I need to upsize a short 1/2" run to 3/4" (it splits from the main line using a tee). This is about 4-5ft long and goes into an appliance directly. Would it be OK to remove just the pipe and keep the 1/2" tee? I'm thinking not, since the restriction is still there, but not sure if flow would be actually noticeably impacted. Any suggestions?
Since you have a union right there changing the T should not be that tough. There is a nipple to the right if lengths change. I might try the existing But any time another appliance with no restrictions turns on the new one may starve for fuel. I have seen your plan work but since doing it right would not be much more work and possibly only changing the T, I would do that so I would not have to go back and do it over with all the new pipe in place needing to be removed to upgrade the T if it doesn’t work.
If I were doing that change, I would do the job right and replace the tee. The get the flow you need 1/2" thread may not flow the amount of gas that you need. That said, the distance you need to go with that branch just may still yield enough gas flow to support the device you are connecting. I would use what is there first to see if I get enough gas flow. If you don't, then change that section of pipe.