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Old 01-09-21, 08:17 PM
  #7  
wesley77803
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Join Date: Oct 2016
Location: Texas
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Bikes: 1989 Trek 660, 1985 Trek 620

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Originally Posted by Jicafold
This was a Bertoni frame made with Columbus SL. That being said, the heat from a camp fire would certainly be less that the heat needed for brazing this frame together. So I doubt it would affect the strength of the steel.
The heat from a campfire is definitely enough to reduce the strength of a frame. Also consider that there is a significant loss of strength in the brazing process (look at the Trek brochures from the 80s where they have a chart with strength before brazing and strength after brazing).

The frames are double butted so the material is thicker where the braze occurs. Heating the center section of the tubing would be a bad idea.

For a data point from another field, the US department of transportation requires any steel gas cylinder to be removed from service and condemned if the cylinder is heated to a temperature above 650F, which is much less than a frame brazing temperatures. The temperature limit for aluminum cylinders is lower (350F).
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