Aluminum and Aluminum Alloys

Aluminum and Aluminum Alloys in the Piping Materials is one of the important element and Piping & Fabrication will end about Piping Materials for a while and continue with the other Piping Elements.

Aluminum and many of its alloys are highly resistant to atmospheric corrosion and to attack by many chemical agents, with the exception of strong alkalis. However, they are subject to galvanic attack if coupled with more noble materials.

Additions of alloying elements increases strengh, but to the detriment of thermal and electrical conductivity, and lowers the material’s melting point. Alloying with Cu, Mg, and Si creates heat-treatable alloys that are age-hardenable. Maximum strength can usually be achieved by heating to about 300 to 500°F (150 to 260°C).

Effects of working or precipitation hardening can be removed by annealing at temperatures of 600 to 800°F (315 to 425°C). A system has been devised to designate alloys of aluminum based on the major alloying constituent. See Table A3.10. 

TABLE A3.10 Designation System for Wrought Aluminum and Aluminum Alloy

Appendix A5 provides a list of material specifications which are acceptable for design and construction of piping systems within the jurisdiction of the ASME Boiler and Pressure Vessel Code and the ASME B31, Code for Pressure Piping. Appendix A6 lists some international material specifications for piping.