corrosion protection 14 corrosion of material 12 preservation of material 10 gas pipes 10 wandering currents 9 pipelines 9 earthing 4 more ... steel 3 utility nets 2 katodická protikorozní ochrana 2 metal constructions 2 measurement 2 electric constants measurement 2 tanks (agriculture) 2 overvoltage 2 crude oil 2 storage reservoirs 2 electrified raillway lines 2 electric voltage 1 alternating current (energetics) 1 electrodes 1 electrostatic field 1 interference (psychology) 1 steel structures 1 lightning protection 1 repairs 1 gasworks industry 1 pipeline transport 1 surface treatment of materials 1 protikorozní ochrana 1 less ...