Dear friends, we have been experiencing a recurring problem in Mexico with the ASTM B819 certified pipeline by the manufacturers IUSA and NACOBRE, when testing the pipes that they deliver the result is unimaginable, you can see it for yourselves in the photos and videos, When a clean cloth is passed, some dirt can be seen, however when it is soaked in alcohol the result is impressive, not only dirt, but also copper particles. I have indicated to the manufacturers but they simply say that they give the B819 certificate. What is your experience in these types of situations?