Explanatory notes
… rendered impermeable by glazing or by vitrification (e.g., chemical piping). (3) Pipe fittings for connecting or … traps, etc.). The heading does not cover : (a) Tubular chimney-parts (e.g., chimney-pots, cowls, chimney liners and … tubing (e.g., combustion tubes), usually of porcelain or china, specially designed for laboratories ( heading 69.09 …