82 NOTES ON RIVETS AND SPACING OF RIVETS FOR OIL-TIGHT WORK. 
leaked slightly. The pressure dropped 5 pounds in six hours, leakage 314 gallons. De- 
flection and permanent set the same as on previous tests.” 
An interesting case of the unsuitability of single butt straps for oil-tight shell plating 
is in the case of the shell plating of the U. S. S. Kanawha below the upper turn of bilge. 
As originally built, the butts of this plating in way of the oil tanks were fitted with 30- 
pound single straps on the inside, quadruple riveted, the shell plating itself being 28 
pounds. The rivets used were 7% inch in diameter, and the spacing in rows of the first 
three rows next to the butt varied from 3 inches to 3 % inches; the spacing of those in the 
fourth row, 5 inches. In service with the vessel loaded with oil, these butts gave con- 
siderable trouble, due to leakage. At the docking of this vessel, numerous butts, seams 
and rivets were caulked to overcome the leakage. After these repairs the vessel went to 
sea and, after encountering two gales, one of unusual severity, the same trouble was 
experienced, 7. ¢., opening of certain butts and the weeping of certain rivets. As the first 
attempt to overcome this leakage was unsuccessful, the bureau directed these butts to be 
double strapped. The work consisted of retaining the old inside strap intact, cutting 
out all of the rivets of the first three rows, reaming the holes to take 1 14-inch rivets, fitting 
a 30-pound outside strap, treble riveted, and driving 1 4%-inch rivets in the enlarged holes 
of the %-inch rivets. These new outside straps were edge caulked; also all rivet points 
were caulked. After these repairs were made the vessel carried three cargoes overseas, 
and the commanding officer reported that there was no evidence of leaks, the cargoes 
being delivered intact as to quantity and no shortage. 
In all recent ships, such as battle cruisers, battleships 49 to 54, destroyer tenders, 
submarine tender, fuel ships, etc., the bureau has required all butts of the shell plating 
in the vicinity of oil tanks to be lapped butts where the thickness of the plating will per- 
mit; otherwise the butts to be double strapped. 
In 1912 the question was raised as to the benefits, if any, obtained by painting fay- 
ing surfaces. This was taken under advisement, and navy yards and superintending 
constructors were requested, in connection with repair work on naval vessels, to observe 
the condition of faying surfaces. While the reports received as a result of the observa- 
tions were not unanimous, they indicated the doubtful value of painting faying surfaces, 
especially those where the riveting was either water-tight or oil-tight. A number of 
cases were observed where the faying surfaces of water-tight connections showed no signs 
of paint, and yet the surfaces indicated no evidence of corrosion. 
In 1917, at the conference held in connection with the revision of the General Speci- 
fications for building ships of the U. S. Navy, at which were present representatives of 
the contractors, the question came up again. Strong arguments were advanced against 
the painting of these surfaces. One of these arguments pointed out that the painting of 
faying surfaces was more detrimental than useful, as it caused dirt and small particles of 
material to adhere to the surfaces which carried them into the joints, it being imprac- 
ticable to handle plates without the surfaces coming at times in contact with the ground. 
About this time Lloyd’s advised the bureau that they at one time had required these sur- 
faces to be painted but had discontinued this practice many years ago. 
After careful consideration of the above, the bureau revised the requirements of its 
General Specifications as follows:— 
‘“‘Where oil tight or water tight spacing of rivets is used, the faying surfaces need not 
be painted. In other cases the faying surfaces shall be painted.” 
It is the bureau’s practice to limit the use of stop waters and oil stops to the mini- 
