Anyone in this business knows that many customers ask for metal compensators by name as soon as they come up-bellows, stainless steel, which sounds reliable. But when you really encounter high-temperature smoke or corrosive media, the metal set will be blind. Stainless steel can't bear oxidation and fatigue failure above 500℃ in acid-alkali environment. What about that?Non-metallic fiber compensator(also calledNon-metallic expansion joint (fabric fiber expansion joint)) is specifically to make up for this shortcoming. It is not an ordinary soft joint. It is structurally composed of multi-layers of fabric fibers, temperature-resistant materials, sealing layers and metal frames. The core advantages are precisely what metal compensators can't do. Today, we will break its ability into pieces and explain it clearly.
Wide temperature range: 1000℃ is not the upper limit
Ordinary metal expansion joints start to oxidize when they reach above 500℃, and the fatigue life of bellows decreases by a cliff. And guess what? The non-metallic fiber compensator chooses the right fiber cloth-such as glass fiber and ceramic fiber-the normal working temperature can reach 1000℃, and the short-term impact is even higher. In the cement industry,Metal Corrugated Expansion Joints in Cement IndustryThe preheater part is often tortured by high-temperature flue gas and changed one after another. Replace withRectangular non-metallic expansion jointLong-term stable operation, and the failure rate is directly reduced. Is that the case? Temperature resistance is really incomparable to metal.
Anti-corrosion, anti-aging: still work in acid-alkali environment
What goes behind the smoke baffle door?Flue gas baffle doorAndDesulfurization flue gas baffle doorThere are all corrosive gases behind, and the acidic flue gas after wet desulfurization is even more corrosive. Stainless steel? No matter how good it is, it is afraid of acid and alkali attack, especially chloride ions. The non-metallic fiber itself is an inert material, coupled with PTFE or the likeRubber PTFE compensatorThe fluoroplastic lining is more than enough to deal with this working condition. Two days ago, a power plant customer told me that after they replaced the stainless steel bellows with non-metallic expansion joints, the maintenance period was extended from half a year to two years. The durability has doubled several times and the cost has been saved a huge chunk.
Large amount of compensation displacement, and can also reduce vibration and noise
The metal bellows is deformed by corrugation, and the single wave compensation is limited. To meet the large displacement, the wave number has to be desperately increased, and the structure is bloated and expensive. The whole fabric layer of non-metallic fiber compensator can be deformed, and can be absorbed in axial, transverse and angular directions. It is especially suitable for large-diameter pipes or complex space directions. You seeDouble hinge expansion joint for air-cooled island vacuum pipelineIn that scenario, if it is changed to a non-metal scheme, the installation flexibility is much higher, and there is no need to bother calculating the hinge angle. Plus the fiber itself has damping-you think about it, the pipe vibration is transmitted to the fiber layer, and the energy is absorbed, not as easily resonating as metal expansion joints. The noise also dropped.
Lightweight structure, easy installation and maintenance
A set of metal bellows expansion joints are heavy and expensive, and the flange connection has to be accurately centered, so it takes half a day to move it. The weight of the non-metallic fiber compensator is only a fraction of the metal of the same caliber, and can be lifted by two people on the spot, so it is easy to install. More critical is maintenance – no need to dismantle the pipes! Just replace the fabric strap and be done. For example: a cement factory'sRectangular non-metallic expansion jointAfter three years of use, the fabric layer wore out. The workers cut off the old cloth and replaced it with a new one, which was done in half a day, and the cost was less than one tenth of the cost of buying a new metal compensator. Tsk, the price/performance ratio is crushed, no suspense.
Keep an eye on three pits when selecting a model
Having said so many benefits, it's not a panacea either. These three points must be fixed when selecting:
- Pressure Class:The withstand voltage of non-metallic compensators generally does not exceed 0.1MPa. Be cautious when the internal pressure of the pipeline is high or there is negative pressure, and add a guide tube if necessary — —Specific Function of Expansion Joint Guide TubeIt's diversion and protection, don't save this money.
- Media Flow Rate:In dusty working conditions, high-speed particles will wear the fibers. You have to choose a thickened wear-resistant layer or add stainless steel mesh inside, don't try to be cheap.
- National standard compliance:Remember national standardsJB/T 12235-2015, all formalNon-metallic expansion joint (fabric fiber expansion joint)All are produced and inspected according to this standard. Look for these points, and the non-metallic fiber compensator can help you save costs, reduce failures, and cost-effective rolling metal scheme.
Back to the question at the beginning-why replace metal? Four words:Make use of strengths and avoid weaknesses。 High temperature, corrosion, large displacement, light maintenance, this is the hardcore nature of non-metallic fiber compensator.