Session: DA-15-02 Coke Drum Materials Considerations

Paper Number: 157900

157900 - Fatigue Property Considerations for Coke Drum Girth Seams 

Abstract: 

Coke drums experience one of the most severe cyclic services of any common pressure vessel type in the process or heavy industries.  While the severe loading is thermal in nature, with an inherently random and statistical aspect to it, the end results are very predictable.  Namely that cracking adjacent to the girth (or circumferential) weld seams, initiating overwhelmingly from the inside surface, tends to set the economic life of the drums.  The concept of calibrating loading to known cracking can be leveraged, but to do so requires meaningful fatigue initiation and crack growth data for typical coke drum welded joints.  Such data is reviewed and analyzed, and property recommendations made for both the inside (with clad restoration) and outside (simple matching weld joint) including appropriate test-based fatigue strength reduction factors.  Focus is given to the most common coke drum materials – namely SA-387 Grades 11 (1.25Cr-0.5Mo) and 12 (1Cr-0.5Mo), Class 2, but other materials such as C-0.5Mo and 2.25Cr-1Mo are also reviewed.  Attention is also paid to clad (410S) and overlay materials (Alloys 600 and 625), and the combination of all of the above into typical coke drum welded joints.  Real world examples are presented to validate that the property recommendations are capable of giving meaningful life predictions.

Presenting Author: Dave Dewees Becht

Presenting Author Biography: Mr. Dewees has over twenty years of mechanical engineering experience in the field of petroleum refining, and fossil and nuclear power generation. He has performed numerous coke drum assessments ranging from thermal-stress analysis to crack growth and lifting and stability evaluations. He is the lead developer of Becht’s coke drum reliability and lifecycle assessment tool.

Authors:

Dave Dewees Becht
Brian Olson Becht
Chithranjan Nadarajah, Phd Becht