You do not have the right to cause a work stoppage unless you or another hourly is in danger, if management has instructed you not to turn off the belt.
You absolutely can be written up and disciplined if you continue what you are doing.
I'm trying to help you. Take it to the proper channels, and don't give management a reason to make it about insubordination instead of safety.
You say that the stewards said they filed a grievance on this?
Why did you not file?
If this is a safety issue that you are passionate about, your name needs to be on the paper. Don't leave it up to chance and others.
If you actually care about making change in your building, then you need to learn the process, and walk the walk. There aren't gonna be shortcuts.