Brass America

Another market appHcation for naphthenic acid is the tire industry, where cobalt naphthenate is used as an adhesion promoter (see Adhesives Tire cords). Cobalt naphthenate improves the bonding of brass-plated steel cords to mbber, presumably by suppressing the de-zincification of brass (50). Its first reported use was in 1970 and the first patent for its use was issued in 1975 (51). About 900 t of cobalt naphthenate is used worldwide as an adhesion promoter, half of it in North America. The unit value fluctuates between 8.75—13.25 /kg because of the volatility of cobalt prices. Although it is the industry standard, the use of cobalt naphthenate is declining with the advent of more economical high metal-containing substitutes. 

In 1797, Joseph Barmah patented the first extrusion process for making lead pipes. The metal used to be preheated and ram was hand-driven. In 1820, Thomas Burr built the first hydraulic power press that was to extrude lead pipes (Sheppard 2013). The process was called squirting. By the end of nineteenth century, the extmsion methods were also in use for copper and brass alloys. Alexander Dick invented a hot extrusion process for nonferrous metals in 1894. North America has its first aluminum extrusion process in 1904. In 1950s, Sejounet introduced molten glass as lubricant in extmsion process. 

It is important to note that large numbers of water systems in the U.S., having no lead service lines or interior lead piping, required some form of enhanced corrosion control as a result of the Lead and Copper Rule, due to a combination (not differentiable from the monitoring data) of leaded brasses and soldered joints in copper plumbing. Therefore, the significant lead release observed in the AWWARF study represented lead contamination from waters already adjusted for some corrosion control, and would not represent nearly a worst-case scenario as may be present elsewhere in North America or Europe. 

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