Did you really choose the right metal expansion joint for ash material conveying?
A client called two days ago, and his tone was quite urgent. It said that the expansion joints in their factory wore out in less than three months, and once they were shut down for two days, the loss of production shutdown alone was worth the money of several expansion joints. This kind of thing is too common on the ash conveying line-the temperature is always hundreds of degrees, the particles are ground like sandpaper, and ordinary bellows can't bear it at all. If you take a wrong step in the selection, there will be pits behind.
How ruthless is the working condition?
Everyone in this business understands the severity of ash transportation. In the pneumatic conveying pipeline, high-temperature ash rushes through at a speed of more than ten meters per second. The particles are hard, the temperature is high, and some of them have a little sulfur, which directly corrodes at high temperatures. Ordinary 304 stainless steel in this environment, hardness is not enough, wear resistance is poor, and it will be perforated in half a year. In the most exaggerated case I have ever seen, a general-purpose corrugated expansion joint was installed, and the corrugated pipe was ground as thin as paper in two months. So don't expect a bargain to hold up.
The core is structure and material
What about that? The two devices look similar, but their lifespan is several times different. The secret lies in the design and materials. Let's start with the structure-you have to addWear-resistant guide tube。 As specifically mentioned in the product information of our station, the guide tube can guide the flow direction of the medium, so that the ash and slag can go along the wall of the tube, without directly washing the bellows. This site'sSpecific Function of Expansion Joint Guide TubeThere are pictures and truths in the question and answer, so I strongly recommend taking a look. In addition, the wall thickness should be sufficient,Large diameter thick wall expansion jointIt is in this business. The tube wall is thick and rigid, and it can withstand the erosion of high concentration particles. In terms of materials, don't kill 304. Replace it with heat-resistant alloy or wear-resistant layer. The cost is a little higher, but the life can be doubled or tripled. In our stationMetal Corrugated Expansion Joints in Cement IndustryAnd the corrugated expansion joints used in the power station industry are specially optimized for this scenario.
Failure is not only due to wear
When it comes to failure, the most common one is bellows wear. However, the ash is mixed with sulfur and chlorine, and the corrosion rate at high temperature is much faster than simple wear. Another kind of trouble is called sticking-ash accumulates in the corrugated gap, the expansion joint can't expand and contract normally, and the thermal stress of the pipe is all concentrated on the weld and bracket, so the pipe may crack. Therefore, when selecting the model, you have to stare at the gap design. If the gap is too small, it will easily get stuck, and if it is too big, it will deviate. The solution is to use external pressure balance or compound structure, such as the compound hinge transverse expansion joint and the curved tube pressure balance expansion joint of our station, which can absorb multi-directional displacement in a limited space, and the corrugated gap is not easy to accumulate dust. And guess what? Some factories use this structure, and the maintenance cycle is directly doubled.
Don't pick the most expensive one right at the start
Temperature range, pressure, displacement amount, ash particle size and flow rate. None of these data can be missing. To give a simple example: if the pipe has only axial displacement, useHigh temperature axial expansion jointIt is enough, and it is cost-effective; However, if the pipeline is complicated and requires lateral or angular displacement, the duplex structure is more reliable. Blind selection of general-purpose type, high probability of stepping on pits. Is it pneumatic or mechanical conveying in your factory? What is the diameter of the pipe? — This information determines whether the match isMetal hoseOr a corrugated expansion joint. We're standingMetal hoseThe series also has a reinforced type for high-temperature particles, which is suitable for small-diameter, high-frequency vibration scenarios.
Don't be careless in installation and maintenance
Do you want to remove the tie rod nut on the expansion joint after installation? Look at where we're standingHow to adjust the tie rod nut of expansion jointQ&A, the tie rod for transportation must be removed or loosened after installation, otherwise the expansion joint will not work properly. However, under ash and slag conditions, sometimes the limit tie rod has to be kept to prevent the bellows from tearing caused by excessive displacement. This thing has to be based on the design drawings, not on the feeling. In addition, check the wear of the guide tube regularly-replace it in time if it is found to be worn out, otherwise it will directly hurt the bellows body. I ran into a power plant. Just because the deflector was worn out, a hole was flushed out of the bellows, and the whole pipeline stopped for a day and a half. Regular inspections don't take much effort, and all that is saved is real money.
Finally, a summary
Ash material conveying is not as simple as you think, and metal expansion joints are not panacea. Focus on the three points of material, structure and guide tube, and combine the information in our stationCorrugated expansion joint in cement industry、Corrugated expansion joint for power station industry、Large diameter thick wall expansion jointWaiting for product selection, there is a high probability that it can save the follow-up trouble.