Study On The Cartridge Connection Technology Of Gas Using Thin-wall Stainless Steel Pipe

Used in the town connection technology of thin-walled stainless steel compression pipe does not require any treatment before performing the connection of the pipes ends, the method is simple and it guarantees long life and enhance the architectural appearance after installation。At present time, thin-wall stainless pipe is being widely used in various industries.Actual researches on using circumstances of thin-walled stainless steel pipes in town gas fields and survey of thin-walled stainless steel pipe installation technology information, has found out the unresolved issues for cartridge compression during installation and construction of thin-walled stainless steel pipes. The main reason is that according to recommendations of different manufacturers, cartridge compression pressure is not uniformed, the deviation between actual pipe and pipe’s fittings varies a lot, caliper design is not uniformed etc., and as a result, cartridge compression process cannot determine the optimal compression pressure values or optimal interference value for thin-walled stainless steel tubes. In addition, China’s researches amount of pipes connection technology is relatively small, restricting the entrapment of stainless steel pipe connection used in the field of gas engineering. Therefore, it is necessary to continue researches on cartridge connection technology of thin-walled stainless steel pipes.Firstly, the theoretical basis of elastoplastic mechanics highlights the actual using of engineering approximation method of simplified material model to the perfect elastoplastic model, and also deduced the general expression of axisymmetric plane stress problem in elasticity and plasticity theories; then, building of thin-walled stainless steel tube mechanic model and elastic compression stage and the plastic stage analyzing during process, eventually deduced axial symmetry plane stress strain theory of thin-wall stainless steel tube elastic deformation, plastic deformation and displacement stress calculation formula expression, and using the example of DN25 type thin-walled stainless steel tube it verified the correctness of the calculation. We get because for the error of the theoretical calculation and the actual card pressure caused by the model is 16%~19%.Then, the ANSYS software is used to simulate the thin-walled stainless steel compression process, to build the finite element model and to analyze the stress and strain distribution of elastoplastic deformation of the pipe joint in the whole process of cartridge compression to learn more about the pipe fittings works. We get the conclusion that follow the pipe joint and pipe contact surface contact stress is increasing, and the joint of the inner wall of the tube will gradually produce plastic deformation, but at the moment, the steel tube is still in elastic deformation, when the contact surface began to appear on the zero contact gap and the density of zero contact gap is larger is considered contact surface has formed an effective seal.Finally, aiming at the DN25 thin-wall stainless steel pipe, simulated the different geometric parameters on the card performance pressure that with the increase of the thickness of steel tube; and with the increase of the amount of interference on the contact surface of the joint and the pipe; with the increase of the entrapment width; contact the average surface contact pressure is higher, the sealing effect is better.