1. The underlying logic of material classification: Which gear does the metal expansion joint count?
In your company's ERP system, which category does the metal expansion joint hang under? If the answer is "hardware machinery" or "plumbing fittings", congratulations, at least it didn't stray. But in reality, I have seen it stuffed into "rubber products", and some into the "valve" category-is it outrageous? What's even more outrageous is that some people bought it for power stations according to the model of "universal corrugated expansion joint". As a result, the pressure didn't match, and the scene exploded directly.
The material classification of metal expansion joints depends essentially on your management dimension. From the general direction, there are materials (metal vs non-metal), functions (compensator vs pipeline accessories) and industries (general-purpose vs power/chemical-specific). Each dimension is reasonable, but once mixed, the purchase order becomes a guessing game.
One setCorrugated expansion joint for power station industryThe material is 316L stainless steel, with a design pressure of 2.5MPa and a temperature of 600℃. If you classify it as "general hardware", the warehouse manager may put a piece with the bolt at hand, and can't find it after looking through it for a long time during the next maintenance-because no one remembers what the goods are called. However, if it is classified as "power station boiler accessories" according to industry classification, the retrieval efficiency is much higher.
Second, from the perspective of functional use: is it a pipeline accessory or a compensator? The two do not conflict
Are expansion joints and compensators the same thing or not? Before, a customer asked me, "I want to buy a compensator. If you recommend an expansion joint for me, will you make a mistake?" I directly threw the explanation in the Q&A library — —Expansion joints and compensators actually refer to different designations of the same type of equipment in industrial piping systems。 You said it was a pipe attachment? Yes, because it is installed on a pipe and is part of the piping system. You said it was a compensator? Right, too, because its core function is to absorb thermal displacement and vibration.
This characteristic determines its "double identity" in material classification. In the material codes of many enterprises, it appears under two categories: "pipeline accessories" and "mechanical compensation components" at the same time. Such asUniversal corrugated expansion jointIt can be classified as "bellows expansion joint" standard in GB/T 12777, and it can also be written as "pipe flexible joint" in the purchase list.
So, don't dwell on the name. You just have to remember: the function of a metal expansion joint is to compensate for displacement, and the installation position is on the pipe-these two points determine that its attribution is not single. If you have to choose one of the two, it is recommended to follow the industry practice: the electric power and chemical industries are used to call them "compensators" and are classified as "pipeline accessories"; However, the machinery and HVAC industries prefer "expansion joints" and are classified as "hardware machinery".
III. Classification according to industry standards: What do you say about JB/T and GB/T? You can't go wrong with referring to these
Talking about classification can't get around national standards. There are several standards related to metal expansion joints:GB/T 12777Is the general technical condition of metal bellows expansion joint;JB/T 12235Then for non-metallic expansion joints. Although the latter is non-metallic, many projects will manage metals and non-metals under one material category.
Then how to reference it? It's simple: see what standards your device performs. Such asHigh temperature axial expansion jointUsually designed according to GB/T 12777, it corresponds to "GB/T standard parts" or "general mechanical parts" in the material classification table. If the purchase order says "JB/T 12235-2015", you have to look for non-metallic or fabric fiber products, such asNon-metallic expansion joint (fabric fiber expansion joint)。
But standards can only help 60%. The remaining 40% depends on your management system. Some enterprises will putDirect buried (fully buried) type expansion jointTo "buried pipeline attachments", and putRotary compensatorListed separately under "Special Compensators". At this time, it is easy to miss the subdivision categories only by relying on standard coding.
IV. Material coding from the perspective of procurement: Why do some people classify it as "hardware machinery" and others as "pipeline fittings"?
And guess what? Same oneCompound hinge transverse expansion jointCompany A's code is FJ-001 (hardware and machinery), but Company B's code is GD-023 (pipeline fittings). There is one reason: the management caliber is different.
When most enterprises use ERP classification, they will refer to the equipment attribution department. If the expansion joints are procured by the equipment department, they are customary to classify them by mechanical components, and the coding prefix may be "M" or "05"; If procured by engineering, it tends to be classified by pipeline system and the coding prefix becomes "P" or "08". This "dual-track system" is very common, but the pit is also here-when calling across departments, there is often an oolong of "I obviously bought it, but I can't find it in the system".
How to avoid it? I suggest doing two things: first, add functional keywords to the material description, such as "metal expansion joint | compensated displacement | for pipeline"; Second, establish a mapping table to correspond the codes of hardware machinery and pipeline fittings. Don't bother, aLarge diameter thick wall expansion jointEasy tens of thousands of dollars, the return cost of buying the wrong is astonishing.
5. Product examples of this site: from general-purpose to power station-specific, to help you understand the classification boundary
It's boring to talk about theory. You can understand where the boundary of classification is by looking directly at the products on our site.
- Universal corrugated expansion joint: The most basic classification, suitable for normal temperature and low pressure pipelines, belongs to the category of "general pipeline fittings". The code is usually classified as "bellows series" under the category of hardware machinery.
- Corrugated expansion joint for power station industry: Specially used for boiler, steam turbine system, the material and design pressure are special. Such products are often divided into separate categories, called "special compensators for power stations" or "accessories for power equipment", which are different from ordinary expansion joint codes.
- Metal Corrugated Expansion Joints in Cement Industry: Wear resistant, high temperature resistant, with guide tube structure. It can be counted as "cement machinery accessories" or "pipeline accessories", depending on your company's main business. If it is purchased by a cement plant, it is more inclined to be classified as "process pipeline parts" in spare parts.
- Sleeve type pipe expansion joint: The structure is simple, used in low-pressure applications, and bellows type is completely different. Many ERPs put it under the "sleeve class" under "pipe fittings".
Can you see the way? For the same product, change the industry, and the classification logic will change. So before buying, find out the classification system of your company first, and then take a seat.
6. What are the consequences of wrong classification? A real case tells you
They are in urgent need of a batch for overhaulDouble hinge expansion joint for air-cooled island vacuum pipelineAccording to the old habit, the buyer searched in the category of "pipeline fittings", and the result was that the general axial bellows was bought back. After installation, it was found that the axial compensation was not enough, and the vacuum degree could not be hit-because the double-hinge expansion joint absorbed the lateral displacement, the axial tube could not be used at all.
Finally, it was shut down for 3 days, which resulted in heavy direct losses. The reason is that the procurement classification is wrong: he classifies the expansion joint of "vacuum pipeline special" under "general pipeline accessories", and the system won't remind you of the performance difference between these two classifications at all.
What kind of material does metal expansion joint belong to?The answer depends on your management granularity-you can think of it as a pipeline attachment or a compensator, but never think of it as "whatever it looks like".
Classification is for easy finding, but also for easy use. Before buying, it is better to ask the supplier, "Is this product consistent with the parameters of the XXX model you sold before?"