Why do you need a non-metallic compensator comparison table?
Last year, a power plant customer installed a rubber compensator in the desulfurization flue in order to save money, but it exploded after less than three months of operation. Why? When the temperature exceeds 120℃, the rubber directly ages and cracks. Later, it was replaced with fabric fiber expansion joints, and there has been no accident for more than two years now. For the same pipeline problem, using the wrong model is equivalent to being installed for nothing-this is not alarmism, but a real lesson.
Nowadays, the non-metallic compensators on the market all look similar, but they are nothing more than soft connections, but the material, structure, temperature resistance and pressure resistance are far different. A reliable oneComparison table of non-metallic compensatorsIt can help you take 80% less detours. Today, we will break up fabric fibers, rubber, PTFE and rectangular shapes to explain clearly.
Mainstream non-metallic compensator types disassembled
Fabric Fiber Expansion Joints (Non-Metallic Expansion Joints)
This thing is the main player, and the main body is silicone cloth, fluorine tape, glass fiber cloth and other composite materials. The temperature resistance range is wide, and it can be done from-40℃ to 1000℃ (depending on the specific number of layers). It mainly absorbs multi-dimensional displacement, and can catch all axial, transverse and angular directions. Flue gas ducts, hot air ducts and dust removal systems are the most common. The disadvantage is that it is not resistant to high pressure, and it is generally used below 0.1MPa. If it is higher, it has to be reinforced or replaced with metal.
rubber compensator
The rubber compensator is made of natural rubber, butyl rubber and EPDM rubber, which has good elasticity and first-class vibration and noise reduction. However, the temperature resistance is generally no more than 120℃, and the high pressure is about 1.0MPa. It is suitable for pump inlet and outlet, compressor pipeline and water system. Two days ago, a buddy who does HVAC told me that they installed a bunch of rubber compensators in the air-conditioning room, and the noise directly dropped by 15 decibels-this work can only be done by it.
PTFE compensator
The corrosion resistance of PTFE materials is ceiling-level, and it is not afraid of strong acids and alkalis and various organic solvents. The temperature resistance can reach 250℃, and the pressure can also reach 1.6MPa. However, the displacement ability is worse than that of fabric fiber, and it is mainly used in chemical and pharmaceutical pipelines with strong corrosive media. Think about it, if concentrated sulfuric acid goes in the pipeline, do you dare to use rubber? Only PTFE compensators can be put on.
Rubber PTFE compensator
This is a hybrid-rubber body with PTFE lining, which has both the elasticity of rubber and the corrosion resistance of PTFE. It is very cost-effective and suitable for scenarios with moderate corrosion and low temperature. But don't expect it to withstand the high temperature above 300℃, and the PTFE layer will soften.
Rectangular non-metallic expansion joint
For square or rectangular pipes, such as flue gas baffle doors, inlet and outlet of desulfurization absorption towers. The structure is similar to circular fabric fibers, but needs to be customized according to the cross-sectional dimensions. The displacement amount can be made very large, and the compensation amount of tens of millimeters is fine. The disadvantage is that it is expensive, the cost of mold opening is high, and the construction period is long. But the adaptability is unparalleled, and the non-standard size is still built for you.
Core parameters: temperature, pressure, medium, displacement
When choosing a non-metallic compensator, look at these four sets of numbers. Take the temperature for example-the ordinary working condition of fabric fiber expansion joint is 150-350℃, and the special layer can reach 800-1000℃, but the price is doubled. The rubber compensator starts to accelerate aging when it exceeds 100℃, so don't take any risks. In this part of pressure, non-metal is naturally weak. If it exceeds 0.2MPa, it is necessary to consider flange reinforcement ring or direct metal compensator. The medium is more important. The flue gas contains sulfur and acid, so we can only choose fabric fiber or tetrafluorine. Finally, there is the displacement. A fabric fiber expansion joint with axial compensation of 40mm is 30% more expensive than a rubber compensator of the same specification, but its life is 3 times longer-whether this account is cost-effective or not, you can calculate it yourself.
Practical selection: Which kind of desulfurization flue gas pipeline should be used? How to choose high-temperature air duct?
Desulfurization flue gas pipeline, the temperature is low (80-120℃), but the medium is highly corrosive (containing SO₂, HF, etc.), and there is vibration. There is no rubber compensator here-the corrosion can't hold it; And no Teflon compensator – too expensive. The best choice is fabric fiber expansion joint, lined with acid-resistant composite membrane and externally reinforced flat flange. Life span 3-5 years no problem. Manufactured according to JB/T 12235-2015 standard, the displacement is calculated according to the direction of pipeline.
The same cannot be said for high temperature air ducts. Like the flue gas at the tail of cement kiln, the temperature is 450℃, and even pulses to 600℃ instantly. At this time, only fabric fiber expansion joints with multi-layer structure, including high-temperature resistant glass fiber cloth, aluminum silicate fiber felt, and surface coating can be applied. Don't think about rubber PTFE compensator, just eliminate it. By the way, pay attention to whether the screw should be disassembled when installing? See the manufacturer's instructions-the transport screw of the vast majority of fabric fiber expansion joints must be removed after installation, otherwise it will affect the displacement. There were quite a few people who stepped on this pitfall.
Pits that are easy to step on
Pit 1: Can non-metal and metal compensators be substituted for each other?Can't. Non-metal mainly absorbs vibration and multi-dimensional displacement, has low pressure resistance, and is suitable for low pressure and large displacement; Metal compensators (such as general-purpose corrugated expansion joints and high-temperature axial expansion joints) withstand high pressure, but can only absorb displacement in a single direction. If the non-metal is replaced with metal, the pipe stress may be directly scrapped. The other way around is the same.
Pit 2: Can the screw be removed during installation?Dismantle. The transportation screw/tie rod is to prevent transportation deformation, and must be loosened or removed after being installed in place, otherwise the compensator is equal to a dead frame and cannot compensate. Before, a customer forgot to dismantle it after installation, and all the flange bolts were broken after one month of operation.
Pit 3: How long is the lifespan?Rubber compensator 2-4 years, fabric fiber expansion joint 3-5 years, PTFE compensator 5-8 years. But the life is not dead, it is directly linked to the working conditions, installation quality and maintenance cycle. Regularly check the surface for cracks, bulges, flange bolts are loose, don't wait for leakage before replacing. In addition, the service life of the expansion joint has a reference value in the factory standard, so you should know it in your heart.
In the final analysis, choosing a non-metallic compensator is not a picture, but a technical job. Put this oneComparison table of non-metallic compensatorsKeeping it in your head will help you filter out at least half of the wrong schemes. If you still hesitate after reading it, then send the four parameters of temperature, pressure, medium and displacement, and let's correct them one by one.