The Coke Drum Banana Effect Syndrome

Coke drum susceptibility to bulging and cracking are a common concern among most refiners operating cokers. Different metallurgies react to coke drum thermal stresses in surprising ways. Depending on metallurgical quality and design, thermal stresses can lead to the so-called “banana effect,” typified by the harmful development of a cold spot on one side of the drum and a hot spot on the drum’s other side, thereby contorting the drum into the shape of a banana.

Thermal stress dealing to coke drum contortion. Graphs compliments of Stress Engineering Services, Coke Drums and Cokers

These identified thermal stresses are among a variety of topics relevant to coker process safety and reliability at the Delayed Coker Operations and Reliability training session delivered by Gary Pitman during the RefComm® Galveston 2016 refining conference. Some of the training session delegates were experienced refinery maintenance professionals recently assigned to coker operations or maintenance. Other delegates were experienced coker unit professionals tasked with gaining a better understanding of the Best Practices adopted by coker professionals and engineers from other refining companies and regions.

Against this backdrop, the class shared experiences on past and recent experiences for avoiding coke drum stress and lessons learned going forward. In one discussion, Pitman emphasized the importance of designing the entire coke drum supporting assembly in such a manner that it does not affect (damage) the unit’s supporting structure should the drum become structurally or thermally contorted. In any event, many other instances can be noted that justifies the need for developing a culture of reliability championed by operations staff from the unit level to the supervisory level.

Delayed Coker training is offered in regional locations across the USA at Galveston, TX, Bellingham, WA (gateway to the San Juan Islands between Seattle and Vancouver), Los Angeles, and Chicago.