Analysis on the Vibration and Cracking Failure of Feeder Pipeline in Ammonia Synthesis Tower

Abstract

Feeder pipeline of synthetic ammonia power is usually located at a high position. Due to the defects in design and construction, vibration and cracking failure of the connecting pipe are not uncommon. Vibration testing and finite element method (FEM) were applied to the phenomenon of cracking failure of the weld seam at the junction between the feeder pipeline and ammonia synthesis tower. Stress concentration of the weld seam due to the dead weight of the newly added connecting pipe and that of the liquid inside and uncoordinated deformation of the pipeline and tower are the reasons underlying the cracking of the weld seam. The pipeline supporting structure was improved by using FEM. The support frames were arranged vertically to relieve the stress concentration of the weld seam, and as a result, the maximum stress declined by 23.6% at the weld seam. Horizontal supports were installed to the connecting pipe and the elbow, respectively, and the uncoordinated deformation of the pipeline and tower was reduced. The maximum vibration amplitude of the pipeline was reduced by 46.8%. Vibration testing was then performed on the modified structure. The result showed that the vibration of the weld seam was coordinated after improvement, which was favorable for preventing the vibration and cracking failure of the weld seam.