What is a non-metallic compensator unit? Understand these parameters, selection is no longer confused
Two days ago, a customer came over with drawings and said, "I want a DN500 non-metallic compensator with a compensation amount of 300". When we looked at it, the pressure was written "6", and there was no unit. When asked later, he thought it was 6 kilograms, but the actual requirement was 0.6 MPa. By an order of magnitude, the fabric layer will bulge or even tear if done at 6kg. You see, just one unit didn't write it clearly and almost scrapped a piece of equipment. So today, let's thoroughly understand "what is the non-metallic compensator unit".
Direct answer: What units exactly do non-metallic compensators use?
Customers often ask "What is the unit of non-metallic compensator?" Actually, they ask two meanings: one is what to measure the product size (such as diameter DN and length mm), and the other is what to measure the compensation ability (such as displacement mm and pressure MPa). Simply put, common units are:
- Diameter:DN (nominal diameter), such as DN100 and DN200, but it is not the actual inner diameter, so you have to look up the table. This site'sNon-metallic expansion joint (fabric fiber expansion joint)In the product parameters, DN corresponds to the flange connection size.
- Compensation amount:Millimeters (mm), and transverse, axial and angular displacements are all in mm or degrees (°). Note: Although the angular displacement is degree, the rectangular expansion joint is sometimes marked with the angular displacement, which is actually the flange deflection angle.
- Pressure:Megapascals (MPa), occasionally with kilogram force (kgf/cm²), 1 MPa ≈ 10.2 kgf/cm². The old drawings say "6K" and "10K" are Japanese standards, 1K ≈ 0.098 MPa, so don't get confused.
- Temperature:degrees Celsius (℃), the upper temperature resistance limit of non-metallic fabric compensator is usually between 200 and 1200 ℃, depending on silicone cloth, fluorine tape or ceramic fiber. For example, the temperature resistance of ceramic fiber is 1260℃, but the long-term work can only reach 1000℃-if the unit is wrong, the equipment will be scrapped in three months.
- Overall Dimensions:The length, width and height are all in mm,Rectangular non-metallic expansion jointIt is also divided into inner diameter, outer diameter and flange hole pitch. On the drawing, both L and B are mm, and the diameter of the center circle of the flange bolt hole must also be in mm.
When you select the model, these units are marked on the manufacturer's drawings. Don't regard DN as inches or kgf/cm² as MPa. Is that the truth?
Why is the compensator destroyed when the unit is wrong?
- Nominal pressure:PN6, PN10 and PN16 (unit bar or MPa) are commonly used in national standards, but "6K" and "10K" written on the old drawings are Japanese standards, and 1K ≈ 0.098 MPa. I have seen a purchase, holding the drawing of PN10, and the default is 10kgf/cm² (about 0.98MPa). As a result, the supplier does it according to 1.0MPa. The understanding on both sides is actually similar, but if it is higher, there will be problems. In fact, the national standard PN unit is bar, 1 bar =0.1 MPa, and PN10=1.0 MPa.
- Displacement Amount:Axial compression and tension are used in mm, transverse displacement is also used in mm, but angular displacement is used in degree. Rectangular expansion joints are sometimes marked with angular displacement, which is actually the flange deflection angle. For example, you require ±50mm, which is actually determined by the number of folds of the multi-layer fiber cloth. If you need 100mm, you have to widen the folds or increase the number of layers, but the pressure loss will also change.
- Installation Length:Includes flange thickness and compensator effective length in mm. On the drawings of products in the station, such as "rectangular non-metallic expansion joint", L and B are both mm.
So how to avoid it? A suggestion for not rolling over: When confirming with the supplier, write all the units clearly, such as "installation length 300mm, axial compensation amount ±50mm, working pressure 0.1MPa, medium temperature 350℃". Don't come up and throw a number, people can't guess your mind.
What is the difference between the units of non-metallic compensators and metallic compensators?
Some people think that the difference is not big, but in fact, the emphasis is different. Metal expansion joints (e.g.Universal corrugated expansion joint、Direct buried (fully buried) type expansion joint) is more concerned about the pressure grade and the number of ripples, and the units are mainly MPa and wave number. The core of non-metal compensator (also called fabric fiber expansion joint) is temperature resistance and corrosion protection, so the temperature unit (℃) and acid-base concentration (%) are more important.
Used in the cement industryMetal Corrugated Expansion Joints in Cement IndustryMainly cope with high-temperature dust, the pressure is not high, but the temperature may reach 800℃. WhileNon-metallic expansion joint (fabric fiber expansion joint)In the desulfurization flue gas baffle door system, to withstand the acid gas after wet desulfurization, "SO₂ concentration ppm" has to be added to the unit at this time. And guess what? Many purchases only focus on pressure units, ignoring whether the unit marked by the upper temperature limit is long-term operating temperature or instantaneous peak. For example, the high-temperature axial expansion joint is specially designed for power stations, and the temperature is marked accurately to ℃. However, if it is an export order, Fahrenheit (℉) should also be careful-1000°F ≈ 538℃. If it is used as 500℃, the fabric layer will be carbonized.
Three unit pits that are easiest to step on during model selection
Pit 1: Nominal diameter DN ≠ outer diameter of flange.The rectangular non-metallic expansion joint of DN200 has an inner diameter of 200mm, but the diameter of the center circle of the flange bolt hole may be 240mm. If you fit the pipe according to the outer diameter of the flange, it can't be installed. So you must look at it when choosing a modelRectangular non-metallic expansion jointDrawings, mark the flange hole spacing clearly.
Pit 2: The conversion of pressure units is reversed.A customer said "I want PN10", and the supplier defaulted to 1.0MPa, which the customer understood as 10kgf/cm² (about 0.98MPa). The result was similar, but a higher level would cause problems. In fact, the national standard PN unit is bar, 1 bar =0.1 MPa, and PN10=1.0 MPa. If you run into the daily standard "10K", that's another story.
Pit 3: "F" and "C" in the unit of temperature.Export orders are common degrees Fahrenheit (℉), 1000°F ≈ 538℃, if used as 500℃, the fabric layer is carbonized. On-site productsHigh temperature axial expansion jointDesigned for power stations, temperature labeling is accurate to ℃. So when you get the order, look at the unit first, and don't think inertially.
Contrast this site'sNational standard for non-metallic expansion joints(JB/T 12235-2015), which clearly specifies the parameter labeling requirements. Or call the manufacturer directly, don't guess for yourself.
One sentence summary: the unit is the compass of type selection, wrong all bias
The unit system of non-metallic compensator is not complicated, with diameter DN, compensation amount mm, pressure MPa, temperature ℃, plus a flange bolt hole distance mm. However, behind the value of each unit, there are different material layer thicknesses, wave heights and layer numbers. For example, the compensation amount of "non-metallic expansion joint (fabric fiber expansion joint)" is labeled ±50 mm, which is actually determined by the number of wrinkles of the multilayer fiber cloth. If you need 100mm, you have to widen the folds or increase the number of layers, but the pressure loss will also change.
Next time, ask "What is the non-metallic compensator unit?" First, turn through the product page of this site. The four fields of "nominal diameter, displacement, working pressure and working temperature" in the product parameter table are the answer. If you don't understand, just copy the parameters and send them, and we will help you correct them. After all, after more than ten years in this business, I have seen too many cases of rework because of mistakes made by the unit-it is really not worth it.