Using wind as an external pressure?
Using wind as an external pressure?
(OP)
Hi all,
When considering buckling as a failure mode due to wind, I was wondering if you could approximate windward wind(pressure) as an external pressure? I know wind should be seen a bending force but I am curious if setting them equal makes sense for the primary membrane stress or would just be a conservative estimate.
Cheer,
Alex
When considering buckling as a failure mode due to wind, I was wondering if you could approximate windward wind(pressure) as an external pressure? I know wind should be seen a bending force but I am curious if setting them equal makes sense for the primary membrane stress or would just be a conservative estimate.
Cheer,
Alex





RE: Using wind as an external pressure?
RE: Using wind as an external pressure?
I've never worked with pressure vessels where buckling due to wind was a controlling mechanism, but I guess anything is possible. I have however worked with API tanks, and buckling due to wind is a very real concern.
EDIT:
I forgot to mention that regardless of the tank/pressure vessel, I agree that you need to look at wind loading separate, not as a uniform external pressure, for the same reason noted above.
Jim Breunig P.E.
XCEED Engineering
Mechanical Engineering
FEA Consultants
RE: Using wind as an external pressure?
Just as an aside, wind can become a controlling mechanism in pressure vessels when you're talking about tall and slender distillation columns with a low design pressure. In these cases you are forced to thicken lower shell sections.
RE: Using wind as an external pressure?
It could be over-conservative if the design to a primary stress which includes the wind load with the the external pressure.
RE: Using wind as an external pressure?
With regards to treatment of the wind load, I didn't see anything in section VIII that gave detailed analysis methods. API-650 however does have some guidance for evaluating this if you're looking for a method.
Jim Breunig P.E.
XCEED Engineering
Mechanical Engineering
FEA Consultants
RE: Using wind as an external pressure?
Wind or seismic are directly applied loads and are not self limiting. Consider a column under wind loading; if it displaces due to the applied wind load it is still under the same amount of load. However, for a true secondary stress, such as would be seen at a head to shell junction, once yielding occurs, the load does not increase. Wind and seismic should be considered to be primary loads.
RE: Using wind as an external pressure?
Thanks for the correction. I mixed up it with the loads in piping system.
RE: Using wind as an external pressure?
take care and thanks
RE: Using wind as an external pressure?
4) Calculate the minimum shell thickness required for the combined loading from design external pressure
and wind - PAG 281 / 302 in pdf.
Regards
r6155