Splash cold water first: The non-metallic compensator itself does not leak water, but this structure leaks water
Give the answer directly —Non-metallic compensator(That is what we often sayNon-metallic expansion joint、Fabric fiber expansion joint) The body will not leak. The reason is very simple. Its main body is a composite layer of fabric and rubber, which is not a dense metal. If it was waterproof by itself, it would have leaked into a fountain.
What really carries the waterproof banner is the internalSealing layerAnd externalskinThe cooperation of. The sealing layer is usually made of fluororubber, silicone rubber or polytetrafluoroethylene film, which is responsible for blocking air and water. The skin (several layers of high-strength fiber cloth plus rubber) provides strength and prevents the sealing layer from bursting by pressure. Once one of the two partners dropped the chain, the water found the seam to drill.
By what waterproofing? Cooperation of sealing layer and skin
TakeNon-metallic expansion joint (fabric fiber expansion joint)In terms of structure, it is generally like this from the inside to the outside: the innermost layer is a corrosion-resistant sealing layer, the middle is a heat insulation layer (such as ceramic fiber felt), and the outer layer is a skin. The sealing layer is like a raincoat, and the skin is like a jacket shell-a hole in the raincoat is useless no matter how waterproof the outside is.
So when you ask "Do non-metallic compensators leak?"The correct answer is: it does not leak itself, but once the sealing layer is aged, damaged or selected incorrectly, what leaks is the peace of mind you bought at a large price.
Dismantling of Water Leakage Case: Rectangular Non-metallic Expansion Joint of Cement Plant Drips in Half a Year
Two days ago, a customer from a cement factory reported that they usedRectangular non-metallic expansion jointInstalled on the kiln tail smoke gas pipeline, it began to drip water in less than half a year. The scene was so anxious that he jumped his feet, thinking it was a product quality problem. As a result, when I removed it, I saw that the sealing layer was full of corrosion holes, but the skin was intact.
What's the problem?
- Flue gas temperature fluctuates year-round: In the design, the silicone rubber sealing layer was selected at 180℃. As a result, the actual operation sometimes rushed to 250℃, and the silicone rubber was directly carbonized and brittle.
- There is condensed acid in the medium: The flue gas contains sulfur, and the temperature drops after shutdown to form sulfurous acid. The ordinary sealing layer can't bear it, and it will perforate in a few months.
This pot really shouldn't be left to the non-metallic compensator-the working conditions were not accurately calculated in the selection stage.
Pits buried in the design and selection stage: temperature, corrosion and pressure, none of them can be missed
No matter how cow the sealing layer is, it is also afraid of "cross-border rape". Three key parameters don't match up, and it is only a matter of time before water leaks:
- Flue gas temperature: Select silicone rubber or perfluorororubber at high temperature, and use EPDM with good aging resistance at low temperature (such as wet chimney after desulfurization). Don't take the general-purpose type to carry the high temperature of 300℃, that is, force the sealing layer to commit suicide.
- Medium corrosivityPolytetrafluoroethylene film or fluororubber sealing layer for acidic gas; Alternative formulation for alkaline or oil mist environments. Customers often ignore the corrosion of condensate and choose an ordinary rubber, which leaks in half a month.
- Pressure rating: Non-metallic compensators are generally used in low-pressure or negative-pressure pipelines, but when the pressure fluctuates greatly, the sealing layer will be "blown and bulged" and then torn. Design with a margin at least 20% higher than the actual pressure.
To put it bluntly, the non-metallic compensator is like a custom suit, and only by measuring the body (working conditions) and tailoring (material selection) can it fit. Buy the ready-made universal model when you come up, and don't shout for the leakage.
The most overlooked details of installation and maintenance
Select the right type, install the hand shake, still leakage. Three details are the hardest hit areas:
Has the tie rod nut been adjusted in place?
Non-metallic expansion joints, usually with tie rods, are used to limit displacement. According to the specification, the tie rod nut should be adjusted to the pre-tensioned or pre-compressed position after installation (see the design drawings for specific data). Many workers screwed to death directly, or didn't adjust it at all. As a result, the skin was torn when the pipe was thermally expanded, and the sealing layer suffered. Refer to our site Q&A"How to adjust the tie rod nut of the expansion joint"It should be divided into two steps: first loosen the nut to the free state, and then adjust the positioning nut according to the compensation amount.
Is the deflector in the right direction?
Non-metallic compensator with guide tube, the arrow must point to the direction of media flow. When installed backwards, the airflow directly washes the edge of the sealing layer, and the wear is aggravated. There was once a client who putRectangular non-metallic expansion jointThe guide tube was installed backwards and worn out in three months. We have written about the specific function of the guide tube, and the core is to protect the sealing layer from being damaged by high-speed particulate matter.
Is the bolt torque enough?
The flange bolts can't be tightened, and the water will seep as soon as the sealing surface runs out. But it can't be screwed dead-the strength of non-metallic skin is limited, and the excessive torque of bolts will crush the skin, resulting in local deformation and cracking. The standard practice is to use a torque wrench and tighten it symmetrically three times according to the torque value given by the manufacturer.
What if a non-metallic compensator leaks? Don't be in a hurry to change, check these 4 places first
When you encounter a water leak, don't scold the manufacturer first, and don't rush to place an order for a new one. Sequencing in order:
- See if the sealing layer is partially damaged: Open the observation port or remove the skin (be careful not to tear it), and check whether there are holes, cracks and bulges on the sealing layer. If it's just a small hole, you can temporarily plug the leak with special repair tape, and then replace it after shutting down.
- Check if the tie rod nut is loose or stuck: If the tie rod nut is loose and the displacement is uncontrolled, the sealing layer may be torn. Reposition the nut to make sure it is within the set stroke.
- Verify that the guide tube is detached or installed backwards: The guide tube falls off, and the high-temperature flue gas directly rushes the sealing layer, which can be burned through in a few minutes. Re-fixed or replaced.
- Measure actual media temperature and composition: Many water leakages are actually due to the change of working conditions-for example, the original burning coal is now mixed with biomass, and the flue gas composition changes, so the sealing layer can't bear it. In this case, the type must be re-selected and the material of the sealing layer must be changed.
80% of the water leakage problems are not the poor quality of the compensator itself, but the hidden pits in the selection, installation and maintenance. After these three links are controlled, the non-metallic compensator will last for three to five years.
By the way, if you still leak after checking, don't hold on. Contact the manufacturer to provide the working condition parameters and let professional technicians recalculate it. It is much cheaper to replace a sealing layer than the entire compensator, and it does not have to move the pipes-this isNon-metallic expansion jointAdvantages of modular design.