For connections on storage tanks with a DN300 diameter or larger, should you choose hoses or expansion joints to prevent settlement?

What you say makes sense. I think metal hoses should be used for pipelines with a relatively small diameter ； For large-diameter pipes, expansion joints are used; however, these joints must be installed vertically, as storage tanks do have a certain height.

Well, that’s also a good approach. By changing the horizontal radial displacement to a vertical one, it becomes a vertical axial displacement, which allows for better utilization of the advantages of expansion joints. @68ZCW @654262293 @LQ198619 @CatalystYiSu @CrazySnail @WiseMan @StorageAndTransportEngineer @RefineryWorker @CentralPlainsNative @RefineryWorker @leo_0088 @ZDICK888

The experts in the group also agree with your view; they just say that an angular expansion joint can also be used. When the vertical distance is insufficient, could it not be arranged at a 45-degree angle?

I think it’s better to use a metal flexible hose; after all, the amount of expansion of an expansion joint is fixed； Regarding the issue of \"the metal hoses being unreliable\", those that are faulty can be replaced during maintenance.

According to clauses 4.0.7 and 4.0.8 of SY/T4073-1994 \"Selection Standards for Metal Hoses and Bellows Compensators for Seismic Resistance of Storage Tanks\", both metal hoses and bellows compensators are used to compensate for lateral displacement, while axial displacement is compensated by the layout of the pipelines.

“Some experts argue that expansion joints are primarily used to counter axial displacement, while settlement represents radial displacement; therefore, it is inappropriate to use expansion joints for large-diameter pipes. ” Experts who say such things really should have their title as experts revoked. There are many types of expansion joints, some of which absorb axial displacement while others absorb lateral displacement. If it is settlement, then using large tie rods or expansion joints with high hinge flexibility will suffice to absorb the lateral displacement. And it is also a relatively common form.

It should be determined based on the medium in the tank; using flexible hoses is more cost-effective and economical, as expansion joints are too wasteful.

An expansion joint is installed on the outlet pipeline of the heat transfer oil pump. Experts who calculate thermal stresses say that this component generates a blind plate force, making it more dangerous than straight pipes. I’m not very familiar with stress issues and don’t know how to answer this; as a layperson, I’d like to ask: then what is the purpose of inventing such an expansion joint?

Everything has its advantages and disadvantages. The advantage of expansion joints is that they provide an elastic element with very low stiffness, which allows it to absorb thermal displacement in the pipes. Increase pipeline flexibility and reduce thermal stress in the pipelines. Disadvantages of expansion joints: they are prone to leakage, and should be used with caution in environments involving flammable and explosive substances. There are a wide variety of types, which impose high requirements on the layout of pipes and the installation of supports; expertise is necessary to ensure everything is done properly. As for the blind plate force mentioned by experts, expansion joints used in free-floating applications do have such a force, and additional fixing supports are required to address this issue. However, for constrained expansion joints, this blind plate force can be balanced by itself, and it does not exert any force on the external pipes and equipment.

So can an expansion joint with tie rods offset the blind plate force on its own? The image is from the Internet