Is the flue expansion joint installed without distinction between positive and negative? I told him that it was a score. Not all expansion joints have a direction, but once there is a direction requirement, they are installed backwards, ranging from wear and air leakage to the whole section of corrugation tearing. Let's break it up and break it down today.
Why do some flue expansion joints have to be oriented?
The key is in the deflector. This thing fits inside the corrugation, like a bell mouth, and functions to guide the flow of the medium and reduce scour and vortex. Think about it, there is much dust in the flue gas pipeline and the flow rate is fast. If the guide tube is installed in the reverse direction, the airflow will go straight to the root of the corrugation, and the wear speed will more than double. Like the one we stand onUniversal corrugated expansion joint、High temperature axial expansion jointThe direction of the guide tube is a hard requirement-the opening must point to the direction of the medium. Why? Because the medium enters from the large port and exits from the small port, the guide tube can smoothly guide the airflow into the corrugation to avoid direct impact.
A high-temperature axial expansion joint was installed backwards. After less than three months of operation, the corrugated root grinded out grooves visible to the naked eye, and the air leakage rate soared to 15%. You say it was wrong or not?
What about the expansion joint without the deflector?
For example, pure rubberrubber compensator, andNon-metallic expansion joints (fabric fiber expansion joints), there is no metal diversion structure inside, and it doesn't matter whether it is positive or negative in theory. However, note that some non-metallic expansion joints will thicken the wear-resistant layer on the upward surface in order to resist erosion. At this time, the manufacturer will mark an arrow on the product, and the arrow points to the flow direction of the medium. If you ignore the arrows, the wear-resistant layer will be installed on the back, which is basically equivalent to wasting money.
In addition,Rubber PTFE compensatorSuch composite products sometimes make a fuss about the lining. In short, don't just look at the appearance, you have to look at the manufacturer's label.
How to judge if there is a direction? Three methods
Look for arrow marks on the outer wall or flange of the product. We often say that "the direction of the arrow of the expansion joint refers to", that is, the direction of the medium flow and the direction of the small mouth of the guide tube. In our stationMetal rectangular expansion joint、Corrugated expansion joint for power station industryWhen you leave the factory, an arrow will be marked in a prominent position, so you can tell it at a glance.
What if there were no arrows? Take apart the flange to see the internal structure. The guide tube is like a bell mouth, and the small mouth is facing the direction of the medium. Otherwise, look forLarge diameter thick wall expansion jointDrawings-This type of heavy equipment generally has installation instructions, and the manufacturer will mark the flow direction.
Then I bought itSleeve type pipe expansion jointIs there any direction? Sleeve type is also divided, but most of them rely on sealing packing, and the direction has little influence. But the corrugated ones are basically particular.
What if I install it backwards? Don't make do
For flue gas pipelines, especially desulfurization systems or high-temperature flues, the inverted guide tube will expose the ripples directly to the dusty gas stream. Doubling the wear rate is light, and in severe cases, it can trigger corrugation tearing, resulting in the outage of the entire pipeline. We handled aDesulfurization flue gas baffle doorThe matching expansion joint was installed backwards by the user, and after half a year, the air leakage exceeded the standard, so it had to be stopped for a new one.
It is recommended to reinstall in the correct direction after shutdown. If the site can't be dismantled (for example, it has been welded or the space is limited), you can consider installing an anti-wear plate on the outside, but it will treat the symptoms rather than the root cause. The guard plate can block for a while, but can't stop long-term scouring. Eventually it will have to be changed.
At the end of the day, take ten minutes to verify directions before installation
It is much more cost-effective than replacing an expansion joint of tens of thousands of dollars in the later period. Whether it isRectangular non-metallic expansion jointStillDirect buried (fully buried) type expansion jointThe rules are the same: if there is an arrow, look at the arrow, if there is no arrow, look at the guide tube, and if there is no mark, ask the manufacturer for drawings. Don't pretend by your feeling, the industry is just like that.
So back to the question of "Is there a positive and negative for the flue expansion joint"-the answer is: those with guide tubes and those marked by arrows must be distinguished between positive and negative; Pure rubber or fabric with no guide tube and no marks, usually not distinguished, but also pay attention to the direction of the wear layer. The heavier the equipment, the worse the working conditions, the less careless. Remember: When you get the right direction, the pipeline can run for the long term.