Research On Sealing Failure And Protection Of Bolted Flange Joint Used In Mobile Tank-car

In the transportation modes of hazardous chemical medium,tanker conveyance becomes a major form due to the characteristics of efficient,flexible and convenient.However,various leakage accidents during the transportation endanger the safety of road transport seriously,also cause high social concern and the attention of relevant management agency and research workers.The project takes liquid-phase flange as research object and is based on the theory of deformation compatibility relationship and forced sealing condition of gasket.After a comprehensive consideration of structural safety and sealing reliability,the project establishes nonlinear finite element model of the sealing system to analyze the influence on sealing performance caused by different factors in structural statics and dynamics using the method of FEA.And it also puts forward corresponding comprehensive preventive and leakage handling measures.Research indicates that,gasket deformation caused by current structural design of flange reduces sealing area by 20.87%;Mechanical interaction that exists in the system and elastic interaction between the bolts have obvious impacts on the residual load of bolts and compressive stress distribution of gasket.The loss coefficient of mechanical interaction reaches 0.19,and decreases with the increasing of preload load.The loss coefficient of elastic interaction ranges between 0.44 to 0.5,and appears different characteristics among different preload operations.Thermal deformation of materials caused by temperature fluctuation changes the sealing state of the system where local stress drops at a maximum rate of 19.7% in a low temperature environment and increases at a maximum rate of 14.4%,though internal pressure fluctuation doesn’t have the impact.Natural vibration characteristics of liquid-phase flange can be the identification reference of sealing state,and the generation of gasket leakage channel caused by vibration environment can be predicted.The comprehensive preventive measures proposed in the research include improvement of structural design in statics,designing reference in dynamics and a recommended third-wheel-cross pretightening operation with the preload load at least 1.5 times theoretical value.And the project also put forward two pressure sealing measures applicable to tanker flange leakage accident.