Mechanics Analysis And Structure Optimization Of Press-in-type Pipeline Fittings

Pipe transportation is one of the five ways of transportation. It was born after the railway transportation, road transportation, waterway transportation and air transportation. Non-welding connection method of metal pipe is a badly-needed technology in oil and natural gas industry. In this paper, the axial press-in type fittings are researched and manufactured by the elastic-plastic mechanics and thin shell mechanics. This way is a typical non-welding connection technology of metal pipe.First of all, based on the connection mechanism of axial press-in type technology and related technique requirements, this kind of pipe fittings are designed. It analysed the mechanics theory and established the mechanics model of this fittings, through the elastic-plastic mechanics, material mechanics, thin shell mechanics and engineering approximation methods. The analytical expressions about pre-tightening force, shrink range, maximum internal pressure and the stress at the time of the sealing failure are obtained.Secondly, according to the sealing performance requirements of axial press-in type fittings, the fittings are optimized structure.2d and3d finite element models are established. MSC.SuperForm finite element analysis software analysed the sealing performance of non-optimized fittings and optimized fittings. The maximum axial load, internal pressure, torsion and bending moment of pipe fittings are obtained. It testified that the sealing performance of the optimized fittings is better.Finally, pipe connection test and tension test are proceeded by WDL. The data of connection load and tension is consistent with the data of finite element results. It verified that the data of finite element results are right, because the relative error is within the scope prescribed.A new kind of pipe connection technology is raised by the research of axial press-in type fittings. It laid the foundation for the engineering application of this fittings.