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What are the types of fastener seals?

Jun 02,2022

This is a forced seal, and there are three forms: external thread snap-in seal, internal thread snap-in seal, and modified snap-in seal.
External thread clamp: The inner face seal is used very frequently. Its gasket is a soft metal gasket of triangular cross-section, made of copper or aluminum. The cylinder flange of the container and the end cap are connected by a threaded sleeve, and the seal is achieved by tightening the compression bolt to apply force to the compression ring to compress the gasket. The advantage of this structure is that the connecting bolts between the end of the cylinder and the end cover are omitted, it is easy to disassemble, and it belongs to a quick disassembly structure. The area of ​​the washer can also be relatively large, so the required compression force and the diameter of the compression bolt are relatively large. Reliable sealing, suitable for containers with relatively small temperature fluctuations. However, the structure is complex, the sealing parts are redundant, the precision requirements are low, and the processing is difficult. This container configuration is typically used for small diameter high pressure containers that require slow disassembly and opening.
Internal Kazary Seal: The working principle of the internal threaded Kazari seal is basically the same as that of the external thread, except that the threaded end cap is indirectly screwed into the end of the cylinder with the internal thread. The gasket is placed at the connection between the end cover and the tail of the cylinder, and a compression ring is arranged on the gasket. The inner surface and bottom surface of the gasket are connected with the end cap tail and the cylinder end surface in turn by pressing bolts to achieve sealing. It is higher than the externally threaded kazari face seal and saves a relatively easy-to-machine threaded sleeve. Its structure is more intuitive, but its end caps need to be thicker and take up more pressure space. The thread is not easy to be corroded by the medium, not easy to disassemble and assemble, and has few working conditions. Usually only used for large diameter high pressure vessels.
Improved Kazary seal: The improved Kazary end-face seal structure does not require a threaded sleeve to connect the end cap and the cylinder, but uses bolted connections, and other parts are similar to the externally threaded Kazary end-face seal. It has no clear advantage and is therefore difficult to adopt.
Flat Gasket Type Seal: This is a mandatory seal. Washers made of soft material or metal are placed between the joining surfaces. Under the action of the pre-tightening force of the bolt, the uneven part of the contact surface (that is, the gap or channel where the medium may leak) is squeezed and filled with plastic deformation gasket material, so as to achieve the purpose of the container.
In order to improve the sealing performance, one or two grooves with triangular cross-section can be formed on the sealing seat surface, the groove depth and groove width are 1 mm respectively, and the middle of the two grooves is 5 mm apart. This type of container is usually only used for small and medium high temperature and high pressure containers and does not produce low temperatures. The structure is intuitive, the sealing is reliable when the diameter is large and the pressure is not low. However, when the diameter is small, the pressure is low, the temperature is low (over 200), or the temperature and pressure fluctuations are relatively small, the required bolt preload is relatively small, and the sealing performance is poor. Because the bolt load is proportional to the medium pressure and gasket area. Therefore, when the pressure is low and the inner diameter of the equipment is small, the size of the Carriage Bolt is small, and the size of the Flange Nut and Flange Bolt is increased, and the structure is light and easy to disassemble.
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