Continuous Beams

Could you supply a drawing or schematic with details of existing structure? and pressure vessel parameters of intended use together with weight and pressure/temp of operational load characteristics, metal types and grades used in construction....

This depends on the stiffness of the baseplate compared with the stiffness of the vessel base. If the baseplate is flexible it will deflect between the legs under less than the distributed load so that the load will concentrate at the legs.

Check with the vessel designer if the vessel needs full circle support or if the four locations are enough.

If the four locations are okay, I would consider the ring to consist of a stiff plate at each leg with arcs between to laterally brace them.

If the vessel needs 360 deg. support, you need a different scheme.

Dear All,

Thanks for response.

Attcahed herewith is the sketch below explaining more details.

Also attached skirt detailed sketch

Tank diameter is 5800 mm height is 16700 mm

design pr at top : 1.5 bar (g)

liquid sp gravity : 1

Hope this helpd

Regards

ASD23789

Which/where is the annular baseplate? Is it horizontal (like a big washer) between the skirt support and the tops of the legs? If so I don't think it contributes much. The stiffness of the skirt, even though it's quite short, for bending moments in the vertical plane is likely to exceed that of the baseplate. In effect you've got something between a UDL and fairly localised loads on the vessel cone at each leg location. As passingtongreen said in #2, it's up to the vessel designer to say whether it can take these loads.

Dear Codemaster Sir,

" Which/where is the annular baseplate? Is it horizontal (like a big washer) between the skirt support and the tops of the legs? "

Yes it is the like a washer between the skirt support and the tops of the legs

Dear passingtongreen Sir,

In your post you expressed strong reservation against assuming the beam as a continuous beam supported at intervals. Please explain.

Thanks for your support.

Regards

ASD23789

I am disturbed that you didn't see what I meant.

The vessel is very stiff in the vertical direction, your ring plate is not. If you insist on using uniform load around the ring, it will get very thick, and still deflect more than the vessel can between the posts.

If you model it as uniformly distributed, you should model the stiffness of the vessel.

Dear passingtongreen Sir,

Will you please explain how to model the stiffness of the vessel?

Also I have ref Roarks Stress and Strain book.

In that book, in the chapter of curved beams, there is a table regarding loading of curved beams in the plane transverse to beam plane (i.e is horizontal in this case).

" TABLE 9.4 Formulas for curved beams of compact cross section loaded normal to the plane of curvature"

Regards

ASD23789

You really need to find a mentor who understands the behavior of structures under load.

As I said in my first post, you should place all of the load on the posts. If you try Roarke, look at the deflection and try to imagine the bin changing shape to match.

I have a pressure vessel supported on a annular baseplate.

Further, you describe the installation you have in some detail, although, perhaps by omission, it appears that the vessel is not fixed to the stand at all ? The first image that comes to mind is a loaded egg-cup...

You need to clarify whether you need to produce (a) an actual design, or (b) a representative drawing of the existing vessel installation/ assembly.

Firstly, I have reservations about identifying a plate as a 'continuous beam'. The load is transferred directly through the annular, to the legs, so the reason for the annular is probably that the vessel manufacturer omitted to include a means of mounting supports (legs) directly onto the vessel.

From a design perspective, you will need to demonstrate by calculation the suitability of the plate (material and dimensions), and demonstrate similarly for the legs.

Unless there are severe operating conditions that must allow free vessel movement (unlikely from what you describe), it appears to me that the annular is nothing more than a support plate integral to the stand, and must be shown as such on the drawing. Again, I have strong reservations about identifying a plate as a 'continuous beam'.