

SPECIFICATIONS. (>") 



SPECIAL METALS. 



141. Cast-iron. Except where chilled iron is specified, castings shall be made of tough gray 

 iron, with sulphur not over o.io per cent. They shall be true to pattern, out of wind and free 

 from llaws and excessive shrinkage. If tests are demanded they shall be made on the " Arbitra- 

 tion M.i r " of the American Society for Testing Materials, which is a round bar, I J in. in diameter 

 and 15 in. long. The transverse test shall be on a supported length of 12 in. with load at middle. 

 The minimum breaking load so applied shall be 2,900 lb., with a deflection of at least fa in. before 

 rupture. 



142. Wrought-Iron Bars. Wrought-iron shall be double-rolled, tough, fibrous and uniform 

 in character. It shall be thoroughly welded in rolling and be free from surface defects. When 



1 in specimens of the form of Fig. I, or in full-sized pieces of the same length, it shall show 

 an ultimate strength of at least 50,000 lb. per sq. in., an elongation of at least 18 per cent in 8 in., 

 with fracture wholly fibrous. Specimens shall bend cold, with the fiber through 135, without 

 sign of fracture, around a pin the diameter of which is not over twice the thickness of the piece 

 ted. When nicked and bent the fracture shall show at least 90 per cent fibrous. 



WORKMANSHIP. 



143. General. All parts forming a structure shall be built in accordance with approved 

 drawings. The workmanship and finish shall be equal to the best practice in modern bridge 

 works. 



144. Straightening Material. Material shall be thoroughly straightened in the shop, by 

 methods that will not injure it, before being laid off or worked in any way. 



145. Finish. Shearing shall be neatly and accurately done and all portions of the work 

 exposed to view neatly finished. 



146. Rivets. The size of rivets, called for on the plans, shall be understood to mean the 

 actual size of the cold rivet before heating. 



147. Rivet Holes. When general reaming is not required, the diameter of the punch for 

 material not over f in. thick shall be not more than fa in., nor that of the die more than J in. larger 

 than the diameter of the rivet. The diameter of the die shall not exceed that of the punch by 



iore than i the thickness of the metal punched. 



148. Planing and Reaming. In medium steel over f of an in. thick, all sheared edges shall 

 planed and all holes shall be drilled or reamed to a diameter of f of an in. larger than the punched 



holes, so as to remove all the sheared surface of the metal. Steel which does not satisfy the 

 drifting test must have holes drilled. 



149. Punching. Punching shall be accurately done. Slight inaccuracy in the matching of 

 les may be corrected with reamers. Drifting to enlarge unfair holes will not be allowed. Poor 



tching of holes will be cause for rejection by the inspector. 



150. Assembling. Riveted members shall have all parts well pinned up and firmly drawn 

 ether with bolts before riveting is commenced. Contact surfaces to be painted (see 182). 



151. Lacing Bars. Lacing bars shall have neatly rounded ends, unless otherwise called for. 



152. Web Stiffeners. Stiff eners shall fit neatly between flanges of girders. Where tight 

 ts are called for the ends of the stiffeners shall be faced and shall be brought to a true contact 



aring with the flange angles. 



153. Splice Plates and Fillers. Web splice plates and fillers under stiffeners shall be cut to 

 t within i in. of flange angles. 



154. Web Plates. Web plates of girders, which have no cover plates, shall be flush with 

 e backs of angles or be not more than \ in. scant, unless otherwise called for. When web plates 



spliced, not more than i in. clearance between ends of plates will be allowed. 

 I 55- Connection Angles. Connection angles for girders shall be flush with each other and 

 rrect as to position and length of girder. In case milling is required after riveting, the removal 

 more than fa in. from their thickness will be cause for rejection. 



156. Riveting. Rivets shall be driven by pressure tools wherever possible. Pneumatic 

 mmers shall be used in preference to hand driving. 



157. Rivets shall look neat and finished, with heads of approved shape, full and of equal size. 

 iey shall be central on shank and grip the assembled pieces firmly. Recupping and calking 



ill not be allowed. Loose, burned or otherwise defective rivets shall be cut out and replaced, 

 n cutting out rivets great care shall be taken not to injure the adjacent metal. If necessary 

 " iev shall be drilled out. 



158. Turned Bolts. Wherever bolts are used in place of rivets which transmit shear, the 

 holes shall be reamed parallel and the bolts turned to a driving fit. A washer not less than i in. 

 thick shall be used under nut. 



159. Members to be Straight. The several pieces forming one built member shall be straight 

 and fit closely together, and finished members shall be free from twists, bends or open joints. 



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