Some things are just dangerous. For example, process piping. You can bump your head on it, trip over it, get burned by it, or wrench your back trying to move around it.
Generally, if you have process piping you have motor-driven pumps. Carefully scope out the process piping at and near the work location, if you're working on the related motors.
Consider that motor you're replacing. Unless it's a small motor you can easily carry, you need to plan a path for the equipment needed to extract the motor from that space. If there's not sufficient room for a lift truck, you may end up using a manual lifting device (e.g., “come along) and carry cart; those present additional hazards.
If the piping contains something that's hazardous to people or the environment, additional procedures for being in that area apply. Wear the correct personal protective equipment (PPE), conduct a visual inspection of leak points such as flanges, and know exactly what you are supposed to do in the event of a spill or leak.