What does the "L" after the non-metallic expansion joint model mean? I looked at it, hey, that's a good question. Many people who purchase and install on-site will most likely be confused when they see this letter for the first time. Today, let's make it clear, and by the way, we will also go through the non-metallic expansion joint.
L is the length, but there's a way here
The "L" on the non-metallic expansion joint is, to put it bluntly, the code name of Length. For example, the drawing says "Non-metallic expansion joint L =500mm", which means that the total length of this compensator is 500mm. This length directly determines how much displacement it can absorb-the larger L, the stronger the compensation capacity. Like our commonRectangular non-metallic expansion jointOrFabric fiber expansion jointSize a truth.
But note that the L of non-metallic expansion joints is not randomly marked. There are two kinds of it: one isTotal length from flange face to flange face, also called installation length; The other isEffective compensation length, refers to the elastic segment (that is, the portion that can be telescoped). Be sure to confirm clearly when ordering, otherwise it will be embarrassing if you can't fit it by hand. And guess what? I have encountered several scenes, just because I didn't understand the difference, the flange didn't match, and the welder cursed.
In addition to L, there are W, H, and DN
Are there other letters on non-metallic expansion joints? Yeah, yeah. For example, "W" stands for Width and "H" stands for Height, which are commonly found in rectangular non-metallic expansion joints. Circular non-metallic expansion joints are typically labeled DN (nominal diameter) and L. You remember a principle: letters followed by numbers are most likely size parameters.
A rectangular non-metallic expansion joint is marked with "L =800mm, W =400mm, H =300mm", so you can know its length, width and height at a glance. But if it is circular, it may just write "DN200 L =500mm". So don't panic when you look at the letters, it's simple to sort out the structure.
Why are non-metallic expansion joints used in power plants, cement plants and desulfurization systems?
Because it can withstand high temperature, corrosion resistance and large compensation. The temperature in the flue gas pipe is always three or four hundred degrees, and there are corrosive gases. Where the metal expansion joint can't bear it, it has to be resolved by non-metallic flexible structures. We're standingFlue gas baffle door、Desulfurization flue gas baffle doorOften used in conjunction with non-metallic expansion joints. For example, at the inlet and outlet of the desulfurization tower, the flue gas baffle door is responsible for cutting off the airflow, and the non-metallic expansion joint is responsible for absorbing the thermal expansion, contraction and vibration displacement of the pipeline, both of which are indispensable.
If you choose the wrong L size, it will not fit, or the pipe stress will burst the seal structure. This is not to scare people-last year, a cement factory customer bought the total length as the effective length. As a result, after installation, the compensation was not enough, the corrugated layer was directly torn, and the whole line stopped for three days.
How to communicate with suppliers without overturning?
Next time you see "Non-metallic expansion joint L =...", don't hesitate, it is the length. If the unit is not marked on the drawing, the default is millimeters. Keep that in mind and make at least half the mistakes when communicating with suppliers. However, for the sake of insurance, it is best to let the supplier confirm two sentences when placing an order: is it the total length from flange surface to flange surface, or the effective compensation length? Also, don't forget to check flange bolt hole spacing and sealing surface dimensions.
If there are other letters that you can't understand, please throw them directly and ask, and let's disassemble them one by one. For example, have you encountered the problem "What does the non-metallic expansion joint l mean?"? In fact, I understand L, and the other letters are just a matter of following the gourd and ladle.
By the way, the national standard for non-metallic expansion joints is JB/T 12235-2015, which contains technical requirements and test methods. The products of our station are all produced according to this standard, includingrubber compensator、PTFE compensatorThese non-metallic ones. If you have special working conditions at hand, such as high-temperature dusty smoke, it is recommended to give priority to fabric fiber expansion joints, which have more reliable temperature resistance and compensation ability.
Buy non-metallic expansion joints just look at the price, the size parameters don't match, and no matter how cheap it is, it is also scrap iron. Is that the truth?