This is a thorny question that is hotly debated. 480 volt 3 phase, 30A, 60A or 100A receptacles are commonly used for a variety of uses. I've seen tons of them in use. Most have a local fused disconnect. Problem is the older style metal body receptacles aren't interlocked with the disconnect therefore can be plugged or unplugged energized.
From a AF standpoint the IE is very low, typical cat 0 due to the wire size #8 or #10, cable run distance and fusing. The real problem is the shock hazard.
I've seen female pins get pulled out of the of the receptacle body leaving a dangling energized conductor. The newer disconnect/receptacle units, Hubble for example, have an interlocking pin that prevents removing or inserting plugs unless the disconnect is off. They are pretty pricey.
Interacting...? From a safety viewpoint you need to assume the welding recpt is going to be energized unless it interlocked with the disconnect handle. Disconnecting or connecting a plug in an energized 480 volt, 3 phase receptacle I would say yes, it fits the definition of interacting from a shock hazard standpoint.
Technically that requires voltage rated gloves, eye protection and be qualified. This is where the issue and debate war starts. Do you buy everyone that uses the welding outlet a pair of voltage rated gloves and qualify them to plug in a cord cap? Or do you have the plant electrician plug in a welder every time the pipe fitter needs to weld? Good luck selling management that idea
First option is label welding receptacles to turn off power before plugging or unplugging. This still doesn't insure its being turned off.
Second and best option is replace the receptacle with an interlocking type. This requires replacing the male body to match as well. Again, pricey but fool proof.