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

Paper Number: 104630

104630 - Assessment of Coke Drum Bulge Deformation Using Online Thermal Data to Determine Optimal Weld Overlay Repair Design 

Studies have shown bulging in coke drums occurs due to several factors. One of which, are large thermal gradients that occur during the drum operating cycle. A thermocouple array comprising of 126 temperature indicators, spanning 1.7 m (5.5 ft) high, full circumference, was installed onto a coke drum at the location of a significant bulge in order to monitor the drum skin temperature distribution over a thirty day period (total of 14 drum cycles). This paper presents the findings of this thermal study, exploring the nature of the hot and cold spots seen during the quench phase and mapping out the resulting stresses and strains local to the drum bulge. A reinforcing weld overlay repair is selected after using finite element analysis (FEA) to optimise weld coverage, placement (internal & external) and final thickness. The weld overlay effectiveness was found to be primarily based on the axial extent of overlay applied and not significantly affected by the thickness of the overlay (number of passes). The paper concludes with a short discussion on post weld heat treatment (PWHT) vs. temper bead welding process when undertaking weld overlay repairs on coke drums. FEA is used to show PWHT after overlay repair has little influence on the remaining life of the coke drum.

Presenting Author: Alex Berry Phillips66

Presenting Author Biography: Alex Berry holds a Master’s degree in Mechanical Engineering from the University of Newcastle upon Tyne and a Diploma in Welding Engineering from the TWI. A Chartered Engineer with the IMechE, Alex has 16 years petrochemical experience and currently leads a Fitness for Service group responsible for mechanical integrity assessments on pressure equipment, undertaking engineering design and driving business improvement both at local and corporate level. Professional interests include Bolted Flanged Joints, Coke Drums, Weld repairs and mentoring younger Engineers.

Authors:

Alex Berry Phillips66
Warren Brown Integrity Engineering Solutions Pty. Ltd.
Richard Brodzinski Integrity Engineering Solutions Pty. Ltd.
Antonio Seijas Phillips66