Non-metal compensator, can it be used in the second construction examination and engineering?
Find out what "second construction" refers to first. The second-level construction engineer examination is divided into professional directions, and mechanical and electrical, municipal and highway will all involve pipeline engineering. Non-metallic compensators (also called non-metallic expansion joints) are very common in industrial pipes, heat pipes and flue gas pipes. Many candidates think that metal bellows is the key point, ignoring products such as fabric fiber expansion joints. Two days ago, a friend who took the electromechanical test asked me, "Did the book mention non-metallic compensators? I had no impression at all when I was reviewing." In fact, flipping through GB50235 of the Construction Code of Industrial Pipeline Engineering, the compensator chapter clearly contains the non-metallic type, but some tutorial books have mentioned it in a stroke.
Will it be taken or not in the exam? Real Questions Speak
Will the non-metallic compensator be examined in the second construction examination? Say it directly: test. Multiple-choice questions and case questions may appear, especially scenarios involving thermal pipeline displacement compensation, desulfurization system and dust removal pipeline. For example, in 2021, a provincial real question asked "Which compensator is more suitable for flue gas pipelines", and the answer was non-metallic expansion joints. Why? Because the non-metallic material is resistant to high temperature and corrosion, it can absorb multi-directional displacement and is cheap. The products of this station are specialized in "non-metallic expansion joint (fabric fiber expansion joint)" and "rectangular non-metallic expansion joint", which are designed for flue gas pipelines of power plants and cement plants. Although the exam syllabus does not list this term separately, the scope of application has long been covered. Think about it, the flue gas pipe is high in temperature and corrosive, and the metal bellows can hold it? Not at all.
Do you dare to use it in actual engineering? Don't be biased by "weak"
Let's talk about actual engineering. The second construction licensee usually serves as the project manager or technical leader, and needs to select the compensator in the construction organization design. Some peers feel that the non-metallic compensator is "weak" and dare not use it. Actually, it is not the case-non-metallic compensators (such as rubber compensators and PTFE compensators) perform well in low-pressure, large-diameter pipelines with a temperature of no more than 600℃, especially the pipelines behind the desulfurization flue gas baffle doors. Metals for corrosive gases are easy to break. The "rubber PTFE compensator" in our station is specially designed to deal with acid-base media. When selecting the model, you should calculate the compensation amount and pressure level, and don't exceed the limit. It is recommended to confirm the model parameters according to the national standard JB/T 12235-2015. No, two days ago, a cement factory project used a "rectangular non-metallic expansion joint", and there has been no problem for three years. So don't listen to anyone's nonsense, non-metallic compensators are much more durable than metals in specific scenarios.
The two easiest pits for beginners to step on. Have you fallen for it?
However, the second construction candidates or engineers who have just entered the industry are prone to stepping on two pits: First, the non-metallic compensator is regarded as a universal piece, and it dares to be used in high temperature and high pressure situations; Second, there is not enough space for the guide tube during installation, or the tie rod nut is screwed to death, resulting in failure. The function of the expansion joint guide tube is discussed in our question and answer-to prevent the medium from washing the fiber layer. Although the non-metallic expansion joint does not have a tie rod (different from the metal bellows), the bolt torque of the frame and pressure plate is particular. Be sure to read the instructions before installation, don't mess around with experience. If you are preparing for the second construction exam, it is recommended to save the question and answer of "National Standard for Non-metallic Expansion Joints" on this site, and turn it over before the exam. If the case questions get the installation details, you can get points. Tsk, don't get blind in the examination room then.
After all, the second construction of non-metallic compensators is like a carpenter who can only use a hammer
In the final analysis, non-metallic compensators can not only be used in the context of second construction, but should also be used. From the examination point of view, it is a must-know point for industrial pipeline installation; From the engineering point of view, it is a mature scheme to solve the displacement compensation of high temperature flue gas and corrosive media. The second construction of non-metallic compensators is like a carpenter who can only use a hammer-he can do his job, but he may not do his job well. Think about it, if a desulfurization flue project is hard on the metal expansion joint, it will rust through in half a year, and it is weird that the owner does not complain. On the other hand, choosing the right non-metallic expansion joint (such as our "rectangular non-metallic expansion joint") can save worry and effort for three to five years. Therefore, don't worry about "whether you can use it", learn when you need to learn, and use when you need to use it. After thoroughly understanding JB/T 12235-2015, and then remembering the parameters of "rubber PTFE compensator", the examination and project will be stable.