Work permits
There are strict procedures when working on installations and systems. After all, there's a risk for noxious substances to be released. Therefore read the Permit to Work carefully and check if the described control measures have been taken. Then take the precautionary measures which belong to your job.
Note: This video is about generally applicable rules. Individual companies may have different, stricter rules. Just ask!
NOTE: This refresher course does not replace the Basic Training Permit to Work. Ask for company specific mandatory training!