I would think that if any current is flowing on the piping system and it encounters a poorly conductive joint, as might be the case across some pipe dope or plumbers putty, a potential difference will exist and present a shock hazard of some degree. I guess it all depends where the bonding occurs in relation to the fault. If the person touches the higher potential side of a poor pipe joint and the other (low potential) side where the bonding to a gas line occurs you will have a possible safety problem.
Anyone?
