In the construction machinery in the Gland Packinging element has more than 10 kinds of number of gasket structure is relatively simple, the application is more common. This article briefly introduces the structure, material and performance of commonly used gaskets and the proper selection.
First, the function and material of the gasket
1 gasket is widely used in engineering machinery and diesel engine pipe, shell of the joint surface of the static Gland Packing, with its elastic deformation to fill the uneven surface of the joint surface, cut off the leakage channel. Increase the leakage resistance, or bear the pressure inside and outside the way to prevent the flow of media leakage.
2 material. Rubber, asbestos, polytetrafluoroethylene, steel, iron, aluminum, copper and stainless steel, non-metallic and metal gasket, metal gasket Wait.
3 gasket leakage form and cause. There are three forms of gasket leakage: interface leakage, osmotic leakage and destructive leaks, of which the previous two are the main forms. The reason for the interface leakage is: the roughness and deformation of the joint surface; the gasket is not pressed; the joint fastening bolt is elongated or loosened: the plastic deformation of the gasket. The interface leakage of about 80% of the total leakage of a 90%: material aging, cracking, deterioration, etc. will lead to dam leakage, but the installation, improper use is the main reason.
Second, asbestos rubber gasket
Asbestos rubber gasket includes ordinary asbestos rubber gasket, oil asbestos rubber gasket, reinforced asbestos rubber gasket, asbestos steel gasket, mixed asbestos rubber gasket and composite asbestos rubber gasket.
1 Ordinary asbestos rubber gasket. Ordinary asbestos rubber gasket is made of asbestos, rubber, binder and other parts of the rolling between the various parts used in the gasket, such as the engine cylinder pad, pipe flange gasket and so on. Ordinary asbestos rubber gasket sheet forming thickness is generally ≤ 3mm.
2 oil asbestos rubber gasket. Oil-resistant asbestos rubber gasket is made of asbestos, oil-resistant rubber and binder as the main material by rolling the gasket, with Ny300 and Ny400 type two. Ny300 oil-resistant asbestos rubber gasket for small and medium-power engine fuel, lubrication and cooling system of the Gland Packing, and Ny400 oil asbestos rubber gasket can be used for temperature 400 ℃, pressure 4MPa oil, solvent, alkali medium Gland Packing. Oil-resistant asbestos rubber gasket sheet forming thickness of 1,2,3 mm three.
3 reinforced asbestos rubber gasket. Reinforced asbestos rubber gasket is composed of asbestos rubber sheet and one or more galvanized steel wire mesh (or stainless steel wire mesh), divided into oil-enhanced and high-pressure enhanced two. Reinforced asbestos rubber gasket sheet forming thickness is generally not more than 3mm.
4 asbestos steel gasket. Asbestos steel gasket is the two sides of the oil asbestos rubber sheet, the middle sandwiching the red eye as a skeleton, pressed, vulcanized, evenly coated with lubricant on the surface of the gasket.
5 mixed asbestos rubber gasket. Mixed asbestos rubber gasket is made of oil asbestos rubber sheet, ordinary asbestos rubber sheet, reinforced asbestos rubber anti-as well as steel frame asbestos and other composite processing from the gasket.
6 compound gasket. Composite gasket is to give full play to the advantages of polytetrafluoroethylene and non-metallic materials, the use of ordinary asbestos rubber sheet and reinforced asbestos rubber sheet made of gasket, with high temperature, high pressure (11 ~ 45MPa), good elasticity, strength High, small pad coefficient and so on.
Third, the choice of gasket
In general, under normal temperature and low pressure conditions, the choice of non-metallic soft gasket, medium temperature and high temperature selection of metal and non-metallic combination of gaskets or metal gasket: the temperature and pressure fluctuations in the larger conditions should be used in good or flexible Tight Gland Packing layer; in low temperature, corrosive media or vacuum conditions, should be used with special performance of the gasket.
By the above known, parts technical conditions and working conditions, gasket materials and Gland Packinging performance on the rational use of gasket have a certain impact.