14 BULLETIN^ 1259, U. S. DEPARTMENT OP AGRICULTURE. 
value of all material tested to destruction shall be 
allowed as a credit upon such payments. 
53. Weight paid The payment for pound-price contracts shall be based 
on the weight of metal in the fabricated structure, includ- 
ing field rivets shipped. The weight of erection bolts, 
field paint, and all boxes, crates, or other containers used 
for packing, together with sills, struts, and rods used for 
supjporting members during transportation, shall be 
excluded. 
Weights paid for shall be shop-scale weights unless 
otherwise provided. If specified in the contract or 
permitted by the engineer, computed weights as herein- 
after provided may be made the basis of pajonent. 
54. Variation If the Weight ot any member is more than 2 per cent 
inweig . -^^gg than the computed weight, it may be cause for re- 
jection. This applies to both pound-price and lump-sum 
contracts. 
If the total scale weight of any structure exceeds the 
computed weight by more than 2 per cent, the weight in 
excess of 2 per cent above the computed weight shall not 
be paid for. 
55. Weighing of Finished work shall be weighed in the presence of the 
members. inspector, if practicable. The contractor shall supply 
satisfactory scales and shall perform all work involved 
in handling and weighing the various parts. 
56. Computed The Weight of steel shall be assumed at 490 pounds per 
weight. cubic foot. The weight of cast iron shall be assimiea at 
450 pounds per cubic foot. 
The weights of rolled shapes, and of plates up to and 
including 36 inches in width, shall be computed on the 
basis of their nominal weights and dhnensions, as shown 
on the approved shop drawings, deducting for copes, 
cuts, and open holes. 
The weights of plates wider than 36 inches shall be 
computed on the basis of their dimensions, as shown on 
the approved shop drawings, deducting for cuts and open 
holes. To this snaU be added one-half of the allowed 
percentages of overrun in weight given in the Standard 
Specifications for Structural Steel for Bridges, Serial 
Designation A7-21, of the American Society for Testing 
Materials. 
The weight of heads of shop-driven rivets shall be in- 
cluded in the computed weight, assuming the weights to 
be as follows: 
Diameter of rivet. Weight for 100 heads. 
}/2 inch pounds- 4. 
Ys inch do___ 7. 5 
34inch do___ 12. 5 
:^inch do--- 18. 5 
1 inch do___ 27. 
The weight of castings shall be computed from the 
dimensions shown on the approved shop drawings, with 
an addition of 10 per cent for fillets and overrun. 
To the total computed weight of metal may be added 
an allowance of 0.4 of 1 per cent for shop paint. 
