Stress Analysis And Crack Propagation Characteristics Of Pressured LPG Storage Tank

The storage tank is a special equipment for storing chemical raw materials and products,and has a wide range of applications in petroleum,chemical,energy and other production fields.Liquefied petroleum gas?LPG?stored in tanks often contains excessive hydrogen sulfide?H₂S?and moisture,these corrosive media will cause serious damage to the tank,at the same time,the serving tank is subjected to internal pressure,self-weight,external load and other functions,resulting in crack initiation,expansion,and then to failure fracture,which seriously affects the safe operation of storage tank.Starting from the safety of storage tank,this paper studies the storage tank from three aspects:stress analysis,stress corrosion cracking experiment and corrosion fatigue crack propagatio n experiment.The main research contents and conclusions are as follows:?1?The finite ele ment ana lys is soft ware ANSYS Workbench was used to simulate the geometr ica l modeling,meshing and boundary condit io n setting of the saddle struct ure and the opening pipe jo int str ucture o f the hor izonta l storage tank,the stress distr ibut ion nephogra m was obtained,and the dangerous section was linearized.According to the assessment results,the tank meets the strength requirements.?2?For the commo n steel Q345R and SPV50Q of two storage tanks,wedge-shaped open-loading?M-WOL?pre-crack specimens were selected to conduct experimenta l stud ies on stress corrosion cracking of different H₂S concentratio ns,crack locations and we lding condit ions.The results show that the stress corrosion crack growth rate da/dt and the stress corrosion crit ical strengt h factor K_ISCC of the two mater ia ls were different in d ifferent H₂S concentratio n media environme nts;For the two materia ls,the crack growth rate da/dt was the highest in t he heat-affected zo ne after we lding,and the crit ica l strengt h factor K_ISCC was the sma llest.After heat treatme nt,t he crack growth rate da/dt was greatly s lowed,and the stress corrosion cracking resistance was improved.Due to the difference of composit ion and structure,the crack growth rate da/dt of SPV50Q was always greater than the crack growth rate da/dt of Q345R.?3?In the st udy o f corrosion fat igue crack growth,three commo nly used corrosion fat igue models were compared and ana lyzed.The corrosion fat igue crack growth experime nt of 07MnNiCrMoVDR in H₂ S solut ion was carried out.Correction coeffic ients C?f?and M?f?related to loading freq uency were introduced according to the exper imental results,and t he corrosion fat igue crack growth model was estab lished.The rema ining life of tanks c ould be predicted.