Why are bends often added to steam pipes?

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Why are bends often added to steam pipes? We often see such scenarios in steam pipelines: sections that could clearly go in a straight line suddenly bend. I believe many people who have seen this are puzzled just like me – isn’t this unnecessary? Actually, it’s not; there are reasons behind the design of these bends in pipelines. Below, I’ll explain the function of these bends in steam pipelines. Steam pipes operate in two different temperature conditions: one with a high temperature and another close to the ambient temperature. As the temperature changes back and forth, thermal expansion and contraction cause displacement and stress on the pipes. The longer the pipes, the greater the displacement and stress. To prevent damage to the pipes, measures need to be taken to address this issue, which is where these bends come in; they are also known as \"expansion joints\" and serve to absorb the axial expansion of the pipes. They also help to meet the requirements related to avoiding collisions with concrete beams and columns, serving two purposes at once. Our country has relevant regulations regarding expansion joints, such as Article 4.8.17 of the \"Design Code for Heating, Ventilation and Air Conditioning\"; the thermal expansion of heating pipes must be taken into account. When the natural compensation of the pipe segment is insufficient, a compensator should be installed. Other standards, such as those for power chemical engineering design, also have such requirements; some even stipulate the use of software for calculations. For example, power plant design institutes generally use GLIF, while chemical engineering design institutes typically use Caesar and similar tools. The amount of compensation must be calculated before installation; the installation process requires cold drawing, especially at the main steam outlet. Brackets are also very important – sliding and fixed brackets need to be carefully inspected. Natural compensation should be utilized as much as possible within the plant. So, just how long is the pipe’s expansion? According to the calculations based on testing, for a length of 1 meter and a temperature increase of 100 degrees, the expansion is approximately 1.2 mm. In some industrial pipelines, such as those in power plants, the temperature can rise to over 500-600 degrees. At this point, 1 meter will expand by 7-8 mm. Metal is a material that can be pulled but not compressed. Imagine that at room temperature, the temperature difference along railway tracks can be as much as 50 degrees; in the early days, the tracks would bulge out, and it was only by using segmented tracks that this problem was solved. Pipelines can be several hundred meters or even dozens of kilometers long, and changes in temperature, whether cold or hot, generate extremely high stresses. When these stresses exceed the pipeline’s limit, the pipeline cannot withstand them, which can lead to serious consequences. When natural compensation is insufficient to meet the requirements of the pipeline, we usually use compensators for compensation. These compensators can absorb axial, lateral, and angular thermal deformations of the pipeline, as well as reduce the impact of equipment vibration on the pipeline. The function of the U-shaped section on the steam pipeline is similar to this as well.