Two types of sealing for fasteners

1

Kazari seal

Kazari seal: This is a forced seal, with external thread Kazari seal, internal thread Kazari seal and improved Kazari seal in three forms. The external thread kazari seal is the most used. Its gasket is a soft metal gasket with a triangular cross-section, made of copper or aluminum. The cylinder flange of the container is connected with the end cover with a threaded sleeve, and the sealing is realized by tightening the pressing bolt and applying more force on the pressing ring and pressing the gasket. This structure has the advantage of eliminating the connection bolt between the end of the cylinder and the end cover, convenient disassembly, belonging to the quick disassembly structure; The area of the gasket can also be small, so the required compression force and the diameter of the compression bolt is also small; Reliable sealing, suitable for large temperature fluctuations of the container. But the structure is complex, the sealing parts are many, and the precision requirement is high, the processing is difficult. This seal structure is often used in large diameter, high pressure, often need to disassemble and require quick opening pressure vessels.

The principle of the internal thread kazari seal is basically the same as that of the external thread, except that the threaded end cap is directly screwed into the end of the barrel with internal thread. The sealing gasket is arranged at the junction between the end cap and the end of the cylinder body, and there is a pressing ring on it. The inner side and bottom surface of the sealing gasket are fitted with the side of the end cap and the end surface of the cylinder body respectively through the pressing bolt to realize the sealing. It is more simple in structure than the external thread kazari seal, which omits a more difficult thread sleeve, but its end cover needs to be thickened, occupying more pressure space, thread is susceptible to medium corrosion, installation and disassembly is not convenient, and the working conditions are poor. Generally only used on small diameter high-pressure vessels.

The improved Kazari seal structure does not use threaded sleeve to connect the end cap and barrel, but uses bolts to connect, and other things are the same as the external threaded Kazari seal. There are no significant advantages, so it is rarely used.

2

Flat pad seal

Flat gasket seal is a mandatory seal, there is a gasket made of soft material or metal between the connecting surface, under the action of bolt pre-tightening force, the uneven contact surface (that is, the media may leak out of the gap or hole), is squeezed after plastic deformation of the gasket material filled, so as to achieve the purpose of sealing.

In order to improve the sealing performance, 1~2 grooves with triangular section can be opened on the sealing seat closing surface, with the depth and width of the grooves being 1mm, and the center of the two grooves being 5mm apart. This seal form is generally only used for small and medium-sized high pressure vessels with low temperature. Its structure is simple, in small diameter, pressure is not high sealing reliable, gasket and sealing seat surface processing is easy, more experience, but also more mature. However, when the diameter is large, the pressure is high, the temperature is high (above 200℃) or the temperature and pressure fluctuation is large, the bolt pretightening force is required, and the sealing performance is relatively poor. Because the bolt load and medium static pressure, gasket area is proportional. Therefore, when the pressure is high and the inner diameter of the equipment is large, the bolt size is relatively large, thus increasing the size of the flange and the top cover, making the structure bulky and inconvenient for loading and unloading.