My dropout/chainstay joint snapped while climbing a hill in Booneville KY (pop 152). The steel frame was repaired by the village smithy at a local auto repair garage. It was a quick repair while I waited and watched. This was during a TransAm tour in 1993. I was able to complete the westbound tour after the repair.
The frame dropout spacing had been reset from 120mm to 126mm the previous year by a local NH frame builder. Not sure if this stressed the braze.
edit: frame geeks, correct me if I'm wrong ... I believe the above was a brazing repair with a torch, not welding with an arc? See golden color bead at joint.