Why does my tank have a bulge? Elephant's Foot Bulge??
Why does my tank have a bulge? Elephant's Foot Bulge??
(OP)
Hi All,
We have a large tank which stores sugar syrup (around 30C). Last week we noticed what I think look like Elephant's foot bulge, I have attached a photo. The bulges all occur where the tank meets a leg support. The bulges aren't equal on each leg support.
Has anyone had experience with such an occurrence? This is a head scratcher for us. Most of the research I have done into this describes the cause as being one of the following:
• Seismic activity (which we have ruled out)
• Axial compression (including frictional drag)
• Transverse loading – generating compressive stresses on one side of the tank - Mostly due to winds or impact, and this tank is inside and has not been impacted.
http://books.google.com.au/books?id=rv0QXKI0HvMC&a...
http://books.google.com.au/books?id=UFBhVrTEHhcC&a...
Any ideas?? Any input would be appreciated.
We have a large tank which stores sugar syrup (around 30C). Last week we noticed what I think look like Elephant's foot bulge, I have attached a photo. The bulges all occur where the tank meets a leg support. The bulges aren't equal on each leg support.
Has anyone had experience with such an occurrence? This is a head scratcher for us. Most of the research I have done into this describes the cause as being one of the following:
• Seismic activity (which we have ruled out)
• Axial compression (including frictional drag)
• Transverse loading – generating compressive stresses on one side of the tank - Mostly due to winds or impact, and this tank is inside and has not been impacted.
http://books.google.com.au/books?id=rv0QXKI0HvMC&a...
http://books.google.com.au/books?id=UFBhVrTEHhcC&a...
Any ideas?? Any input would be appreciated.





RE: Why does my tank have a bulge? Elephant's Foot Bulge??
RE: Why does my tank have a bulge? Elephant's Foot Bulge??
RE: Why does my tank have a bulge? Elephant's Foot Bulge??
Have you any more details or section drawings of the tank, things like diam, height, wall thickness, material, design code, other things mounted on tank, what the seam distortion is that appears in part of the shot - was that always there or has it just arrived?
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Why does my tank have a bulge? Elephant's Foot Bulge??
RE: Why does my tank have a bulge? Elephant's Foot Bulge??
RE: Why does my tank have a bulge? Elephant's Foot Bulge??
Very true. If this is at the location of a hard point in the support system of the exterior tank wall, this deformed shape could very likely occur. Modifying the support system, or lowering the level of the material in the tank, or a combi8nation of both, is warranted.
Mike McCann, PE, SE (WA)
RE: Why does my tank have a bulge? Elephant's Foot Bulge??
Thanks for your replies. I have attached a bigger picture of the tank, however in this shot you can only see one of the bulges (and the worst bulge isn't visible as it is next to the wall and hard to get into frame!).
This tank was installed in the year 2000, and the bulges were only identified about a week ago.
> Tank has an internal agitator and a wall thickness of 3mm (0.118")
> We have conducted wall thickness tests which confirm that there is no thinning of the walls
> We have confirmed that the vent valve on the top of the tank is working, and fully operational as per design
> Tank was designed to Australian Standards
The only thing (That we know of!) that has changed, is that the piece of equipment which has been determining the concentration of the incoming sugar syrup has been malfunctioning - so there have been variances in syrup density.
I will dig out some more details on the tank and post them today.
We have lowered the level in the tank for the time being until we can figure out what has created the distortion.
Thanks for your help on this! Appreciate all your comments.
RE: Why does my tank have a bulge? Elephant's Foot Bulge??
RE: Why does my tank have a bulge? Elephant's Foot Bulge??
RE: Why does my tank have a bulge? Elephant's Foot Bulge??
Has the sugar solidified or thickened in the tank? Is the heat source on the bottom? What exactly is the sugar? What is the viscosity and how does it change with temperature?
RE: Why does my tank have a bulge? Elephant's Foot Bulge??
Furthermore, the amount of instability in an agitator varies widely with it's placement in the vessel. If the agitator has been updated/moved/repositioned recently, that's certainly something to consider.
David