Differences in the tuning of hot-zero suspension springs and cold-zero suspension springs
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This post was last edited by wangzhanzhuce on 2020-1-11 at 11:13. Dear experts: After the springs have been installed on site, the hydrostatic testing and insulation work have been completed; now we are ready to remove the pins from the springs and adjust the load under cold conditions. However, there are two types of springs on site – ones for zero adjustment in the cold state and those for zero adjustment in the hot state. I would like to ask: what is the difference between these two types of springs when performing adjustments in the cold state? Here are photos of the spring identification tags: (From the appearance, there is no difference between springs that are at zero tension when cold and those that are at zero tension when hot; it’s just not clear what differences exist in terms of spring adjustment between the two.)
Construct in accordance with the spring installation diagram, which should indicate the direction and displacement of cold-state adjustment for each spring. The spring installation load is determined during calibration; once the pin is removed, it becomes a cold-state load. At this point, it is important to check whether the spring’s scale matches the design specifications, and if there is a significant error, the design team should be consulted. Cold-state zero hanging and hot-state zero hanging are two approaches to pipeline stress calculation, not two different types of springs. Generally, the spring used for cold-state zeroing requires little adjustment in the cold state – so little that almost no adjustment is needed – but it does not perform as well under stress when the pipeline is in a hot state. Hot-zero suspension provides better stress resistance when the pipeline is hot, but the spring requires more adjustment when it is cold. In fact, when we issue the spring installation drawings, we don’t specify the method for leveling; the installation party should just carry out the work as required.
Hello, for those springs that are set at the zero position in the hot state, after the pipeline insulation is completed, is it necessary to adjust the pointer just like with the springs that are set at the zero position in the cold state, so that the pointer points to the cold-state value?
I’m puzzled as to why you are more familiar with zeroing in the cold state; under normal circumstances, heat pipes are generally designed for zeroing in the hot state. By adjusting the pointer, you probably mean setting the spring to its compressed value, which is the installation value. Also, usually installation diagrams are sent to the manufacturer during procurement, who then adjusts them at their factory. After all the checks related to water pressure and the like are completed, the spring pin is removed; the spring then takes effect and starts adjusting the force acting on the pipes, and it is at this point that the cold-state values are obtained.
Because the vast majority of springs here are at a cold-zero setting, with only a small portion being at a hot-zero setting. So, I want to know how to adjust the cold-state value of a spring that is in its hot-state zero position, that is, to adjust it to a compressed state, after the pipe insulation is completed.
Because the vast majority of springs here are at a cold-zero setting, with only a small portion being at a hot-zero setting. So, I want to know how to adjust the cold-state value of a spring that is in its hot-state zero position, that is, to adjust it to a compressed state, after the pipe insulation is completed.
How are you installing the springs that are at zero tension in a cold state?
For springs that are in a cold, zero-tension state, the spring pins are not removed before insulating the pipes； After the pipeline hydrostatic test is completed and insulation is applied, remove the positioning pin of the spring. If there is a change in the spring load, it is possible to adjust the spring’s locking nut or flange screw, etc., in order to set the spring at the cold-state pointer position. This is the cold-state adjustment.
This is the standard procedure for installing variable springs. Whether it is hot-zero hanging or cold-zero hanging, it is installed in this way. I have already said that hot-zero hanging and cold-zero hanging are issues to be considered in the design. In terms of the installation phase, the spring used for hot-zeroing has a larger adjustment range in the cold state, whereas the spring used for cold-zeroing has a smaller adjustment range in the cold state.