Numerical Study Of The Key Accessories Referring To The Subsurface Safety Valve

The work reliability of subsurface safety valve is directly affected by the performance of plunger seal parts,cylindrical compression spring,flapper torsion spring and flapper.In this paper,the researches on key components of subsurface safety valve were made by finite simulation and theoretical analysis.Under the initial assembly magnitude and 10 MPa work load,ANSYS software was used to study sealing performance simulations of O sealing ring,Flexiseal and C metal seal.Results showed that the contact stress referring to O sealing ring,Flexiseal and C metal seal respectively were 15.3MPa,23.14 MPa,59.94 MPa and the biggest effective sealing surface width was obtained by Flexiseal,followed by O sealing ring.Considering factors of simulation data,processing technology and working condition,the Flexiseal part was regarded as the relatively superior seal form in the three types of sealing under 10 MPa pressure.The research that stress relaxation and creep of cylindrical compression spring and flapper torsion spring was launched by ANSYS software and theory of spring design.In the simulations of cylindrical compression spring,the maximum von mises stress was 865 MPa under the maximum displacement load 260 mm,and it was accordant to strength requirement.After 8760 hours stress relaxation function,attenuation amplitude of shear stress increased from 13.38 MPa under the minimum displacement load to 140 MPa under the maximum displacement load,at the same time load loss rate increased from 0.79% to 24.38%.The residual restoring force was 1002 N in accordance with the job requirements.Under the maximum torsion angle 90°of flapper torsion spring,the maximum bending stress was 664 MPa.After 8760 hours creep effect,the residual torque was 216 N.mm satisfied the requirements of the work.The torque load loss rate increased from 5.74% under the minimum angle to 68.34% under the maximum angle,and it was shown that torsion angle was one of the main factors influencing the torque load loss.As were shown above,all the results had some significance on the structural design,manufacture,installation and material selection of the cylindrical compression spring and flapper torsion spring.Based on the method of quasi static state simulation,the simulations that included flow field,balance ability of hole and stress of instantaneous impact on valve plate were carried out.The results showed that pressure difference of valve plate was increased by closed angle.When the closed angle was 85°,the differentia pressure was 6MPa,at that time the differential capacity of balancing hole was 66.17%.The biggest impact of equivalent stress which was generated at the time of closed was 704 MPa that meet the requirements of strength of materials,because stress concentrations were found in the transition of pin shaft hole and valve plate,more attention should be taken during the design of valve plate.