410 



SPECIFICATIONS 



Manufacture. 



Standard Test Piece 



Elastic Limit. 



Tension. 



Bending Test. 



Timber. 



Painting 



during the rolling, and be straight, smooth and free from in- 

 jurious seams, blisters, buckles, cracks or imperfect edges. 



130. No specific process or provision of manufacture will 

 be demanded, provided the material fulfills the requirements 

 of these specifications. 



131. The tensile strength, limit of elasticity and ductility, 

 shall be determined from a standard test piece of as near ^ 

 square inch sectional area as possible. The elongation shall 

 be measured on an original length of 8 inches. 



132. Iron of all grades shall have an elastic limit of not 

 less than 26,000 pounds per square inch. 



133- When tested in specimens of uniform sectional area 

 of at least 3/2 square inch the iron shall show a minimum ulti- 

 mate strength of 50,000 pounds per square inch, and a mini- 

 mum elongation of 18 per cent in 8 inches. 



134. All iron for tension members must bend cold 

 through 90 degrees to a curve whose diameter is not over 

 twice the thickness of the piece, without cracking. When 

 nicked on one side and bent by a blow from a sledge, the 

 fracture must be mostly fibrous. 



TIMBER. 



135. The timber shall be strictly first-class spruce, white 

 pine, Douglas fir, Southern yellow pine, or white oak timber; 

 sawed true and out of wind, full size, free from wind shakes, 

 large or loose knots, decayed or sapwood, wormholes or other 

 defects impairing its strength or durability. 



PAINTING. 



136. All iron work before leaving the shop shall be 

 thoroughly cleaned from all loose scale and rust, and be given 

 one good coating of pure boiled linseed oil or paint as speci- 

 fied, well worked into all joints and open spaces. 



137. In riveted work, the surfaces coming in contact 

 shall each be painted before being riveted together. 



138. Pieces and parts which are not accessible for paint- 

 ing after erection shall have two coats of paint. 



