In order to ascertain the influencing factors and rules of the inner corrosion on the insulating joint unprotected side of the buried pipelines, a model of the buried pipeline’s insulating joint protected side and unprotected side cathodic protection system was established using the BEASY software with the help of the coupling calculation method for finite element and boundary element. The influences of different internal dielectric conductivity, potential difference between the protected side and the unprotected side as well as the damage rate of the inner coating on the internal corrosion of the unprotected side of the insulating joint were studied by numerical simulations, and the influence laws of various factors on the internal corrosion of the non - protected side of the insulating joint were analyzed with the help of analytical method. Results showed that the main factors affecting the internal corrosion of the unprotected side of the insulating joint were potential difference between the protected side and unprotected side, dielectric conductivity and the damage rate of the internal coating on the unprotected side. Furthermore, the corrosion rate was proportional to the potential difference between the protected side and the unprotected side, and to the dielectric conductivity, and were inversely proportional to the damage rate of the inner coating on the non - protected side.
