Regarding the thickness of the saddle pad
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In NB/T47042, regarding the reinforcing role of the saddle gasket, it is required that the thickness of the gasket be no less than 0.6 times the thickness of the cylinder; it is also stated that generally, it should have the same thickness as the cylinder. So, is it feasible if the thickness of the pad for the standard saddle is greater than the wall thickness of the cylinder? Is it useful for checking the circumferential stress?
According to NB/T47042, by using a standard saddle, the calculation of the saddle’s strength can be omitted, and thus there are no issues.
It’s fine if it’s thicker; it just increases the cost. It also doesn’t look good if it’s too thick; it makes the head appear light and the feet heavy, resulting in a mismatched appearance.
I usually choose according to the standards and only approve it after verification.
Thicker shims are certainly possible, but they are not aesthetically pleasing and are of no use for checking circumferential stress.
This post was last edited by Chen Xiaoxi on 2017-8-11 at 11:06. I came across a statement in an article saying that if the shimming plate is too thick, it will increase the circumferential stress values at the corners of the saddle area (that is, in cases where the shimming plate serves to provide reinforcement), which is not favorable for large-diameter thin-walled cylinders.
According to formula 16-23 in NB/T47042, I believe that using thicker shims has no effect on reducing circumferential stress. I don’t understand why it increases; could it be that the local stiffness has increased, and since the weld leg height has also increased, this makes local deformation less likely?
After reading the description carefully, I think it seems to state that when the shims serve a reinforcing purpose, the wrap angle needs to be increased by 12 degrees. That is, the gusset plates with a 6-degree arc length on each side form a cantilever structure, which not only increases the support length but also allows for a small amount of deformation. If the shimming is too thick, it loses its ability to deform elastically and behaves like a rigid support; this leads to stress concentration peaks at the edges on the cylinder body (circumferential stress). I’m not sure if I understand correctly:$。