Reasons for internal leakage in valves
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This post was last edited by xlxuiin on 2010-3-3 at 13:38. The inlet and outlet valves of the pump in our equipment tend to leak internally, which makes it difficult to carry out maintenance on the pump; sometimes it’s even hard to install blind flanges. Medium: Liquefied gas. Valve: Gate valve. Temperature: 70~80. Pressure: 2.0 MPa (at the outlet). The medium is relatively clean, free of impurities. The newly installed valves all passed the pressure testing, but internal leakage occurred after just a few months of use. Other types of valves have also been used – those with soft and hard seals, ball valves, etc. Please let those with experience discuss and analyze the specific reasons! ! ! ! ! ! ! ! ! !
Mainly, the erosion at the pump inlet and outlet is too severe, causing internal leakage in the valve. It would be better to use valves with tungsten carbide seat coatings; that might work better.
It is mainly caused by erosion damaging the seal
Based on the data you provided, the temperature and pressure are quite normal; it’s not that difficult. Personally, I think the problem lies in the quality of the valves. Also, apart from globe valves, the gate valves and ball valves you mentioned should be used in either fully open or fully closed positions; otherwise, it can cause significant damage to the sealing surfaces. Additionally, it seems that check valves are also installed on other pump inlets and outlets to prevent the medium from flowing back; however, these valves are usually located behind the gate valves. Wouldn’t it be better if the check valves were placed in front of the shut-off valves?
It’s probably a problem with the quality of the valve; adding a check valve might help
For pipelines using liquefied gas as the medium, there are specialized valves designed for liquefied gas. Moreover, depending on the operating temperature, the models and materials of these valves also vary
Mainly, the erosion at the pump inlet and outlet is too severe, causing internal leakage in the valve. It’s best to add a check valve
It might be that the valve is closed too tightly or the seal is worn out
Personally, I believe the valve selection is incorrect; it is recommended to consult the valve supplier and provide parameters such as the medium, pressure, and temperature. The supplier can then give you some recommendations, after which you can consider those options further. I’ve seen butterfly valves used in pipes installed by gas companies, but I don’t know what material they are made of. Considering the application range of butterfly valves, they are also suitable for liquefied gas. For reference only.
In addition to erosion damaging the seal, improper operation (excessive force when switching) can also cause damage to the seal. Furthermore, gate valves are generally not used for regulating flow; their principle of use is to be either fully closed or fully open.
Have you tried using a gate valve to temporarily adjust the flow rate? That could cause the gate to loosen, leading to internal leakage