Actually to stress relieve it properly...you heat it until it has a dull red glow..then wrap it with a fire blanket (get them at a welders supply store) and it lets it SLOWLY cool down (we are talking hourse here). Never had a crack while doing this. Also, if you ever need to MIG weld cast iron: preheat the hell out of it, weld it, then reheat it and wrap with same blanket and leave it till morning. Butt welding is not the best idea in an instance like this. Inserting the tube part way and seam weld inside, then as Barge said stitch weld the outter perimeter to give it some stress relief. Weling inherently creates a stress riser and that is wh you se most cracks will be outsie the weld. It is sometimes from overheating the part but mostly due to the fact that is the highest place of stress.



BTW....nice work so far....keep it going....and invest in a TIG welder..its worth every penny

People suck. Rev it till it MELTS.....