Session: OAC-06-01 Operation and Maintenance of Pressure Vessels, Heat Exchangers, Piping and Supports

Paper Number: 62435

Start Time: Wednesday, July 14, 2021, 09:00 AM

62435 - A Case Study of a Challenging Coke Drum Skirt Repair: A Through Wall Crack Extended 360 Degrees Around Circumference 

An unusual finding of a through wall crack in the skirt just below the skirt to bottom head was discovered to be extended almost the complete 360-degree circumference. The crack allowed the drum to fall 2.5 inches into the lower skirt resulting in a visible lean.

 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 analysis included stability analysis of the coke drum, Repair approach development, lifting approach design and assessment, controlled deposition welding (CDW) in for weld repair, and non-destructive examination (NDE) techniques for repair quality control. A skirt crack monitoring program and operation cycle optimization were implemented following the successful repair of the severe cracked drum skirt.

An unusual finding of a through wall crack in the skirt just below the skirt to bottom head was discovered to be extended almost the complete 360-degree circumference. The crack allowed the drum to fall 2.5 inches into the lower skirt resulting in a visible lean.

 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 analysis included stability analysis of the coke drum, Repair approach development, lifting approach design and assessment, controlled deposition welding (CDW) in for weld repair, and non-destructive examination (NDE) techniques for repair quality control. A skirt crack monitoring program and operation cycle optimization were implemented following the successful repair of the severe cracked drum skirt.

Presenting Author: Huidong Gao Shell

Authors:

Huidong Gao Shell
Jorge Penso Shell Global Solutions Inc (US)
David Dewees Becht Engineering Co., Inc.
Everett Chatham Shell Exploration & Production Company