RULES TO FACILITATE ERECTION. 



411 



Where unequal legged angles arc used mark the width of one leg of the angle on the leg. 



Where heavy laterals are spliced in the middle by a plate, ship the plate riveted to one angle 

 only. 



Do not countersink rivets in long pieces unless absolutely necessary. 



Do not draw any more of a member than necessary, and do not dimension the same piece 

 several times. 



Revising Drawings. When drawings have been changed after having been first approved, 

 tli.-y must be marked, Revised (give date of revision). 



cvi 



6" 



(a) 



9'-o" 



(b) 



FIG. 20. 



Measuring Angles. All measurements on angles are to be made from the back of the angle, 

 and not from the edge of the flange. The center to center distance between open holes should 

 always be given for each piece that is shipped separate, in order that the inspector can check the 

 piece. 



Width of Angles. The widths of the legs of angles are greater than the nominal widths, 

 unless the angle has been rolled with a finishing roll. The over-run for each leg is equal to the 

 nominal width of the leg plus the increase in thickness of leg made by spreading the rolls. For 

 example finishing rolls are used for rolling 3" X 3" angles with a thickness of \". The actual 

 length of the leg of a 3" X 3" angle is as follows: angle 3" X 3" X i", leg 3"; angle 3" X 3" X ft", 

 leg 3ft"; angle 3" X 3" X f", leg 3 J"; angle 3" X 3" X i", leg 3 J"; angle 3" X 3" X f", 

 leg 3t". 



The over-run of Pencoyd angles are given in Table 27, Part II; and the over-run of Pennsyl- 

 vania Steel Company's angles are given in Table 28, Part II. 



POINTS TO BE OBSERVED IN ORDER TO FACILITATE ERECTION. The first 

 consideration for ease and safety in erection should be to so arrange all details, joints and con- 

 nections that the structure may be connected and made self-sustaining and safe in the shortest 

 time possible. Entering connections of any character should be avoided when possible, notably 

 on top chords, floorbeam and stringer connections, splices in girders, etc. When practicable, 

 joints should be so arranged as to avoid having to put members together by entering them on end, 

 as it is often impossible to get the necessary clearance in which to do this. In all through spans 

 floor connections should be so arranged that the floor system can be put in place after the trusses 

 or girders have been erected in their final position, and vice versa, so that the trusses or girders 

 can be erected after the floor system has been set in place. All lateral bracing, hitch-plates, rivets 

 in laterals, etc., should, as far as possible, be kept clear of the bottoms of the ties, it being expensive 

 to cut out ties to clear such obstructions. Lateral plates should be shipped loose, or bolted on 

 so that they do not project outside of the member, whenever there is danger of their being broken 

 off in unloading and handling. Loose fillers should be avoided, but they should be tacked on with 

 rivets, countersunk when necessary. 



In elevated railroad work, viaducts and similar structures, where longitudinal girders frame 

 into cross girders, shelf angles should be provided on the latter. In these structures the expansion 



