Discussion on internal leakage issues in valves
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This post was last edited by security on 2011-7-10 at 13:54. Many of the valves used in our company’s power systems suffer from internal leakage, which causes a lot of trouble in terms of pipeline maintenance and equipment cleaning. System pressure: 0.35-0.55MPa ； Media: circulating water, low-temperature water (7–15 degrees Celsius), saline water (-15 degrees Celsius). Valve types: butterfly valves are commonly used in circulating water and low-temperature water systems, while gate valves are more frequently used in saline water systems. The power system is one that has been in operation for many years; it is not a newly launched project. Is the issue related to the selection of valves, or are there other reasons?
What is the quality of the circulating water? If the management is inadequate, substances such as plastic films can adhere to the valve discs, making it very easy for the valves to not close properly and leading to internal leakage. Butterfly valves inherently have poor sealing performance
Has this situation arisen recently, or has it been the case all along? If this has been the case all along, then it is a reason for the selection decision; if it has only started to occur recently, there are generally two possibilities: 1, the valve has reached the end of its useful life – most valves do have a limited service life – 2, the medium in question is impure
Based on its years of operation, it’s likely not a selection issue; rather, it’s some other problem. The medium is causing corrosion of the valve or some other type of damage, which results in internal leakage, and the valve needs to be repaired.
Reply to 1# capricorn_wl: The valve selection in most units is the same as yours. Regular maintenance of the valves is very important; when operating them, do so slowly and stop once they reach the proper position, without forcing them beyond that point. Quality, service life, and the replacement of seals are also important. Consider the pump’s inlet filter as well.
If your circulating water system is an open system, impurities such as dust and sand will inevitably be present in it. The opening and closing of valves can cause wear on their sealing surfaces, especially in the case of butterfly valves, which in turn leads to internal leakage of the valves； It is recommended to replace it with a hard-sealed butterfly valve! For reference!
Butterfly valves are used in applications with large diameters, low pressure, and modest sealing requirements; ball valves are used when higher standards are required, but they are much more expensive. Very large diameters also present limitations
Reply to 6# clguan: We will consider hard-sealed butterfly valves during the next inspection. Thank you!
This post was last edited by capricorn_wl on 2011-7-11 at 17:56. Others also mentioned the routine maintenance of valves； What I understand is to implement proper external waterproofing and anti-corrosion measures, as well as to ensure proper lubrication of the internal moving parts and friction elements of the valve. Does anyone have any systematic information on the maintenance of various types of valves? I’ve started learning it!
Reply to 1# capricorn_wl: A regular butterfly valve should be used; the sealing performance of regular butterfly valves is quite poor. Especially those with large diameters leak internally, and small manufacturing companies simply cannot guarantee the quality
In fact, valve manufacturing technology is also constantly improving these days. The circulating water systems in our facility use butterfly valves, and they have performed well. The problem you mentioned might be caused by the valves remaining in a semi-open state for long periods of time, or it could be due to poor water quality, with impurities getting stuck in the seals during opening and closing and thus damaging those seals