Patent ID: 8911660

Claim:
A method for producing a biaxially oriented tube from thermoplastic material comprising: drawing a tempered tube over an expansion device to transform the tube from a preform condition into a biaxially oriented tube with thermoplastic material that is oriented in an axial direction and in a circumferential direction; cooling the biaxially oriented tube; and sealingly engaging, by the tube in preform condition, a sealing member, wherein the sealing member forms an effective seal that prevents fluid from reaching a lumen of the tube upstream of the sealing member; wherein the expansion device comprises: a non-deformable expansion part having a gradually increasing diameter to a maximum diameter at a downstream end of the expansion part, wherein the expansion part is contacted by the tube and exerts an expanding force on the tube to expand the tempered tube in preform condition in the circumferential direction; a run-on part located upstream of the expansion part, the run-on part having an upstream nose end and the sealing member, the sealing member being arranged upstream of the expansion part and having a diameter that is greater than the run-on part downstream of the sealing member; and one or more fluid supply ducts having a port in the outer surface of the run-on part or the expansion part of the expansion device, wherein the fluid is introduced and forms a fluid volume between the expansion device and the tube; and wherein the expansion device is absent an external part at the height of the sealing member that presses the tube in preform condition onto the sealing member.