Catastrophic Carburisation in Petrochemical Industry

Singh, S R (2001) Catastrophic Carburisation in Petrochemical Industry. In: Proceedings of Workshop on Recent Trends in Structural Integrity Assessment. National Metallurgical Laboratory, Jamshedpur, Jamshedpur, pp. 46-57. ISBN 81-87053-62-3



This paper reports catastrophic carburisation (metal dusting corrosion) of radiant tube of a Paco] reactor which has undergone service life of 67,000 hours in a petrochemical plant. The 6" dia. tube conforms to Sch. 40 of ASTM A335-P11 (1.25Cr-O.5Mo steel)- The failure of tubes occurred due to nonuniform thinning of tube wall leading to fracture. The failed tube was investigated by x-ray diffraction phase analysis, scanning electron microscopy,energy dispersive spectroscopy and optical microscopy for characterisation of reaction products. The inner wall of tube surface contained wustite, magnetite, Cr2C, M23Cb, rounded iron metal particles and irregular shaped carbon soot.The presence of wustite in scale deposit revealed that the tube temperature was above or around 600°C. while the absence of hematite, which grow in presence of water vapour and thermodynamically unstable to high reducing gas atmosphere, was consistent with the atmospheric condition in the tube. The structural identification of Cr2C and M23C6 phases and morphological features near the base metal of inside surface revealed highly carburised inner tube metal surface. The wall thinning in thicker region of the tube is in the form of rounded pits, whereas in thinner region of tube, metal loss in the form ofuniform localised thinning was encountered. The carbon soot deposits were mostly on the thicker wall region. All these observations indicate that the metal wastage was due to carburising condition.

Item Type:Book or NML Publication
Uncontrolled Keywords:Catastrophic Carburisation; Pacol Reactor
Divisions:Material Science and Technology
ID Code:2766
Deposited By:Sahu A K
Deposited On:19 Apr 2011 21:46
Last Modified:06 Jan 2012 12:16
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