Increasing of the resistance against contact corrosion of LAIDP with steel tool joints

This paper discusses the possibility of protection enhancing against contact corrosion of light-alloy drill pipes (LAIDP) by forming a ceramic coating on threaded parts of the aluminum drill pipe using the micro-arc oxidation (MAO) method. When such a coating is formed in the zone of connection of the pipe with steel tool joint and on the threaded part of the pipe, a barrier for contact corrosion between the steel tool joint and the surface of the aluminum pipe is created. Studies of this paper were directed to determine the electrochemical potentials (ECP) on samples in a pair of aluminum alloy 1953T1 and steel 40KhN2MA in a 5 % NaCl solution at 20 degrees C and their influence on the contact corrosion. The results obtained showed that protective MAO-coating reduce the contact corrosion of the pipe and increase the reliability of connection between the LAIDP pipe body and the steel tool joint.