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Correlation of non‐destructive measurements with structural degradation in stainless steel pyrolysis tubes for ethylene cracking
Author(s) -
Rho H.,
Buchanan R.C.,
Ford E.A.
Publication year - 1999
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/(sici)1521-4176(199912)50:12<706::aid-maco706>3.0.co;2-d
Subject(s) - materials science , microstructure , oxide , cracking , ethylene oxide , pyrolysis , spinel , composite material , metallurgy , analytical chemistry (journal) , chemistry , chromatography , polymer , organic chemistry , copolymer
A commercial NDE technique was investigated to monitor structural degradation in stainless steel tubes used for ethylene cracking. In this study, data derived from a non‐destructive magnetic measurement technique were compared to magnetic permeability measurements on sample sections taken from ethylene cracking tubes. These data in turn were correlated to microstructural and chemical changes occurring in the tubes after various operational conditions. Detailed microstructure and phase analysis on the oxide layer, Cr‐denuded zones and oxide phases formed were carried out using Optical, Scanning Electron Microscopy and X‐ray diffraction techniques. The microstructural data showed that the Cr‐denuded zone, the oxide layer thickness and the spinel phase formation all increased with operational time. These data could be directly correlated to an increase in magnetic permeability and to the NDE effective thickness measurements. Excellent agreement between these two techniques was found, which indicate that magnetic Mike measurement technique can be used to track metal degradation in the ethylene cracking pyrolysis tubes.