NOTES ON RIVETS AND SPACING OF RIVETS FOR OIL-TIGHT WORK. 65 
expense, it might be well worth considering whether or not there would be serious 
objection to single-riveting the longitudinal seams of center-line bulkheads with 
the exception of the lower seam. A cargo is sometimes made up of more than one 
kind of oil, and it is therefore important that the transverse bulkheads be abso- 
lutely tight, but different kinds of oil have seldom been carried on opposite sides 
of the center line, and it would appear that a single-riveted longitudinal bulkhead 
would fulfil every function the trade demands. 
As noted above, Lloyd’s in their first announcement, more or less official, 
recommended three diameters for all oil-tight spacing. This was, in some cases, 
applied literally. Two vessels were converted in the vicinity of New York to 
carry oil in bulk, on which a spacing of three diameters was required in both rows 
of rivets in the flanges of single 5 inches by 5 inches bulkhead bounding bars, 
which both crowded the rivets and unnecessarily impaired the strength of the 
shell plating. Classification societies now allow a spacing of five diameters 
connecting bulkhead bounding bars to shell. 
Lloyd’s formerly recommended single double-riveted bulkhead bounding 
bars but later gave the builder the option of using double single-riveted bars. 
The general practice now is to use double single-riveted bars with countersunk 
heads and points and bars caulked on both flanges on each side. The writer is 
inclined to favor single double-riveted bounding bars and pan-head rivets in 
standing flange with caulking on one side because it is believed this lends itself to 
cheaper and better workmanship and would insure the parts being drawn up more 
closely. Countersunk heads are, of course, unavoidable in the shell flange. 
On the Clyde, bulkhead bounding bars are frequently hydraulically riveted 
on the ground, using pan-head rivets and finishing with snap heads and points. 
Similar practice is universally followed in this country in the case of locomotive oil 
tenders and tank cars. Snap rivets driven by hand are also satisfactorily used in 
the construction of oil storage tanks. 
There are two vessels now building for the same owner in different yards 
with double single-riveted bulkhead bounding bars with countersunk head rivets 
where in one case every rivet is required to be caulked head and point before 
testing, while in the other case none of the rivets are being caulked before testing. 
A good pan-head rivet should never require caulking before testing. Pan-head 
rivets are used in the bulkhead stiffeners and are not required to be caulked before 
testing, which seems to indicate that it is considered the countersunk head rivet 
requires more doctoring. 
In the case of another vessel now building the inspectors are instructed that 
rivets are to be caulked before testing, in bulkhead bounding bars, heads and 
points, in all four flanges, also rivet points through bulkheads in clips connecting 
longitudinal brackets to bulkheads, while in the same instructions it is recom- 
mended that as few rivets as possible be caulked before the water test, as it is 
desired that the rivets be driven in such a manner as to be tight without caulking. 
Where double bounding bars are fitted, careful workmanship is necessary to 
insure the two shell flanges lining up perfectly for intimate contact. To overcome 
