Here in my plant TTXD_3 got open so we looped with other TTXD of same processor for temperory basis. But my question is that suppose doing that work by mistake if TTXD-4 got open thane what will happen?

 

I don't know what control system you are using (maybe you can reply), but Combustion Monitor should see the T/C as "failed" and you could be OK, but there is a possibility that you could get a trip. It is not good to have 2 adjacent T/C failed.