Abstract: There is described a process and apparatus for flaring the end of a thermoplastic tube to form a flange thereon to provide a flanged adapter for joining sections of plastic pipes. An end portion of a tube of suitable thermoplastic resin is heated to soften it and is then placed in a flanged sleeve with the heated tube end projecting from the sleeve. A flanged male plug is inserted into the heated end of the tube and the plug is pushed by means of a press into the tube to cause the flanged plug to flare the heated end of the tube outwardly through an obtuse angle against the flange of the sleeve so that a flange is formed on the tube. A cylindrical member embraces the flanges of plug and sleeve and limits outer flow of the formed tube flange. The tube is then cooled in situ in the press, is removed from the press after cooling and placed in a cold water tank for further cooling. After cooling, the flanged tube is constrained between top and bottom clamping disks and is reheated to about 160.degree. F.