A process to fabricate ultra-fine grain metal hollow object, comprising: inserting an annealed hollow prototype in an Equal Channel Angular Pressing (ECAP) die, providing a flexible elastic polyurethane mandrel to fill the central hollow space, optionally (if needed) provide polyurethane support to fill the spaces between the outer boundary of the prototype and the inner surface of the ECAP channel and to exert sufficient pressure to complete the ECAP process. The process is designed to improve thermal conductance and mechanical properties of hollow metal parts and is especially applicable to achieving the maximal heat conductance and tensile strength of titanium piping, construction tubing, and cylindrical reactors.