight work, as contained 
in its “‘Specifications for Riveting,” limits the maximum spacing of rivets in seam laps 
and seam straps to 3% diameters, regardless of thickness of plating; also in butt con- 
nections 314 diameters is the maximum spacing allowed, unless otherwise approved or 
directed. This specification limits the spacing in angles to 4 diameters, unless otherwise 
approved, and to 4%4 diameters in bulkhead stiffeners, if caulked. The 4-diameter 
spacing in angles necessitates fitting compensating liners to strength members to which 
oil-tight structure is connected. Aside from the weight involved it is very desirable to 
eliminate compensating liners wherever practicable, because the fitting of the same 
requires an additional thickness of plating to be riveted. Each thickness means that 
much more difficulty in obtaining satisfactory work. 
On the Colorado class of battleships and subsequent capital tins, the compartments 
formed by the torpedo bulkheads are fuel-oil tanks which requires this structure to be 
oil-tight. The spaces between the longitudinal torpedo bulkheads are divided by 
transverse bulkheads at intervals of about 24 feet into fore and aft tanks. The longi- 
tudinal bulkheads are stiffened at each frame on which a transverse bulkhead is not 
fitted by vertical web plates. Aside from the longitudinal strength that the torpedo 
bulkheads contribute to the ship, they must be capable of deflecting like a disc before 
rupture occurs, in order to accomplish the full purpose for which they are designed. 
It is therefore paramount that there be no marked line of weakness nor weak spot where 
a tear might readily start. As mentioned above, all work in connection with these bulk- 
heads is required to be oil-tight and to compensate for the lines of weakness, caused by 
the close spacing of rivets connecting the vertical members to the torpedo bulkheads, 
compensating liners are required at each frame, each being about 30 feet in length 
amidships. It is obvious that, in a vessel as long as a modern battleship, this would 
require a large amount of bulkhead liners. It also means four-ply riveting in most cases. 
In laying out these bulkheads, the contractors were instructed to obtain the maximum 
strength with the widest possible spacing of rivets. 
_ The above indicates that the point had been reached in United States naval con- 
struction where wider spacing of rivets in oil-tight work would have to be seriously 
considered and investigated in order to make practicable the construction of the torpedo 
bulkheads and to obtain the desired results sought in their design. This was the origin 
of the bureau’s departure from its practice for oil-tight riveting prior to 1916. 
The contractors about this time began to investigate the possibilities of increasing 
