reclaiming process of melting, drossing, and casting is acceptable under this specification if chemical composition requirements are within the limits specified here. Grades C and D lead shall be either primary or secondary
lead produced from ore or other materials by a conventional process of reduction and refining or other processes which equally preclude the presence of unusual deleterious elements. Reclaimed lead is not acceptable for grades C and D.
3.1.1 Grades C and D lead sheet shall be reduced by rolling from an original casting not less than twice the thickness of the finished sheet.
3.2 Chemical composition.
3.2.1 Lead sheet shall conform to the chemical composition requirements shown in table I.
TABLE I---Chemical composition
------------------T-----------------T----------------T-----------------
I Grade B I Grade C I Grade D
[4] Element I percent I percent I percent
I maximum I maximum I maximum
------------------+-----------------+----------------+-----------------
Lead..............I [1] 99.50 I [1] 99.90 I [1] 99.85
Antimony, tin and I I I
arsenic (total)..I --- I 0.002 I 0.002
Iron..............I --- I .002 I .002
Bismuth...........I [2] I .025 I .025
Zinc..............I --- I .001 I .001
Copper............I --- I[3]. 040 to .080I[3] .040 to .080
Silver............I --- I .02 I .020
Tellurium.........I --- I --- I[2] .085 to .060
------------------�-----------------�----------------�-----------------
[1] Minimum by difference.
[2] When specified (see 6.2), the bismuth content of grade B shall be 0.025
percent maximum.
[3] Range.
[4] For grades C and D, no element other than those specified shall exceed
0.001 percent maximum as determined by a normal spectrographic analysis.
3.2.2 The contractor shall furnish an analysis of each melt showing the percentage of each of the elements specified in 3.2.1.
3.3 Hardness. Grade D lead sheet shall have an "as rolled" hardness of
40 to 68 as read on the Rockwell "R" scale (1/2 inch ball, 60-kilogram (kg.)
load, 10 seconds), or a Brinell hardness of 6.0 to 7.5 measured with a 10 mm.
ball a 100 kg. load for a duration of 30 seconds. The hardness values shall be
obtained within a 24 hour period after the final rolling of the sheet.
3.4 Dimensions.
3.4.1 Thickness. Lead sheet in ordered weights up to and including 3-1/2 pounds per square foot shall not vary in thickness by more than plus 0.008, minus 0.005 from the thickness calculated from the ordered weight per square foot (see 6.2). For the purpose of calculation it shall be assumed that a piece of lead sheet one-foot square and one-inch thick weights 59.04 pounds.
3.4.2 Weight. Lead sheet in ordered weights over 3-1/2 pounds per square foot shall not vary in weight by more than plus or minus 5 percent of the ordered weight per square foot (see (6.2).
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