Shaft currents, insulating pipework flanges

[magneticted]

If we have a large MV motor fixed speed with forced lubricated sleeve bearings and the motor manufature is offering insulated bearings DE & NDE ( with DE earth cable )Does the oil inlet & outlet pipework which has ANSI / DIN flanges, do these flanges have to be insulated. And if so how are are they insulated.

 

[7anoter4]

Only one of synchronous motor bearings is grounded and the other has to be insulated. So, also the metallic conduit connected with. In my opinion a flexible rubber conduit grease resistant and suitable to required pressure could be inserted close to the bearing.