First, find out which four kinds "four kinds" refer to?
"What are the four kinds of metal expansion joints?" In fact, strictly speaking, according to the structural form and compensation function, there are four mainstream categories:Axial, transverse, angular and pressure balanced。 But this is not random-each type corresponds to a specific pipe displacement scenario. Such asUniversal corrugated expansion jointMainly absorbs axial displacement,The transverse expansion joint of the compound hinge is specialized in treating the transverse displacement,Curved tube pressure balance type expansion energy saving balance internal pressure thrust,Sleeve-type pipe expansion joint is good at absorbing large axial displacement and resisting high pressure. To put it bluntly, if you choose the wrong type, the pipeline will go wrong sooner or later.
2. Disassembly one by one: the core characteristics of these four types of products
1. Universal corrugated expansion joint-the "old scalper" of linear pipeline
The structure is the simplest, and it absorbs axial displacement by elastic deformation of bellows. Straight line pipes suitable for power stations and cement industries. Inside our stationUniversal corrugated expansion jointAndHigh temperature axial type expansion joints all belong to this category. Note: It is only axial, don't expect it to handle lateral or angular displacements.
2. Compound hinge transverse expansion joint-specialized in treating "non-straight line" pipelines
The lateral displacement compensation is realized by two sets of bellows and hinge structures, and the key is that no blind plate force is generated. Inside our stationThe lateral expansion joint of double hinge is a typical representative. A steam pipe that turns 90 degrees? Large lateral displacement? It would be right to go.
3. Curved tube pressure balance expansion joint-the "pressure reducing valve" of pump and valve equipment
There is a pressure balancing element inside, which can eliminate the thrust of the medium pressure on the fixed bracket. Pump, valve, compressor inlet and outlet sensitive equipment, must use this. Inside our stationCurved tube pressure balance type expansion joint specializes in this. If the ordinary axial type is used, the thrust of the bracket is too large, and the equipment interface will crack sooner or later.
4. Sleeve-type pipe expansion joint-the "tough guy" of high temperature and high pressure
The displacement is absorbed by the relative sliding of the inner and outer sleeves, and the pressure resistance is extremely strong, but the sealing requirements are high. Inside our stationSleeve type pipe expansion joints are suitable for high temperature and high pressure steam pipes, such as main steam pipes. The disadvantage is that it cannot absorb lateral displacement and can only slide axially.
3. Pits that are easy to step on when selecting models: don't confuse types
Two days ago, I met a customer, and the expansion joint should be selected for the steam pipeline, which should be universal-as a result, the pipeline on site turned 90 degrees, and the lateral displacement was very large. Universal type can't solve it at all, and it is necessary to upper double hinge transverse type or angular type. Do you think this pit is injustice or not?
① Displacement direction of pipeline(axial, transverse, or angular);② Operating pressure and temperature(Decide whether to choose bellows or sleeve type);③ Whether it is necessary to balance the pressure(Pressure balanced type is preferred when pump and valve equipment is available).
In addition, don't forget to look at the media-choose corrosive mediaPTFE-lined hoses orPolytetrafluoroethylene compensator, do not use common metal expansion joints. Otherwise, the bellows will be corroded through in a few months.
4. Practical application scenarios: from power stations to cement plants, each shows its magical abilities
Power station industry
The main steam pipeline has high temperature and high pressure, which is usually usedSleeve type pipe expansion joint orExternal pressure single type axial type expansion joint. Inside our stationThe corrugated expansion joint used in the power station industry is specially designed for this kind of working condition. In addition, the air-cooled island vacuum pipe has to be usedAir-cooled island vacuum pipe double hinge expansion joint, this thing can absorb multi-dimensional displacement.
Cement industry
The axial displacement and vibration of the high-temperature flue gas pipeline and the inlet and outlet of the fan are large,Universal corrugated expansion joints andHigh temperature axial type expansion joints are used the most. Inside our stationMetal corrugated expansion joints in cement industry have served many production lines, and some have not been changed for 8 years.
Desulfurization system
The flue gas contains sulfur and is corrosive, and it needs to be isolated. At this time, it is often matchedFlue gas baffle doors andDouble-sealed single-axis circular baffle door, expansion joint is selectedNon-metallic expansion joints orPTFE-lined hose. Don't use metal, it won't withstand corrosion.
5. Installation and maintenance: Details determine life
Many customers bought expansion joints, but they failed early because of improper installation. For example, the direction of the arrow of the expansion joint refers to the flow direction of the medium. If the bellows is installed backwards, it will be squeezed. There is also the adjustment of the tie rod nut-the tie rod and nut for transportation should be loosened to the designated position after installation, otherwise the expansion joint will not be able to displace normally. For specific adjustment methods, please refer to the "How to adjust the tie rod nut of expansion joint"and"Correct installation method of expansion joint of large tie rod》。
In addition,expansion joint guide tubeNor can it be ignored-it protects the bellows from being washed by high-speed media, especially must be retained under high-flow conditions. And guess what? Some customers disassembled the deflector in order to save money, and as a result, the bellows wore out in half a year.
In short, if you choose the right type, install it correctly, and check it regularly, the metal expansion joint will last for 10 years without any problem. If you are really unsure, go directly to the product information in our station:Universal corrugated expansion joint、Compound hinge transverse expansion joint、Curved tube pressure balance expansion joint、Sleeve type pipe expansion jointEach model has detailed parameters. Don't pat your head and choose, look at the working conditions more.