Expansion joint tie rod

This post was last edited by ylb913 on 2016-1-8 at 20:37. Used for setting limits during operation, as well as for fixing during transportation and installation. In practice, the management during operation is not very strict; many devices lack limit nuts and are simply left loose. But I’ve also seen cases where there is a nut at each end at the time of manufacturing, which is fixed in place to serve as a limit. But during the installation process, at our site, due to changes in the manufacturing process, when the old pipelines were removed, the construction team said they failed to take proper care of protecting and securing the expansion joints. As a result, the expansion joints became bent at 90 degrees; they were very panicked at the time (though I didn’t see it with my own eyes). Since those expansion joints still needed to be used, no issues were detected during the reinstallation through dye penetrant testing, and they are still in use today. In total, they have been in use for 14 years, with an additional 6 years likely passed since they were stored.

If the nut is tightened while in operation, the expansion rod will break; I’m not sure what the standard term for this is

We have experienced one instance where the limit nut came loose. Each expansion joint has its designated pressure level and range of expansion; when the pressure inside the pipe exceeds this designated level, the expansion joint expands. At such times, the limit nut is loose, but even with slight expansion, the nut still serves to limit movement, thereby protecting the expansion joint from damage. When the pressure inside the pipe **exceeds the design pressure – which is exactly what happens in our case – the nut cannot withstand the tensile force exerted by the expansion joint, and it will pop out; as a result, the expansion joint gets damaged, and its elastic capacity becomes zero. This is how I understand it. I hope those with more expertise can give me some guidance:victory:

Transportation struts and limit struts are not the same; for expansion joints without internal pressure, the struts serve only as a protective measure during transportation. After installation and before operation, these transportation struts need to be cut or removed. The tie rods used for limiting movement ensure that the internal limit nuts remain tight during transportation and installation, thereby preventing the expansion joint from deforming. However, before operation, these nuts need to be loosened, and external nuts and washers are used to allow the expansion joint to absorb lateral thermal displacements. The question raised by the poster needs to be clarified: is this rod a transport rod or a limit rod? If it is a transport rod, then it being unable to break is abnormal; if it is a limit rod, I think it’s actually very difficult to break it – usually, the expansion joint deforms first. Of course, if it is indeed the limit tie rod that is broken, it still needs to be replaced, and attention should be paid to the external nuts and oval washers – they are not ordinary flat washers and nuts.

Some tie rods can be removed after operation, while others must not be removed; it depends on the specific type of expansion joint.