It is double-wall pipe, that's why it necks down for that joint.
That joint 'wore out' on mine, I ground down the flanges (what was left of them) and used a short piece of 2-inch pipe over the whole joint.
I had to grind down the weld on the inside of the pipe, 2.25 inch pipe would be a lot easier, but you'd have to really crank down on the clamps.
2.25-inch flex pipe might be the best easy choice.
That joint 'wore out' on mine, I ground down the flanges (what was left of them) and used a short piece of 2-inch pipe over the whole joint.
I had to grind down the weld on the inside of the pipe, 2.25 inch pipe would be a lot easier, but you'd have to really crank down on the clamps.
2.25-inch flex pipe might be the best easy choice.