What Is a Liquid Storage Tank?
Created on 2024.03.22
What Is a Liquid Storage Tank?
A liquid storage tank is a specialized container designed to hold, process, or transport liquids safely and efficiently. Ranging from small 500-gallon chemical vats to massive 5-million-gallon aboveground structures, these tanks are the backbone of modern infrastructure. They safely contain everything from municipal drinking water and agricultural fertilizers to highly volatile petrochemicals and crude oil.
Core Types of Liquid Storage Tanks
The design, placement, and engineering of a tank depend entirely on what it holds and the environmental conditions it must withstand.
1. Aboveground Storage Tanks (ASTs)
These are the most common industrial tanks. Because they sit above ground, they are significantly easier to inspect, maintain, and repair. ASTs are heavily utilized in oil refineries, municipal water treatment plants, and chemical manufacturing facilities.
2. Underground Storage Tanks (USTs)
Designed to be buried beneath the surface, USTs are typically used for storing fuels at gas stations or for commercial heating oil. By placing them underground, facilities save surface space and reduce the risk of fire or explosion, though they require strict leak-detection monitoring systems to prevent soil contamination.
Design Standards: The Rules of Construction
To ensure safety, structural integrity, and the prevention of catastrophic leaks, liquid storage tanks must adhere to rigorous global engineering codes.
Standard | Pressure Rating | Primary Material | Common Applications |
API 650 | Atmospheric (Low) | Welded Steel | Crude oil, refined petroleum, chemicals, water |
API 620 | Low to Medium (Up to 15 psig) | Welded Steel | Refrigerated products, liquefied natural gas (LNG) |
AWWA D103 | Atmospheric | Bolted Steel / GFS | Municipal potable water, wastewater, fire protection |
UL-142 | Low Pressure | Steel | Aboveground flammable and combustible fuels |
Key insight: If you are storing regular liquids at atmospheric pressure, API 650 is the globally recognized gold standard. For highly pressurized or refrigerated liquids, API 620 is required.
Materials Used in Tank Construction
● Carbon Steel: The most common choice for large-scale oil and chemical storage due to its reliable balance of strength, workability, and cost-effectiveness.
● Stainless Steel: Essential for highly corrosive chemicals or food-grade products where contamination and metal degradation are major risks.
● Glass-Fused-to-Steel (GFS): Often used in bolted tanks, this material combines the structural strength of steel with the chemical and corrosion resistance of glass, making it ideal for highly reactive wastewater.
● Fiberglass Reinforced Plastic (FRP): Lightweight and highly resistant to chemical corrosion, often used for smaller industrial chemical storage or underground water containment.
Frequently Asked Questions (FAQ)
What is secondary containment, and why is it necessary?
Secondary containment acts as a fail-safe backup system—such as a concrete dike, containment berm, or double-walled tank structure—designed to catch liquids if the primary tank leaks or ruptures. Strict federal and environmental regulations mandate secondary containment to prevent toxic spills from reaching soil and groundwater.
How long does a liquid storage tank last?
A well-maintained steel tank built to API 650 or AWWA standards can last 30 to 40 years—and often much longer. A tank's actual lifespan depends heavily on the corrosiveness of the stored liquid, the quality of the protective internal coatings, and strict adherence to routine inspection and maintenance schedules.
How are large industrial tanks transported to a site?
Most industrial tanks over 50,000 gallons are simply too large to transport fully assembled on highways. Instead, they are field-erected. Steel plates are shipped flat to the installation site and are welded or bolted together course-by-course (ring-by-ring) on a specially prepared concrete foundation.
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