Extruders for extruding plastic tubing, plastic extrusion lines and systems, and plastic corrugator lines and systems; extrusion moulding machines; machine parts, namely, molds for use in the manufacture of profiled extruded plastic pipes; mechanical winders and machines for forming coils with pipes made of plastic materials; pipe corrugator machines; mold blocks for pipe corrugator machines; equipment used in the manufacture of plastic pipe, namely, mold blocks, mold block carriers and vacuum controls in a pipe mold all being machine parts for pipe corrugator machines