The customer asked "Does it count as equipment"? Find out what a non-metallic compensator is
Two days ago, a purchaser of desulfurization projects called and asked, "Does the non-metallic compensator count as equipment? Our boss asked me to go through the equipment procurement process, but the finance said that this thing is a pipe fitting, and I argued for a long time." This problem is actually quite typical. You say it is a pipe, it does fit on a pipe; But you say it's just a pipe fitting, and it comes with flanges, with deflectors, with insulation, and even with tie rods and limit devices. Tsk, everyone was confused.
Non-metallic compensator, also called non-metallic expansion joint, fabric fiber expansion joint, rubber compensator, rubber PTFE compensator, is essentially a flexible connection device. It is composed of skin (fluorine adhesive tape, silicone cloth, PTFE, etc.), insulation cotton, steel structure frame, beading and bolts. Unlike metal expansion joints, which absorb displacement by bellows, non-metals are deformed by fibrous materials and elastomers. It absorbs a large range of heat displacement, compensation directions, and can also be resistant to corrosion and high temperature. Its shadow is everywhere in the flue duct of power station, the flue gas at the tail of cement kiln, and the inlet and outlet of desulfurization tower. Does it count as a device or not? Let's look down.
Classification by Industry Standard: Does it fall under "Pipe Accessories" or "Equipment"?
Look at the national standard JB/T 12235-2015 "Non-metallic Expansion Joint". The standard name says "Expansion Joint", and the catalog is classified in the machinery industry standard, juxtaposed with pumps and valves. However, in GB/T 20801 "Pressure Pipe Code", non-metallic compensators are classified as "pipe components" (that is, pipe accessories). This brings up an interesting situation: from the perspective of pipeline system, it is just a flexible section of pipeline; However, from the manufacturing and design point of view, it has independent structural design, bearing pressure calculation and fatigue life evaluation.
Metaphorically, like a turbocharger on a car – it counts as an accessory on the engine, but when you buy it separately, it's a piece of equipment. The same goes for the non-metallic compensator: it is responsible for thermal compensation in the pipeline, but in fact its skin, insulation, frame and seal have to be designed individually according to the working conditions. Have you seen which tube sells for 1500 and still have to do finite element analysis? A non-metallic compensator will do. So from the perspective of engineering procurement, I prefer to treat it as equipment. Otherwise? You buy it as a pipe fitting, but it can't be installed on site. Who is responsible?
Compared with metal expansion joints, are the "equipment properties" of non-metals weak or strong?
Metal expansion joints (such as general-purpose corrugated expansion joints and high-temperature axial expansion joints) usually only use bellows and end pipes, and their structure is relatively simple. However, the structure of the non-metallic expansion joint is more complicated: the skin is covered with at least three layers (anti-corrosion layer, airtight layer and insulation layer), the inner lining has a guide tube, and the outside has a steel frame and compression bolts. If it is a rectangular non-metallic expansion joint, the frame is still a welded part, which involves blanking, assembling, welding and airtightness inspection. Can such a set of things be called pipe fittings?
Let's talk about shopping. You can select the metal expansion joint according to the nominal diameter, pressure and compensation amount, but for non-metal expansion joints, you have to provide the medium composition (acid fog? Wet smoke?), temperature range (what is the instantaneous high temperature?), three-dimensional displacement (axial, transverse and angular), and installation space size. Here, can you tell me which pipe fitting requires such complex technical parameters? Therefore, the "equipment attribute" of non-metallic compensator is not only weak, but stronger than that of metal expansion joint. It is essentially a customized flexible structural component.
From power stations, cement to desulfurization flue gas, how to identify and select the type on site?
Non-metallic compensators used in power station industry, such as corrugated expansion joints used in power station industry, sometimes choose non-metallic, but more of them are rectangular non-metallic expansion joints used in flue ducts. When selecting the model, focus on the temperature-the flue gas temperature at the boiler outlet can reach 450℃, and the skin must be made of fluorine tape plus multi-layer ceramic fiber. Both metal corrugated expansion joints and non-metals are commonly used in cement industry, but the dust at the outlet of the preheater is large and the temperature fluctuates drastically, so the fatigue resistance of non-metals is better. Desulfurization flue gas is more typical-flue gas has high moisture content and is corrosive, and it is often used with flue gas baffle door and desulfurization flue gas baffle door. When purchasing on-site, some units classify it as "valve accessories" and some as "boiler auxiliary machines". Very few are thrown directly to the hardware vault anyway.
I have seen a power plant buy the non-metallic compensator as an ordinary pipe fitting. As a result, after the arrival, the flange bolt holes didn't match, and the skin material was wrong. Finally, it returned it and redone it. It delayed the construction period for half a month. What are you saying this isn't a device? The equipment must have technical agreement, drawing confirmation and factory inspection report. The standard of non-metallic compensator clearly requires air tightness test and withstand pressure test, and each one should be done. How can pipe fittings get this treatment?
Conclusion: Non-metallic compensators are equipment-but don't buy them as regular pipe fittings
Do non-metallic compensators belong to equipment? The answer is: in terms of functionality and how it is used, it is the device. You can go through the equipment procurement process, file according to equipment management, write technical agreements, and accept the goods. But the key is not the status, but how to use it. If you regard it as equipment, you will naturally pay attention to the selection parameters, installation specifications and later maintenance; If you regard it as a pipe fitting, there is a high probability that you will ignore the details of the installation direction, the fixed bracket setting and the skin tightness control. And those details are precisely the key to whether it can be used for its full life.
Alas, at the end of the day, the name doesn't matter, it's important not to treat it like a pipe that can bend. Next time someone asks you, "Is the non-metallic compensator considered equipment?" Let him see the test clause of JB/T 12235-light air tightness pressure test, which is enough to draw a clear line between it and ordinary pipe fittings.