Metal axial expansion joints first understand-it sucks axial displacement, not a panacea
Many people regard the metal axial expansion joint as a "panacea" that can cure any pipeline problem, which is wrong. It does only one thing: absorbs the expansion and contraction along the axis when the pipe expands and contracts thermally. You go and see the one in our stationExternal pressure single axial expansion jointAndHigh temperature axial expansion jointThe principle is the same-the deformation of the bellows absorbs the displacement, and the guide tube protects the bellows from being washed by the medium. Structurally RatioUniversal corrugated expansion jointOne more guide tube, specifically for high-speed fluids or particulate media.
Then it followsStraight pipe pressure balanced expansion jointWhat does it matter? The latter has an extra balanced bellows, which is used to offset the blind plate force, and is suitable for high-pressure and large-diameter working conditions. While the metal axial expansion joint has simpler structure and lower cost, which is suitable for most straight pipe sections. Remember: It only absorbs axial displacement, don't count on it for lateral or angular displacement, otherwise the bellows will be forced laterally, and the life will be directly halved.
Power stations, cement, petrochemicals-where is the pipeline most inseparable from it?
Two days ago, I met a power plant customer. As soon as the temperature of the steam pipe rose, the bracket was deformed by hard pulling. reloadingHigh temperature axial expansion jointAfter that, the problem is solved directly. Another example is cement industry, rotary kiln hot air duct, flue, high temperature, large dust, in our stationMetal Corrugated Expansion Joints in Cement IndustryIt is designed for this kind of working condition. AndDesulfurization flue gas baffle doorMatching axial compensation, flue gas temperature fluctuates greatly, displacement is not small.
Medium temperature, working pressure, maximum displacement. If you count one wrong of these three, the bellows will retire early. For example, if the temperature exceeds 400℃, you have to useHigh temperature axial expansion jointOrdinary 304 won't work, so you have to use 321 or 316L. If the pressure is high, the wall thickness of the bellows should be thickened.Large diameter thick wall expansion jointIt's specialized in high pressure.
Don't just look at the model when you choose the model-stiffness, tie rod and guide tube can't be missed
Many people come up and ask, "Do you have a DN200?" Thinking that the caliber is right. Wrong.Axial stiffnessDetermines the thrust. If you install it on a large pipe rack, the stiffness is too great and the pipe rack will be crooked. How to calculate stiffness? From our stationStiffness and Calculation Formula of BellowsThat article is very thorough.
Againguide tubeDon't underestimate it. Its core function is to reduce the medium scouring and flow resistance, and protect the bellows root from being cut by high-speed fluid. Specifically talked about in the FAQSpecific Function of Expansion Joint Guide TubeWhen installing, the direction of the arrow is the flow direction of the medium, and when the guide tube is installed backwards, it will become an obstacle, and the flow resistance will greatly increase.
Andtie rodAndnutHow to adjust? Does the screw of the expansion joint need to be removed? These are required courses before installation. The limit nut on the tie rod when leaving the factory is temporarily fixed to prevent the bellows from deforming during transportation. After installation, it must be loosened or removed, otherwise the expansion joint cannot move, which is equivalent to installing a rigid short joint. It is recommended to go to our station aboutHow to adjust the tie rod nut of expansion jointAndDo you need to remove the screw of the expansion jointTwo responses from.
How much energy saving does axial expansion save compared to other compensators?
Someone asked "Is there any difference between metal and corrugated expansion joints？” The answer is basically the same thing, but metal axial expansion joints specifically refer to those that absorb linear displacement. If you have a large lateral displacement, you have to lookCompound hinge transverse expansion joint； If you are stressed and afraid of blind force,Straight pipe pressure balanced expansion jointMore appropriate. Don't use axial direction instead of transverse direction to save trouble, otherwise the bellows will be forced laterally, and the life will be directly folded in half.
By the way,Non-metallic expansion joints (fabric fiber expansion joints)Although it is cheap, it is different in pressure and temperature resistance, and the high-temperature and high-pressure scenes have to be metal. However, non-metals have their advantages: corrosion resistance, large compensation, light installation, and are good in low-temperature and low-pressure environments such as flue gas desulfurization. Which one to choose depends on the four parameters of medium, temperature, pressure and displacement direction.
Those pits in installation and maintenance-don't let a good product be ruined in details
Will the nut on the tie rod be removed when the expansion joint leaves the factory? Many on-site workers screwed it to death directly, and as a result, the expansion joint couldn't move, which was equivalent to installing a rigid short joint. The correct method is: after installation, remove the limit screw, or adjust it to the working position to ensure the free expansion and contraction of the bellows. Our station specializes inCorrect installation method of expansion joint of large tie rodQuestions and answers, go and check them out.
In addition, the direction of the arrow on the expansion joint refers to the flow direction of the medium, which becomes an obstacle if the guide tube is installed backwards, which not only increases the flow resistance greatly, but also may cause vortex vibration. In addition, a reminder: steam pipeline belongs to pressure pipeline, and the fatigue life of axial expansion joint is usually designed according to 1000 cycles. However, if it starts and stops frequently in actual use, such as once a day, it is recommended to choose high fatigue grade products. From our stationLarge diameter thick wall expansion jointAndDirect buried (fully buried) type expansion jointIt is optimized for this kind of working condition, and the bellows has more layers, large wall thickness and longer life.
Don't use expansion joints as load-bearing parts. It only absorbs displacement, regardless of support. The self-weight of the pipe must be supported by a bracket, otherwise the bellows will deform under force and crack in two years. When installing, be sure to check the position of the bracket to ensure that the expansion joint is in a free expansion and contraction state.