Straightening a muffler

I have a Cummins L423D diesel engine that I am trying to slightly fix up.
It has a muffler that was hit from the top sideways (when the engine
was being moved on a forklift, I suppose).
Anyway, the muffler attaches to exhaust manifold by means of a diamond shaped flange and two bolts on the far ends of that diamond. (I can make and post pictures on my webpage).
The impact made that flange non-flat, like a "saddle". The thickness of the flange is about 1/4". The deflection is about 3/32" (guesstimate).
I would like to straighten the flange somewhat. I do not have a forge but I have a piece of rail, some assorted 4140 blocks and sledgehammer (3 and 8 lbs, IIRC). I also have a decent TIG welder.
I see two choices:
1) try to straighten the flange by putting it on the rail or flat 4140 block and pounding. (cold)
2) Try to weld a little filler to some areas and then grind the surface to be reasonably flat (should be fine with a gasket).
The muffler's body was also bent a little bit (where the pmuffler's pipe enters its cylindrical main body) but I already fixed that sufficiently to provide clearance for the oil fill cap.
So... any flange straightening suggestions will be gratefully received. I can provide pictures, as I said.
thank you.
i
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Ignoramus11550 wrote:

Cut the flange off the pipe, flatten appropriately with hydraulic press, sledge and backer, etc. then TIG back on to the pipe.
Pete C.
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I think that it's a great idea, thanks Pete. Could be the easiest also.
i
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That was my thought too. That or make a new flange and replace the old one - what ever is easier.
Peter
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Ignoramus11550 wrote:

How thick is the flange? If not too thick you could use a hand held O/A torch or even a MAPP or propane torch to heat it to red heat.
dennis in nca
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I would say it is 1/4" thick and the size is about 3".
i
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On Tue, 14 Nov 2006 16:29:56 +0000 (UTC), Ignoramus11550

remove the flange and muffler, turn the flange upside down, put a block under the muffler hole, and pull the ends down with a pair of bolts, or a pair of C clamps etc etc. Id take a piece of scrap, drill and tap holes to match the flange holes and use bolts, myself..shrug
This is far far more controlable than beating on it with a BFH.
Gunner
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Thanks... I will experiment tonight or in a couple of days...
i
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The best answer is here.
http://tinyurl.com/y8a3nr
i
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