Let's talk directly about the answer: DN1000 is a 1m caliber
DN1000, a nominal diameter of 1000 mm, that is, the inner diameter of the interface of this expansion joint is just 1 meter. In industrial pipelines, the number followed by DN is the inner diameter of the pipe, in millimeters. However, when users ask, "What does the metal expansion joint DN1000 mean?", they often want to know not only this number, but also where and how to choose this thing.
Metal expansion joints have a function to put it bluntly-absorb the thermal expansion and contraction of pipes, and prevent pipes from being cracked or damaged due to temperature changes. DN1000 is a large-diameter expansion joint, which is generally used in large-scale pipeline systems, such as the connection of steam pipelines in power stations, hot air pipelines in cement plants and flue gas pipelines.
I met a customer two days ago, and I asked how much the metal expansion joint of DN1000 was. I asked him what the temperature of the medium was, what the pressure was, and what the compensation amount was required, and he was immediately stunned. Therefore, just knowing DN1000 is far from enough, the parameters are mismatched, and no matter how cheap it is, it is still scrap iron.
What doorways are hidden in the model?
DN is the diameter, PN is the nominal pressure, and there may be bellows layer number, wave number, and material code behind it. For example, the general-purpose corrugated expansion joint will write DN1000-PN1.0-4 waves in the model, which means that the diameter is 1000mm, the pressure is 1.0MPa, and the bellows has 4 waves.
There are dozens of expansion joints on our station, such as large-diameter thick-walled expansion joints and external pressure single axial expansion joints, and their structures are very different. What scenarios is DN1000 commonly used in? The steam pipeline in the power station industry has high temperature and high pressure, which requires high-temperature axial expansion joint or straight pipe pressure balance expansion joint; In the hot air duct of cement industry, the medium temperature may exceed 400℃, so metal corrugated expansion joint with guide tube must be used-the guide tube can protect the corrugated tube from being directly washed by high-temperature flue gas. This function is clearly explained in the common question and answer "Specific function of expansion joint guide tube".
In addition, the flue gas baffle door will also be used in conjunction with the expansion joint, which is common in desulfurization systems. Therefore, DN1000 is just a starting point of size, and the following parameter combination determines the specific product.
The first pit of type selection: only look at the caliber and don't ask the pressure
When choosing DN1000 metal expansion joint, the first pit of most people is to only look at the caliber and not ask the pressure. The nominal pressure is PN0.6, PN1.0 and PN1.6, and the corresponding wall thickness and layer number of bellows are completely different. PN0.6 bellows may use a layer of 0.5mm stainless steel, while PN1.6 has to use two or even three layers.
There is also the temperature-over 400℃, it is necessary to use high-temperature resistant 316L or Inconel alloy, and ordinary 304 can't bear it. The compensation amount is also key: the pipeline is 100 meters long, the temperature difference is 200℃, and the thermal expansion is about 240mm. By hard absorption by one expansion joint alone, the bellows may break by fatigue. At this time, a double hinge transverse expansion joint or a rotary compensator may be required to share the displacement.
There are many products on our station that are specifically aimed at specific working conditions, such as the double hinge expansion joint of air-cooled island vacuum pipeline, which is used in the air-cooled system of power plants with special working conditions. If you only report a DN1000 to the manufacturer, the manufacturer will have a headache, because it can't recommend the most cost-effective and safe scheme for you.
Installation? This thing is big, don't be careless
Because of its large size, the weight of DN1000 expansion joint often exceeds several hundred kilograms, so special care should be taken when hoisting and fixing. Do you know the function of expansion joint tie rod? The tie rod is not used to bear force, but to prevent the bellows from being compressed or stretched and deformed before installation, and it should be removed after installation. Regarding this question, our FAQ "Does the screw of the expansion joint need to be disassembled" clearly states: it must be disassembled.
In addition, there is generally an arrow direction on the expansion joint, pointing to the flow direction of the medium, and the guide tube will not play a protective role if it is installed backwards. It is mentioned in the "Correct Installation Method of Large Tie Rod Expansion Joint" on our station that the large tie rod expansion joint should ensure that the tie rod nut is adjusted in place and sufficient telescopic space is reserved.
And guess what? I have seen some construction sites use the tie rod as a support, and they don't dismantle it. As a result, as soon as the pipeline heats up, the bellows burst directly. Therefore, when you buy the expansion joint of DN1000, you must get the installation specifications together.
To summarize: just shouting "DN1000" won't solve the problem
The user asked "What does the metal expansion joint DN1000 mean?", which is essentially to confirm whether this product can solve its own pipeline compensation problem. My suggestion is: first confirm whether the actual inner diameter of the pipeline is exactly 1000mm, and then look at the four core parameters of pressure, temperature, compensation amount and medium type.
If it is used for flue gas system, you can take a look at the desulfurization flue gas baffle door and rectangular non-metallic expansion joint on our station. In some places, the cost of using non-metallic expansion joint is lower. If it is a steam pipeline, the corrugated expansion joint for power station industry is preferred. Don't underestimate a model. If you choose the right one, it will last for ten or eight years, but if you choose the wrong one for half a year, it will leak.