Impact of Overlay Welding Repair on Bulges during Normal and Short Cycles in Coke Drums.

With no doubts, bulging in delayed coke drums is one of the most common thermo-mechanical damage to that component linked to their design, fabrication, and normal operation. Coke drums are exposed to several cycles of thermal stresses which will initiate cracks, especially in the welds because of low-cycle fatigue. The bulging is affecting the integrity of the delayed coke drum. If left without repair in the long run, it would subsequently form many cracks on both the internal and external surfaces of the bulges. Therefore, and as recognized by many operators in the last ten years to limit the growth and the progression of bulges, the most common repair method used has been automated, weld overlay using consistent parameters. The first outcome of this paper illustrates the impact of overlay repair on bulge growth during normal cycles. On the other hand, some operators decided to shorten the operation cycle after introducing the repair to exceed the production rate. The second outcome of this paper is discussing the impact of this decision on coke drum integrity and how the overlay weld repair withstands the bulge growing during short cycles. [ABSTRACT FROM AUTHOR]