Is thermal compensation needed for pipes at normal temperature?
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On pipe galleries, heat pipes require mounting frames and thermal compensation; so is it necessary to do the same for pipes at normal temperatures? If necessary, what determines the amount of compensation? Since the operating temperature is the same as the ambient temperature, it seems that Caesar II can’t perform the calculation Some of the pipes I saw at normal temperatures had π-shaped bends, but there were no supports between those π-shaped bends; the amount of compensation seemed to be estimated based on experience. Is it useful to have a compensating bend without a fixing bracket like this? Additionally, if temperature-controlled pipes are not compensated, do they require a horizontal thrust?
Should this post be classified under the pipeline section or the pipeline stress section? If it’s in the wrong section, please ask the moderator to move it
The last edit to this post was made by ylb913 on 2016-7-6 at 20:09. As an example, low-pressure gas pipelines operate at normal temperatures and don’t even have insulation; but what happens when work needs to be done on them and welding is required? In any case, our factory always uses steam for purging. There was once an incident, at least over twenty years ago, where steam cleaning was used; it is said that pipeline expansion and deformation caused the pipe supports to collapse, and the pipes to hang down from those supports.
Yes, but that’s another question: do the pipes that need to be purged from time to time require compensation, just like steam pipes? If I do it, I won’t blow it for a long time – it’s too wasteful, and the owner isn’t very happy about it either ； If I don’t do it, what will I do when I need to blow? I also posted a question about this and didn’t get very good answers; it seems that the decision is made based on experience. The compromise answer given was to not do it, but to increase the temperature slowly during purging. Returning to this question, if it is a regular, unpurged pipe at room temperature with a long straight section, is thermal compensation necessary? The examples I saw on site showed that it is necessary to do this, but there are relatively few such cases; moreover, no fixing frames were used. According to our stress specialists, if fixing frames are used for pipes at room temperature, the thrust generated will be very high. But is a π without a holder useful? How is his compensation amount determined? When building pipe galleries, is it necessary to model pipes at normal temperature in the stress calculations?
This post was last edited by ylb913 on 2016-7-6 at 20:21. The low-pressure gas pipelines in our factory are all located on the top layer of the pipe tray; they form a continuously ascending structure without any vertical up-and-down bends similar to those found in gantry systems. Therefore, horizontal U-shaped bends are used instead. The question is: if the natural bend of the pipe is sufficient for compensation, then there’s no need to add a horizontal U (using a tablet, I don’t know how to type “pai”).
Normal-temperature pipelines do not require π-bends; the thermal displacement is given by △L=αtL△t. Since there is no temperature difference in normal-temperature pipelines, the thermal displacement is essentially 0, so whether a fixing bracket is used or not makes no difference
Normal-temperature pipes are not taken into account in the calculations; in a previous project, all such pipes didn’t even have fixing frames – load-bearing frames and guide frames were used instead throughout