A check valve is a valve used to prevent backflow of media in pipes and equipment. The steam extraction check valve is set on each extraction pipe of the external heater of the extraction steam regenerative system in the steam turbine unit. Its function is to automatically close the valve plate when the unit rejects the load to prevent the steam in the steam side of the heater and the steam inlet pipe from returning to the steam turbine, avoiding the steam turbine to overspeed and accidents. ...
The Overhaul of Check Valves in Power Plants Read
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1. Stainless steel 304 Stainless steel 304 is the cheapest and most widely used austenitic stainless steel for equipment used for food, chemical, atomic energy and other industry. It is suitable for general organic and inorganic media, for example, nitric acid with concentration less than 30%, temperature less than and equal to 100°C or concentration higher than and equal to 30%, temperature less than 50°C, carbonic acid, ammonia and alcohols with various concentrations and...
Stainless Steel in Water Solutions Containing Chlorine Read
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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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