I have just had my entire house repiped from copper to pex after several leaks in the house and at least one slab leak. All the shutoffs on the old coper pipe are closed, but I still would like to seal the old pipes. I was going to use 1/2" copper caps and probably put a little taro in the pipes just in case any ants found their way in. Any better suggestions? I also have a hose bib that now passes through a concrete block from inside to outside. I would like to fill it to provide more support for the connection, should I fill it with concrete or can I just use some of that spray foam stuff.

Thank you in advance,

Paul

If the old pipes are staying in place and the stops are all closed I don't think you have anything to to seal. Any pipe without a stop can take a quick shot of spray foam and that's it.