Shrink-wrap a Bridge to Make it Stronger

Instead of using a blow torch, would it be better to use something similar to the portable heating systems used for stress relieving metal components (typically after fabrication)? A web search showed up equipment for pipeline welding stress relief, but I couldn't quickly find the sort of thing I've seen used for stress relieving large fabrications in coal handling applications in the 80's. I hope that this may lead to a quicker and more uniform result although I accept that it could be pretty difficult to apply in some applications.

Depends on the memory temperature of the material. Normal stress relief is around 1650 degrees F.

Ron