Why can’t a large-diameter butterfly valve be opened? What should I do?
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This post was last edited by zhaoqingsheng on 2018-11-19 at 15:20. The large-diameter butterfly valves with a diameter of 400–800 millimeters used in our company’s heat exchange stations simply cannot be opened when the working pressure in front of the valve exceeds 0.25 megapascals. If forced to be turned on, it often damages the turbine and worm gear. Therefore, whenever it is necessary to open such a valve, it is necessary to find a way to reduce the working pressure in front of the valve to below 0.25 MPa first. However, this also affects normal production. In recent years, we replaced some butterfly valves with a diameter of 400–500 millimeters with gate valves, which solved the problem. However, for some butterfly valves with a diameter of 800 millimeters, it is indeed inconvenient to replace them, given that gate valves of the same diameter are too large in size. I would like to ask: are there any good solutions to the above difficulties?
I don’t think it’s a quality issue with the valve. I checked online: some people say that using a triple-eccentric butterfly valve can solve this problem. I wonder if that’s true?
Yes, many heating systems these days use triple-eccentric butterfly valves. Mine works fine; gate valves aren’t the preferred choice either. Were the butterfly valves you’re using purchased a long time ago? What driver is being used?
May I ask: When a triple-eccentric butterfly valve is used, can it truly solve the problem of the valve not being able to open under high pressure differences before and after the valve? Additionally, to answer your question again ； We use a manually driven worm gear turbine ； There are also ball valves of this type; in fact, the structure of these ball valves is basically the same as that of butterfly valves.
In that case, tell me the parameters such as pressure before and after the valve, temperature, diameter, etc., and I will analyze them together
Some of the butterfly valves currently in use in our company are for steam pipelines, with a steam pressure of 0.7 to 1 MPa and a temperature of 300 degrees℃； Caliber: 400–500. In addition, there are also some butterfly valves used in the circulating water of the primary heating network, with a pressure of 1.5 MPa and a temperature of 90–120 degrees℃ ； For valves with a diameter of 500–800, there is a problem of difficulty in opening when the pressure in front of the valve exceeds 0.25 MPa. Therefore, we can only open it by first reducing the pressure before the valve.
May I ask: does the eccentric butterfly valve you mentioned refer to a double-eccentric butterfly valve? Still a three-eccentric butterfly valve?
One more question: why are triple-eccentric butterfly valves easy to open? I don’t understand this principle. Thank you!