13 



54- The pitch of rivets in all classes of work shall never 

 exceed 6 inches, or sixteen times the thinnest outside plate, 

 nor be less than three diameters of the rivet. ( 81, 96.) 



55. The rivets used shall generally be J inch diameter for 

 main members of the trusses and floor, and not less than } 

 for lateral or other bracing. 



56. The distance between the edge of any piece and the 

 centre of a rivet-hole must never be less than 1} inches, 

 except for bars less than 2j inches wide ; when practicable 

 it shall be at least two diameters of the rivet. 



57. For punching, the diameter of the die shall in no case 

 exceed the diameter of the punch by more than T ^ of an 

 inch, and all holes must be clean cuts without torn or ragged 

 edges. 



58. All rivet holes must be so accurately spaced and 

 punched that when the several parts forming one member 

 are assembled together, a rivet -^ inch less in diameter than 

 the hole can generally be entered, hot, into any hole, with- 

 out reaming or straining the metal by " drifts"; occasional 

 variations must be corrected by reaming. 



59. The rivets when driven must completely fill the holes. 

 The rivet-heads must be round and of a uniform size for the 

 same sized rivets throughout the work. They must be full 

 and neatly made, and be concentric to the rivet-hole, and 

 thoroughly pinch the connected pieces together. 



60. Wherever possible, all rivets must be machine driven. 

 The machines must be capable of retaining the applied 

 pressure after the upsetting is completed. No hand-driven 

 rivets exceeding } inch diameter will be allowed. 



61. Field riveting must be reduced to a minimum or 

 entirely avoided, where possible. 



62. All holes for field rivets, except those in connections 

 of the lateral and sway systems, shall be accurately drilled 

 or reamed to an iron template or be reamed (rue while the 

 parts are temporarily connected together. 



63. The effective diameter of a driven rivet will be as- 

 sumed the same as its diameter before driving. In deduct- 

 ing the rivet-holes to obtain tut sections in tension n 



