Study On Resistance Ability Of All-Welded Pipeline Ball Valve To Geological Hazards

The all-welded ball valve has the advantages of high reliability,long service life,smooth and smooth flow channel in the valve,and its safety and reliability is greatly improved than ordinary ball valve,so it is widely used in the transportation pipeline of natural gas,petroleum,chemical raw materials,etc.Our country is located in the Eurasia seismic belt and the Pacific seismic belt,geological disasters occur frequently,so the safety of all-welded ball valve under geological disasters is the focus of people’s attention.In the early stage of our country,all welded ball valves were imported from abroad,and it was not until 2007 that they were fully domesticated.But due to the lack of design means,materials and other aspects in our country,in order to ensure the safety of the valve in geological disasters,are in the design stage through the experience design,the use of large safety factor to ensure,resulting in the valve body wall thickness,large quality and other shortcomings.With the continuous improvement of design methods and the proposal of sustainable development strategy,this method is no longer applicable,so a new design method is urgently needed to ensure its safety.In this context,for all welded pipeline ball valve working condition(open)the resistance ability of geological disasters,this paper takes sichuan fly ball group production of 48 "FW-600-lb-WE all welded pipeline ball valve as the carrier,analysis its structure safety,and by using finite element analysis of seismic design method and structure theory of numerical simulation,the key for long distance pipeline with large full welded ball valve series products and piping,to study the resistance of geological disasters(the ability of subsidence,earthquakes,etc.),the main research content is as follows:For the safety of ball valve under earthquake disaster,most of the current studies remain in the stage of statics,and ignore the impact of one of the three factors of ground motion,which is not strong applicability to the random space-time load of earthquake.Therefore,this paper innovatively proposed to use time-history analysis method to study the safety of valves under earthquake disasters.Firstly,the valve modal analysis is carried out to calculate the valve modal frequency,vibration shape and dynamic calculation related parameters.At the same time using the target acceleration response spectrum,from PEER natural select two seismic ground motion database,using the software Simqke synthesis of an artificial seismic wave,and then calculated respectively using time history analysis method of seismic response of the valve under different seismic load,pressure vessels and related specification to evaluate the safety of the whole and the parts,valve results show that the earthquake affected the valve,the biggest impact is around the seat and the valve body,valve under the seismic load will not be destroyed;Finally,the feasibility and correctness of the method are verified by comparing with the calculation results of the traditional equivalent static method.According to the safety of ball valve under subsidence disaster,the formula of determining subsidence load is put forward according to different pipe diameter valve and different buried depth.Then,finite element analysis software is used to calculate the stress and strain characteristics of the valve under the subsidence load.The safety of the valve is evaluated by using the relevant specifications.The results show that the valve is safe under the subsidence load and will not be damaged.Finally,the subsidence experiment is designed,and the test results are compared with the finite element simulation results to verify the correctness of the formula of subsidence load and the finite element analysis.Through the study of the earthquake resistance of all welded pipeline ball valve and subsidence analysis,summed up get all welded pipeline ball valve geological disaster resistance ability,structure improvement suggested according to the analysis and calculation results that the mutation in the valve body structure can be changed to the gradient structure,adopt the structure not only can make the stress distribution is more reasonable,also can make the body thin,shorten the body length,so as to reduce the overall quality of the valve.At the same time,the analysis method provides the basis and parameter support for the design of all-welded pipeline ball valve in the future.