An apparatus and process for removing corrossive contaminants from a hydrocarbon including the steps of mixing water with a hydrocarbon contaminated with corrossive ions into a mixture and conducting the flow of the mixture tangentially relative to a surface of a plurality of microporous hydrophobic hollow fiber membranes and separating a permeate flow of decontaminated hydrocarbon from retentate mixture. An apparatus (10) is provided for this separation process which includes a mechanism for removing resistance to flow through the hollow fiber membrane (16) aiding in increased uniform tangential flow through the membrane (16).