APPENDIX B. 329 



Finished bars must be free from injurious seams, flaws, or cracks, and have a 

 workmanlike finish. The properties must be as follows : 



Maximum amount of phosphorus, o.io per cent, for both soft and medium steel. 



Soft steel, ultimate strength, 52,000 Ibs. to 62,000 Ibs. per square inch; elastic 

 limit not less than one-half the ultimate strength; elongation, 25 per cent; bend- 

 ing test, 1 80 degrees flat on itself when cold, without fracture on outside of bent portion. 



Medium steel, ultimate strength, 60,000 Ibs. to 70,000 Ibs. per square inch; elastic 

 limit not less than one-half the ultimate strength; elongation, 22 per cent; bending 

 test 1 80 degrees to a diameter equal to thickness of piece tested when cold, without 

 fracture on outside of bent portion. 



If the United States provides no mill inspector, two tests of each melt shall be 

 made by the manufacturer, prior to shipment, one for tension and one for bending, 

 and a certified report of the results shall be forwarded to the Engineer Officer. 



The variation in cross-section or weight of more than 2^ per cent from that 

 specified will be sufficient cause for rejection, except in the case of sheared plates, not 

 ordered to gauge, which may vary 5 per cent. 



All castings shall be tough gray iron, free from injurious cold-shuts or blow-holes, 

 true to pattern, well cleaned, and of a workmanlike finish. Sample pieces, i inch 

 square, cast from the same heat of metal in sand molds, shall be capable of sustaining 

 on a clear span of 4 feet 8 inches, a central load of 500 pounds when tested in the 

 rough bar. 



56. Inspection. Inspection will be made by the authorized agent of the Engineer 

 Officer before shipment, and before painting, and any facilities desired by him for such 

 inspection must be furnished by the contractor without extra charge. The decision of 

 the inspector regarding material and workmanship shall be final, and any piece rejected 

 must be satisfactorily replaced at once by the contractor, without expense to the 

 United States. 



57. Workmanship. All workmanship must be first-class, and especial care must 

 be taken to secure a neat finish to the work. The rivet-holes for splice-plates of abut- 

 ting members shall be so accurately spaced that when the members are brought into 

 position the holes shall be truly opposite before the rivets are driven. The pitch of 

 rivets in all classes of work shall not exceed 6 inches, unless shown on the drawings, 

 nor 1 6 times the thinnest outside plate, nor be less than three diameters of the rivet. The 

 rivets used shall generally be f , f , and inch diameter. The distance between the edge 

 of any piece and the center of a rivet-hole must never be less than i inches, except 

 for bars less than 2^ inches wide. When practicable it shall be at least two diameters 

 of the rivet. Rivets must completely fill the holes, have full heads concentric with the 

 rivet, of a height not less than .6 the diameter of the rivet, and in full contact with the 

 surface, or be countersunk, when so required, and be machine-driven wherever prac- 

 ticable. The diameter of the punch shall not exceed by more than j, inch the diam- 

 eter of the rivets to be used, and all holes must be clean cut without torn or ragged 



