Research On Switching Torque And Sealing Of Large Diameter Gate Valves

Large-diameter gate valve has the great characteristics,such as simple process,low fluid resistance,high reliability,long service life.It is widely used in the liquid transportation of mining,metallurgy,petrochemical and other industries.In the practice of the process,there are problems such as excessive deformation of valve body and gate plate,and deformation of valve stem.In order t o solve these problems.The method of increase the thickness of the valve body is in common use,which leads to the high cost of large-diameter gate valve,heavy equipment and other phenomena.Part of the optimization of the valve body using stiffeners to increase the stiffness of the valve body.However,in the optimization process of the gate valve,there is a lack of research on the problems of the gate plate and the influence of the setting of the switching torque of the gate valve on the valve stem ben ding instability and the valve sealing.The design of large-caliber gate valves is mostly a combination of original theoretical formulae and experience.With the development of computer technology,and the combination of finite element and computer technol ogy.ANSYS can gradually meet the technical requirements of various dynamic simulation analysis.By changing the model materials and parameters It is convenient that can change model materials and parameters,the stress and deformation of the valve are analyzed under various conditions in the process of analysis.Compared with the use of original theoretical formulas,analysis using ANSYS can reduce man-hours,reduce costs,and produce accurate results,providing an accurate theoretical basis for actual production.This paper takes a Class150 NPS24 ZA40 type gate valve as an example,analyzes the gate and torque setting problems,and analyzes the gate and valve stem using FEM.The modeling and contact way is the binding contact between the valve stem and the gate plate,the friction contact between the gate plate and the valve seat,and the friction contact between the valve stem and the filler.The contents are as follows:(1)The valve stem is subjected to an axial force in the gate valve closed state under the valve stem instability critical force and design closing force conditions at room temperature.In the critical force,the stability of the valve stem and the sealing pressure of the valve seat sealing surface are analyzed in case of the effect of the upper seal stem on the stuffing box.(2)The stress and strain of the gate valve in the closed state are analyzed under high temperature conditions.Observe the deformation of the valve stem and the gate plate,and study whether the specific pressure of the sealing surface of the valve seat meets the sealing requirements,and compare the analysis results at room temperature.Change the axial force calculation to obtain the force that meets the strength requirements of the material and meets the sealing requirements.Calculate the torque calculated and provide reference for setting the switching torque at high temperature.