Comparison of gas pipeline cutting devices
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I am currently working on the design of gas pipelines, and the shutdown devices available include water seals combined with butterfly valves, blind flanges combined with butterfly valves, and plug valves combined with butterfly valves. I would appreciate it if experts could analyze the advantages and disadvantages of each method – which one is better? Please consider factors such as cost-effectiveness, safety, ease of operation, and maintenance. Thank you!
It’s hard to say! It depends on the owner’s* habits. However, in the north, water seals are rarely used (due to issues with freezing and heat retention in winter)! Some people consider valves to be unreliable, so they opt for a butterfly valve + blind flange or a butterfly valve + water seal!
For the safety and convenience of maintenance, it is better to use blind flanges together with butterfly valves; although it is not the most economical option, this method is necessary for certain enclosed equipment, and the higher cost is worth it.
Reply to 3# ray1513: But my master said that butterfly valves do not provide good sealing performance for gas pipelines, and suggested that I use gate valves instead. Is that statement correct? Also, the connection point of my current gas main is too close to the burner; installing a blind flange does not comply with the regulations. GB6222 states that blind plates shall not be used within 10 meters of the combustion device. So I used a gate valve + quick shut-off valve + water seal. When this water seal is operating normally, it is filled entirely with gas, functioning like a gas tank. It can only serve as a barrier during equipment maintenance. Is this okay?
For just one valve, a gate valve should be used, as butterfly valves don’t seal properly. What I’m referring to is a blind flange combined with a butterfly valve; it’s a combined valve； In the situation you mentioned, your approach indeed should be adopted; unless there are special circumstances, it is necessary to comply with national standards.