Flow accelerated corrosion and thinning mechanism of the pipeline after the butterfly valve based on CFD

Abstract

Severe thinning was found on the pipeline after the butterfly valve of a hydrogenation unit, gravely threatening the safety and reliability of the unit. The mechanism of pipeline thinning was fully investigated in this work. The results of microstructure analysis showed that the corrosion products of thinned pipeline were mainly FeS2. The CFD results showed that flow accelerated corrosion was the main cause of pipeline thinning. The fluid behind the valve was violently disturbed due to the flow restriction of the valve disc. As a result, the pipeline suffered from erosive effect from high velocity flow with a very large wall shear stress. The region of high velocity and high wall shear stress was basically the same as the actual thinning region. The thinning mechanism of the pipeline was systematically dissected and described.