First, let's find out a question: Why do nonmetallic compensators have to be divided into M and N?
Many peers engaged in pipeline design get the drawings, and their scalp is numb when they see "rectangular non-metallic compensator M-type" and "N-type". Obviously, it looks like it's all fabric circles and frames, so why do you still have two models? To put it bluntly, this is not made up by manufacturers in order to sell more goods, but two completely different structural logics. M-type emphasizes "multi-wave" flexible compensation, while N-type prefers "single-layer large displacement" design. You used the wrong model before, and the compensation amount was not enough to crack the pipe, and the vibration of the whole flue system exceeded the standard. The internal skeleton, belt layering and flange connection methods of these two goods are different. Today, we will break it up and talk thoroughly.
Type M: Like an accordion, eating large displacements
M-type rectangular non-metallic compensator is also called "multi-wave type" in the industry. Its loop-strap construction is wavy-folded, similar to the bellows of an accordion. Each wave can absorb the displacement independently, so the overall compensation is particularly large. It is generally used in occasions where the flue gas temperature is high (≤1200℃) and the pipeline direction is complicated and multi-directional compensation is required, such as the flue duct of power station boiler and the kiln tail pipe of cement industry. However, M-type also has a shortcoming-dust is easy to accumulate at the folded part of the ring belt. If the dust content of the medium is large, it must be cleaned regularly or a diversion device must be installed. Our station "Rectangular non-metallic expansion joint"and"Non-metallic expansion joint (fabric fiber expansion joint)"In, many customers specify this M-shaped structure.
Type N: Flat design, hard core compression resistance
N-type is also called "single-layer flat plate type". Its loop strap is not folded, but a multi-layered tiled composite structure with high-strength fibers sandwiched in between and a temperature-resistant coating. The advantages of N-type are compact structure, small installation space, and large radial stiffness-to put it bluntly, it can hold the pulling force at the pipe flange interface. What about the disadvantages? Single-wave compensation is not as good as M-type, which is usually only good at absorbing axial displacement, and its angular displacement ability is weak. Therefore, N-type is mostly used in occasions where the space is limited and tight sealing is required, such as the front and rear sections of desulfurization flue gas baffle doors, air-cooled island vacuum pipes, etc. You flip through the "Desulfurization flue gas baffle door”“Double hinge expansion joint for air-cooled island vacuum pipeline"Technical parameters, there are basically N-type compensators.
Key Difference One: Compensation Ability and Direction
M-type axial compensation can usually be more than 200mm, and both angular and transverse directions can be taken into account; N-type generally does not exceed 100mm in axial direction, and its angular ability is worse. Therefore, when you encounter that kind of project with large thermal expansion of pipelines, it's basically right to choose M-type. However, if the pipeline space is narrow and the vibration frequency is high, N-type will be more stable. Two days ago, I met a customer who insisted on using N-type instead of M-type in the flue. As a result, the flanges were pulled and deformed during the test run-this is because the compensation amount was not calculated correctly. So what to do? If the displacement is around 150mm and you want to save space, you can try M-type but reduce the wavenumber? Not recommended, it is easy to tear when the twists and turns are too shallow. Follow the data honestly.
Key difference two: ring belt material and temperature resistance
In fact, the materials are similar, and the core is silicone gel, fluorine glue coating plus glass fiber or ceramic fiber cloth. However, M-type has many twists and turns, and each fold is a stress concentration point. The loop belt needs thicker coating and more wear-resistant fabric, and the cost is about 30% higher. N-type is flatter, and the coating thickness can be thinner, but in order to compensate for the low strength of single layer, multi-layer lamination and wire mesh reinforcement will be added. Note that the national standard JB/T 12235-2015 for non-metallic compensators has clear technical requirements for these two forms. Don't forget to compare them when selecting. For example, the temperature resistance grade, M-type has good heat dissipation at the twists and turns, and the actual allowable temperature is slightly higher than N-type, but manufacturers usually uniform nominal, so you better ask the supplier to provide the temperature resistance curve of each layer of the ring belt.
How to choose to not overturn? Explain in three sentences
Look at the displacement first, and go directly to the M-type for large displacement (> 150mm); The second sentence: the space is limited, and the height is How to adjust the tie rod nut of expansion joint"That Q&A. In addition, if you encounter the situation that the rectangular pipe has many turns and great vibration, you can use it in combination with metal rectangular expansion joints, so don't kill one form.