That afternoon, Lao Li squatted by the boiler of the power plant, staring at the seventh cracked weld and cursing
For three years, the metal expansion joints had been replaced and replaced, and each time they cracked in the same place — the heat displacement and vibration in the high-temperature flue tortured the bellows like pieces of paper. Gray-white smoke seeped from the weld, and the pungent smell of sulfur choked his eyes sour. The workers were all hiding far away, only Lao Li was squatting there, holding the scrapped parts just removed in his hand, thinking that he would have to work overtime for repairs tonight. Until Lao Zhang handed over a dusty circle and said to try this welded round non-metallic compensator. Old Li put it on with a grain of salt, guess what? Until now, that crew has never had a temper again. Lao Li said to everyone that if he used this thing three years earlier, he could spend three more Spring Festivals with his daughter.
What's the difference between this stuff and normal expansion joints?
To put it bluntly, its "non-metallic" part is made of temperature-resistant and corrosion-resistant fabric fiber layer, which is the same as the "non-metallic expansion joint (fabric fiber expansion joint)" in our station. But there was an additional welded round joint-welded meant it was welded tightly to the pipe, unlike flanged connections, where the bolts loosened over time and the air leaked. Well, it is naturally suitable for circular flues or pipes, and it is good at compensating axial and radial displacements. The point is, it is not afraid of acid and alkali corrosion, nor is it afraid of frequent vibration. The flue gas of Lao Li's boiler has high sulfur content, and the metal bellows can't bear it, so it will rust through in three months; But what about non-metallic materials? Instead, the more you fight, the more brave you are, like wearing a body armor, and the corrosive medium hits the fabric layer, like a tickling.
Where is this treasure used more?
Flue gas pipelines in power plants, cement plants and steel plants, especially where there are desulfurization devices. You see, there are "desulfurization flue gas baffle door" and "metal corrugated expansion joint in cement industry" in the product list in our station, but the welded circular non-metallic compensator is suitable for those places where the temperature is not too high (generally below 600℃), but it is highly corrosive and needs a large amount of compensation. For example, the wet flue gas coming out of the desulfurization tower is low in temperature but contains acidic droplets. Metal parts will rust through in two or three years, but non-metals can last for seven or eight years. Moreover, it is lightweight, and there is no need for a crane when installing it. Lao Li and two or three people lifted it up. Tsk, just that saved thousands on the crane rental fee.
But you have to be careful when installing it
Welding type, the end face of the pipe should be cleaned before welding, and the welding current should not be too large, otherwise the non-metallic ring belt will be burned out. There is also a guide tube (Lao Li specially turned over the question and answer in the station "The specific function of the guide tube of the expansion joint"), which has to be installed on the side where the medium flows to prevent high-speed airflow from washing the fabric layer. The tie rod nut (see Q&A "How to adjust the tie rod nut of the expansion joint") should also be pre-tightened first, and then fine-tuned after the pipeline runs stably. Don't install it dead. When Lao Li installed it for the first time, he didn't pay attention to the guide bolts. As a result, the displacement deviated and almost torn the ring belt. Fortunately, it was adjusted in time, otherwise it would have to be reworked again. If you also encounter this kind of work, remember: reduce the welding current, don't reverse the direction of the guide tube, and leave some allowance for the tie rod nut.
In the end, when it comes to equipment selection, you can't just look at the parameter table
Temperature, pressure, medium, displacement... Welded circular non-metallic compensator is not a panacea, but it is a savior in those working conditions where metal expansion joints can't bear it. As Lao Li said: "If the machine is not bad, people can work less overtime." If you also encounter similar headaches, you might as well flip through the National Standard for Non-metallic Expansion Joints (JB/T 12235-2015) in the station, or ask the technology directly.