17 plastic pipes for plumbing purposes; plastic pipe fittings, namely, reducers, collars, couplings, sleeves, joints, Y and Tee branches, elbows, clean-outs and pipe saddles; plastic support pipes; seals for gas or water pipe connections; pipe insulation; plastic sheathing or jackets for water pipes; plastic fire protection collars and bulkheads for pipes; plastic conduit for plumbing use; plastic in extruded form for general industrial use