A storage tank is a thin shell that only stands up because of what is inside it and how it is anchored. Empty, in wind, it is one of the least stable structures on a plant — and that, not the operating case, is often what governs the design.
Techso designs and verifies atmospheric and low-pressure tanks to API 650, API 620 and EN 14015, including seismic verification and the foundation loads the civil design needs.
Shell design
- Course thickness by the applicable design method
- Corrosion allowance and its distribution between courses
- Shell openings, reinforcement and nozzle flexibility
- Bottom plate arrangement and annular plate design
Stability
The empty tank in wind is the case that decides anchorage; the full tank in an earthquake is the case that decides the shell. Neither is the operating condition, and both have to be run.
- Top and intermediate wind girders against shell buckling
- Overturning, uplift and anchorage design
- Internal pressure and vacuum where the tank is designed for them
Seismic verification
- Impulsive and convective response of the stored liquid
- Sloshing wave height and the freeboard it requires
- Anchored and unanchored configurations, with the uplift they imply
- Compressive stress at the shell base and foundation reaction
Roofs and foundations
- Fixed roofs: supported and self-supporting cone and dome
- Floating roofs, internal and external, with seal and drainage arrangement
- Frangible roof-to-shell joint as a pressure relief device
- Foundation loads, ringwall design input and settlement criteria
- Assessment of tanks in service, for repair or re-rating