What are the standard English names of metal corrugated expansion joints? Don't call it wrong again
Two days ago, I met a customer and sent an inquiry sheet writing "Metal Corrugated Expansion Joint". At first glance, there was nothing wrong with it, but the foreign engineer was immediately stunned when he saw it-Corrugated is the corrugation of Corrugated cardboard, which is wrong when used on pipeline compensators. The correct way to say this isMetal Bellows Expansion Joint, or simplyExpansion Joint、Bellows。 Which one is the most standard?
In the EJMA (American Association of Expansion Joint Manufacturers) standard, the core term isBellows, referring to the bellows body. WhileExpansion JointIt is an assembly, including bellows, end pipe, guide tube, tie rod and other accessories. So you say "I need a bellows for a 12-inch pipe", and foreigners know that you want a bellows body; You say "I need a metal expansion joint for high temperature" and they know you want the whole set. When we communicate with our own people, the most secure method for metal corrugated expansion joints isMetal Bellows Expansion JointNone of the words must be missing, but they are often abbreviated in spoken language asBellows Expansion Joint。
English Expression of Different Structural Types- -How to Distinguish General Type, High Temperature Type and Pressure Balance Type
The structure type is confused, and the quote can be two or three times worse. Such asUniversal corrugated expansion jointEnglish is calledUniversal Expansion JointOrSingle Axial Expansion Joint, it can only absorb axial displacement. But if you use it on a high-temperature steam line, you have to chooseHigh Temperature Expansion Joint, usually with thermal insulation and heat-resistant filler. Once, a power plant purchased the high-temperature type as "High Temp Bellows", and the manufacturer reported the ordinary type, which leaked after two months of on-site installation-this is the price of inaccurate terminology.
Another examplePressure balanced expansion joint, English isPressure Balanced Expansion Joint(PB for short). It comes in two kinds:Straight Pipe Pressure Balanced Expansion Joint(Straight Pipe Pressure Balance Type Expansion Joint) andElbow Pressure Balanced Expansion Joint(Curved Tube Pressure Balance Type Expansion Joint). The core of the pressure balance type is the built-in pressure balance bellows, which can offset the internal pressure thrust and is suitable for large diameter and high pressure pipes. We have "straight pipe pressure balance expansion joint" and "curved pipe pressure balance expansion joint" in our product library, and the English terms should be correct.
AndCompound hinge transverse expansion joint, called in EnglishDouble Hinged Lateral Expansion JointIt relies on two hinges to absorb lateral displacement. Commonly used on air-cooled island vacuum pipelineDouble hinge expansion joint(Double Hinged Expansion Joint). You see, different structures, the English prefixes are different: Axial (Axial), Lateral (Lateral), Angular (Angular), Universal (general). Figure it out, send an inquiry form to avoid overturning.
Comparison of Chinese and English Terms and Parameter Interpretation of International Standards (EJMA, ASTM)
EJMA is the "Bible" of the expansion joint world. It writes out the terminology, design method, and fatigue life calculation clearly. Such asBellows Spring Rate ( Bellows spring stiffness), unit N/mm, this parameter directly determines the pressure bearing capacity and displacement compensation amount of the expansion joint. Our question and answer specifically talked about "the stiffness and calculation formula of bellows", which engineers love to ask.
ASTM A240 is the common stainless steel plate standard, and the grades of 304 and 316L are in it. However, it is noted that the corrugated pipe material for the expansion joint alsoInconel 625、Hastelloy C276These superalloys correspond to ASTM B443, B575. When purchasing, you have to say "Material: SS304L per ASTM A240, bellows thickness 1.5mm" so that foreigners can confirm it.
We have it on our websiteNational standard for non-metallic expansion jointsYes JB/T 12235-2015, but international projects usually refer toEJMA 10th Edition。 Such asDesign pressure (Design Pressure)、Design temperature (Design Temperature)、Number of CyclesThese parameters must be written in the inquiry form. The EJMA standard has aFatigue Life Curve ( fatigue life curve)According to the number of cycles, the allowable displacement is inversely inferred-this technical point is not understood by most purchasers, but if you know it, you can avoid premature failure caused by too small selection.
