For the layout of pipes in utility tunnels
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When arranging pipes in utility tunnels, according to SH3012 4.2.1 c>, pipes whose medium operating temperature is equal to or higher than 250°C should be placed in the upper layer. Why? Explanation of Article 7.2.5 of GB 50160: The operating temperature of the medium for most bottom pump systems is equal to or higher than 250°C. When these bottom pumps are installed beneath pipe trays (bridges), in order to minimize the liquid level in the tower and ensure that the required net positive suction head is met, this article stipulates that the pipes can be arranged on the outer side of the lower layer of the pipe tray. I don’t understand how the explanation in the text relates the placement of pipes in the lower layer of the pipe tray to meeting the net positive suction head requirement of the pumps. If it is in the pipe gallery on the pump outlet pipeline, there is no impact between the upper and lower layers ； Conversely, if the pump’s inlet pipe is located in a ductwork system on an upper level, the head pressure is higher, so the effective net positive suction head should be greater, right?
Pipes with a medium operating temperature of 250°C or higher should be arranged in the upper layer. Why? My understanding is that it facilitates the installation of expansion bends without blocking other pipes
This post was last edited by ylb913 on 2016-10-14 at 20:30. The pump inlet is an exception, but placing it on the outside is intended to reduce the likelihood of the problems I mentioned later. Assume that the high-temperature pipelines are arranged in the lower layer; in this case, if there is a leak in the low-temperature combustible pipelines in the upper layer, the fluid flowing into the high-temperature medium pipelines in the lower layer will increase the risk of fire.
Moving the pump inlet pipe to the upper layer does not increase the head; it only increases the frictional loss along the pipeline.