Getting ready for the return of my engine, and I need to get the welding
on my exhaust reworked.  Based on prior discussions here on the list, I
know I must get the exhaust tubes rewelded to the inside of the mounting
flange.  Before doing this, though, do I need to remove the exterior
welds, or are welds on both the inside & outside acceptable?

Mark

I had discussions with my welder about my exhaust.  he fabricates a lot of
race car exhausts and used to race himself (F-1s), so I respected what he
had to say.  he welded mine on the outside.

Kevin Lane

It is a simple problem in engineering statics.
Simple logic and reason. Basically a seesaw.
Not a matter of opinion.

First it is well known the tube always cracks just
on the edge of the weld where the material properties are
obviously affected by the welding process weakening the material.
This zone could be as little as 1/8 th of an inch wide. I have
seen dozens of pictures of this cracking phenomena. If you have
been around exhaust system or steel tube space frames you too
may have seen it.

If the heat affected zone is inside the 3/8th thick exhaust flange
it will be well supported. If it is outside the flange
it will have no support what so ever. If inside the support will
be applied to the tube in a place on the tube where the material
strength will be at a maximum unaffected by the welding process.

I suspect your welder has not thought this through.

Paul Lamar

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