Common English pitfalls in purchase inquiry: expansion joint vs compensator, metal vs corrugation
"Is the expansion joint the same as the compensator?"-We answered in the FAQ: Essentially the same, but customarilyExpansion JointMore commonly used in metal products,CompensatorSome more in rubber or non-metallic fields. If you search for "rubber compensator", you will find rubber compensator, and if you search for "metal expansion joint", you will find metal corrugated expansion joint. So don't mix it up, otherwise the supplier will give you the error type.
Some people write "Metal Corrugated Pipe", which in engineering refers to Metal Corrugated Pipe (such as for threading cables), not compensation equipment. There is also the one that says "Flexible Joint", which is a Flexible Joint. It may not even have corrugations, just a rubber Joint. What you wantMetal corrugated expansion jointMust beMetal Bellows Expansion Joint, a word cannot be less.
How to avoid pits? Directly on abbreviations:MBEJ。 Although it is not universal, it can be seen in the internal documents of many engineering companies. If you send an inquiry, writing "RFQ: Metal Bellows Expansion Joint, DN200, PN16" in the title is a hundred times more reliable than writing "Flexible Connector".
Common English abbreviations and model interpretation (single axis, double hinge, direct burial, etc.)
There is a lot of information hidden in the product model. Such asUniaxial axial typeLabeled asAX(Axial),Compound hinge transverse typeLabeled asDH(Double Hinged). Our products are "Air-cooled Island Vacuum Pipe Double Hinge Expansion Joint", English isVacuum Double Hinged Expansion Joint for Air Cooled Island。 Pressure balance type abbreviationPBStraight Pipe Pressure Balanced TypeSPB(Straight Pressure Balanced), Curved tube pressure balance typeEPB(Elbow Pressure Balanced).
AgainDirect buried (fully buried) type expansion joint, called in EnglishBuried Expansion JointOrUnderground Expansion Joint。 This product has an anti-corrosion layer and insulation layer on the outside, which is directly buried underground and does not need an inspection well. Remember to add when writing an inquiry "for direct burial service".
AndSleeve type pipe expansion joint, in EnglishSleeve Type Expansion JointIn fact, it is not a corrugated structure, which belongs to the sliding seal category, but many customers also classify it into the expansion joint category. That's what the "sleeve-type pipe expansion joint" on our station means.
Necessary for technical communication: English keywords such as installation, stiffness, guide tube, etc.
To talk to foreign engineers about technology, you have to be able to say these words:
- Spring Rate ( stiffness): Unit N/mm, determines the ability of the expansion joint to resist deformation. The lower it is, the softer it is, and the compensation displacement is large but the pressure bearing capacity is weak. Our FAQ is dedicated to "Bellows Stiffness and Calculation Formula".
- Flow Liner ( Guide tube): Mounted on the inner wall of the bellows to reduce the scouring of the corrugation by the medium and reduce the flow resistance. Also calledInternal SleeveOf. We wrote about the function in the question and answer (see "Specific function of expansion joint guide tube"), so I won't be long-winded here.
- Installation Pre-compression: Many axial expansion joints are pre-compressed when installed to compensate for thermal elongation. English speak "Pre-compress the bellows by 20mm before welding".
- Limit Rod ( Limit rod): Prevent excessive stretching or compression of bellows. Do not remove limit rods before system cool-down.
- Cold Pull ( Cold tight): Equivalent to pre-stretching, used to compensate for cold shrinkage. Used when writing technical briefings "Cold pull value: 15mm".
Oh, by the way, andBellows Effective Area ( Effective area of bellows)This parameter is used to calculate the pressure thrust, and the formula is F = P × A_eff. Must be used when selecting the support and fixing the bracket.
You see, metal corrugated expansion joint English is not so mysterious, but if you use a wrong word, you may buy the wrong thing. Next time you send an inquiry to a supplier, you might as well check it against this article-it saves time and money, and it appears professional.