Building Design and Construction

Applications of Lead

Exposure tests indicate corrosion penetrations of sheet lead ranging from less than 0.0001 in to less than 0.0003 in in 10 years in atmospheres ranging from mild rural to severe industrial and seacoast locations. Sheet lead is therefore used for roofing, flashing, spandrels, gutters, and downspouts.
Because the green patina found on copper may wash away sufficiently to stain the surrounding structure, lead-coated copper is frequently employed. ASTM B101- 78 covers two classes, defined by the weight of coating.
Lead pipe should not be used for the transport of drinking water. Distilled and very soft waters slowly dissolve lead and may cause cumulative lead poisoning.
Hard waters apparently deposit a protective coating on the wall of the pipe and little or no lead is subsequently dissolved in the water.
Principal alloying elements used with building leads are antimony (for hardness and strength) and tin. But copper, arsenic, bismuth, nickel, zinc, silver, iron, and manganese are also added in varying proportions.
Soft solders consist of varying percentages of lead and tin. For greater hardness, antimony is added, and for higher-temperature solders, silver is added in small amounts. ASTM Standard B32 specifies properties of soft solders.
Low-melting alloys and many bearing metals are alloys of lead, bismuth, tin, cadmium, and other metals including silver, zinc, indium, and antimony. The fusible links used in sprinkler heads and fire-door closures, made of such alloys, have a low melting point, usually lower than the boiling point of water. Yield (softening) temperatures range from 73 to 160F and melting points from about 80 to 480F, depending on the composition.


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