Questions about saddle-type supports when used for pipe supports
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There is no calculation method for the supports of large-diameter thin-walled circular flue ducts in China. The power industry currently uses manuals from decades ago, which do not include calculation methods for local stress.； I used excel to sort out the saddle design methods of NBT47042-2014 "Horizontal Container" before, but I have been thinking about this problem these days.: Pipes generally do not have heads. When saddles are used in pipe structures, the beneficial effect of the heads should not be considered. The K6 value should be in the column of A/Ra≥1. ； Formulas 18, 21, and 23 all have the parameter cylinder length L, and L only has a great impact on the results. For the piping system, this is more troublesome. How to determine the value of L? Find the length of the straight section where the support is located?
The K6 value is taken based on the condition that A/Ra is greater than or equal to 1.
Press L/R>8, the length value is meaningless, there is no need to determine the length.
Press L/R>8, the length value is meaningless, there is no need to determine the length.
What if L/R is less than 8? How to get the pipeline?
This post was last edited by Gu Xicun on 2018-11-29 15:36. When designing and calculating the saddle, the vessel considers the calculation length L. The pipeline considers the span spacing. It is recommended that the pipeline's own design standards be used for design calculations. For details, please refer to "Petrochemical Process Pipeline Design and Installation"
I think it is wrong to calculate the pipeline saddle according to the saddle design method of NBT47042-2014 "Horizontal Vessel". This is inconsistent with the mechanical model of the saddle. It is not simply a double-hinged fulcrum extended beam that bears uniform loads. The force and moment generated by the load of the pipeline system at the saddle will greatly affect the local load-bearing capacity of the pipeline. We use stress analysis.
This post was last edited by FMSD on 2018-11-29 16:40 This is a non-standard pipe, not a simple one that is slender. The general design of supports and hangers for slender pipes does not require local stress to be considered. The span of the pipe support and hanger is also easy to determine. Let me show you my picture and you will understand.
This post was last edited by FMSD on 2018-11-29 17:03 Regarding the load of the saddle, it can be obtained using pipe stress calculation software or finite element software. Of course, if the saddle is torsion, it may exceed the range of the saddle.； Now I just try to see if there is no torque and see if I can use the saddle calculation method to calculate it.
The main problem with the flue duct is its expansion and contraction. For extremely long flue ducts, expansion joints should be considered. Since the pipe is not load-bearing or under pressure (or has a small negative pressure state), the bracket or support should be able to bear the weight of the pipe itself. So, is this a physical problem?