Pete Hall
Member
- Location
- Pennsylvania
Just did a railcar crude oil unloading station design. The rails for the train, and every third steel member of the unloading rack were grounded and a ground loop was provided around the platform area and rails with 10' Cu Clad rods driven at 20-feet increments around this loop. The suction pipe for the unload operation that pumps crude to tankage sits on the platform that is grounded. The owner added a ground testing unit with alligator clip for operator to clamp onto train from rack structure to test ground prior to unloading operation.
The unloading arms feeding into suction pipe appear to go through a series of insulated fittings, flexible connections, etc. on its way back to suction pipe. I recommended each loading arm be bonded to rack structure to provide intentional, direct ground connection at most critical instrument of operation. Mindset being operators could potentially see a good ground indicator on unit, because the train and rack will be at equipotential. However loading arm could be picked up by operator shuffled over to train, possibly creating charge, and at point where connection to train is made, create potential arc.
The owner believes this is not required. But because the connection from each loading arm to suction pipe appears to be not electrically continuous, i made this recommendation. Is this appropriate? Their arguement was that on a truck unload, this ground unit and clip connection is adequate. I would argue that on a truck unload, if the loading arm connection is assembled in the same manner, I would provide this additional bond as well. The only difference in system being truck sits on 4 tires and once clip is attached, truck and train would be equipotential, and the additional grounding made at rails of train etc. would be only difference in system configuration. Thoughts?
The unloading arms feeding into suction pipe appear to go through a series of insulated fittings, flexible connections, etc. on its way back to suction pipe. I recommended each loading arm be bonded to rack structure to provide intentional, direct ground connection at most critical instrument of operation. Mindset being operators could potentially see a good ground indicator on unit, because the train and rack will be at equipotential. However loading arm could be picked up by operator shuffled over to train, possibly creating charge, and at point where connection to train is made, create potential arc.
The owner believes this is not required. But because the connection from each loading arm to suction pipe appears to be not electrically continuous, i made this recommendation. Is this appropriate? Their arguement was that on a truck unload, this ground unit and clip connection is adequate. I would argue that on a truck unload, if the loading arm connection is assembled in the same manner, I would provide this additional bond as well. The only difference in system being truck sits on 4 tires and once clip is attached, truck and train would be equipotential, and the additional grounding made at rails of train etc. would be only difference in system configuration. Thoughts?
