Various corrosion and measures of valves are as follows: 1. Stress corrosion Stress corrosion is generated for stainless steel in a corrosive medium environment containing oxygen and chloride ions. The proportion of the failure caused by stress corrosion is as high as about 45%. Commonly used protective measures for stress corrosion Reasonable selection of materials: the selection of stress corrosion resistant materials mainly include austenitic chromium-nickel steel with...
Various Corrosion and Measures of Valves Read
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(2) Cracks in the valve body due to external environmental factors The external environment such as low temperature, high temperature and high pressure will cause the valve body to undergo creep, fatigue and impact, which will cause the valve body to break. Some literature mentions that the reason for the breaking of the valve body of the coke oven ascending tube is mainly the long-term compound corrosion of high temperature and other working conditions, resulting in deformation,...
The Failures of the Valve & Its Cause Analysis (Part Two) Read
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Valve failures and cause analysis 1. Leakages Leakages are mainly divided into external leakages and internal leakages. External leakages mainly refer to the fluid flowing to the outside of the system due to sealing failures and other reasons, and while the fluid flowing to the inside of the system is called internal leakage. The main reason for the leakage of the valve is the sealing failure. The valve of a 300MW steam turbine...
The Failures of the Valve & Its Cause Analysis (Part One) Read
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A valve is a control component in the fluid delivery system, which has the functions of cutting off and adjusting the fluid, preventing the reverse fluid, stabilizing the pressure, dispersing the fluid, overflowing and relieving the pressure. There are many types and specifications of valves such as globe valves and ball valves with simple structures, as well as complex valves suitable for automatic control systems. With the increasing manufacturing demand and the improvement...
Solutions to Failures of Valves Read
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Inspection and testing The strength or hydraulic test, sealing test and necessary non-destructive test of the valve are necessary conditions to measure whether the valve is qualified, but they are not sufficient conditions to measure the quality of a valve. At least for high-pressure hydrogenation valves, they can't completely reflect the comprehensive quality of a hydrogenation valve. Take the valve's sealing as an example. Generally, as long as the machining...
Quality Control for Valves Used for High-pressure Hydrogenation Units Read
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The pressure-bearing parts of the valve should be subjected to strength analysis and strength design. These parts mainly include valve bodies, bonnets, wedges and bonnet bolts. For the globe valve, sometimes, it is necessary to carry out the verification of strength on the valve seat part. As a non-pressure-bearing part, the valve stem is also an important part that must be designed for strength. The so-called design for strength should include two parts, that is, strength and...
Strength of Valves in High-pressure Hydrogenation Units Read
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The control of internal leakages and external leakages The internal and external leakages control of the valve is an important parameter that reflects the quality of the valve. The manufacturer has adopted various measures to minimize the internal leakage and external leakage of the valve. The internal and external leakages of oil and hydrogen will not only pollute the environment, but also cause a fire or an explosion. The internal leakage of the valve mainly occurs at the wedge,...
The Leakage Control of Valves Used for High-pressure Hydrogenation Units Read
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A valve is one of the important pressure piping components in petrochemical plant, among which process valves are used in a relatively large amount. They are mainly used for opening, closing, and throttling. A process valve is a relatively complex and high-tech mechanical product assembled from multiple parts in pipeline components. The particularity of the petrochemical industry determines that its special requirements for valves will continue to increase, and at...
The Development Trend of Valves in the Petrochemical Industry Read
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1. Technical requirements 1.1 Requirements on valves for large-scale devices As the equipment becomes large-scale, the size of process pipelines is getting larger and larger. The number of valves is also increasing. Taking a 3.8 million t/a continuous reforming unit as an example, the number and specifications of process valves are shown in Table 1. Table 1 Statistics of 3.8 million t/a continuous reforming process valves Valve types Specifications/DN...
Research on the Application Status of Valves in Petrochemical Devices Read
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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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