An unusual finding of a through wall crack was discovered along the skirt to bottom head weldment. The crack extended nearly 360-degrees along the circumferential weld seam. This flaw resulted in the drum level dropping approximately 2.5 inches onto the skirt resulting in a visible lean of the drum relative to the adjoining support structure.
This paper describes the inspection, engineering analysis, and repair performed after discovery of this challenging situation. Initial inspection included quantitative measurement of the drum displacement and skirt cracking. Engineering analyses included stability analysis of the coke drum, development of a robust and technical viable repair plan, design of a lifting & rigging system to enable repair in the field, controlled deposition welding (CDW) approach, and detailed description of non-destructive examination (NDE) techniques to assure repair quality control. A skirt crack monitoring program and operation cycle optimization were also implemented following the successful repair of the severe cracking along the drum skirt.