SPECIFICATIONS FOR STEEL HIGHWAY BRIDGES. 7 
foreign matter and the parts shall be assembled while the 
paint is plastic. 
The component parts of a built member shall be as- 
sembled, drift-pinned to prevent lateral movement, and 
firmly bolted to draw the parts into close contact before 
reaming, drilling, or riveting is begun. Assembled parts 
shall be taken apart, if necessary, for the removal of burrs 
and shavings produced by the reaming operation. 
The member shall be free from twists, bends, or other 
deformations. 
Preparatory to shop-riveting full-sized punched material, 
the rivet holes shall be cleared for the admission of the 
rivets by reaming. 
End connection angles, stiff ener angles, etc., shall be 
carefully adjusted to correct locations and rigidly bolted, 
clamped, or otherwise firmly held in place until riveted. 
Connecting parts assembled in the shop for the pur- le. Match- 
pose of reaming or drilling holes in field connections shall °^^'^'^^°^- 
be match-marked, and a diagram showing such marks 
shall be furnished to the engineer. 
The diameter of rivets indicated upon the plans shall i7. Rivets. 
be understood to mean their diameter before heating. 
Heads of driven rivets shall be of approved shape, 
concentric with the shanks, true to size, full, neatly 
formed, free from fins and in full contact with the sur- 
face of the member. 
Field rivets, for each size and length, shall be supplied is- Field riv- 
in excess of the actual number to be driven to provide 
for losses due to misuse, improper driving or other 
contingencies. Rivets shall be free from furnace scale 
on their shanks and from fins on the under side of the 
machine-formed heads. 
Bolted connections shall not be used unless specifi- ^^jj^^soits^^^n d 
cally authorized. Where bolted connections are per-tions. 
mitted the bolts furnished shall be unfinished bolts 
(ordinary rough or machine bolts) or turned bolts, as 
specified or directed by the engineer. 
Unfinished holts. — Unfinished bolts shall be standard 
bolts with hexagonal heads and nuts. The use of 
''button-head" bolts will not be perniitted. Bolts 
transmitting shear shall be threaded to such a length 
that not more than one thread will be within the grip 
of the metal. The bolts will be of lengths which will 
extend entirely through their nuts but not more than 3^ 
inch beyond them. The diameter of the bolt holes 
shall be iV i^^ch greater than the diameter of the bolts 
used. 
Turned holts. — Holes for turned bolts shall be care- 
fully reamed or drilled and the bolts turned to a driving 
fit by being given a finishing cut. The threads shall 
be entirely outside of the holes and the heads and nuts 
shall be hexagonal. Approved nut locks shall be used 
on all bolts unless permission to the contrary is secured 
from the engineer. When nut-locks are not used, 
