Building Design and Construction Handbook - Merritt - Ventech!

4.80 SECTION FOUR
other metals, the faying surfaces should be insulated by painting with asphaltic or
similar paints, or by gasketing. Steel rivets and bolts, for example, should be insulated.
Drainage from copper-alloy surfaces onto aluminum must be avoided. Frequently,
steel surfaces can be galvanized or cadmium-coated where contact is expected
with aluminum. The zinc or cadmium coating is anodic to the aluminum
and helps to protect it.
4.57 ALUMINUM BIBLIOGRAPHY
‘‘Aluminum Standards and Data,’’ ‘‘Engineering Data for Aluminum Structures,’’
‘‘Designation Systems for Aluminum Finishes,’’ and ‘‘Specifications for Aluminum
Structures,’’ The Aluminum Association, Washington, D.C.
E. H. Gaylord, Jr., and C. N. Gaylord, ‘‘Structural Engineering Handbook,’’ 3rd
ed., McGraw-Hill Publishing Company, New York.
COPPER AND COPPER-BASED ALLOYS
Copper and its alloys are widely used in the building industry for a large variety
of purposes, particularly applications requiring corrosion resistance, high electrical
conductivity, strength, ductility, impact resistance, fatigue resistance, or other special
characteristics possessed by copper or its alloys. Some of the special characteristics
of importance to building are ability to be formed into complex shapes,
appearance, and high thermal conductivity, although many of the alloys have low
thermal conductivity and low electrical conductivity as compared with the pure
metal.
4.58 COPPER
The excellent corrosion resistance of copper makes it suitable for such applications
as roofing, flashing, cornices, gutters, downspouts, leaders, fly screens, and similar
applications. For roofing and flashing, soft-annealed copper is employed, because
it is ductile and can easily be bent into various shapes. For gutters, leaders, downspouts,
and similar applications, cold-rolled hard copper is employed, because its
greater hardness and stiffness permit it to stand without large numbers of intermediate
supports.
Copper and copper-based alloys, particularly the brasses, are employed for water
pipe in buildings, because of their corrosion resistance. Electrolytic tough-pitch
copper is usually employed for electrical conductors, but for maximum electrical
conductivity and weldability, oxygen-free high-conductivity copper is used.
When arsenic is added to copper, it appears to form a tenacious adherent film,
which is particularly resistant to pitting corrosion. Phosphorus is a powerful deoxidizer
and is particularly useful for copper to be used for refrigerator tubing and
other applications where flaring, flanging, and spinning are required. Arsenic and
phosphorus both reduce the electrical conductivity of the copper.