Abstract: An apparatus for flanging tubular articles of a thermoplastic polymer which has been drawn and heat-set to an elevated temperature comprises a heating die (20) shaped to receive an end of one of the tubular articles (10) and to restrain it from shrinkage, transfer means such as a star wheel (24) to transfer the article (10) from the heating die (20) to a forming die (22) shaped to form an outward flange (12) on said end. Heater coils (33,40) are provided to maintain the dies at the required temperatures; namely the heating die (20) at a softening temperature above the glass transition temperature of the polymer but below the elevated temperature to which it has been heat-set and the forming die (22) at a forming temperature below the softening temperature.