Vertical 20K Tank on Stilts
Vertical 20K Tank on Stilts
(OP)
Simple question. Is it ever appropriate to take a 10' diameter vertical storage tank (34' tall)and weld I-beam stilts to the shell effectively raising the bottom of the tank 12-18" in the air. I have never seen this done. I believe the installer did it to prevent corrosion from standing water within the secondary containment area. The stilts are seam welded to the sheel and extend up the shell approximately 24". The stilts are also welded to anchor plates embedded in the floor of the containment area. I feel I need to at least check these tanks for stability / overturning issues, and possibly localized stress issues in the shell. Anyone run into this before? I have been asked to assess the suitability of the tanks, which are currently in service and used ot hold recycled fuel oil. Thanks.
Chris
Chris





RE: Vertical 20K Tank on Stilts
You didn't mention the type of tank you're dealing with; if it has some sort of conical or formed bottom head you're probably in good shape. If it has a flat bottom you will soon have a formed head! So that little detail is worth checking also.
jt
RE: Vertical 20K Tank on Stilts
While NFPA 30 is silent, the 2006 International Fire Code requires the column protection to meet ASTM E-1526.
Please don't tell me the columns are 1/2-inch L-shaped carbon steel columns. They lack sufficient mass to meet ASTM E-1526 or UL 1709.
If this is the case the tank most likely does not meet UL 142. Scrap the tank.
RE: Vertical 20K Tank on Stilts
RE: Vertical 20K Tank on Stilts
Note that in some cases, a leg attachment can be treated similarly to an anchor bolt chair.
RE: Vertical 20K Tank on Stilts
Joe Tank
RE: Vertical 20K Tank on Stilts
RE: Vertical 20K Tank on Stilts
RE: Vertical 20K Tank on Stilts
Questions:
1) How many legs (stilts ?)are there and what size are they ?
2) Has the tank ever been filled or hydrotested ?
2) Was the tank originally flat-bottomed and what does it look like now ?
3) When "Cooter-and-the-boys-from-maintenance" change things around and "weld stuff up",is it then the job of engineering to justify the changes and take responsibility ? Does your boss have an MBA ?
4) While I am sure that your organization has discarded all design drawings and calculations, are there any markings, or API-type nameplates on the tank ? Is it possible to get the original fabricator involved ?
5) Where are you located and does your state have any periodic tank inspection program ?
- My opinion only
-MJC