Shields or Trident #148 is rated for below waterline connection, so ok to use for sink drain. If you're concerned about putting boiling water down it, people have been dunking the ends of #148 in boiling water to soften them enough to get it onto fittings for as long as I can remember. However, you could run cold water to mix with any boiling water you want to dump down the sink...or you could just pour the boiling water over the side instead of down the drain.
However, I'm wondering why you'd need 25' of it for sink drains. #148 has -0- odor permeation resistance so it should only be used for toilet intake line and vent line in a sanitation system...never in any line that carries sewage.
--Peggie