Abe's a pro so he was able to achieve the results without any special equipment. Edges were deburred, a tube polisher with a surface conditioning belt was used to clean clean the surface, acetone was used to degrease, clean gloves were used, pure argon with a healthy flow was used to back purge and care was taken to ensure that the bead was completely shielded by the cup until it cooled. The low amount of alpha case is due to shielding. While he's used a parts-per-million (PPM) oxygen analyzer at other job to insure a proper shield, he doesn't have one in his shop. Instead he just runs more gas than he normally would. To ensure that the hot bead is always under the cup he closes the doors to prevent an errant breeze, he's careful with torch angle and he only does 10-12 dabs before stopping. At which point he flips his helmet up while keeping the cup over the bead with the gas running for another 15-20 seconds after which he rotates the tube and repeats the process. Given his experience level and that this isn't an aerospace part, he doesn't use a thermometer to determine when the bead is cooled. An excess of argon wastes a little gas and takes a few more seconds per cycle. Too little and you get alpha case.How did you guys keep it so clean and free of alpha case when welding?