Session: DA-15-02 Coke Drum Damage Mechanisms and Material Evaluation

Paper Number: 106008

106008 - Remaining Life Assessment of Coke Drums Based on Bulge and Crack Growth Rate Analysis 

Prediction of the remaining life of coke drums is difficult, due in part to the varying thermal loads applied during the cooldown of successive operational cycles, but moreover due to the complex interaction between the thermal load, the drum bulging and resulting crack growth rates. In this paper we develop a methodology for assessment of the interaction between crack growth rates and severity of bulge. This allows the normalisation of historic crack growth rates to remove the effect of the interaction between bulging and cracking, enabling the development of a stronger basis for predicting future crack growth rates without the influence of the bulge on the crack rate.

The method can then be used for assessing what-if analysis of future possible bulge growth rates on crack propagation, enabling limit analysis of possible crack growth and bulge severity scenarios for the next opportunities to repair. This, in turn, allows a sound technical basis for determining coke drum repair extents and timelines.

Finally, the method highlights the importance of the interaction between bulging and cracking in cyclic service, which allows improved technical decisions for whether online monitoring of bulge propagation as a key indicator of remaining life and/or necessity to repair is appropriate. In addition, the method may be applied to other pressure equipment or structures that are bulged in a similar manner, in order to determine the impact of the bulge on stress levels. Use of the assessment method is illustrated by example based on the actual oerational history of an example coke drum.

Presenting Author: Richard Brodzinski Integrity Engineering Solutions

Presenting Author Biography: Later

Authors:

Warren Brown Integrity Engineering Solutions
Richard Brodzinski Integrity Engineering Solutions
Alex Berry Phillips 66 Limited
Shae Tylor Integrity Engineering Solutions Pty Ltd