Don't panic if the flue expansion joint is damaged, I will teach you how to deal with it on the spot
Two days ago, I met a customer, and I called in the middle of the night to say that the flue expansion joint was cracked, the smoke went out, and the scene was a pot of porridge. In fact, 90% of the anxiety comes from being unbottomed. Today, let's disassemble it step by step, so that the next time you encounter the damage of the flue expansion joint, you can calmly take out your mobile phone and follow the steps.
Step 1: Don't be in a hurry-take a picture of your phone to determine the type and severity of the damage
That's right, take pictures first. It is not for you to send a circle of friends, but to leave on-the-spot evidence to facilitate follow-up comparison and finding faults. After taking the picture, he looked closer at the damaged area:
Is it a crack? Small piercings? Or a massive tear? Are the edges crunchy and discolored?
If it's stainless steel bellows (like oursUniversal corrugated expansion joint), mostly fatigue cracks or corrosion perforations. If it isNon-metallic expansion joints (fabric fiber expansion joints)The common ones are delamination, ablation, or scratching by hard objects.
Shine the back with a flashlight again-is it only the single layer broken? Is the deflector still there? This step determines whether you want to apply some glue to fool the past, or honestly replace it with a new one.
Step 2: Temporary plugging or direct replacement? Select the scheme according to the flue working condition (temperature, pressure, medium)
"Can you weld it?" Brother, it depends on the working conditions. The flue gas temperature exceeds 300℃, the pressure is above 0.3MPa, and the medium contains sulfur and acid. If you weld a patch on it, it will collapse again in two days, and the construction period will be delayed.
Then what circumstances can temporarily plug the leak? Low temperature (rubber compensatorThe material preparation belt can last for a month or two.
However, if it is a high-temperature section, the inlet of desulfurization tower, or with corrosive gas, don't hesitate to replace it directly. Note when selecting the model: use for high temperatureHigh temperature axial expansion jointDesulfurization environmental useDesulfurization flue gas baffle doorcomplementaryNon-metallic expansion jointFor high voltage systemsStraight pipe pressure balanced expansion joint。 Remember:Treatment of Flue Expansion Joint DamageThe most important thing is to prescribe the right medicine, don't use general parts to carry high temperature and strong corrosion.
Step 3: Replace practical operation-from removing old parts to installing new expansion joints, step by step to help you avoid pits
The first step is to stop the machine and relieve the pressure, and reduce the temperature to below 50℃. Don't bother, it's not worth the burn.
Step 2, dismantle the old parts. Loosen the flange bolts on both sides first, and be careful not to disassemble them all at once-leave two diagonally to prevent the components from falling suddenly. Then remove the old expansion joint and clean the old gasket and rust residue on the flange surface. It is best to smooth it with a wire brush.
Step 3, install the new one. First put on the sealing gasket (either fluororubber or graphite wound pad will do), align the flange hole, and put the new expansion joint on it. Note:Arrow direction of expansion jointIt must be pointed in the direction of the flow of the medium, which many masters ignore, and as a result, additional stress is generated by installing it backwards.
Step 4, put on the bolt. Diagonally tighten sequentially, and the torque is applied in three times to avoid flange deflection. If it is a model with a tie rod (such asLarge tie rod expansion joint），How to adjust the tie rod nut of expansion joint？ First, relax the pull rod to the installation length, and then adjust the nut after the flange is fixed, so that the pull rod is in a free state without excessive preloading or relaxation.
Step 4: Don't go in a hurry after installation-pressure test, pull rod adjustment, seal check, three inspections can't be less
It's over after changing? Don't make this mistake. First, test the pressure. Conduct pressure test with 0.2MPa compressed air or water pressure, hold pressure for 10 minutes, and observe whether the pressure gauge is dropped. Second, adjust the pull rod. Expansion joints with tie rods (e.g.Compound hinge transverse expansion joint) The tie rod nut needs to be adjusted according to the hot and cold displacement of the pipeline, otherwise the bellows will be damaged as soon as the system heats up. For specific operation, you can turn over the question and answer of "The Function of Expansion Joint Tie Rod" in our station. Third, check the seal. Spray a smoker or soapy water on the flange connection and bellows trough to see if there are bubbles. If there are air bubbles, re-tighten the bolts or change the spacers.
After completing these three steps, you can basically start it with confidence.
Step 5: How to do daily inspection? Keep these points in mind, and you can save half the time for the next damage
Surely you don't want to climb the flue every two months, do you? Therefore, daily inspection should focus on several points:
A look at the surface: are there rust spots, bulging, discoloration? EspeciallyMetal rectangular expansion jointof fillet welds andNon-metallic expansion jointFiber layer seams. Second, listen to the sound: Is there a "hissing" air leak sound during operation? Sometimes small cracks are invisible to the naked eye, but can be heard by the ear. 3. Measure the displacement: Use a caliper or marker to measure the actual expansion and contraction of the expansion joint. Compared with the design value, if the deviation exceeds 20%, you have to be vigilant. Four temperature records: The infrared temperature measuring gun sweeps the temperature of the shell. If the local temperature rises abnormally, it means that the internal guide tube may fall off.
In addition, check the torque of the flange bolts once a quarter to prevent vibration from loosening. Take photos and file the records of each inspection-that is, the photo you took in the first step. When it is damaged next time, take it out and compare it. You can probably judge whether it is fatigue or corrosion, and you will know how to select replacement parts.
At the end of the day,Treatment of Flue Expansion Joint DamageIt's a skilled job. Following these five steps, you can avoid half the detours. If you really want to encounter something that is unsure, flip through the product manual on our station, or ask the manufacturer directly. Don't carry it yourself.