Let's be clear: what the hell is a non-metallic four-corner compensator?
It wasn't made out of thin air. To put it bluntly, it is what we often sayRectangular non-metallic expansion jointA form of application of. Unlike a circular non-metallic compensator, the four corners of a rectangle are the most stressed, and the thermal displacement is the most difficult to deal with-think about it, the four corners of a rectangular pipe are like the armpits of clothes, which are easy to tear apart with just two pulls. Therefore, a four-corner compensation structure is specially developed to deal with it, and flexible materials are concentrated in the corners to absorb these "awkward" displacements. You think of it as a'joint'of a rectangular pipe that specializes in absorbing thermal expansion, contraction and vibration up, down, left and right. And this stuff isMetal rectangular expansion jointDifferent, it relies on the flexibility of fabric fibers, not the elasticity of metal bellows.
How do you build the materials?
The core layer is fabric fibers-the one in our stationNon-metallic expansion joint (fabric fiber expansion joint)The subject of. The outside is pressed with rubber or polytetrafluoroethylene for sealing, and in some working conditions, insulation cotton is stuffed inside. To put it bluntly, it depends on the deformation ability of flexible materials, not the head-to-head elasticity of metal bellows. Therefore, it is resistant to high temperature and corrosion, and is especially suitable for the environment where the flue gas contains sulfur and dust is large. And guess what? It can even withstand acid-base smoke, as the fluoroplastic layer eats hardly any chemical corrosion. But don't think it is universal-if the temperature exceeds 500℃ and the pressure exceeds 0.1MPa, you have to weigh it.
Where is this stuff used most?
Preheater pipelines in the cement industry, desulfurization flue gas systems in power stations, and dust removal ducts in steel plants. A few days ago, a cement factory customer told me that the rectangular air duct at the tail of their kiln was replaced with the metal expansion joint twice a year.Non-metallic four-corner compensatorIt lasted three years. Of course, the specific life depends on the temperature and pressure of the medium. Generally, it is the most reliable to not exceed 500℃ and the pressure is about 0.1MPa. Why? Because the temperature is higher, the fabric fibers begin to carbonize; No matter the pressure, the rubber seal will be blown bulging. But to be honest, most flue conditions are in this range, so it has become standard. By the way, this thing is often equipped behind the desulfurization flue gas baffle door, which can absorb heat displacement and prevent corrosion.
Don't pat your head when you select a model
Non-metallic quadrilateral compensatorIt is not a standard part. It must be customized according to the pipe section size, displacement (axial, transverse and angular directions must be calculated clearly), and media characteristics (acidic or alkaline? Is there any dust?). Just find a similar one and install it, ranging from air leakage to tearing and breaking the pipe bracket. There was a steel mill before to save trouble and take the general-purpose modelrubber compensatorInstead, it turned out to tear in two months because the corner stress simply couldn't handle it. Under referenceNational Standard for Non-Metallic Expansion Joints JB/T 12235-2015That document has hard rules on fatigue life and airtightness testing. Don't bother, calculate the displacement accurately, measure the flange right, and find someone to customize it-this is how to save money.
Don't screw the wrong screw when installing
The tie rod nut is used for pre-tightening, not fixing dead. The transport screw must be removed or the compensator won't move at all. The four corners of the rectangular flange should be specially reinforced, because the non-metallic ring belt is most afraid of the stress concentration at the corner. How exactly to adjust? Look at the one in our stationQuestions and answers on how to adjust the tie rod nut of expansion jointThe diagram is clear. Remember one principle: leave the compensator free when installing it, and don't pull it hard. If you find that the tie rod nut can't be twisted, first check whether the transport screw has not been disassembled? I have seen this problem no less than ten times. As soon as the installation team came up, they twisted hard, and as a result, the ring belt cracked.
Finally pour some cold water
Non-metallic four-corner compensatorIt's not a panacea. If the pipeline pressure exceeds 0.2MPa, or the temperature fluctuates particularly frequently (the kind of going back and forth more than a dozen times a day), be honest and practicalMetal rectangular expansion jointOr a composite type with a guide tube. Don't just figure cheap, the loss of equipment shutdown is enough for you to buy dozens of compensators. Also, if the medium contains a lot of hard particles (such as slag powder) and the non-metallic band wears off quickly, it is better to spend more money at this timeHigh temperature axial expansion joint。 Alas, at the end of the day, choosing a compensator is the same as choosing a tool-there is no best, only the most suitable.