78 NOTES ON RIVETS AND SPACING OF RIVETS FOR OIL-TIGHT WORK, 
the spacing of rivets for oil-tight work. One of the contractors showed by calculations 
that the spacing of oil-tight riveting would be somewhat greater than that allowed by 
the bureau for water-tight work. As a result of these calculations, permission was 
requested to use water-tight spacing for rivets in oil-tight work where the weight of the 
plating is 15 pounds and over and to use 4 diameters in seams of 14-pound plating. 
The bureau granted this permission except in single-riveted joints where 314 diameters 
was adhered to. Prior to this, at the request of the contractors, approval had been given 
to use 4 diameters in the seams of shell plating and inner bottom; this plating was 15 
pounds or more and the seams double riveted. 
The bureau’s approval to use water-tight spacing for oil-tight riveting in seams 
and butts resulted in the following spacing :— 
Single riveted throughout, 314 diameters. 
Double riveted, 14 pounds and under, 4 diameters. 
Double riveted, 15 pounds and over, 4% diameters. 
Subsequently one of the contractors requested approval of 41% diameters in plating 
less than 15 pounds, basing his request on experience which convinced him that well- 
driven rivets, spaced close enough to hold water, would also hold oil. Approval of 
this spacing was held in abeyance, pending comments from other building yards. How- 
ever, at the suggestion of another contractor, approval was given to use 5 diameters as 
a general proposition in angles to plates in order to eliminate compensating liners in the 
way of oil-tight floors and bulkheads. Subsequently tests on the U. S. S. Tennessee 
have proven satisfactory with this spacing in oil-tight floor and bulkhead bounding 
angles connected to 25-pound plating and over. 
The building yards, in commenting on the 414 diameter spacing in plating less than 
15 pounds, did not confine their remarks to this particular question but made suggestions 
covering various phases of oil-tight riveting, such as riveting in floor plate and bulkhead 
bounding bars, bulkhead stiffeners, compensating liners, etc. These suggestions were 
largely based on the practice at each yard under different conditions which made it 
very difficult for the bureau to lay down general rules to be followed by all yards. In 
this connection it should be remembered that the contractor is solely responsible for 
the oil-tightness of the structure of the ship he builds. The contractor must build a 
structure and guarantee its tightness under certain specified heads, and he therefore 
must be cautious in his suggestions to depart from practice which has been found to be 
satisfactory. The bureau has assumed a liberal attitude towards approving the con- 
tractor’s suggestions, provided they are well founded and not too radical a departure 
from practice in vogue at other building yards. 
Early in 1920 the bureau advised the building yards that, in consideration of the 
past practices and suggestions, it believed that satisfactory results would be obtained 
with the following spacing — 
PLATES, SEAMS AND BUTTS. 
Single, 314 diameters. 
Double, under 14 pounds, 3% diameters. 
Double and treble, 14 pounds and under 20, 4 diameters. 
Double and treble, 20 pounds and over, 4% diameters. 
