Understand first: What exactly is a non-metallic compensator?
When many people hear the word "non-metal", the words "bargain", "not durable" and "makeshift" immediately pop up in their minds. Alas, this is a big misunderstanding. In the product list in our site, fromNon-metallic expansion joint (fabric fiber expansion joint)Torubber compensatorAnd then toRubber PTFE compensatorAndPTFE compensatorJust take one out, it's not a simple "cloth bag" or "rubber tube".
To put it bluntly, non-metallic compensator is a flexible connector made of non-metallic materials such as fabric fiber, rubber and fluoroplastics as the main body and a metal frame. The gray fabric bands you see may have fiberglass, silicone rubber, and PTFE film sandwiched inside, layer by layer. It can absorb the thermal displacement of the pipe, dampen vibration, and also resist corrosion. It's not the same thing as the "knockoff" you think.
Which occasions must use non-metals?
Can the non-metal compensator be used? The answer is: under some working conditions, the metal compensator can't work at all, but the non-metal is the optimal solution. Take three typical scenarios:
- High temperature flue gas pipeline: For example, power plant boiler outlet, cement kiln tail flue gas. The temperature is always four or five hundred degrees Celsius. Even if the metal expansion joint can hold it, it will be frequently replaced because of excessive thermal expansion stress and short fatigue life. However, the non-metallic expansion joint (especially the fabric fiber type) is resistant to high temperature, soft, can absorb multi-directional displacement, and the cost is much lower.
- Strong corrosive media: The wet flue gas in the desulfurization system contains sulfuric acid and hydrochloric acid, and the metal is quickly corroded and perforated. At this time, useRubber PTFE compensatorOrPTFE compensator, corrosion resistance hanging stainless steel. The station is distributed for desulfurization of power plantsDesulfurization flue gas baffle doorAndNon-metallic expansion jointA lot of them have not been changed for more than ten years.
- Large diameter low pressure pipeline: The diameter of the air duct and flue is two or three meters, and the pressure is only a few kilopascals. With metal corrugated expansion joints, the wall thickness, weight and cost are frightening, and the compensation amount is limited. Non-metallic rectangular expansion jointRectangular non-metallic expansion joint) Can be made into any cross-section, with large compensation and small installation space, and workers can install it when they carry it.
So don't hit it with a stick, use it in the right place, it's a treasure.
Nonmetallic vs Metallic: What's the Difference?
Don't just stare at the price yet. Metal expansion joints (e.g.Universal corrugated expansion joint、High temperature axial expansion joint) The pressure can reach several MPa or even tens of MPa, but the compensation amount is limited, and it cannot absorb the lateral displacement. The compensation amount of non-metallic compensator can be 3~5 times that of metal, and the vibration and noise reduction effect is obviously better. Low installation space requirements – metal expansion joints often need to reserve straight sections of several meters long to absorb displacement, and non-metals only require a few hundred millimeters.
It's really nothing when the pressure is high。 The withstand voltage of non-metallic compensators usually does not exceed 0.1~0.3 MPa. If it is higher, the structure with metal reinforcing ring should be used, or the metal expansion joint should be directly attached. If you have to use non-metal to top the steam pipe (pressure 1.6 MPa), that is to look for scrap. So the first thing when selecting a model: look at the medium pressure.
Three Common Pits of Model Selection Rollover
I met a customer two days ago, who bought a non-metallic compensator for cheap, and it leaked after three months of use. After asking, he found out that he chose a silicone rubber fabric with a medium temperature of 450℃, and the upper limit was only 350℃-can this not be burned through?Upper temperature limitIs the first pit: different materials have different temperature resistance, silicone rubber about 250~350 ℃, fluororubber about 200 ℃, polytetrafluoroethylene about 260 ℃, glass fiber fabric plus coating can be above 600 ℃. Must be compared with national standardsJB/T 12235-2015Select the temperature limit table in.
Medium corrosivity。 Don't think that non-metals must be corrosion-resistant. Rubber tetrafluorine is good for strong acids, but strong alkali will expand fluoroplastics. Some media contain oil, and the rubber quickly swells and softens. In our stationrubber compensatorAndRubber PTFE compensatorThe material is very different, and if you choose the wrong one, you will take money to waste.
Guide tube configuration。 Many people don't know that it is also recommended to add a guide tube inside non-metallic expansion joints (refer to "Specific Function of Expansion Joint Guide Tube" in FAQ). The high-speed dusty airflow directly washes the fabric band and wears out in a few months. With the addition of a guide tube, the life is extended several times. The national standard JB/T 12235-2015 clearly stipulates the material and thickness requirements of the guide tube, but many small factories directly omit it in order to save costs. You must write it clearly in the contract when you choose a model.
Real cases speak
- Power plant desulfurization systemWe have a power plantNon-metallic expansion joint (fabric fiber expansion joint)Andrubber compensatorWhich is used in that inlet and outlet flue of the absorption tower. The medium is saturated wet flue gas, the temperature is 50-70 DEG C, and contains sulfuric acid droplets. After 8 years of use, the surface of the loop band is slightly aged, but the whole is in good condition. The metal expansion joint installed at the same time began to crack the weld joint in 3 years.
- Cement kiln tail: The kiln tail waste gas temperature is 350~400 ℃, containing a large amount of dust. They used metal rectangular expansion joints before, and insufficient compensation caused the top crack of the pipe. changedRectangular non-metallic expansion jointThe compensation amount is doubled, and the ring belt is changed every two or three years, and the cost is much lower than repairing a metal frame. The front-line operation and maintenance master said: This thing is worry-free, and it is easy to change if it is broken, so there is no need to stop production and overhaul.
- Iron and steel plant flue: The blast furnace gas pipeline diameter is 3 meters, and the pressure is extremely low. With a non-metallic compensator, the displacement in three directions is directly absorbed. When installing, it doesn't need to be adjusted for half a day like a metal tie rod, and the worker can finish it in 20 minutes.
Can non-metallic compensators be used？ Yes, but not mindlessly. Find out the working conditions, the accurate parameters of the card, and compare with the national standard. It is the "all-around oil" in the industry. If you are still entangled, go directly to the product information in our station:Non-metallic expansion joint (fabric fiber expansion joint)、rubber compensator、Rubber PTFE compensator、PTFE compensatorThe technical parameters are clearly marked.