Erosion Corrosion of 90° Elbow Containing Welds in Gas Gathering Pipelines

A failure elbow containing welds in a gas gathering pipeline was analyzed. The mechanism of erosion corrosion of gas gathering pipelines at 90° elbow and weld was analyzed through simulation of fluid flow patterns at these positions in pipeline by Fluent software. The results showed that the corrosion products were peeled off from the metal surface of the weld and the inner wall of outer arc side of the elbow because of higher vortex intensity. The stripped corrosion products quickly moved to main flow under the influence of fluid with high turbulence intensity near the wall. The exposed metal matrix continued to be corroded, and finally serious erosion corrosion occurred in the weld and the inner wall on the outer arc side of the elbow. The elbow with welds at both ends in natural gas gathering and transportation pipeline had a high erosion corrosion rate in the weld and the inner wall on outer arc side, and it was prone to corrosion perforation in the service process without internal protection.