80 NOTES ON RIVETS AND SPACING OF RIVETS FOR OIL-TIGHT WORK. 
the 15-pound plating leaked. The only leakage was through the butt caulking of the 
single-strapped seams and amounted to 1% gallons for the hour. Deflection the same 
as on section (A). 
‘‘aIR TEST ON SECTION (B). 
“Pressure was gradually raised up to 30 pounds. The tank was tight up to 13 
pounds when the seams in the 12-pound and 15-pound plating began leaking and con- 
tinued to leak during the two hours the pressure was on the tank. Pressure dropped 18 
pounds in two hours. All of the leakage was through the butt caulking in the 12-pound 
and 1s-pound seams. Electric welding, riveting and other connections were perfectly 
tight during this test. The 12-pound plating deflected 74 inch under the 30-pound pres- 
sure and retained a permanent set of 14 inch. 
‘“SECTION (A) AIR TEST. 
‘“The air test on this section was similar to that on section (B), with slightly better 
results due to the seam of the 15-pound plating being double strapped. The pressure 
dropped 834 pounds in two hours, all of the leakage being in the butt caulking of the seam 
in the 12-pound plating. The electric welding, riveting and other connections were per- 
fectly tight. Deflection and permanent set were same as on section (B). 
‘“The method used to locate air leaks during the air tests was by painting all seams, 
laps, rivet points, etc., with soapy water. 
‘‘45-FOOT HEAD OIL TEST ON SECTION (A). 
“The tank was filled and a constant pressure of not less than 19 pounds and more 
than 20 pounds was kept on the tank for twenty-four hours with the following results :— 
‘‘During the twenty-four hours the tank leaked 134 gallons of oil, the greater portion 
of which came through the butt caulking of the 12-pound plating. A small portion, how- 
ever, leaked through the caulking of the bulkhead bounding bar where same was riveted 
to the 12-pound plating. A very slight leakage around a very few rivets was too small 
to measure. Electric welding on the bounding bars did not show any sign of leakage. 
The deflection and permanent set were about the same as when under water and air 
pressure. The pressure was maintained by applying air pressure to the top of the stand 
pipe, which was filled with oil. 
‘as-FOOT HEAD OIL TEST IN SECTION (B). 
‘Results not as satisfactory as the test on section (A), as the butt caulking in the 
seam of the 12-pound plating leaked continually and it was necessary to refill the stand 
pipe during the test. The leakage for the 24 hours was 1834 gallons, all of which came 
through the butt caulking in the way of the seam strap in the 12-pound plating. A few 
rivets showed signs of leaking, but this leakage was too small to measure. The deflection 
and permanent set were about the same as when under water pressure. 
‘*6s-FOOT HEAD OIL TEST IN SECTION (A). 
‘Pressure gradually applied up to 30 pounds. The deflection was slightly greater 
in the r2-pound plating under the 30-pound pressure than under 20-pound pressure; but 
the leakage through the butt caulking was slightly less. The leakage during the twenty- 
four-hour test was only 7 pints against 134 gallons under twenty-four-hour test. This was 
