The Major Dangerous Source Evaluation And Reliability Analysis Of The Large Storage Tank

Storage tank is the high risk special equipment of storing up raw oil、liquid chemicalraw materials and other products, once the storage tank is failure at work, theconsequence is very serious. In order to ensure the safety of the storage tank in service,research risk-based safety assessment technology and formulate risk-based failure modesinspection procedures.In the background of risk-based large storage tank failure analysis,based onactual cases provided by the testing organization and designing、manufacturing、maintenance procedures, identify the failure modes and consequences of the storage tank,establish large storage tank failure tree by FTA, then develop the software which cancalculate minimal cut sets of storage tank failure tree and structure important degree ofthe end event by VB, sort the relative important degree of the end event and find outthe greatest dangerous source, put forward preventive measures to ensure the safeoperation of the storage tank. Finally, propose some suggestions on the risk-based failuremodes inspection procedures of the large storage tank.Take10×10~4m~3large storage tank for example, establish the finite element modelof the contact with the bottom of the storage tank and the foundation according toANSYS software. In the operating conditions of hydrostatic test, calculate the storagetank wallboard and bottom plate radial and axial stress、radial and axial displacement,assess fillet weld stress of storage tank bottom and wallboard.Explore general characteristics and mechanisms of stress corrosion cracking inthe form of the large storage tank failure, obtain crack growth rate and analyze stresscorrosion cracking at the fillet weld of the storage tank, then get the approximatecalculation method of the critical stress intensity factor of stress corrosion cracking inpractical engineering.Finally, research the reliability analysis of large storage tank at the fillet weld, using the FOSM method to calculate reliability of the storage tank fillet weld at dynamiccrack extension based on stress-strength interference model, create a three-dimensionalcracked slab model according to ANSYS1/4node singular element method to calculatethe crack tip stress intensity factor. Calculate the crack extension reliability by ANSYSProb-Design module using the Monte-Carlo method to provide reference basis in theengineering application..