PEP tubes are centrifugally cast tubes with a profiled inner diameter that maximize heat transfer in steam crackers. The starting point for manufacturing an internally profiled tube is a conventionally cast round tube.

The tube wall is cast thicker than with a conventional tube in order to permit subsequent profiling in the bore by contactless electrochemical removal of material.

The tube to be machined is mounted on the machine and carefully aligned to ensure concentricity of the bore.

The tube ends are sealed and an electrolyte current is passed through the tube. A copper head containing a negative of the desired profile is then drawn through the tube at constant speed as a profiling tool.

The tool becomes the cathode and the centrifugal casting tube the anode. The material is electrochemically removed from the tube wall and flushed away by the electrolyte current.