Need advice, keeps burning exhaust gaskets

[Camrolla]

Hello,
Has anyone had any problems with their Corolla (1996) burning out the exhaust gasket between the exhaust manifold and primary pipe?
This thing has defied all my efforts to keep it quiet. I've replaced the gasket about 6 times in the past 2 years. I've tried orange permatex, loctite, lock washers, I've even fabed some tabed washers that you bend a tab over one of the flats on the nuts to prevent rotation. My latest creation involved using bolts instead of studs and nuts and drilling a small hole in the head to safety wire them together. The primary pipe has been replaced as well as the manifold. I've also switched form NAPA gaskets to OEM Toyota gaskets. (way better quality, but they still burn out) It's nice and quiet after the installation of each new gasket, but only for a few months. The bolts don't show any sign of rotation, yet the pipe becomes loose as the gasket burns out. I've been working on cars for many years, and this has got me stumped.
Any advice or suggestions will be appreciated, Thanks.

[josh2009s]

Check the flange. It could be bent just slightly enough to cause that to happen over and over again.

[speedy25]

Typically its from rust keeping the fasteners from tightening down to get good gasket crush, but since you have changed the fasteners that shouldnt be the problem. Soooo you dont have two flat mating surfaces. Its common for rust to keep the surface from being flat and also the ears of the flange get bent and wont let it seal. A liitle work on the "ears" or some filing to make the surfaces flat will solve the problem.

-SP

[josh2009s]

Originally Posted by speedy25

Typically its from rust keeping the fasteners from tightening down to get good gasket crush, but since you have changed the fasteners that shouldnt be the problem. Soooo you dont have two flat mating surfaces. Its common for rust to keep the surface from being flat and also the ears of the flange get bent and wont let it seal. A liitle work on the "ears" or some filing to make the surfaces flat will solve the problem.

-SP

This is what I would have said if I weren't so tired last night, lol.