Those who do pipeline design and equipment procurement have asked nine times out of ten: Which non-metallic compensator is the best?
This question cannot be answered in one sentence. Non-metallic compensator is not a "universal artifact". It is a general name for a class of products, and there are several kinds below. You pick the wrong type, and it's all trouble behind. Let's break up the key points one by one and explain them clearly. After reading it, you will know in your heart.
First distinguish the types: fabric fiber, rubber, PTFE, it is not the same thing at all
Non-metallic expansion joints (also called fabric fiber expansion joints) are usually covered with glass fiber and ceramic fiber, which have outstanding high temperature resistance and large compensation, so they are especially suitable for working conditions such as flue gas and dust. When you go to the inlet and outlet of the desulfurization tower and the pipelines near the chimney, you basically use this kind of pipeline.
The rubber compensator is different. It is good at vibration reduction and displacement absorption, and can help you isolate the vibration of pump and fan. However, its temperature and pressure resistance are limited. If the temperature exceeds 100℃, you have to weigh it, and it can't stand it even if the pressure is high.
There is also rubber PTFE compensator, which takes into account both anti-corrosion and flexibility, and is more used in acid-base medium pipelines. PTFE compensators also do this, which is more resistant to corrosion.
So you see, marking "non-metallic" doesn't mean omnipotent. Choose the type according to the working conditions first. This step is wrong, and no matter how much money you spend later, it will be in vain.
Look at the working condition parameters: temperature, pressure, medium, none can be missed
The core of choosing a non-metallic compensator is actually how to match the skin material layer. How to match the skin is completely determined by the working conditions.
How much is it resistant to temperature? Is it continuous or intermittent? Is the medium containing sulfur, acid and alkali or dust? Is the pressure negative or positive? With one less of these parameters, manufacturers can only guess according to experience. If you guess right, it is luck, and if you guess wrong, there will be smoke at the scene.
Take an example. The non-metallic expansion joint behind the desulfurization flue gas baffle door is located in a wet and acid environment, and there is a risk of condensation. At this time, the skin has to consider acid corrosion resistance and waterproof penetration. If you move the parameters of the corrugated expansion joint used in the power station boiler or cement kiln, copy it and use it directly, it will probably not last long.
Will the skin be deflated? Some on-site expansion joints are obviously good, but when the negative pressure is large, the skin is directly attached to the internal guide tube, and the wear is aggravated, and it leaks soon.
How to determine the compensation amount and installation size? Don't just look at caliber
The biggest advantage of non-metallic compensator is that it can compensate in multiple dimensions-it can absorb in axial, transverse and angular directions. However, how much it can be compensated is directly related to the structural form and the number of fiber layers.
In the same DN500 circular pipeline, some non-metallic expansion energy saving absorbs 50mm axial displacement, and some can only absorb 20mm. The gap lies in the number of skin layers and the internal structure design.
Rectangular flues generally use rectangular non-metallic expansion joints, while circular pipes use circular structures. This is not difficult to understand, but many people stumble on the installation size.
For example, if the direction of the guide tube is installed backwards, or the flange spacing is not enough according to the drawings, it will be hard-pulled and hard-pulled when installed, and most of the compensation amount will be consumed in the installation stage. Equipment life is directly discounted-it is not that the product is not working, it is that you have installed it incorrectly.
See execution standards and production processes
There is a national standard for non-metallic expansion joints, JB/T 12235-2015, which has clear requirements from materials, welding, inspection to factory test. Products with standard constraints, at least the bottom line is there.
However, the implementation of the standard has to be seen by the eyes. When you get the product, check whether the skin has a cut-proof layer, which protects the skin from scratches during transportation and installation. Then look at whether the flange surface is flat and whether the bolt hole spacing is accurate-these details can be judged with the naked eye.
Skin strength and sealing are not done enough, which is often reflected in these small places. The national standard is not a bondage, but a protection. Products with no standard constraints mostly cut corners out of sight.
Calculate the comprehensive cost: not the cheaper the better, nor the more expensive the more insured
When you buy a non-metallic compensator, you are buying the compensation capacity, not a bunch of metal frames. It is really cost-effective to have no leakage and worry-free maintenance for two years after installation.
I met a customer two days ago, and I bought a non-standard product cheaply. It cracked in less than a maintenance cycle. Not to mention the replacement, it also delayed the production. The loss of a day's downtime is much more than the small purchase fee saved.
Procurement cost + maintenance cost + downtime loss. Put these three items together, and you will not panic when you compare the quotes.
After all, which is the best non-metallic compensator? Suitable for your working conditions, produced according to national standards, and the details can stand to be seen, is the best.