NOTES ON RIVETS AND SPACING OF RIVETS FOR OIL-TIGHT WORK. 71 
6. The satisfactoriness, or otherwise, of single-riveted seams in double-bottom tank 
tops is largely a matter of height of test head. The tank top is naturally a stiffer struc- 
ture than decks or bulkheads, but when you get a 4o or 45-foot test head it is well to 
pause before adopting single-riveted seams. 
ComMANDER A. H. Van KeEvren, C. C., U. S. N., Member:—When the advance 
copy of this paper was received at the navy yard, New York, it was noted that mention 
is made of tests conducted at the yard, as well as of navy practice in general. It is 
thought that a brief statement as to these tests and as to present oil-tight riveting 
practice on naval vessels may be of general interest. 
The first test, as mentioned by Mr. Frear, was made on a tank representing a 
section of adjacent torpedo bulkheads stiffened by T bars and separated by transverse 
oil-tight bulkheads. This test fully demonstrated the efficiency of six-diameter spacing 
for T-bar stiffeners and for bounding bars to the torpedo bulkheads, the pressure head 
running up to 93 feet. Naturally the five-diameter spacing in bounding bars to the 
transverse oil-tight bulkheads stood up under the same pressure head. 
The further test alluded to by Mr. Frear was made on a tank built up of four thick- 
nesses of plating, namely, 12, 15, 20, and 25 pounds, respectively, on the four sides, 
and with 15-pound and 25-pound ends. A 20-pound bulkhead divided the tank into 
two sections, A and B. Each side had two seams, one lapped, the other strapped. 
The 12-pound plating had a single seam strap double riveted in both A and B sections; 
the 15-pound plating had a single strap double riveted in the B section and a double 
strap in the A section; the 20-pound and 25-pound plating had both single and double 
straps similar to the 15-pound plating. The bounding bars were mitred in two corners 
of each end of the divisional bulkhead and electric welded in place. Double bounding 
bars were used but stapled on one side only. The rivets were only caulked as necessary 
to take up leaks on the first test. The rivet spacing was as follows: 
CONNECTIONS. RIVETING. 
Plating: Winders 4p poundsSeeaeeer eee ee Cee cen 
Straps and butt laps.......... Over 14 pounds to 20 pounds............... 
20 ;poundsrandioverpaeereeea cence. 
Under 14 pounds. (Straps 9 pounds)........ 
Over 14 pounds to 20 pounds. (Ck. strap 
Double butt straps........... 15 pounds; inside strap 10 pounds)........ 
Or over, 20 pounds or over. (Ck. strap 
20 pounds; inside strap 15 pounds)...... 
Underwi4 pounds ee seeee recone ee ene 
Seam laps and seam straps..... Or over, 14 pounds to 20 pounds............ 
Or over, 20 pounds or over................. 
Wharelere WS) jororbtovels) sib bo oc scabouccoudduoubadee 
Angles to plates, including staples .|{15 pounds or over.................--0.00 
US) joorwuaGlS OF OEP oo coccovasscqoovsobes00Ke 
Rivet holes were punched small and reamed. All rivets were pan head and counter- 
sunk point except in bounding bars of ends and division plate where they were counter- 
sunk head and point. 
In testing this tank it was desired to obtain a comparison between the tightness 
when under pressure with water, air, fuel oil and gasoline, respectively, no work 
