The HTSUS item at issue in HQ H281950 (Jan. 26, 2017) 9802.00.60, which provides a partial duty exemption for:
Any article of metal (as defined in U.S. note 3(e) of this subchapter) manufactured in the United States or subjected to a process of manufacture in the United States, if exported for further processing, and if the exported article as processed outside the United States, or the article which results from the processing outside the United States, is returned to the United States for further processing . . . .To qualify, the metal article must be manufactured in the United States. The question presented in this ruling is whether scrap metal collected from industrial production in the U.S. is "manufactured in the United States." The scrap metal at issue here is copper. The question is potentially complicated by the fact that some of the original copper was domestic in origin while some was originally foreign. Some of the scrap will be derived from production processes. Some will just be collected in the form of obsolete U.S-origin wire.
The tariff does not define "manufactured" in this context. In prior rulings, CBP has held that metal is manufactured when it is subject to operations such as "splitting, annealing, milling, rolling, brushing, and leveling." Here, the industrial scap results from the application of those manufacturing processes to copper. As a result, Customs held that the scrap was also manufactured in the U.S.
Customs has also held that the process of making metal into U.S.-origin products is sufficient manufacturing to allow used, obsolete products to be considered manufactured in the U.S. [Note: I realize that seems self-evident, but that's the fact of the matter.]
Consequently, in this case, all of the goods, when re-entering the U.S. after further processing abroad, qualify for the partial duty exemption. There are, of course, documentation requirements. If you are going to try this, look at 19 C.F.R. 10.9.