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Reg. 182
SHELLS
Thickness of Butt Straps
The minimum thickness of butt straps for the longitudinal seams
of cylindrical shells shall be determined by the following formulae
but all straps should be of sufficient thickness to permit of
efficient caulking and in any case shall not be less than 3/8
inch in thickness.
Single butt straps having ordinary riveting :-
Single butt straps having every alternate rivet in the outer
rows omitted:-
| 1.125T x |
(P – D)
|
= T1 |
Eqn.(6) |
| (P – 2D) |
Double butt straps of equal width having ordinary riveting :-
Double butt straps of equal width having every alternate rivet
in the outer row omitted :-
| 0.625T x |
(P – D)
|
= T1 |
Eqn.(8) |
| (P – 2D) |
Double butt straps of unequal width either having ordinary riveting,
or having every alternate riveting the outer rows omitted :-
| 0.75T = T1 (Wide strap) |
Eqn.(9) |
| 0.625T = T1 (narrow strap) |
Eqn.(10) |
Where
T = the thickness of the butt straps in inches. The other symbols
have the same significance as in Regulations
177.
Single and wide butt straps shall, wherever practicable, be
on the inside of the shell.
Should the thickness of butt straps be less than that above
described, the least percentage of joint as determined under
Regulation 177 shall be
reduced in the proportion of the actual thickness to the prescribed
thickness.
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