Pressure and Temperature Effects in Underground Storage Tanks

January 27, 2017

Subsurface storage vessels are expected to deliver peak performance characteristics in all imaginable condition. No matter how wet, acidic, or physically oppressive the underground terrain becomes, the below ground fluid depot must securely contain its potentially hazardous load. In designing the vessels to accommodate this below ground backdrop, we need to understand how pressure and temperature variables affect underground storage tanks. What are these subterrestrial variables? More importantly, how do they impact vessel design?

Not an Equal Opportunity Locale

If the soil was composed of a pure silica base, granules that were evenly sized, then the design would be an engineering no-brainer. The uniform stuff would apply equal amounts of stress from all directions. The ground beneath our feet is rarely so obliging. Sedimentary layers and rocky outcroppings press in from one side while air pockets and cavities occupy the other end of the mounting zone. Fortunately, the varying geological conditions are accounted for by a meticulously fabricated vessel architecture, a build that adds internal ribs and reinforced weld seams to the final outlay of the tank.

Appreciating the Effects of Thermal Loads

The concrete or brick hollow acts as a stable mounting pedestal, with the walls of the pit supplementing the reinforced container. Next, temperature variances exist in the enclosed space. Warm water is removed via an installed drainage channel, but trapped heat conspires with the soil conditions to produce corrosive liquid compounds. The heat treated and post-coated tanks defeat these chemical reagents, but a soil assessment should be conducted before the underground tanks are mounted so that the acidity or alkalinity (pH) quotient can be evaluated.

The Frost Factor

A seasonal switch delivers a potent blow, and the underground containment facility experiences stress from a new direction. Frost-hardened ground contracts the soil. The ground becomes a solid block of dirty ice. Water content reverses this effect, with the ice expanding as it leaves its liquid form. In this arctic chill, low temperatures and soil conditions combine adversely to generate pressure. Desert conditions cause a similar scenario, but the event fluctuates due to the nature of the environment. Baking heat penetrates the ground pit during the day, but the desert night forces that same filled ground depression to contract.

Underground tanks are as materially robust as their surface counterparts, but they also incorporate an added elasticity factor, a series of material and architectural attributes that manages the pressure and temperature variances that dwell below ground.

Contact Details

Fusion - Weld Engineering Pty Ltd
ABN 98 068 987619

1865 Frankston Flinders Road,
Hastings, VIC 3915

Ph: (03) 5909 8218

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