66 NOTES ON RIVETS AND SPACING OF RIVETS FOR OIL-TIGHT WORK. 
this difficulty and with a view to better and more economical work, T-bars have . 
in some cases been used, although the present available 614 inch by 6}4-inch 
T-section does not provide sufficient width of shell flange on that side on which the 
bulkhead plating connects to the standing flange for best spacing of the rivets. 
A more general use of this type of bounding bars has been recommended by some 
owners, and with this in view two of the large shipbuilding concerns have without 
success urged the steel companies to roll a larger section. Conditions, however, 
would be substantially the same as with single bounding angles. Pan-head rivets 
could be used except in one flange, three-ply work would be eliminated, and only 
two edges would require caulking. A single angle as recommended above would 
have the same number of rivets, the same amount of caulking, and be more 
easily set. 
In gunwale bars, Lloyd’s require four and one-half diameters for water-tight 
work and five diameters for oil-tight work, which does not seem consistent. Ina 
recent case, I-inch rivets were spaced five diameters in a 5-inch by 5-inch gunwale 
bar for oil-tight work and appeared to be too crowded for the width of flange and 
size of rivets. Probably a larger bar or six diameters would have presented a 
better appearance. 
The table on the following page gives, for a number of selected parts, the 
rivet spacing recommended by Mr. Martell in 1894 for oil-tight work and present 
requirements for both oil and water-tight work of Lloyd’s, American Bureau, 
United States Navy, and British Admiralty. 
Conditions briefly referred to in the table, no doubt, justified Mr. Martell in 
recommending a spacing of three diameters for satisfactory oil-tight work, but 
better design, construction, and workmanship have demonstrated that strong, 
staunch ships can be built with wider spacing and be suitable for carrying oil in 
bulk. Scantlings and riveting must be sufficient to resist the stresses brought 
upon them, and there must be no slipping of the joints. When this condition is 
fulfilled the work should be oil-tight whether-the spacing is according to present 
oil or water-tight practice. It will be noted in connection with merchant vessels 
converted to carry cargo or fuel oil that the spacing is generally four and one- 
half diameters in the shell. 
If oil-tight work depended less on the strength of the riveted joints and of the 
structure as a whole, and to a greater extent on spacing that would permit caulking 
without the edge raising, wider spacing could be used. Work that might be tight 
under static head would not necessarily be tight on parts subject to the working 
stresses of a vessel in a seaway, but might on certain parts where these stresses 
were in a measure absent. Any design, spacing, or workmanship which will not 
permanently prevent the joints from slipping will not remain oil-tight. 
The extensive use of oil for fuel in naval vessels during the last few years has 
brought up for consideration and settlement many problems in design which did 
not exist in coal-burning vessels. In vessels of great length such as scout cruisers 
and battle cruisers, longitudinal bulkheads are used as strength members. The 
riveting connections in these bulkheads must be designed to obtain maximum 
