1. Let's talk about where the compensator is most wasted in the steel plant first
Hot blast furnace, sintering flue, dust removal pipe, desulfurization system-these locations are high temperature, dust, and the medium is corrosive. We commonly use rectangular non-metallic expansion joints and non-metallic expansion joints (fabric fiber expansion joints) in these places. But to be honest, many factories have to change a batch in two or three years, tearing, burning and leaking. And guess what? Most of the failures are not because the product itself is not working, but because the right choice is not selected from the beginning.
For example, at the outlet of the hot blast stove, the flue gas temperature soars above 400℃ at every turn, and the ordinary silicone rubber fiberglass cloth skin can't bear it at all. The desulfurization system is more ruthless, the condensed acid drips directly, and the ordinary rubber compensator perforates in three months. The airflow in the dust removal pipe carries iron powder and polishes the skin like sandpaper. Alas, I have seen these scenes no less than dozens of times, and every time I take them apart, "cause of death" is written on my face.
2. Who is the culprit of the failure?
Say it in a few scenes.
First, the temperature exceeds the standard.
The skin material of non-metallic compensator usually has a limited temperature resistance range. For example, the long-term temperature resistance of silicone rubber glass fiber cloth is about 300℃. If there is a sudden "flash explosion" or local overtemperature in the smoke, the fabric will be directly carbonized and broken. Last week, there was a case in an ironmaking plant. The temperature of the hot blast stove rushed to 650℃ instantly when the furnace was changed, and a big hole burned out of the skin on the spot. Do you say you can blame the poor quality of the compensator for this? It is simply that the working conditions are not clear.
Second, the corrosive medium.
There is condensed acid in the desulfurization flue gas. If the anticorrosive coating is not used or the ordinary rubber compensator is selected, it will perforate in less than three months. The most exaggerated one I've ever seen, leaking into a sieve in half a month. PTFE compensator or rubber PTFE compensator is the right solution, but many purchase charts are cheap, so I bought the general type in confusion.
Third, the deflector design is sloppy.
The function of the guide tube is specifically mentioned in the FAQ of this site-to guide the airflow away from the skin and avoid direct erosion. Many failures are precisely because the guide tube is not long enough or not installed, and the airflow directly hits the skin and wears out. Once, a customer said that their non-metallic expansion joint leaked after half a year. When it was disassembled, it was found that the guide tube had been burned by high temperature, and the airflow forcibly tore the skin.
Fourth, the tie rod was not adjusted properly during installation.
How to adjust the expansion joint tie rod nut? If the tie rod is locked or the amount of pre-compression is incorrect, the compensator has no room to absorb the displacement at all, and the deadlift cracks. This is a typical installation accident. You can flip through the question and answer of "How to adjust the tie rod nut of the expansion joint" on our station. The tightening sequence and compression amount are particular, and it is not just screwed on.
3. Then how to choose a type to avoid stepping on pits?
Don't ask "which is cheaper" as soon as you come up. Find out the working condition parameters first. Temperature over 400℃? It is necessary to use multi-layer fabric fiber expansion joints plus heat insulation layer. Medium contains acid? Add PTFE compensator or rubber PTFE compensator as liner. The pipe has a rectangular section? Then choose the rectangular non-metallic expansion joint correspondingly, don't change it with the circular shape, the seal and compensation amount will not match. The pressure area also depends on the strength of the skeleton, otherwise the bulge will deform. This is not a matter of patting the head. Each parameter is a little worse, and the lifespan is a few years worse.
List the parameters of flue gas temperature, pressure, medium composition, pipe displacement and pipe diameter (rectangular or circular) at the site, and then select them according to the selection table in our product information. For example, the temperature resistance grade of "non-metallic expansion joint (fabric fiber expansion joint)" ranges from 200℃ to 600℃, but heat insulation layer must be added above 300℃. This detailed manual is clearly written, but unfortunately no one reads it.
4. "Invisible killer" in installation and routine maintenance
Many factories leave it alone after installing it, but the non-metallic compensator really needs to be looked at regularly. For example, whether the tie rod nut is loose, whether the skin is bulging or discolored, and whether the guide tube falls off. Two days ago, I met a customer who said that their non-metallic expansion joint had leaked after half a year. As a result, when I disassembled it, I found that the guide tube had been burned by the high temperature, and the airflow was directly on the skin. Also, don't try to save trouble when installing, the steel frame must be welded flat, and the bolts should be tightened diagonally-these details will be tears if you say too much.
In addition, don't ignore the sudden working condition of "flash explosion". If the system process is unstable, local overtemperature can scrap a compensator in a few minutes. It is recommended to install temperature measurement patches on the skin surface, which can provide timely warning once the temperature exceeds the standard.
5. When must I change it? How to change without delaying production?
Cracks or perforations visible to the naked eye appear in the skin, local bulging exceeds 30% of the original thickness, and obvious air leakage at the seal. Don't wait until it's down for repairs to remember stocking up. When replacing, pay attention to release the pipeline displacement first, then dismantle the old parts, install new parts according to the original factory parameters, and re-adjust the pull rod to the designed pre-compression amount. If your factory uses rubber compensator, you have to pay attention to the aging time. Generally, it is recommended to prepare a set of emergencies in 3-5 years.
In the final analysis, the non-metallic compensator is a "consumable part" in the steel plant, but if you choose it correctly, install it correctly, and watch it diligently, it is not a blow to double your life. For example, we have a customer who extends the guide tube to cover the whole skin area according to the above method, and adds an anti-corrosion coating outside the skin, which just extends the replacement cycle from two years to five years. The saved downtime and procurement costs are enough to buy several sets of good goods.
So, stop complaining about "the compensator is always broken". Ask yourself first: Are the working condition parameters really filled in correctly? Is the deflector installed? Has the pull rod been adjusted? If you don't do it, then no matter how expensive it is, it will be useless.