Don't panic when the desulfurization flue expansion joint leaks! Self-check + repair according to these 4 steps to save thousands of maintenance costs

Step 1: Find out the leakage point first-is it the expansion joint itself or the flange interface?

The desulfurization flue expansion joint is leaking. Don't hurry to call the manufacturer to change it. Take ten minutes to do a "physical examination" yourself. If you pay for it without looking at anything, you may waste your money in vain.

Find a flashlight, stand on the side of the expansion joint, and see where the water is dripping from. The two most common types:

• Expansion joint body leakage: Water drips directly down the skin of the non-metallic expansion joint (fabric fiber expansion joint) or seeps out of the trough of the metal bellows. Most of the materials are broken or corroded.
• Flange interface leakage: Water seeps out from the gap of the flange gasket and around the bolt hole. In this case, if you screw the flange bolt, it may be loose, and the gasket may be aged or biased.

Dry the suspected leakage with a dry rag, wait for 30 seconds, and then touch it with your hands-the leakage point can be felt directly. Don't just look at the pool of water on the ground, it may have dripped from a height.

Step 2: Find out the root cause of the leak-corrosion, wear, or buried mine during installation?

After finding the leak, you have to ponder: Why did it leak? Everyone knows the flue environment of desulfurization-high temperature, sulfur and particles, which is simply the "torture chamber" of equipment.

• corrosion: The condensed water in the flue gas is acidic, soaking the skin of the non-metal expansion joint for a long time, or corroding the weld of the metal rectangular expansion joint. Especially in the circle of the flange interface, the acid accumulates in the seam, and the gasket is wasted in a few months.
• abrasion: The dust particles in the flue are like sandpaper, washing the inner wall of the expansion joint at high speed. Over time, the fabric layer wore down and water seeped out. This is commonly found in the expansion joint near the outlet of the fan.
• Installation of buried mines: Most commonly-the expansion joint is installed without enough pre-tension, or the tie rod nut is not adjusted in place. The pipe was hot and cold, and the expansion joint was torn; Another is that the baffle door and the expansion joint are improperly matched, and the door is deadlifted when opening and closing. And guess what? I met a customer two days ago, and after changing three expansion joints, it still leaked. Finally, I found that the smoke baffle door next to it was installed offset, and it was done immediately after correction.

If it is an installation problem, no matter how good the expansion joint is, it will be useless. Check the stress of the pipeline system first, and then replace the parts.

Step 3: Prescribe the right medicine-supplement if you can, change if you should, don't mess around

Now that you know the cause, how to treat it? Let me give you a simple criterion:

• Small area leakage (needle eye size): For non-metallic expansion joints, stick them with special repair tape (such as fiber tape with temperature resistance above 150℃), press a stainless steel sheet on the outside, and punch self-tapping screws. It can last months against condensate leakage. If this small hole appears in the rubber compensator, you can use rubber to cold patch the glue and patch the sheet after polishing.
• Extensive damage or tear: Don't make it up, just change it. It won't take long to make up, and it may get bigger and bigger the leak. Remember the last one when you change it-check for installation problems.
• Slight water seepage at flange connection: The easiest-tighten the flange bolts, three times in diagonal order, the torque is not too large, otherwise the gasket collapses. If it still leaks, replace the gasket. It is recommended to use the gasket material of PTFE compensator, which is corrosion-resistant and non-aging.

When many people see a leak, their first reaction is "playing glass glue" and "paste cement". Don't do this! As soon as the smoke passes, as soon as the temperature rises, all those things crack, and you are working for nothing. Change when you need to, and don't feel bad about that little money.

Step 4: How to choose when replacing? — Non-metal, rubber, fabric…You should keep an eye on these points

If you are sure you want a new one, don't buy the cheapest one with your eyes closed. The root cause of water leakage in desulfurization flue expansion joint mostly lies in wrong selection. You choose according to the following points, and you will be guaranteed to use it for more than three years:

• Look at the temperature: The desulfurization flue temperature is generally 80℃ ~150℃, but occasionally there is instantaneous high temperature. chooseNon-metallic expansion joints (fabric fiber expansion joints)When, pay attention to asking the manufacturer's skin temperature resistance grade, at least nominal above 200℃. Don't use a regular rubber compensator, that thing doesn't withstand high temperatures and will be mushy in a few months. Of course, if it is the normal temperature area of the bypass flue, the rubber compensator lined with PTFE can also be used.
• See corrosion: The flue gas contains sulfur, and the material selection must be anti-corrosion. The skin of the non-metallic expansion joint should be lined with PTFE, and the flange sealing surface should be lined with a fluoroplastic layer similar to a PTFE hose. Metal bellows? If you have to use it, you have to choose 316L or higher grade alloy, otherwise it will be perforated in half a year.
• Look at the amount of compensation: The desulfurization tower inlet and outlet position displacement is large, non-metal expansion energy saving multi-direction compensation, is the first choice. If it is a straight pipe, you can selectUniversal corrugated expansion jointBut pay attention to adding a guide tube to protect the bellows. Don't choose the one without a guide tube, where the particles go in and wear the skin.
• Look at the matching set: There is often a side of the expansion jointDesulfurization flue gas baffle doorOrFlue gas baffle door。 If the baffle door interferes with the expansion joint when opening and closing, the expansion joint will be broken. When selecting, let the manufacturer match the interface form of the expansion joint with the size of the matching flange of the baffle door to avoid later on-site repair.

This site hasRectangular non-metallic expansion joint、Non-metallic expansion joint (fabric fiber expansion joint)、rubber compensator、PTFE compensatorWait, send to customer service working condition parameters before placing an order, and help you match the most suitable model.

Bonus: The secret of not leaking after installation-baffle door cooperation, regular inspection these small actions can save lives

Put on a new expansion joint, and you thought everything would be fine? No, no, no, I don't know how to maintain it, and I have to leak it again half a year later.

• Adjust stroke with baffle door: When installing the expansion joint, letSingle-axis double-flapper doorOrDouble-sealed single-axis circular baffle doorIn the closed state, then adjust the tie rod nut of the expansion joint so that the expansion joint is in the free state (not stretched or compressed). When the baffle door is fully open, check whether the expansion joint has been hard-pulled. Many people ignore this step. As a result, as soon as the baffle door is opened, the expansion joint is directly pulled and deformed.
• Regular inspection to see two places: First, see if there is any bulge or white color on the surface of the skin, which is a sign of aging. Make up as soon as possible. Second, see if the flange bolts are loose, especially after the boot heats up, thermal expansion and contraction will make the bolts loose, so tighten them in time after parking.
• Don't let water soak the expansion joints: If there is poor drainage at the bottom of the desulfurization flue, acidic condensate will soak the lower part of the expansion joint for a long time. You can open a small drainage hole at the bottom of the flue, or raise the installation position of the expansion joint by 5 cm to avoid direct soaking in water.

Alas, say a thousand words, 70% of the leakage of the expansion joint of the desulfurization flue is the pot selected and installed, and only 30% is normal aging. Follow these four steps, you can solve it yourself, and if you can't solve it, go to this site to find the corresponding products, which saves worry and money. Is that the truth?