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Compared with other mechanical manufacturing processes, the valve manufacturing process has the following characteristics: A. The manufacture and inspection technology of valve rough is very complicated. The valve's casting blank is a thin-walled shell with complicated structure. Casting requires a smooth surface, casting characters clear, especially to have a dense structure, and do not allow the...
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To understand the difference between globe valve and stop check valve, we should first figure out what is a stop check valve. Stop check valve combines the functions of a general globe valve and check valve, which means besides isolating and regulating the flow rate, it can also prevent reverse flow. From the appearance, globe valve and stop check valve almost look the same. The main difference li...
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Valve actuator is a device for operating and connecting valve. The device can be driven by power source of electric power, air pressure, hydraulic pressure or other combination, and its motion process can be controlled by the stroke, torque or axial thrust. Because the actuator working characteristics and utilization rate depend on the valve type, the working specifications, and the position of th...
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These three materials of stainless steel 304, 304H and 304L are often used in valve industry. Among three, 304 is the most common one, like SS304 ball valve, SS304 gate valve, SS304 globe valve, SS304 check valve we often see. In fact, according to the content of chromium and nickel, they all belong to stainless steel 304, since they all contains 18% chromium (Cr) and 8% nickel (Ni). The ma...
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The properties of steel depend not only on the chemical composition but also on the metallographic structure. Through the process of heating, holding and cooling to get different metallographic structure and desired property is heat treatment. Common heat treatments include normalizing, quenching, tempering, and annealing. Normalizing treatment: The steel is heated to 30 ° C ~ 50 ° C above the AC3...
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(6) Effect of surface hydrophilicity on sealing property The hydrophilicity of the surface affects the amount of leakage due to the characteristics of the capillary. When there is a thin film of oil on the sealing surface, it is necessary to increase the pressure of the water passing through the gap. Due to the good hydrophilicity of the metal surface, kerosene can easily penetrate the gap between...
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3. The influence of pressure difference before and after valve on sealing performance Theoretically, the pre- and post-valve pressure difference and leakage are proportional. However, the test proved that, under the same conditions, the increase in leakage is more than the increase in pressure difference. 4. The influence of sealing surface material and its treatment state on sealing performance T...
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The factors affecting the sealing performance of the c are as below: A. sealing surface quality; b. sealing surface width; c. pressure difference; d. sealing surface material and its processing state; e. medium properties; f. surface hydrophilicity; g. the existence of sealing oil film ; h. the solid and structural characteristics of the closure. 1) Influence of sealing surface quality on valve se...
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(1) Soft sealing material A. Nitrile rubber (NBR). Nitrile rubber has excellent oil resistance; heat resistance is superior to natural rubber and styrene-butadiene rubber; air tightness and water resistance are better. Nitrile rubber can be divided into butyronitrile-18, butyronitrile-26 and butyronitrile-40. Nitrile rubber is suitable for petroleum products with a temperature of -60 ° C ~ +120 ° ...
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Sealing is to prevent leakage, so the principle of valve sealing is also studied from leak prevention. There are two main factors that cause leakage. One is the most important factor affecting the sealing performance, that is, there is a gap between the sealing pairs, and the other is the pressure difference between the two sides of the sealing pair. The principle of valve sealing is also analyzed...
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