The issue of pipes changing direction in utility tunnels
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When the direction of a pipe in a duct needs to be changed, for example when a pipe running from north to south is to be redirected eastward or westward, why is it generally necessary to first move it downward before changing its direction to eastward or westward?
It depends on how your pipe rack is designed; in some cases, it can be arranged horizontally. But try to ensure that the pipe level rises and falls gradually.
When pipes in a conduit bend, the elevation is usually lowered or raised to ensure that the flow direction of the medium in the conduit is either consistently upward or consistently downward； Under normal circumstances, horizontal turning is not used.
Step by step, lower and lower, haha! !
In addition to considering the issues related to BBK, does it mean that when turning, it has to avoid colliding with other pipes, so it can only bend downward before turning? There can’t be any other reason, right? Relevant standards certainly do not mention the need to reduce the elevation when turning.
As long as there are no bag-shaped pipes, that should be fine. Of course, the need for stepped arrangements arises from the requirements of piping layout; if there is only one pipe in the conduit, then such stepped arrangements aren’t necessary. But since it’s a conduit, it’s rare to find a situation with just one pipe inside. Hehe
Many pipes are arranged in the same direction along the pipe tray; pipes installed on the same horizontal level must certainly be in the same direction, otherwise they will intersect and interfere with each other
I am currently in charge of the duct design for this project. None of the regulations state that a change in direction necessarily requires a change in elevation; it’s possible to make a horizontal turn. But remember, there isn’t just one pipe in the duct – usually there are several layers, with hundreds of pipes. To prevent interference between them and to make better use of the limited space within the duct, a change in direction does require a corresponding change in elevation. Try to avoid the formation of pockets; taking the overall situation of the entire plant into account, design strictly in accordance with the requirements of PI&D.
Thank you to everyone above. I basically understand. The main reason for step-up or step-down is to prevent bag-shaped piping. Of course, if there is a pipe collision, the height also needs to be changed; there’s nothing special to say about that. I don’t have the ability to give ratings today; thank you all here. I can only give 1 point per person, sorry!
When a pipe changes direction as it moves forward, its elevation usually changes as well. The goal is not to ensure that the pipe’s elevation rises or falls with each step, as straight bends do not cause fluid accumulation. It has two main purposes: 1. To prevent pipe collisions ； 2. Prevent the outer pipes of the horizontal elbow from collapsing at the 90° bend due to inadequate support; by using angled elbows, it is possible to arrange the pipes so that one side is longer than the other at the two crossbeams, thereby ensuring proper support.
There have been those who have achieved it. The elevation is changed to prevent the pipes from altering their position within the pipe rack after changing direction, as this makes it difficult to make a direct horizontal turn.