Why do you need a non-metallic compensator for straight pipe sections?
Many people think that the pipeline, what can be the problem of going straight? Thermal expansion and contraction, equipment vibration, and large-diameter pipes can make your system deflate. Metal compensator is not impossible, but in the face of high temperature, corrosive medium and multi-directional displacement, its rigidity becomes a burden. Two days ago, I encountered a cement plant project. The diameter of the pipe was almost two meters. The cost of using a metal compensator was ridiculously high, and it was often stuck-as soon as the flange surface was deformed, the whole segment was wasted. Instead of a non-metallic compensator, the fabric fiber layer eats all the multi-directional displacement, and it is corrosion-resistant and does not produce thrust, so it is much worry-free.
It does not transmit blind force. The metal bellows expansion joint will generate huge thrust under high pressure, which requires additional fixing brackets, while the fabric fiber expansion joint itself is highly flexible and hardly produces reaction force. So, if your pipe diameter exceeds DN600, the medium temperature exceeds 300°C, or there are vibration sources such as fans and pumps in the system, don't hesitate to go directly to the straight pipe section of the non-metallic compensator.
What does the structure of straight pipe section non-metallic compensator look like?
To put it bluntly, the main body is a multi-layer fabric fiber layer-that is, the "non-metallic expansion joint (fabric fiber expansion joint)" on which we stand. The outer metal frame is used as support, and the inner guide tube is added to protect the corrugation from being washed by the medium. The role of the guide tube is described in detail in the FAQ: it guides high-speed airflow or particulate matter to the center, avoiding direct impact on the fabric layer, and can significantly prolong the life.
For example, rubber compensator and rubber PTFE compensator are essentially different products of the same family, and the difference lies in the temperature and corrosion resistance grade. Rubber is used on water pipes at room temperature, and tetrafluorine can carry acid and alkali and within 200°C. In addition, there are rectangular non-metallic expansion joints, which are specially used in non-circular pipes such as air ducts and flues. When selecting, you have to see the working conditions clearly. Don't use rubber in desulfurization flue gas, which is to dig a hole for yourself.
Don't just focus on caliber in model selection
Many people buy compensators, and when they come up, they ask: What caliber? — — Of course, the caliber is important, but the pressure, temperature and displacement can't be less. Non-metallic compensators mainly absorb axial displacement in straight pipe sections, but they can also eat some lateral and angular directions, but the compensation amount is limited. How to calculate? According to the parameter tables of "Rectangular Non-metallic Expansion Joint" and "Universal Corrugated Expansion Joint" on our website, calculate the thermal expansion amount first and then determine the model. For example, if the pipe length is 50 meters, the temperature change is 200°C, and the thermal expansion coefficient of steel is 0.012mm/m·°C, the total axial displacement is 120mm. The single wave compensation amount of non-metallic compensator is generally between ±20mm and ±50mm, which can be selected according to the wave number.
And there's the pressure. The bearing capacity of non-metallic compensator mainly depends on the metal frame and internal skeleton layer, which is conventionally 0.1~0.5MPa. When exceeding 0.5MPa, it is recommended to use metal bellows or external pressure single axial expansion joint. If the diameter exceeds DN600, the cost performance of metal compensator plummets, but non-metal is a more cost-effective choice-if you don't believe me, look at the price of large-diameter thick-walled expansion joint, and then compare it with fabric fiber expansion joint to make a judgment.
The installation thing
The straight pipe section is equipped with non-metallic compensators, and there are many pits. First of all, the pipes at both ends must be parallel, and the flange surfaces must be aligned. If the deviation exceeds 2mm, wait for air leakage. Secondly, the problem of the tie rod screw: the transport screw is temporarily fixed and must be removed after installation; The lead screw is used to adjust the amount of pre-tension of the compensator and must be retained. How to tune it? Look at the FAQ "How to Adjust the Expansion Joint Tie Rod Nut" article for detailed steps.
The direction of the guide tube must be toward the direction of the medium flow, and the arrow is marked. Don't install it backwards. I've seen people try to save trouble by using the compensator as a pipe support and sitting directly on the bracket-that thing doesn't bear weight, and the fabric layer cracks after being pressed for a long time. Also, don't let the welding slag splash on the fabric during installation, and the high-temperature melted cave will be directly scrapped.
What should I do if something goes wrong with it
The most common failure is the aging and cracking of the fabric layer, especially in the acid-alkali environment of flue gas desulfurization. Refer to our "Desulfurization Flue Gas Baffle Door" package scheme and choose corrosion-resistant fluororubber or PTFE layer. The other is that the guide tube falls off, mostly because the spot welding is not firm during installation, or inferior welding electrodes are used. If you find air leakage or abnormal noise, stop the machine for inspection quickly. Don't hold it hard. If minor problems are not repaired, the whole compensator will be directly replaced by major rectification, and the cost will double.
Pipe support settlement. If the stent settling at both ends of the straight pipe section is inconsistent, it can apply additional shear forces to the compensator, accelerating fabric tearing. It is recommended to check the foundation settlement regularly, especially in heavy-load areas such as cement plants and power plants.
The straight pipe section of non-metallic compensator is not a permanent part, and its life is generally 3~5 years, which may be shorter in bad working conditions. Only when spare parts are changed frequently can the system run for a long time. Don't wait until it's down for maintenance to remember it-you'll lose more than one compensator at that time.