What should I do if the skin of the expansion joint of desulfurization flue is broken? Let's talk about fixing that
In the dry desulfurization business, who has not encountered problems with the skin of the expansion joint? Alas, two days ago, a colleague called, saying that the skin of the non-metallic expansion joint in their factory was cracked, and the smoke went straight out, which was extremely anxious. Today, let's talk about this matter-how to repair the skin of desulfurization flue expansion joint.
First, find out why the skin is broken-the working conditions are more complicated than you think
Don't think that the skin is just a cloth cover. It is soaking in that environment every day, which is much more tired than we go to work. There is everything in the desulfurization flue: high-temperature flue gas, acidic condensate, and constantly jittering pipe stress. Over time, the skin of the fabric fiber expansion joint was either corroded by acid, crisped by high temperature, or worn out by mechanical wear.
There are only a few common "wounds": cracks, perforations, and delaminations. Cracks are generally due to aging or temperature exceeding the limit; Perforation is mostly the result of long-term erosion of fly ash or slurry particles; Layering is troublesome, which means that the coating and base cloth have been separated, and this thing is basically dying. Think about it, can a non-metal expansion joint carry such a large temperature difference and pressure every day without any problems?
Second, don't rush to dismantle, first judge whether it is partial repair or overall replacement
When the skin is broken, is the first reaction to replace it with a new one? Don't hurry. You have to see how big the wound is. Small cracks-such as a length that does not exceed 10% of the total width of the skin and are not located in the corner stress zone-can be completely fixed with patches or cold bonding. But if there is a large area of perforation, or corrosion like a sieve, then don't bother, the overall replacement is much more efficient.
The break is at the crest of the expansion joint, and it has seeped into the insulating cotton inside. Then it is useless for you to repair it. It is soaked inside. As soon as the insulation layer absorbs water, the rigidity and compensation ability of the whole expansion joint are completely wasted. This must be replaced as a whole, don't hesitate.
How to judge? You just take a flashlight to see if there is any fluid in it and smell if there is any pungent sour smell. If you have one, just arrange new non-metallic expansion joints.
3. How to choose repair materials? Don't forget our non-metal expansion joints and fabric fiber expansion joints
When it comes to materials, many people come up and ask, "Is there ready-made repair glue?" Yes, but it depends on the working conditions.
In our product line, the most used are non-metallic expansion joints (fabric fiber expansion joints) and rectangular non-metallic expansion joints. Their skin material is typically a fluororubber coated cloth, a silicone coated cloth or a polytetrafluoroethylene film composite cloth. If you do local repair, it is best to use the same material as the original skin repair piece, with special cold glue. Don't just take a general-purpose glue and paste it on it. As soon as the temperature rises, it will degumm and dry for nothing.
In addition, if you have rubber compensator or rubber PTFE compensator scraps on site, sometimes you can save emergencies-but only in low temperature conditions, so don't mess around.
4. Steps and precautions for hands-on repair, and avoid detours
Okay, let's talk about something practical. Suppose you have judged that you can repair it partially. How do you do it?
- Step 1: Shutdown, pressure relief, ventilation.Don't underestimate this. There may be residual sulfur dioxide in the desulfurization flue, which is troublesome to inhale. Safety comes first.
- Step 2: Clean up the damaged area.Use an angle grinder to polish the old glue, oil and corrosion layer around the break to reveal the fresh fiber layer. The area should be one circle larger than the patch, at least 50mm more.
- Step 3: Cut the patch.The patch should leave rounded corners and not cut into right angles, otherwise it is easy to tear secondarily due to stress concentration. The material must be selected correctly, for example, fluorine rubber cloth should be matched with fluorine rubber cloth.
- Step 4: Apply glue, laminate, and press.Cold adhesive should be evenly painted, double-sided glue, and wait for the surface to dry (fingers do not stick) before fitting. Compact with a roller and squeeze out the bubbles. Pressure with a clamp for two hours if conditions allow.
- Step 5: Cure, check.Don't rush to turn it on. Cure at room temperature for at least 24 hours, and longer in low temperature environments. After curing, do an airtightness test and feel if there is any air leakage with the back of your hand. If conditions permit, try it with low-pressure smoke.
After the repair is completed, brush a layer of acid-resistant sealant on the edges, which can greatly extend the repair life.
5. How to accept after repair? By the way, let's talk about routine maintenance
Finished repairs don't mean everything will be fine. You have to check and accept it. What do you think? First, are there any bulges and wrinkles in the appearance; Second, touch the repair area with your hands, the temperature should be consistent with the surrounding area, and the fever indicates that there are still leakage points; Third, if conditions permit, measure the displacement of the expansion joint after ventilating the smoke to see if it can expand and contract normally.
As for routine maintenance, to put it bluntly, there are two things: inspection and cleaning. Look at the skin surface at least once a month for cracks and peeling; Clean up ash and acid mud around the expansion joints quarterly. Don't underestimate the ash. After absorbing moisture, it will become an acidic liquid, which will slowly corrode the skin. And guess what? The expansion joints of many factories are damaged by dust accumulation, not by their own aging.
In addition, if it is found that the tie rod nut of the metal expansion joint (such as the corrugated expansion joint used in the power station industry) is loose, or the guide tube is worn, it has to be disposed of easily. If these minor problems are not solved, sooner or later they will be implicated in the skin.
After all, the repair of the skin of the expansion joint of the desulfurization flue depends on repair and maintenance. If you usually have more snacks, it will dry for a few more years. If you really get to the point of replacing a new one, don't worry about the money. Go directly to the fabric fiber expansion joint of a regular manufacturer. Don't buy knockoff goods cheaply. That's a real pit.