“Where are you going to put your storage tanks?” It’s a simple question but such information is a critical part of the proper design of storage tanks.
Tanks can be mounted indoors or outdoors, near other equipment, or separated and far away from other equipment… The answers to these questions will help to drive decisions on the specific and safe design of your storage tanks.
But one of the first considerations is to design the mounting surface for your tank. The size of the tank, the liquid being stored– even the geography of the site–are all elements to be considered.
If the tank is to be kept outside, the engineers need to be concerned about wind loads and potential hurricane or earthquake compliance regulations that need to be followed. The area designated for storage tanks needs to be completely level, so the terrain of the area needs to be taken into consideration. If there is unlevel topography that could channel run-off from the rain, that needs to be engineered right from the beginning.
It’s important to properly engineer the footings for any tank. Houston PolyTank’s exclusive extrusion wound plastic tanks have very thick, rigid walls and a thick base, which can be sturdier and heavier than rotomolded tanks. To properly position a tank, it should rest on a very flat, very clean reinforced cement pad. There should be no pebbles or rocks underneath the tank, as this can lead (over time) to the development of a crack in the tank, which would affect the longevity of the tank.
How large will the mounting surface be?
Make sure you have enough space for the storage tanks that you need. Footings need to be larger than the tank bottom in order to bolt the bottoms of the tanks to the mounting surface, and the bolts should not be too close to the edge of the cement footing. Typically, the surface would be at least 1.5 feet larger than the diameter of the tank to accommodate the mounting brackets and allow for the expansion and contraction of a plastic tank.
Specific Gravity and Stress
Whether indoors or out, it’s important to account for the weight of the storage tank and the specific gravity of the liquid that you are going to be storing. If you are storing water, specific gravity would be “1” and the calculation is easy in terms of the stresses on that mounting surface… But if you are planning to house a chemical that has a higher specific gravity, your engineers need to make sure to calculate the overall stress on that cement pad and ensure that it can handle the entire load. Fortunately, our tank bottom acts as a membrane and disperses the weight of the liquid in the tank to the cement pad. The thickness of a cement pad may be 6-8 inches deep and could include metal rebar within, depending on the particulars of the project.
Do you need a skirt on the tank?
Many storage tanks require a cone bottom. All Houston PolyTank’s non-flat storage tanks (such as cone-bottomed tanks) are supported by a baseleg skirt made from the same material. This skirt is actually part of the cylinder of the tank. By having a skirt with the same material as the tank, it eliminates time-consuming maintenance, mitigates the potential for rot or corrosion, and is aesthetically pleasing. A skirt protects the integrity of the tank and provides something that is visually attractive, while maintaining access to the bottom of the tank through cutout access holes in the skirt. While it does often make the tank a bit taller than it otherwise would be, it can also be a great solution for providing support for necessary piping that runs to and from the tank. These skirts can include drainage holes (so that snow or rain doesn’t accumulate and add weight to the tank structure) or manways for constant undercarriage access.
All of these issues need to be considered as a part of engineering the proper mounting surface for a tank. If you’d like to discuss your storage needs and how we might be able to help you get exactly what you need, give us a call at 660-778-3393 or send us an email at Sales@HoustonPolyTank.com.