Valve leakage is very common in life and production. It can cause waste or cause danger to life. For example, leakage of tap water valve can lead to serious consequences, such as toxic, harmful, flammable and explosive in the chemical industry. Corrosive interfering properties, etc., are serious threats to personal safety, property safety and environmental pollution. An electric butterfly valve relies on external force rotary drive to open and close the valve is designed with a sealing device to install a certain amount of packing sealing ring in the packing culvert to achieve the sealing effect, but what about the sealing situation? The leakage of the filler at the valve is one of the most prone to leakage faults in the valve, but there are two reasons for this.
First, the reasons for the filler.
The main fillers are now used: 1. Asbestos, due to the presence of chloride ions in the asbestos material, the valve stem is corroded, and the asbestos contains carcinogens, which endangers human health. The state-to-site products have been banned or used less; Synthetic resin and synthetic fiber, tax planning consultation, some of these products are limited in scope of use, such as pure PTFE, the use temperature must be ≤150 ° C, filled with PTFE ≤ 250 ° C, polytetrafluoroethylene particles The filler compensation performance is poor, and it is only suitable for low-pressure valves, tetrafluorofiber, carbon fiber or both mixed packing, and the price is too high, which is unfavorable; 3. When expanded graphite, severe electrochemical corrosion occurs.
Second, the corrosion problem is also the cause of one aspect.
Corrosion conditions are: 1. Natural oxidative corrosion of the valve stem, the electric butterfly valve is oxidized due to the surface of the valve stem packing, and the ferritic oxide (rust) is detached, causing the valve stem to become thin and cause leakage; Leakage caused by chloride ion corrosion of asbestos fillers; Corrosion of stainless steel by graphite filler; 4. Corrosion of the valve to the valve stem.
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Label: Analysis of the cause of valve leakage
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