Reconsideration: Maximum operating pressure of the container — at the top or at the bottom?
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On 09-5-8, Haiyou Haiyangfirst issued a proposal regarding the \"Regulations on Safety Inspection of Pressure Vessels\"; for pressure vessels subjected to internal pressure, the maximum operating pressure refers to the highest pressure that may occur at the top of the vessel during normal use. Why does the highest pressure inside the container occur at the top rather than the bottom? After reading their posts and replies, it was found that there are two viewpoints: The first is as explained by Haiyou KFYZQ – regarding safety regulations, the state of the medium contained in the containers covered by these regulations is generally considered to be gaseous, and this point is explicitly specified in the second clause of the regulations. When a gaseous medium is exposed to ambient or operating temperature increases, the internal pressure in the container rises due to volume expansion and the upward movement of the hot gas; as a result, the pressure at the top of the container is slightly higher than that at the bottom, making the top part of the container more dangerous than the bottom. Only when the temperature is stable will the pressure inside the container be re-balanced, that is, it will be equal everywhere within the container. Further addition: 1. The top of the container is usually filled with a gaseous medium, while the bottom is filled with a liquid medium, except for containers such as gas buffer tanks ； 2. The hydrostatic pressure at the bottom of the container, resulting from the height of the liquid column, is generally much lower than the pressure that can occur at the top of the container due to the gaseous medium during operation ； This is because 10 meters of water column corresponds to only 0.1 MPa, and in ordinary pressure vessels (horizontal or vertical) that hold liquid media, the height of the liquid column is rarely 10 meters or more, except in the case of towers. For reference! Haiyou ujjzxc added further comments to the discussion: he believes that the term \"gaseous\" is not accurate; rather, potential gases include those with temperatures higher than their standard boiling points as well as liquefied gases. Second, Haiyou pzq argued that the highest pressure within a container does not occur at the top, but rather at the bottom. The static pressure of the liquid column is taken into account during calculation. It is not taken into account during classification. And Haiyou ljfdd2002, who holds a similar view — regardless of the medium contained within a pressure vessel, the top part is generally occupied by the gas phase. Containers with the same top pressure will have different bottom pressures due to differences in height, the medium they contain, and the liquid level height. For vertical containers, the pressure at the bottom is generally higher than the pressure at the top. I believe that, as analyzed in viewpoint one, the time difference is extremely small; it can be considered an instantaneous operating condition, and tolerance specifications do not apply to such instantaneous conditions ； The second viewpoint is a very common analysis, and it is easier to accept. Looking at the replies, it seems that more people support View 1. I wonder whether the majority has overcome the minority, or whether victory lies with the minority, or perhaps everyone is correct in their analysis – it’s just that flexibility is needed when applying these ideas in practice?
The highest pressure in the container should be at the top; at the bottom, it is only the static pressure of the liquid column that is highest.
Refer to the reading on the pressure gauge at the top of the pressure vessel!
The bottom is subjected not only to the gas phase pressure transmitted from the top but also to the hydrostatic pressure of the liquid column; therefore, the pressure at the bottom is greater than the gas phase pressure at the top
I think the pressure at the top is high, because the specifications mention only the top and not the bottom
This post was last edited by selba on 2010-10-24 at 10:29. Haha, “Why does the highest pressure inside the container occur at the top rather than at the bottom?” ”This is fundamentally a false proposition! ! You’ve been misunderstanding! ! Of course, the highest pressure inside the container is at the bottom! The regulations specify that the value for the \"maximum operating pressure\" is determined based on the \"highest pressure that may occur at the top during normal use.\" Of course, the highest pressure that may occur at the bottom could be higher than that at the top, but this is not taken into account as a basis for monitoring; instead, the top level is used as the reference!
I really don’t know the answer to this question; usually, people talk about the pressure at the top of the container, so I assumed that the maximum operating pressure is at the top.
This post was last edited by yanyi on 2010-10-24 at 14:46. The specification clearly states that the operating pressure refers to the highest pressure that may occur at the top during normal use. Add the word \"maximum\" to work pressure, of course still at the top. But the word \"highest\" has no meaning, because work pressure is already at its maximum. However, the highest pressure in the container is at the bottom due to the hydrostatic pressure of the liquid column. There’s absolutely no conflict here. It entirely depends on whether there is the word “job”.
I’ve learned it, hehe~~~~~
The bottom under pressure should be at the highest level; in addition to the static pressure of the medium, internal pressure acts on it as well.