17 pipes, tubes and conduits; pipe connectors and connector sleeves; thermoplastic heat fusion pipe connectors and sleeves; parts and fittings for all the aforesaid goods, all made wholly or principally of plastics
19 non-metallic building materials; pipes, tubes and conduits; pipe connectors and connector sleeves; thermoplastic heat fusion pipe connectors and sleeves; parts and fittings for all the aforesaid goods