Changes in material characteristics of pyrolysis furnace tube coils

Abstract

Tube coil of hydrocarbon pyrolysis furnace result-ing in aggregate failures have been considered. It is shown that with the appearance of the cracks non-magnetic high-alloyed grade of Cr-Ni steel reveals magnetic properties. Changes in mechanical properties coil during operation have been studied and extreme operation time relationships have been obtained. To analyse the changes in metal struc-ture involving failures multifractal parameterization meth-ods were applied. It is shown that the changes in mechani-cal properties are connected with the evolution of sigma-phase and other intermetallic compounds arising in service.