Why do the pipes on the pipe rack have to bend out and then bend back again?

It is generally used in long, large-diameter pipelines, with the aim of mitigating thermal expansion and contraction of the pipelines. It’s a bit similar to the expansion joint of a heat exchanger. It's just my personal opinion; feel free to share your thoughts or criticize~

Reply to 2# scdxhjy: It seems reasonable :)

Since the installers are high-paid daily workers, they can install only one pipe per day – they have to bend each pipe several times before connecting it back – which results in a higher salary and less physical strain

Outdoor metal pipes are subjected to significant temperature fluctuations due to the nature of the fluids they transport and the climate conditions. The direct consequence of these temperature changes is thermal expansion and contraction; the large internal stresses resulting from this can cause straight metal pipes to crack or bend. Therefore, these pipes are designed with bends in a \"cross\" shape, taking advantage of the plasticity of the metal to counteract the deformations caused by thermal expansion and contraction without damaging the pipe. Thermal expansion and contraction of pipes can cause damage to them; a preventive measure is to install expansion joints in the piping system. The professional name for a telescopic device is a compensator. There are many types of compensators; the \"S\"-shaped pipe you mentioned is a type of basic square compensator. Next, we will introduce pipe compensators. When steam pipes transport steam at a certain pressure and temperature, the rise in temperature of the pipes can cause deformation or damage to them due to thermal expansion or temperature stress. It is therefore necessary to install compensators on the pipes to account for this thermal expansion, thereby reducing the stress on the pipe walls as well as the forces acting on valve components or support structures. Thus, the biggest challenge in installing steam pipes is dealing with compensation issues. A device used in piping systems to compensate for thermal expansion and contraction of pipes is called a compensator. Commonly used types include square compensators, sleeve compensators, spherical compensators, corrugated compensators, etc.; compensators are also known as expansion joints. It turns out that when installing fixed supports and compensators for thermal pipelines, natural compensation using the bends in the pipelines should be considered first. When natural compensation is insufficient, square compensators are generally used in thermal pipelines. Square compensators are generally made by bending pipes, or by assembling stamped elbows. The advantages of square compensators are: simple manufacturing, reliable operation, and no need for special maintenance. Its disadvantages are: large floor space and high water flow resistance. Due to the irreplaceable advantages of square compensators, despite the emergence of many new types of compensators, they are still used in thermal piping systems. With the advancement of technology, new types of compensators with small sizes and high efficiency have emerged, such as sleeve compensators, spherical compensators, and corrugated compensators.

The large internal stresses generated by thermal expansion and contraction can cause straight metal pipes to crack or bend, so they are made into a \"J\"-shaped curve, taking advantage of the plasticity of the metal to counteract the deformations caused by thermal expansion and contraction without damaging the pipe. It’s called a square pipe compensator; quite detailed indeed{:1_90:}

Some trainees also asked this question during a recent training session; the answer given at that time wasn’t as professional. I’ve learned about it since then

Agree with the view from the fifth floor; it was explained in great detail.

Reply to 5# ouhsahs: What was said on the fifth floor makes sense. Please stop saying things that show a lack of knowledge from now on.

It is mainly about considering the issue of thermal expansion and contraction, acting like expansion joints or compensators.

What was said on the 5th floor is absolutely correct – it’s for stress compensation!