Cathodic Protection Potential Distribution and Anode Ground Bed Optimization Scheme for Low-Pressure City Gas Pipe

The low-pressure gas pipes in some old residence communities of China are often electrically connected and groundings, which brings about great challenges to the design of cathodic protection (CP) systems due to large CP current consumption and attenuation effects. The field tests on the potential distribution of three types of anode ground beds were conducted, including a deep well auxiliary anode ground bed, shallow auxiliary anode ground bed far from gas pipes, and shallow auxiliary anode ground bed close to gas pipes. The results showed that the shallow auxiliary anode ground bed close to the gas pipe provided more protection with less current than the other two types of ground bed. Numerical simulations on CP potential distribution of different anode ground beds were conducted and the boundary conditions were determined by inversion calculation based on field tests. Based on the field test and numerical simulation results, the anode ground bed suitable for CP of low-pressure gas pipes electrically connected to groundings is the shallow auxiliary anode ground bed close to gas pipes and the optimized distribution scheme for shallow anode ground beds was proposed.