46 TOWERS AND TANKS FOR WATER-WORKS. 



7. Chemical Properties. Steel for railway bridges: Maximum phos- 

 phorus, .08 per cent. Steel for buildings, train-sheds, highway bridges, 

 and similar structures: Maximum phosphorus, .10 per cent. 



8. Physical Properties. Steel shall be of three grades, rivet, soft, and 

 medium. 



9. Rivet Steel. Ultimate strength, 48,000 to 58,000 pounds per 

 square inch. 



Elastic limit, not less than one-half the ultimate strength. 



Elongation, 26 per cent. 



Bending test, 180 degrees flat on itself, without fracture on outside of 

 bent portion. 



10. Soft Steel. Ultimate strength, 52,000 to 62,000 pounds per 

 square inch. 



Elastic limit, not less than one-half the ultimate strength. 



Elongation, 25 per cent. 



Bending test, 1 80 degrees flat on itself, without fracture on outside 

 of bent portion. 



n. Medium Steel. Ultimate strength, 60,000 to 70,000 pounds per 

 square inch. 



Elastic limit, not less than one-half the ultimate strength. 



Elongation, 22 per cent. 



Bending test, 180 degrees to a diameter equal to thickness of piece 

 tested, without fracture on outside of bent portion. 



12. Pin Steel. Pins made from either of the above-mentioned grades 

 of steel shall, on specimen test-pieces cut at a depth of one inch from 

 surface of finished material, fill the physical requirements of the grade 

 of steel from which they are rolled, for ultimate strength, elastic limit, 

 and bending, but the required elongation shall be decreased 5 per cent. 



13. Eye-bar Steel. Eye-bar material, \\ inches and less in thickness, 

 made of either of the above-mentioned grades of steel, shall, on test- 

 pieces cut from finished material, fill the requirements of the grades of 

 steel from which it is rolled. For thickness greater than i inches, 

 there will be allowed a reduction in the percentage of elongation of i per 

 cent, for each of an inch increase of thickness, to a minimum of 20 per 

 cent, for medium steel and 22 per cent, for soft steel. 



14. Full-size Test of Steel Eye-bars. Full-size test of steel eye-bars 

 shall be required to show not less than 10 per cent, elongation in the 

 body of the bar, and tensile strength not more than 5000 pounds below 

 the minimum tensile strength required in specimen tests of the grade of 

 steel from which they are rolled. The bars will be required to break in 

 the body, but should a bar break in the head, but develop 10 per cent 

 elongation and the ultimate strength specified, it shall not be cause for 



