Why does it take 80,000 turns to close the valve?
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According to the report, after the valve lost power, it had to be manually closed by turning it 80,000 times to achieve closure. What kind of valve is this and why is it so difficult to open? Also, can the valves on similar oil pipelines not be set to close automatically in the event of a power loss? Are safety valves not installed on oil pipelines to prevent overpressure? Is the pipeline too thick to install a safety valve, or is it impossible to drain the pipeline once a valve is installed?
OP: What report? 80,000 laps? Must be a misunderstanding; even for gate valves, there’s no need for that many turns. The gate valves used in the tanks at the Dalian oil depot do take a long time to close manually
It’s the place you mentioned; the report says that it takes 80,000 turns to close a valve
Oil transport pipelines are generally of large diameter; the one in Dalian is also 24”, which means a stroke length of at least 600 mm. To enable humans to operate such large valves, worm gear technology must be used, as it reduces the effort required but slows down the operation. Since these valves use pneumatic actuators, they are very expensive; electric actuators are more commonly used in them, and there is no such thing as a faulty location.
Bro, seriously? It’s going to take that long? It seems like you’ll need to bring a few people along with boxed meals to go and handle those valves! What valve? The pitch of the turbine teeth is so small; it’s extremely difficult to close it!
Here is what the media reported: “At 18:12 on July 16, an explosion in an oil pipeline in the free-trade zone warehouse at Xingang Wharf in ** City, Liaoning Province, caused a fire to break out in tank No. 103; the leakage of crude oil led to the spread of the fire.” Near Tank 3, there are also multiple tanks distributed densely. Sang Wu and three other firefighters turned the valves 320,000 times by hand before they could be closed. ”
Oh my God! It’s so tiring!
I think there definitely aren’t that many turns; there must be a gear ratio that reduces the number of turns through several stages of transmission
This post was last edited by WQC on 2010-11-20 at 20:46. For a 24\" gate valve that is electric, according to American standards it should be able to close completely within two minutes when in electric operation. Assuming there are three threads per inch on the valve stem (which is already the maximum thread pitch; otherwise self-locking isn’t possible), it means the valve stem nut needs to rotate three times to close one inch, so for 24 inches that’s 72 rotations. In manual operation, if a reduction gear mechanism is used, the number of rotations required of the handwheel can be determined by multiplying one rotation of the handwheel by the gear ratio; this value is then multiplied by the number of threads per inch to find out how many rotations the handwheel needs to make in order to move the valve stem one inch. Taking the example of a 24\" gate valve with three threads per inch on the valve stem, 24*3 = transmission ratio * number of turns of the handwheel. If the handwheel turns 80,000 times, what is the transmission ratio? 1 to 1000! Oh my God! In China, covering press conferences can be deadly.
Reply to 7# Shi Yonggang: Don’t you know that most media outlets these days are just misleading people? :lol