Let's talk about what the hell this thing is
Non-metallic air duct fabric compensator, to put it bluntly, is what we often call non-metallic expansion joint (fabric fiber expansion joint). The biggest difference between it and metal expansion joints (such as metal rectangular expansion joints and high-temperature axial expansion joints) is that it does not use metal bellows, but uses multi-layer fabric fiber composite structure. This layer structure usually includes silicone cloth, fluorine cloth, glass fiber cloth, ceramic fiber, etc., with thermal insulation cotton sandwiched in between. And guess what? This structure allows it to naturally withstand high temperatures, corrosion, and the ability to compensate for displacement is much greater than metal.
The core advantage is three words: resistance, large and economical
Resistance— — High temperature resistance (up to over 1000℃), corrosion resistance (not afraid of acid and alkali smoke), fatigue resistance (flexible structure is not easy to break).Large— — Large compensation displacement, axial, transverse and angular absorption, especially suitable for large-diameter air duct.Province— — Light weight, low requirements for pipeline support, and easy installation. Two days ago, I met a customer. The metal expansion joint originally used in their power plant leaked in half a year, and the non-metallic one actually lasted for more than three years. Is that the truth?
Where is it mainly used? Power stations, cement, steel…almost inseparable
The power station industry is the largest user (refer to the corrugated expansion joint and desulfurization flue gas baffle door used in the power station industry of this station), such as the boiler outlet, flue and desulfurization tower inlet and outlet. The temperature is high, the medium is corrosive, and the non-metallic compensator is almost standard. The kiln head, kiln tail and preheater pipeline of cement industry (metal corrugated expansion joint in cement industry) are also widely used because of the large dust and temperature fluctuation. There are also steel, chemical industry, waste incineration, and even air-cooled islands (air-cooled island vacuum pipe double hinge expansion joint).
You need to be careful about choosing the model
Temperature is the primary parameter-silica gel cloth is used below 200℃, fluorine tape is used at 200-400℃, and ceramic fiber composite layer is used above 400℃. The pressure generally does not exceed 0.05MPa, but the air duct pressure is usually only a few kilopascals, which is enough. There is another key point: the deflector. The specific function of the expansion joint guide tube is to prevent airflow from washing the fabric layer and reduce wear. When selecting the model, it is necessary to confirm whether the guide tube is included. In addition, the adjustment of the tie rod (refer to how to adjust the tie rod nut of the expansion joint in the FAQ) is also very important. When leaving the factory, the pre-stretching amount should be set according to the calculation, and the site should not be disturbed.
So is it easy to break?
To tell the truth, the most common failure of non-metallic compensators is the aging and cracking of the fabric layer, especially in high temperature and strong corrosive environments. But fortunately, it doesn't burst suddenly like a metal expansion joint, but leaks slowly, with a premonition. Maintenance is also simple-after a leak is found, just repair or replace the fabric layer locally, instead of removing it entirely. Refer to the rubber compensator and rubber PTFE compensator in this site. They are both flexible compensators, but the non-metallic fabric compensator is more resistant to high temperatures. The life is generally 3-5 years, depending on the working conditions.
Don't put it in complete opposition to a metal expansion joint
In many scenarios, such as steam pipelines and high-pressure oil pipelines, metal (general corrugated expansion joint, external pressure single axial expansion joint) has to be used. However, non-metallic air duct fabric compensator is the best choice in low pressure and large displacement situations such as air duct, flue duct and dust duct. Choose the right one and save worry and money; If you choose the wrong one, you will fix it every three days. How to choose? Look at the temperature, the pressure, the medium, and of course, the specific parameter table we provide.