Design and Crack Analysis of Pressure Vessel Saddles Using Finite Element Method

Background/Objectives: Saddles are one of the important parts of vessel as they support the vessel. In this study, how Mode II type crack propagated inside the junction of saddle and vessel connection would spoil the entire setup of the vessel was investigated. The main intention of this work was to avoid the repeated failures of saddles during operation in energy development industries and wherever it is used. Methods/Statistical Analysis: Two different types of saddles were considered and fabricated using IS2060 Grade B material. The saddle parts were welded as per the code rule of API. Findings: Normally, welding in inclined saddle is difficult in comparison with straight saddle. This may be reason; the failure rate of inclined saddle is high in comparison with straight saddles during operation and loading conditions. The other possibility of failure is the gap formation inside the weld during joining the plates. This is due to non-deposition of weld materials. The gap would grow during operation and loaded conditions. To avoid these types of failures, external and internal crack inspections were done. Once the inspection was done, it was examined the load carrying of the fabricated saddles using FEM. Then the solid works software was used to simulate the solid model which it’s developed similar like original saddle fabricated for estimating the load carrying capacities. The obtained results of NDT and FEM were presented and the design recommendations based on investigation and study are also suggested. Applications/Improvements: The obtained results of NDT and FEM were presented and the design recommendations based on investigation and study are also suggested.