I hate to be the bearer of bad news, but some quick searching seems to suggest that it's just as much of mess in Argentina as here ;-)

https://www.totaline.com.ar/wp-content/uploads/2016/08/17-Ca...

My Spanish is rather bad, but I think this:

> Los tubos son producidos según los estándares establecidos por la norma internacional ASTM B88 y B88M.

Says that ASTM B88 and it's metric equivalent are accepted. As you'll see from the listed dimensions the latter is truly metric, while the former is imperial.