Static sealing usually refers to the sealing between two static surfaces, and it mainly uses gaskets. (1) Materials of gaskets (a) Non-metal gaskets: They are gaskets made from materials such as paper, linen, cowhide, asbestos products, plastic, rubber, etc. Paper, linen and cowhide have capillary pores and are easy to penetrate, so they must be impregnated with oil, wax or other impermeable materials when used. Generally, they are rarely used for valves. Asbestos products...
The Static Sealing of the Valve Read
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The sealing of the valve cannot be ignored, because most of the valve's leakages occur due to sealing. The related information of dynamic sealing of valves is discussed in this article. 1. The dynamic sealing of the valve The dynamic sealing of the valve mainly refers to the sealing of the valve stem. Preventing the medium in the valve from leaking due to the movement of the valve stem is the key to solving the problem of the valve's dynamic sealing....
The dynamic sealing of the valve Read
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2.3 Finding and confirming the failure (1) The inspection of the valve body The pipeline was opened and it was found that the valve plate was in the middle state. The valve plate was knocked lightly with a copper rod and nothing happened, indicating that the drive part of the valve plate has jammed and caused the valve body to fail to move (Figure 4). Figure 4 The jamming of the valve plate (2) The inspection of the hydraulic station The globe valve, one-way...
The Analysis and Maintenance of Failure Causes of Hydraulic Check Valves (Part Two) Read
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Abstract The reliability of the hydraulic check valve on the pipeline of the circulating water system directly affects the safe operation of the circulating water pump. The hydraulic pressure of the hydraulic check valve at the outlet of the circulating water pump could not be maintained after inspection, and the oil pump was frequently started and stopped. The check valve could not be opened or closed. After the valve was opened, the motor and oil pump tank were overheated. In view...
The Analysis and Maintenance of Failure Causes of Hydraulic Check Valves (Part One) Read
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An eccentric semi-ball valve is a relatively new type of ball valve, which has some unique advantages related to the structure, including opening and closing without friction, sealing not being worn easily, and small opening and closing torque. This can reduce the size of the actuator and a multi-turn electric actuator can be equipped, which can achieve the purpose of the adjustment and close cutting off of the medium. An eccentric semi-ball valve is widely...
Eccentric Semi-ball Valves and V-shaped Ball Valves Read
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In order to study the performance, rules of size changes at low temperatures, changes of microstructure, and cracking of surfacing layers of the valve body's material AISI 304 and the sealing surface surfacing Ni40 and Ni60 hard alloys at low temperatures, the following tests were carried out: The hardness gradient test from the base metal to the surfacing layer before and after the cryogenic treatment AISI 304 impact and tensile tests at room...
Low-temperature Physical Property Analysis of Key Materials of Valves Read
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Because of the special structure of cryogenic valves, the installation of cryogenic valves also has special requirements. The direction of the valve stem must be within a vertical angle of 45 degrees when the cryogenic valve is installed due to the structural characteristics of its long-neck bonnets, and installation on vertical pipelines should be avoided as much as possible. Otherwise, the low-temperature medium will fill the extended part of the valve bonnet, causing the valve...
The Installation Requirements for Cryogenic Valves Read
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(2) The structure design of the dripping board Since the medium in the valve is a low-temperature medium, in order to avoid or reduce the transmission of the medium's temperature to the valve stem and the filling material at the upper end, and prevent these materials from failing due to freezing, a dripping plate can be added to the valve. Some research institutes have carried out experimental verification on this kind of valve with a drip plate, and proved that the upper...
The Design of Petrochemical Cryogenic Valves (Part Two) Read
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In recent decades, with the development of modern science and technology, there has been an increasing demand for cryogenic valves in engineering projects. Cryogenic valves are widely used in fertilizer, LNG and petrochemical fields and they are suitable for medium with temperatures between -40℃ and -250℃. Cryogenic valves include cryogenic ball valves, cryogenic solenoid valves, cryogenic gate valves, cryogenic globe valves, cryogenic safety valves, cryogenic check...
The Design of Petrochemical Cryogenic Valves (Part One) Read
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3. Analysis of low-pressure sealing test standards for check valves 3.1 Requirements in the Chinese standard system In the current national standard system, the main regulations related to check valves include GB/T 13932-2016 Iron Swing Check Valves and GBT 13927-2008 Pressure Tests for Industrial Valves. GB/T 13932-2016 section 5.2 Pressure Test stipulates that the shell's strength test and sealing performance test of the check valve shall be carried out in accordance with the method...
The Analysis of Low-pressure Sealing of Swing Check Valves (Part Two) Read
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Abstract In industrial practice, the high-pressure sealing of swing check valves is generally guaranteed, but the low-pressure sealing is often overlooked, which may cause serious abnormal working conditions. The principle of low-pressure sealing of swing check valves, the reasons for low-pressure sealing being neglected, and the applicable standards of low-pressure sealing are discussed based on this to improve the reliability of low-pressure sealing of swing check valves. Treatment of the...
The Analysis of Low-pressure Sealing of Swing Check Valves (Part One) Read
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1. The working principle and function of the gate valve Gate valves are cut-off valves used to cut off or connect the medium in the pipe, which are usually installed on pipes with a diameter greater than 100mm. The disc is shaped like a wedge. The gate valve has the advantages of easy opening and closing and low flow resistance. However, the sealing surface is easy to wear and leak; the opening stroke is great, and the maintenance is difficult. The gate valve cannot...
Repair Standards for Gate Valves Read
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