3. Setting Out.-Before any setting out is done, each plate must pass through the rolls three times, the first bending to a curve, and the following ones straightening. 4. Planing, Punching, and Drilling.-All plates (and bars if used instead of plates) shall be machine-planed on all edges, and the joints in every case shall butt evenly. This also applies to flooring plates, which must butt all along their four sides to the adjacent plates. When the flange is formed of more than one plate in thickness, each plate must be planed to the same width, and finish straight with the others. All rivetholes, except those specified to be drilled, shall be truly punched with the overlapping plates, tees, or angles; and where the holes in flanges are specified to be drilled, the whole of the plates must be put together and drilled through solid (no smaller holes having been previously punched), after which the sharp arris around each hole shall be taken off before any rivetting is commenced. The rivet-holes in all diagonal and vertical bracings in lattice girders, and cross-bracing or tees in solid-web girders, shall be drilled and not punched; and all tee-iron stiffeners or gussets and angle irons shall be dressed-off flush with the flanges top and bottom, and each must be made to template length in order that the flanges may be quite straight and without wave in any way. 5. Rivetting. No rivetting will be allowed until the whole girder is put together, and no drifting will be permitted. All rivets shall be of the sizes and pitch shown on the drawings, and must be upset throughout their whole length, and entirely fill all the hole. All rivets that are not horizontal, and that are in a position admitting of it shall be upset throughout the whole length of the work. All rivet-heads shall be of the proper size, and shall be carefully snapped, both heads bedding truly on the plates, and their centres coinciding with the centre line of the rivet. Any found loose or imperfect in any way whatever must be cut out and replaced at the contractor's expense. All the wrought ironwork shall be well oiled before commencing to build the girders. All rivets on bearings, and wherever required by the engineer, shall be countersunk, and all countersunk rivets shall have their holes cut to the proper shape to form a strong head, and in no case must the taper of the punch be taken as a sufficient spread for the head. All bolts and nuts shall be of the best scrap iron, and shall have a strong and chased head cut upon them of uniform pitch. Heads and nuts must be hexagonal, and the nuts shall have a washer under each, and when screwed up shall have a clear thread standing through. In roof work, or where specified, all bolt holes shall be drilled true to template, and the arrises taken off, and the bolts shall be turned. All bolts and nuts, and the screwed ends of the rods, &c., shall be made to Whitworth's standard. 6. Cast-Iron Work.-The metal for the castings shall be of such a mixture of irons as is best adapted for the purpose, and shall be such that a bar 1 inch square and 4 feet between the supports shall bear without fracture not less than 550 lbs. in the centre. The castings, when cold, must be of the pattern and dimensions shown on the drawings, and shall be cast smooth, with sharp arrises, and free from air-blows, twists, and flaws of every description. The edges of all road plates, as well as all joints and bearing areas, shall be planed to an even surface. 7. Testing Cast Iron.-The contractor shall provide for the use of the engineer, for testing purposes, bars, each 5 ft. long and 1 in. square (giving an exact sectional area of 1 in.); four shall be cast for each girder, &c., from the same metal and melting as the girders, &c., are being run. Should any of the tests be lower than 1 per cent. of the above strains they will be rejected. Each test shall be taken independently, and no averages of results taken. 8. Columns. All columns shall be cast vertically, and in dry sand, a head of metal being left on each casting; and for the purpose of gauging the thickness of the metal, small holes shall be drilled in the column where directed, and the thickness of metal shall be uniform in all parts of the circumference. These holes shall be afterwards filled up at the expense of the contractor. 9. Dimensions and Weights.-The whole of the iron work shall be made of the exact dimensions shown on the respective drawings; any iron work made of less dimensions than those shown on the drawings will be rejected, and any excess of weight caused by the given dimensions having been exceeded will not be paid for. Before being sent out to the works the whole must be carefully erected and fitted together in the maker's yard, and each piece numbered or lettered, so as to come together again and correspond when being permanently fixed in position. 10. Steel Rollers.—If steel rollers for expansion are used, they must be of the best quality steel, and shall be truly turned on every face, each roller being of the same diameter in order to insure a perfect bearing; care being taken that room is left at each end for the girders to expand or contract, and that the framei s left in the centre of the space between the angle iron stops when the girder is brought to bear upon the rollers. Sliding plates for expansion must be planed on their faces of sliding contact. 11. Steel. The quality of steel shall be such that the tensile strength be not less than 26 tons per square inch, with an elongation of not less than 20 per cent. in a length of 8 inches. The work when finished shall be of the best description, the steel being of Landore, Siemens Steel Company, Bolton Iron and Steel Company, West Cumberland Iron and Steel Company, Colville and Company, Motherwell, Butterley Company, or Steel Company of Scotland manufacture. 12. Painting Iron Work-The inner surfaces of all plates, bars, &c., which are to be rivetted together, shall be well coated whilst hot with best common black paint before joining. The whole cast- and wrought-iron work shall have four coats of approved colours when completed. The underside of all girders and road plates, where directed, shall have four coats of best common oil paint on the completion of the bridge. The iron work shall not be painted before an examination of it has been made by or under the orders of the engineer, who must be apprised in writing when it is ready. 13. Seating to Girders -All girders shall have seatings of the best hair felt, graduated in lengths so as to insure the pressure being on the centre of bearing when the greatest load is on the girder. The cast-iron bed plates and columns shall have seatings of 8 lbs. lead for the full length of their bearings on masonry. |