Weld Process Effects on Fatigue Performance in the Repair of Coke Drums

Coke drums experience failures in through-wall cracking throughout their operating life, resulting from low cycle fatigue. Coke drums are typically fabricated from high strength low alloy (HSLA) steels. This study was performed on 1-1/4CrMo base material using ER70S-B2L and Alloy 625 (ERNiCrMo-3) filler materials. Specimens were welded with the temperbead/controlled deposition welding technique. The weld processes used were Hot Pulse^TM GTAW, GMAW and SMAW. The fatigue performance, HAZ hardness and toughness of the weld samples was evaluated. The Hot Pulse^TM GTAW welds exhibited an order of magnitude improvement in fatigue performance when compared to the other weld processes using ER70S-B2L filler material. The Hot Pulse^TM GTAW welds also exhibited improved HAZ hardness and toughness when compared to the other weld processes. This presentation will introduce the Hot Pulse GTAW^TM process, its features, and benefits and where it is applied in Coke drum repair welding. Comparative test results of the different weld processes for fatigue performance, HAZ tempering, and toughness will also be presented.