Session: DA-15-02 Coke Drum Materials Considerations

Paper Number: 152046

152046 - C-½Mo vs 1cr-½Mo: A Comparative Study of Coke Drum Shell Materials 

Abstract: 

To mitigate the impact of severe thermal loads during operation, two different design methodologies are typically adopted when selecting materials for coke drum fabrication. The first approach, which favors the use of chromoly steels, prioritizes strength characteristics to improve resistance to bulging. The second approach, which favors carbon steel and C-½Mo, tacitly acknowledges the inevitability of bulging, and targets materials with lower strength and finer grain size instead, to optimize fracture ductility and accommodate larger bulges prior to the onset of cracking. The inherent trade-off involved in optimizing bulge resistance versus resistance to cracking is a crucial one to be weighed, especially in light of additional considerations that may bias material selection one way or another, such as the greater reparability of C-½Mo. The current study investigates eight coke drums from the same upgrader unit, six of which were fabricated using a C-½Mo alloy, with the remaining two fabricated using a 1Cr-½Mo alloy. The two sets of coke drums have the same geometric specifications, inlet configuration, feed, and clad material. This collection of vessels therefore provides a sound methodological framework with which to compare the two base metal materials directly. To this end, historical data available for both sets of drums is evaluated in this study to assess the performance of each material in a controlled manner.

Presenting Author: Henry Kwok Zachry Integrity Engineering Ltd

Presenting Author Biography: Henry Kwok currently serves as the Director of Engineering & Technology for Zachry Integrity Engineering Ltd located in Calgary, Alberta. Zachry Integrity Engineering Ltd is a Canadian owned engineering and consulting firm with over 40 years of experience. His career focused in forensic engineering and fitness-for-service type of investigation for piping and pressure vessels in oil and gas upgraders and refineries.

Authors:

John Fernando Zachry Integrity Engineering Ltd
Enzo Falo Suncor Energy Inc
Millar Iverson Suncor Energy Inc
Henry Kwok Zachry Integrity Engineering Ltd
Simon Yuen Suncor Energy Inc
Haixia Guo Suncor Energy Inc
Leanne Wong Zachry Integrity Engineering Ltd
Luke Chan Zachry Integrity Engineering Ltd