Metal wound gasket is a kind of high-quality sealing packing. It has very good sealing effect, long service life and strong practicability. It is widely used in various industries. Why is it so popular? What is the sealing principle? Let me first talk about what the leak is all about. Leakage is the phenomenon that the medium is outside the flow path inside the limited space or from the outside into the limited space. This is a phenomenon that people do not want to happen. The medium flows through the interface between the inner and outer spaces, that is, the sealing surface leaks. The root cause of the leakage is due to the presence of a gap on the contact surface, and the pressure difference and concentration difference on both sides of the contact surface are the driving force for leakage. Due to the influence of the form of the sealing surface and the processing precision, it is inevitable that there is a gap on the sealing surface, which causes the sealing surface to not completely match, and leakage occurs.
To reduce the leakage of the metal wound gasket, it is necessary to make the contact surface a large degree of fitting, that is, to reduce the cross-sectional area of the leakage passage, increase the leakage resistance, and make it larger than the leakage driving force. Applying a compressive load to the sealing surface to generate a compressive stress increases the degree of contact of the sealing surface. When the stress is increased enough to cause significant plastic deformation of the surface, the gap of the sealing surface can be filled and the leakage passage can be blocked. The purpose of using the gasket is to use the gasket material to easily produce plastic deformation under the action of the compaction load, so as to fill in the unevenness of the flange sealing surface, thereby achieving sealing. In a bolt-flange-gasket connection, the force of the compression pad deforms the gasket material to fill the micro-gap between the flange sealing faces. The magnitude of the preload stress depends on the number of bolts, the torque of the bolts, the lubrication state of the bolt system and the compression area of the gasket.