Customization of high-quality metal expansion joints: From working conditions to factory delivery, these five steps determine success or failure
A few days ago, a customer called and asked: How much is the expansion joint per meter? I said OK, you can tell me the working conditions-what medium is going in the pipeline? What's the temperature? How stressful? What is the displacement amount? The opposite side was silent. This phone call is basically unable to continue. Customization of high-quality metal expansion joints is never as simple as quoting a price. It is calculated, selected, welded and tested, and finally it has to be installed correctly.
Settle accounts before customization: media, temperature, pressure, displacement, none can be missed
Is the medium corrosive flue gas or high temperature steam? Do you want to choose PTFE-lined hoses? Or a nickel-based alloy that resists high temperatures? When the temperature exceeds 400℃, the material creep problem must be considered. The pressure determines the wave number and the number of layers, and the displacement determines the wave height and wave distance. If you don't give me these numbers, I really can't calculate them. And guess what? Some customers bring a drawing, and the medium column reads "flue gas"-flue gas is different from flue gas. The wet flue gas from the desulfurization tower contains chloride ions, which can chew through 304; Boiler tail dry flue gas abrasion and another talk. Customization with unclear media components is basically equivalent to letting the manufacturer blindly guess. Who dares to take it?
Structural selection Don't pat your head: axial, transverse or angular? Look at displacement and space
It is also a metal expansion joint, the general corrugated expansion energy saving absorbs axial displacement, the external pressure single axial expansion joint is more suitable when the space is limited, and the compound hinge transverse expansion joint is specialized in treating transverse displacement. There are many pipeline turns and compact space, so the pressure balance type of curved pipe and the bypass pressure balance type of double straight pipe are the correct solutions. Let me ask you rhetorically: Is there enough installation space on site? Some people only look at the paper data when choosing a model, but as a result, the expansion joint arrived, blocked by the column next to it, and the hinge couldn't be unfolded at all-who carries the pot? Before choosing, take a tape measure to the site to measure it, which is more useful than anything else.
Material and process: Corrugated pipe is not a "wrinkle of iron sheet"
The fatigue life of 304 and 316L can be different under the same working conditions, and Inconel is another order of magnitude. Material grade, thickness, number of layers, wave height and wave distance, each item is actuarially calculated, not determined by patting the head. Hydroforming and roll forming have their own applicable scenarios, and the flaw detection ratio and heat treatment process of longitudinal seam welding directly determine the service life of bellows. To put it bluntly, high-quality customization is expensive on these invisible parameters.
The deflector is not just welded onto the block plate. It should be diverted, wear-resistant and erosion-resistant, and in some working conditions, it has to open holes to relieve pressure-the direction, length and material are all particular. Where did you say the money went? Just spend it in these details.
Inspection before leaving the factory: No report, equivalent to streaking
Regular manufacturers will provide pressure test, air tightness test records, as well as measured data of bellows stiffness and fatigue life. You take the metal expansion joint weight gauge and check it: Is the wall thickness right? Has the flange thickness shrunk? Is the flange bolt hole spacing matched? It is useless for the sales to say that "it meets the standard". Spread out the inspection report and read it item by item. Nowadays, only those who dare to hand over the complete report to your manufacturer can have the confidence to customize high-quality metal expansion joints.
Installation and after-sales: pull rod, guide tube, pre-deformation, don't step on these pits
If you install it wrong, no matter how good the customization is, it will be useless. How to adjust the tie rod nut? What is the amount of pre-deformation set? Is the guide bracket distance sufficient? These details directly affect the service life. The medium flow direction arrow must be consistent with the flow direction of the pipe. If the direction of the guide tube is installed backwards, wear and vibration will immediately come to the door. I think of something: after installing the expansion joint in a chemical plant, the transportation tie rod was not disassembled, and the bellows was fatigued and cracked after running for a quarter. When the manufacturer went to see, the tie rod was still locked tightly-who do you blame?
So, customization is not just paying for it and delivering it. Installation disclosure, technical support and after-sales response have to be asked in advance. It is better than anything to find a manufacturer that can complete these steps.