Consider a 2 meter SS316 tube of some diameter (say half inch). This tube is kept inside a partitioned rectangular container as shown in the attachment. There are about 3 partition plates which makes each compartment to be 0.5 meter length. Hot oil of about 300 degree Celsius is flowing through the tube which makes the temperature of the SS316 tube to be about 280 degree Celsius. The thermal expansion coefficient of SS316 is 16 μm/mK. Now my question is whether this is due to high temperature, the linear expansion of the tube will affect the welds made between the tube and the partition plates?
I think for sure that the linear expansion will effect the weld joint as both of them will be having different coefficient of expansions.
@ Harpreet - Everything is stainless steel - tubes, partition plates and even the weld (ie. weld rods)
Yes you are right Hakeem, however, i think that during welding the properties of the steel will affected. As a result, you could expect different properties for both the bulk and weldment.
Yes hakem sahb definitely linear expansion also effects on the weld. And this temp: is also sufficient to creat linear thermal expansion and that expansion can damage the weld of pipes.
As in question u have not mentioned about filler material used for welding, we have to assume few condition's
1. filler mat is same.
2. proper heat treatment.
3. neglecting the 3D thermal stress
4. Homogenus and isotropic.
If above all are true then no stress will induce on free joint made.
But in practical case in weld area the grain size vary and any above assumptions will not be followed, so in major Radial thermal stress will be more(as radially length of weld is piD), but linearly will not make much differance.
Dear Hakeem Sahib,
Yes it will affect the weld joints... Because of the metallographic changes during welding process, weld throat material thickness etc.. However, whether to model weldments or not depends on the functional needs and research interest... If the focus is on weldments and consequent evaluation of checking weld strength, one should considering modeling welding, though complex, but it appears from figure one can explore Bi-Axial Symmetry... If weldment is not the interest, we are making an assumption weld is not failing, then we can avoid all issues related to Modeling weldments.
Regards
Ramanan
The thermal expansion will be grater in the tube that in the square section. That is because there is a thermal gradient between them, so this diferrents lenghts between sqare and tube, will increase the stress in the welds between them. Evan more the stress in the tube will be dependent on the external temperature of the square section. So the stress and the wled resistance wil depend on the material and thermal status of the every part, not on the filler material or so.
if the materials have the same coefficients then there will be some reduction in stress due to t change 1st off. This is level 1 rule.
Because strain due to Delta T is non linear due to geometry some locations will experience stress values that are not linear.
Detailed stress analysis is required. FEA, best.
Heat treatment of components is used to "stress relieve" for this reason. - to let the components - relax. allowing higher stress values for critical locations. in design.
I have got an alternate idea - instead of welding the partition plate to the tube, i am thinking of pouring a small amount of concrete (say about 5 cm). So in place of a single partition plate, we need 2 partition plates and concrete. Any comments on this ?
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