Natural gas piping in walls

I want to run black pipe in walls behind sheetrock. 2414.3 says no bushings in concealed locations. What if I welded 2 inch and smaller? Any ideas would be appreciated.

We aren't allowed to use bushings at all here. I'm not really sure what the reason is. Reducing couplings, elbows, and tees are perfectly acceptable however. I'm sure it's the same where you are and I'm sure you can find a way to do it with one of those fittings.
To weld the pipe you would have to be licensed to weld pressure vessels.

bushings

The reason for no bushings is that all bushings other than 1 1/2"x1 1/4" are cast and therefore can crack under stress, which would be okay for water, but intolerable for gas. But there is no reason to use bushings anyway. EVERY reduction is size can be done with approved fittings and no need to weld the piping.