Stress Analysis At The Opening And Nozzle On Large-scale Spherical Head Under High Pressure

Large scale vessels are widely used in oil refining and other chemical industry under high pressures.The safety of these vessels has been attached much attention in the process of design,manufacture and usage.In this paper,the stress concentration at the openings on a spherical head has been studied,and it is of benefit to the safety of a pressure vessel used under high pressures.Based on finite element analysis method,the stress distribution on connecting area of large scale spherical heads and nozzles is numerically simulated.Nozzles are in different forms and different directions.The stress concentration of these structures is obtained,and the strength of the structures is checked according to national standards.The stress concentration of multiple openings has been studied,taking large ammonia synthesis tower as an example.The numerical simulation and stress analysis results show that the inserted nozzles can effectively reduce the maximum equivalent stress,that is inserted nozzles can award reinforcement to the openings.Compared with the non-inserted nozzles,the inserted type can reduce the maximum equivalent stress by 47.68MPa which is 14.1%of non-inserted type;the farther the nozzles are away from the axial of the head,the greater the maximum stress caused by axial direction nozzle opening will be.But the radial nozzles are not significantly affected by their positions on the head.The degree and influence range of stress concentration of multiple openings closely depend on the space,size and type of the nozzles.The varying laws of the stress concentration with the form and location of the nozzles obtained from this paper provide the basis for further study of the stress concentration and are positive for promoting the application of finite element analysis method in pressure vessel analysis design.