• Prokopchuk, S. M.
• Nyrkova, Lyudmila
• Osadchuk, S. O.
• Goncharenko, L. V.

Abstract

<jats:title>Abstract</jats:title><jats:p>Corrosion and mechanical behavior of weld joint samples of the straight-weld pipe of 17G1S-U pipeline steel in the conditions simulating the operating conditions of internal and external corrosion has been studied. It is shown that the initiation of local corrosion of welded joints from the inner surface of the pipeline is due to thin-film corrosion in a two-phase medium (hydrocarbon-water) under deformation conditions. The depth of local damages of the base metal and weld metal can reach 0.337 mm and 0.381 mm. Stress corrosion cracking is a danger for the outer surface which is under cathodic protection. Maintaining the potential at the level of the maximum protective potential -1050 mV increases the stress corrosion cracking inclination of pipeline 17G1S-U steel and its weld joint, due to deterioration of the plastic properties of the metal during longtime exposure at cathodic polarization: decreasing in the relative elongation of the base metal is equal near 11 %, weld joint – by 20%. The K<jats:sub>S</jats:sub> susceptibility, estimated by the K<jats:sub>S</jats:sub> coefficient, under these conditions is equal to 1.8 for 17G1S-U steel, 1.5 for weld joint.</jats:p>

Topics

• impedance spectroscopy
• surface
• polymer
• phase
• steel
• susceptibility
• stress corrosion