When the ratio D/6 for 2 inch sch. XXS pipeline is estimated, it was found greater than the pipeline thickness , which implies that more consideration should be required rated to theory of failure as in ASME B31.3. So I want to know, the reason to consider the ratio D/6 as the limiting ration in such calculation
B31.3 uses simplified equations assuming thin walled pipe. The Section 304.1.2 of ASME B31.3.defining the limits where the thin walled pipe equation is no longer correct. This is because the variation of stress through the wall of the pipe is different for thick pipe. According to this provision D/6 divides the thick and thin pipes. The stress distribution through the wall thickness is not uniform as it is assumed in thin-walled pipe. For Thick pipe one needs to use Lame’s equations for thick cylinder, which is also valid for thin pipes. If the nominal wall thickness is greater than D/6 you need to use a modified value for the Y factor and pay particular attention to fatigue, thermal stress and the actual failure criterion.
As per ASME B31.3:
● For t t and P/SE < 0.385 you have to use the equations for thick wall (high pressure). UK codes for pressure piping are based on thick pipe theory which is valid for all thicknesses.
Very thick pipes are rigid and any constraint causes a lot of stresses due to the thermal effect leading to excessive deformation or/and fatigue. B31.3 is warning against such possibility.
Thanks Sirous , I want a clarification about your appreciated answer ,
Firstly, as per ASME B31.3: ,for, t ≥ D/6 : Y = (d + 2c)/(D+d+2c), it is not clear in the code that is still valid to use the thickness equation only with calculated Y coefficient without changing in the remaining terms ,or there is another equation ,and if not can you please send me UK code covering this issue?.
Currently I am working on Computational Fluid Dynamics and Heat Transfer study of a mixing T junction. I have carried out analysis and have obtained results for the same. My query is I want to convert the model made into 1 part 1 body instead of i part 2 body so that the grid generation becomes feasible and smooth.
Please guide me for the same by describing the steps against how to overcome the problem.
By any cad software or Ansys workbench through unit in boolean tool
sir i have already used bolean tool, thats convert the model 1 part and 2 body otherwise model is 1 part 3 body.
inner part i used frozen and outer part solid. so inner part i used voolean tool. if i again boolean tool use conver a model in single body without wall.
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