Coke Drum Services

Industry-leading engineered repair and upgrade solutions 

Delayed coking has been in use since before the 1950s. Because delayed coking is a batch process, the components involved see significant temperature and pressure fluctuations during operation that are not common in other refinery assets. These cyclic changes cause low cycle fatigue failure mechanisms in the coker drums of the system. Since these drums are extremely costly to replace and are a critical asset, solutions that extend life, shorten turnaround cycles, and improve operational reliability and safety are of prime importance.

AZZ Specialty Welding has provided advanced repair options to address the more prevalent coke drum failures for decades. This includes bulging and cracking of the pressure boundary shell, cracking of the support skirt to shell interface weld area, and cladding damage of the lower cone. Today, AZZ Specialty Welding is the largest provider in the industry of structural repairs for coke drums. 

Our unique process consists of installing a highly engineered weld metal overlay to the existing vessel to modify the structure of the vessel to mitigate bulging and cracking caused by the low cycle fatigue mechanisms to which the vessels are exposed. 

Because the welding parameters are tightly controlled by the use of closed loop automated welding systems, controlled deposition techniques (temperbead) are implemented to eliminate the need to perform post-weld heat treatment of the deposit. This approach has been implemented in over 100 coke drums throughout the world with flawless performance.

For support skirt crack repairs, AZZ Specialty Welding utilizes proprietary welding processes to replace the critical welds and, in some cases, install new sections of skirt, also without requirement for post weld heat treatment. With dozens of skirt repairs installed throughout the industry without subsequent cracking, this approach has been demonstrated to be superior to conventional methods of repair.

Our long history in the development and implementation of specialty coke drum life extension and repair processes positions us to be your primary source for coke drum reliability.

AZZ Specialty Welding engineered solutions for coke drums

  • Bulge repair and structural shell reinforcement
  • Lower cone replacement welds utilizing the HotPulse® critical weld process
  • Shell and support skirt crack repair
  • ID cladding damage and defect repair

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