Pipelines transportation
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I have a question for all of you experts. For pipeline transportation (of steam), U-shaped buffer bends are installed at regular intervals. I want to know whether a valve is necessary in this system – should it be placed 3 meters before or after the buffer bend, or can it be installed on the buffer bend itself? I personally think it should be located either before or after the buffer bend, but the client insists that it should be installed on the U-shaped bend. I’m not sure which approach is correct!
Placing it on a buffer bend yields better results.
I wonder what industry the original poster works in? What is the purpose of using buffer bends on steam pipes? In petrochemical plants, I have only seen π-shaped bends added to increase the flexibility of pipelines.
It is an expansion joint, commonly known as a “expansion element”; there is a drain on the top side of the expansion joint and a backflow preventer on the bottom side
It depends on where the fixed support is located; the valve should be placed as close as possible to the fixed pipe rack in order to reduce stress.
Maybe I didn’t express myself clearly. The situation is as follows: it’s necessary to create a tee connection on the pipeline, so that gas can be supplied from either side. The supply from the left side is intended to prevent insufficient gas supply; it’s not used under normal circumstances, so a valve is needed to control it! Party A intends to create a U-shaped bend at the junction of the two pipelines, with the valve located on the vertical pipe of the U-shape. I’m asking whether this is reasonable, or if there are any better suggestions!
It is best not to install valve fittings at the π-shaped bends, as those areas have high stress concentrations and are prone to problems
I understand that the owner suggests making a U-turn at the branch tee; a valve should be installed on the left arm of this U-turn (the vertical pipe) in order to shut off the alternate supply line, while the right arm (the vertical pipe) can be used normally. It is important to install a set of steam traps before the tee, as this is at the end of the upstream steam pipe. Closing the valve on the vertical pipe can help prevent water hammer
I still can’t understand what the original poster means. I suggest you draw a diagram and upload it, so that everyone can analyze it for you; guessing what you mean would be a waste of time.
Personally, I believe valves should not be installed at U-turns. Firstly, stress is concentrated in such areas; when the valve is opened, the temperatures before and after the valve differ, which can lead to shear forces. If the condensate cannot be drained quickly enough, steam may force its way past the valve gasket, resulting in accidents. Such an accident has happened in our factory. But this is only one of the reasons for the accident; the main issue is that the pipe warming time was insufficient, resulting in too much condensate water
It’s probably used for drainage; if the U-bend is higher than the main pipeline, then it needs to be added at both the front and back (this is the most common setup)； If it is below the supervisor’s level, it should be added at the U-turn ； If it is at the same level as the main pipe, it may not be necessary to include it; it should be placed at the lowest point of this pipe system.