Study on corrosion mechanism of the weld seam of submarine pipeline’s spool

Abstract

This paper studies the corrosion mechanism of the weld seam of the submarine pipeline’s spool. The types and causes of inner tube weld corrosion are simulated by EDX and XRD analysis of the on-site pipe corrosion products, combined with OLGA Software simulation pipeline flow pattern. The tensile testing, impact testing and hardness testing were carried out on the base metal and the weld by tensile tester, pendulum impact tester and Brinell hardness tester to analyze the mechanical properties of the base metal and the weld; the microstructural difference between the weld and the base metal were analyzed by optical microscopy; The results show that the liquid phase flow rate along the line is between 3.5m/s and 7.5m/s, which aggravates the mixing between the gas and liquid phases to form a bubble flow. When the entire weld area is immersed in the same simulated medium solution, the galvanic corrosion occurs in three parts of the weld zone. The weld seam and heat affected zone will be accelerated to corrode as the anode region of the galvanic couple. The weld seam has the lowest corrosion potential and is always used as an anode to accelerate corrosion.