Reliance Industries Ltd. - Umakanthan Anand
Amec Foster Wheeler - Tej Chadda
The aging coke drums and connected piping in delayed coking unit, DCU, experience cracks commonly at skirt junction and critical welds due to low cycle thermal fatigue and/or vibration induced fatigue. These aged vessel and piping components require field repair for continued operation.
Various reasons for these fatigue cracks are due to the original design of coke drum and piping not being fatigue resistant, thermal operation and gradient being too severe, fabrication of the vessel and piping not being fatigue resistant.
The life management, reliability, and safety consideration of coke drum and piping require consideration of fatigue and stress risers during field repair. The service life, reliability, and safety of these components require fatigue life consideration during the field repair instead of continuing simply with monitoring cracks and repairing them with the original design and continuing to operate with original thermal operation practice of coke drums.
Case studies will be presented to demonstrate implementation of fatigue life and reliability improvement consideration in field repair of coke drum skirt junction and overhead piping welds and optimization of upgraded fatigue resistant repair design methodology and thermal operation/gradient optimization.