Archimede in pipe into pipe

[normanbug]

Dear Eng-tips people,
I have to calculate the buoyancy of a 36" steel pipe (1) inserted into a 48" casing pipe (2).
The interspace is filled with grouting (density is about 1500 [kg/m3]).

I applied Archimede's principle, calculating the weight of (1) which is around 600 [kg/m] and the vertical force generated by the weight of the volume of grouting displaced. The pipe appears to be floating.

I have one doubt: is the principle still valid even if there is not enough space to accommodate all the fluid volume theoretically displaced by the pipe (1)?
Or maybe the principle is not valid in this conditions?

Looking forward to your thoughts and advice. BR, Ed

 

[IRstuff]

How long are the pipes? Why wouldn't you orient the pipes vertically to avoid the buoyancy question altogether, or place spacers around the inner pipe to keep it centered? What is your concentricity requirement?

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