I have been using Harvey for over 30 years. I've used it on gas lines, water lines, and sodium hypochlorite lines and it has worked. No leaks on products I pumped 30 years ago. I use Teflon tape and Harveys on every bolted connection I make on site to ensure safety and prevent leaks. I use it on copper, galvanized pipe, stainless steel and PVC. It can dry out before you use it and the brushes can break if the paste gets too thick, but I recommend Harvey's to everyone! I will continue to use it for all my plumbing work until Harvey stops making it.