Solutions for the leakage at the inlet flange of the catalytic smoke extractor
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This post was last edited by Refiner on 2017-11-18 at 14:36. The flange at the inlet of the exhaust fan in our workshop has experienced leaks on multiple occasions. Tightening the bolts didn’t work; applying too much force could easily break the bolts. Later, we installed disc springs on the nuts, which improved the situation. We also wrapped a layer of graphite rope around the gap between the flanges and secured it with wire, but smoke still seeped through at those areas sometimes. I would like to ask: do any of you marine enthusiasts have any good solutions for leaks at the flange where the range hood connects to the ship?
For the locking nuts, it is recommended to replace the bolts during maintenance in order to upgrade their material and increase the pressure rating
This post was last edited by xlxuiin on 2017-11-18 at 10:42. Are the fluctuations in the smoke machine’s input large/frequent? Are no expansion joints installed in the inlet pipelines (for temperature and flow rate)?
Iron cement does not exhibit good elasticity under different pressures and temperatures; it is not very good!
We used thin washers produced by Kaitek Company and applied torque tightening synchronously, and the flange has never leaked.
Over the years in our workshop, whenever there’s a leak, we just enclose it by welding things together on both sides of the flange
Due to high temperatures, as well as the material used and its coefficient of expansion, flanges are prone to leakage. It is recommended to use specialized tools for tightening flanges, ensuring even force application； Refine the frequency of heat tightening, gradually carrying out heat tightening starting from preheating ； In the event of a leak, it can be sealed by wrapping it in a box or applying high-temperature glue; direct welding is rarely used.
Back in 2013, I used a technique that involved using lifting washers along with hydraulic tightening (I won’t mention the manufacturer’s name to avoid any appearance of advertising); the results were much better than those achieved with disc springs, and there have been no leaks to date. However, the cost was very high. It was used at the flange on the side of the high-temperature gate valve; since the flange on the other side wasn’t used, leaks still occurred occasionally. It really leaked; since it couldn’t be tightened, I had to plug the leak and use a clamp. It is necessary to replace the gasket every time it is serviced. Under such high-temperature conditions, it seems there is no particularly suitable gasket available at the moment; over time, graphite will definitely oxidize and become ineffective.
1. Use high-grade quality bolts made of alloy steel, such as GH132. 2. After the flange in front of the smoke extractor inlet is installed, heating up during startup should be done gradually and evenly, at a rate of ≤100°C/h. When heated to 500°C, the bolts are thermally tightened. 3. During normal production, strengthen inspections regularly and pay close attention to whether there are any abnormalities with the sliding supports in the flue.
There is little fluctuation. There is an expansion joint before the inlet pipeline