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tank wall spiral stair

tank wall spiral stair

tank wall spiral stair

I need to tell our fabrication dept. the correct diameter to role several 20' lengths of 1 1/2" sch. 40 pipe so they will fit as a hand rail for the tank stairway I designed. Tank dia.=46.15',tank height=46', stair stringer angle = 35 deg., stair height (vert.) 34'. I can't find a formula to figure this one out.

Thanks, John

RE: tank wall spiral stair

Here is what I would do.
The angle of the projection of the stair on the horizontal plane is:
α=34'*tan35°/(46.15'/2)=1.0317 rad
Assuming the stair is 3' wide, the radius at the handrail is
The arc length of the horizontal projection of the handrail is
The developed length of handrail is now:
And don't forget to add provisions for intermediate and end floors! prex

Online tools for structural design

RE: tank wall spiral stair

There is a mistake in my previous post: the first formula should be:
and the final result becomes


Online tools for structural design

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