I don't have the latest guidelines but most spec's I've seen lately call out from 0.03% to 0.1% which corresponds to the producers numbers for lead and antimony. The trend is to no lead.
The lead content can be up to 0.5% on some older HDG components.
The highest zinc lead content used for HDG used to come from Mexico and Italy.
When I worked with zinc we were careful to select our suppliers of the zinc as the lead content caused 'spangle' on thin components. We actually received zinc ingots with lead contents higher than the 0.5% mentioned above that required careful additions to the baths.
I think that in the US the EPA has or is coming out with new guidelines for lead and HDG. I've seen some price increases in HDG that supposedly resulted from lower lead content requirements.
I know of some chemical plants that have done extensive measuring of the lead content in their run-off. In those cases they have a lot of galvanized structures and low pH rain. They were looking at it because they found a lot of the HDG had Pb levels above 0.5%, they were older structures (and prob. imported).
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Corrosion never sleeps, but it can be managed.
Western prime zinc can have up to 2% impurities, alloying though lead is soluble in zinc up to 0.9%. I believe that lead is used in the galvanizing kettle to remove the dross, Fe-Zinc compounds. Some galvanizers add lead to the kettle for this purpose, a thick layer of lead can be found at the bottom of the kettle.
