Pipe

Abstract

A polyetheretherketone pipe of length greater than 250 meters and a residual stress of less than 5 MPa may be made using a calibrator device () which includes a cone shaped opening () arranged to receive a molten extruded pipe shaped polymer. Attached to the front member () is a vacuum plate () and successive vacuum plates (-) are attached to one another to define an array of vacuum plates, the vacuum plates being arranged to allow a vacuum to be applied to a pipe precursor passing through opening (). The vacuum plates () also include () temperature control means for heating or cooling the plates and therefore heating or cooling a pipe precursor passing through the openings. With a vacuum applied to opening () and heating/cooling the plates, an extruded hot plastics pipe is inserted into calibrator () via opening () and conveyed through opening () in plates (), whereupon it is urged by the vacuum against the cylindrical surface defined by plates () to maintain its shape and the () temperature of each plate is controlled to control the rate of cooling of the pipe precursor passing through. The pipe may be cooled at a relatively slow rate so that a pipe made from a relatively fast crystallizing polymer crystallizes and the crystallinity of the pipe along its extent and throughout its thickness is substantially constant.