10 
). Annealing. 
30. Pins 
rollers. 
and 
the heads. The holes in the ends of bars shall be bored 
simultaneously and shall be so accurately located that 
when the bars of the same truss panels are placed in a 
pile the pins may be completely inserted in the pinholes 
without driving. All eyebai*s intended for the same 
locations in the trusses shall be interchangeable. 
All eyebars shall be annealed by heating uniformly to 
the proper temperature followed by slow and uniform 
cooling in the lurnace. The temperature of the bai's 
shall be imder full control at all stages. 
Forged pins, and other steel parts requiring their full 
strength, which have been partially heated shall be 
subsequently annealed. Slight bends in pieces of 
secondary importance may be made without heating the 
metal. Crimped web stiff eners need not be annealed. 
Pins and rollers shall be accurately turned to detailed 
dimensions and shall be smooth, straight, and free from 
flaws. The final surface shall be produced by a finishing 
cut. 
Forged pins. — Pins having a diameter greater than 6 
inches shall be forged and annealed. 
Bored pins. — Pins larger than 8 inches in diameter 
shall have a hole not less than 2 inches in diameter bored 
longitudinally through their centers. Pins showing 
defective interior conditions shall be rejected. 
31. Boring pin Pmholcs shall be bored true to detailed dimensions, 
smooth and straight, at right angles with the axis of the 
member and parallel with each other unless otherwise 
required. A finishing cut shall always be made. 
The length outside-to-outside of holes in tension mem- 
bers and inside-to-inside of holes in compression members 
shall not vary from detailed dimensions more than -^ 
inch. Boring of holes in built-up members shall be done 
after the riveting is completed. 
32. Pin clear- xhc difference in diameter between the pin and the 
pin hole shall be not more than -^ inch. 
Welding of steel shall not be permitted except to 
remedy minor defects and then only with the approval 
of the engineer. 
Screw threads shall make close fits in the nuts and 
shall be U. S. Standard, except that for diameters greater 
than lyi inches, they shall be made with 6 tlireads to 
the inch, 
puot and Two pilot nuts and two driving nuts shall be furnished 
for each size of pin, unless otherwise specified. 
33. Welds. 
34. S c r 
threads. 
35 
driving nuts 
MILL AND SHOP INSPECTION. 
36. Notice of The coutractor shall give ample notice to the engineer 
cS.'°^ ''''"■ of the beginning of work at the mill and shop, so that 
inspection may be provided. No material shall be rolk^d 
or fabricated before the engineer has been notified 
where the orders have been placed. 
