Effect of gasket on the sealing of flange
We usually see flanges that use the pre-tightening force of bolts to maintain the tightness of flanges.Specifically,enough pressure is generated between gasket and flange sealing surface,and the deformation of gasket surface is enough to fill the micro-roughness of flanges’ sealing surface,so as to achieve the purpose of no leakage.Therefore,the sealing effect of flange depends on the high quality of gasket.
Here sharing some tips about the usage of gaskets.When the pipeline is under operating pressure,under the action of inward force,the two flanges show a trend of separation,bolts will produce elastic or plastic deformation,and the compressive force acting on the gaskets will be reduced.When the compressive force on the effective section of gasket is reduced to a critical value and the seal can still be maintained,then the residual compressive force on the gasket is the effective tightening force of the gasket.When the effective tightening force is below a certain critical value,leakage will occur,and even the gasket will be dislocated.Therefore,the effective tightening force of gaskets must be greater than the operating pressure of piping system.The ratio of effective tightening force of gasket to working pressure of piping system is called gasket coefficient M.The distance between the sealing surfaces of two flanges is larger in the operation state than in the initial state.At this time,the tightness between the gasket and the sealing surface of the flange is ensured by the springback force of the gasket. It can be said that in the initial sealing stage,the plastic deformation of gasket surface plays a decisive role in filling the micro-roughness of flange sealing surface, while in the operating state, the elastic recovery inside gasket plays a leading role.
In addition,any form of flange can not guarantee 100% leak-free,because there are a variety of possible factors.Some can not be avoided,but what we can do is to reduce such leakage,or ensure timely repair when find leaks,to make the flange connection achieve greater sealing effect.