Alyeska electrical engineers believe that the persistent 250 mV difference observed between the piping and ground was due to the cathodic protection system. Dry air flowing past a metal surface may generate static electricity. Helicopter blades are the most familiar example of this phenomenon. During construction, some workers believed that air flowing through the lattice of a crane was generating electricity in this manner. Vapor flows through the vapor arms at speeds up to 65 knots when they are in use.
Wind also passes over the outside.
However, the electrically isolated portion of the vapor arm is grounded to its pedestal via a chain each time the arm is stowed. Static charges could not persist in the arm from an earlier load. It is also improbable that static charges could persist on other parts of the terminal, as they would dissipate through the cathodic protection system. Geomagnetic storms may induce currents in long pipelines. The effects of these storms are most noticeable at high latitudes near the magnetic poles.