I have a question regarding the spring bracket. Please advise

This post was last edited by macjordan on 2011-6-11 00:45. Reply to 1# zhgf86: The springs in spring supports and hangers are all under compression; just search for sample materials from spring support and hanger manufacturers online, and it will become clear right away. CAESAR2 calculates the displacements and operating loads at the spring supports and hangers by considering the operational conditions of the entire piping system. Then, based on the spring standards you choose, it selects springs with the appropriate strength and stiffness, and finally uses the stiffness of these springs to determine the installation loads. These data are provided to the spring manufacturers, who then use information on displacement changes, load variations, and load ranges to produce a qualified spring. If the displacement at the pipe spring support points is upward, then the installation load is greater than the operating load ； Conversely, if the displacement at that point is downward, then the installation load is smaller than the operating load. Whether a spring bracket or a hanger is chosen, the direction of the force on the spring remains the same: downward. For thermal zeroing, find sample data from a spring manufacturer. First, select a spring that can withstand the operating load based on that load; it’s best if the operating load falls in the middle of the spring’s load range. Then determine what the installation load corresponds to at that displacement. If the load variation is large, choose a spring with lower stiffness (so that the load variation is smaller for the same displacement). The installation load and the operating load need only differ by no more than 25%; it doesn’t matter if one is higher or lower, as long as the support for that particular piping system can handle it. Springs are identified by two markings; one marking is used to distinguish the load ranges that each spring can handle, that is, to determine the strength of the spring. A label determines the range of variation in the spring load for the same displacement, that is, the stiffness of the spring.

Reply to 2# macjordan: Thank you very much for your reply. I have another question – when is it generally possible to remove the pin of the spring? Is it in operational status or installed status? If the pin can only be removed while it is in operation, then what supports the weight when it is installed?

This post was last edited by macjordan on 2011-6-11 00:53. Reply to 3# zhgf86: The spring pin is removed while it is still in the installed state, because the factory determines the force exerted on the spring based on the installation load specified in the spring data sheet. If you calculate it accurately, the pin can be pulled out easily. Once the plant is started up, the temperatures of the piping systems and the equipment connected to them reach the operating temperature, causing the stresses on the supports throughout the piping system to be redistributed.

Reply to 4# macjordan: Do you mean that the position at which the pin of the spring gets stuck is the force exerted on the spring when it is in its installed state? Also, you mentioned using stress analysis software to determine the forces acting on the spring in its hot state and cold state. So what should be done if the forces on the spring in these two states differ by more than 25%? I think there’s some rule stating that the difference in stress between the cold and hot states shouldn’t exceed 25%, right? Can this be submitted to the manufacturer? PS: 1. You mentioned the force on a hot spring and the force on a cold spring; in stress analysis, one is the result of considering temperature effects, while the other is the result of not considering temperature effects, right? 2. I remember that in a book, the calculation for springs was done by first determining the force acting on the spring in its hot state, and then using a table based on the displacement to find the force in its cold state. What is the difference between this method and the one you mentioned?

This post was last edited by macjordan on 2011-6-11 00:51. The plug gets stuck during installation under load; it is removed after the hydrostatic test is completed. With your manual calculation method, if the value exceeds 25%, don’t even consider giving it to the manufacturer; it’s recommended to use a spring with lower stiffness or a constant-force spring (with zero stiffness). In the cold state, it only bears weight. The situation in the hot state is more complex: the additional displacement at the pipe ends, along with the thermal expansion of the pipes, causes vertical displacement of the pipe at the spring point, which in turn results in changes in the force exerted on the spring depending on this displacement. We use C2 software to calculate the installation load, operating load, and spring displacement, and provide these values to the manufacturer, who then creates a spring with the appropriate stiffness and strength. If one selects a spring with a certain stiffness, the calculated results may differ from the actual cold-load exerted on the pipe; in such cases, the pin will get stuck and be difficult to pull out. But after it is pulled out, it’s fine if the mounting load of the spring is slightly higher or lower

As a supplementary note, the pin is removed after installation and hydrostatic testing, before the pipeline is heated. The spring selection method shown by the original poster was used when calculation software was not yet advanced, and it relied mainly on manual calculations for selecting springs. Now, it is the calculation software that selects the appropriate type automatically. If the load variation rate is set at 25%, none of the springs can meet the requirement that the load variation rate be less than or equal to 25%; in such cases, the software automatically chooses a constant-force spring.