A header pipe crush gasket will compress -- a lot.

That gasket will work OK if pulled up with moderate wrist torque using a standard rachet (no torque wrench, just feel).

Each time you  tighten it up it reseats slightly differently, collapsing a little bit each time.  Try to keep the flange going down straight and don't always start out tightening the same side of the pair of bolts.  

Think of it like a kid's see-saw with what you are doing with the bolts and the flange

Every time you check the bolts they will seem "loose", just snug them down again just a little bit each time.  (expansion contraction going on here every time the engine gets hot and cools down - this is normal)

All you are doing right now is using up all the "redos" all at once with the torque wrench set at maximum torque setting.

as to the torque wrench, it may not be broken - there's two types.

a. when in reaches set torque, it loudly clicks and "jumps" about 15degrees, letting you know you've reached it.
b. the very top of the wrench (where the socket goes) gives in and "swivels" few degrees. No click, nothing.

I got the second one, which seems to be the trend with chinese torques. The point is - it takes some focus to actually SEE, let alone FEEL the point of set torque.

Find a well rusted, tight nut somewhere, set the wrench to low torque and slowly try to tighten. Practice on it, you will catch the drift...