millinghill wrote:
Hi.
I've lots of that black foam rubber pipe insulation, but it's for 1/2"
diameter. The (cold water) pipes I need to insulate are 1". I want
to insulate them to prevent consdensation in my basement. If I split
two of them down the middle, it will cover the 1" pipe. But what do I
seal/glue/tape it with? Duct tape will just get old and unstick after
a few months/years. Any ideas?
Advice appreciated.

If you find a good commercial plumbing supply house near you that will sell to
the public, they will likely have what you want. It probably won't be super
cheap, but it will fit properly and last.

If you've seen a place with a big yard outside of 20 foot lengths of all kinds
of pipe, including big diameters, that might be the place.