Types of Storage Tanks

In the chemical and petrochemical industries, the production, manufacturing, and refining all rely on storage tanks. The right storage tank protects the product as well as the equipment, environment and personnel.

Built to contain liquids, vapors, and gases, storage tanks are designed to contain spills and reduce the risks and damage of ruptures and leaks. Having the right storage tank type improves the effectiveness of tank heaters, as well as better maintaining the integrity of your product.

LNG Tanks

Liquid natural gas (LNG) storage tanks have specialized designs, built to contain products like methane. LNGs are stored at supercooled temperatures, changing the gas to a liquid state. The result is a product that takes up 1/600th of the space it takes in their natural state, as well as reducing the hazards of transportation and storage.

To meet these needs, liquid natural gas storage tanks are able to contain products as cool as 323℉ (162℃). To maintain temperature, the tank is insulated, and a double container is used to prevent leaks or contamination. The tanks are generally either fixed or transported.

Fixed LNG storage tanks can be above ground or in-ground tanks. Depending on the design and size, fixed LNG tanks typically range from 1000 m3 to 160,000 m3. Although tanks as large as 200 million liters have been made.

Transport LNG tanks are built to be carried by truck, rail, or ship. They have safety features such as shutoff devices and must adhere to the regulations of the Department of Transportation (DoT) or other national/international governing bodies.

Pressure Tanks

Unlike LNG tanks, these are built to contain products under pressure. Pressure vessels present a greater potential hazard in potential BLEVEs (boiling liquid expanding vapor explosion) resulting from excess heat or damage.

To compensate for these risks, pressure storage tanks must follow ASME Boiler and Pressure Vessel Code. ASME regulations help to select the right materials, shapes, and uses of pressure tanks.

High-pressure fluids are generally stored in spherical pressure tanks. The shape evenly distributes stress on the container, preventing weak points in the structure. This shape also reduces the surface area, which results in less heat being transferred from the external environment.

For lower-pressure fluids, cylindrical pressure storage tanks are more commonly used. Although they lack the structural integrity of the sphere, they are also less expensive. It’s important to understand whether or not they are an appropriate vessel for your product.

Floating Roof Tanks

Floating roof tanks are designed to reduce vapor emissions and volume inside of the tank. This is achieved with the roof floating on the surface of the liquid inside the vessel. The roof raises and lowers with the liquid level, preventing a buildup of vapor inside.

Internal

An internal floating roof tank has two roofs. The floating roof is the internal component, floating on the liquid. Above it, there is a fixed roof at the top of the storage vessel.

External

External floating roof tanks only have one roof. The top of the tank is open and the single roof deck floats on top of the liquid or on pontoons at the liquid level.

Some floating roof tanks use a domed design. This design is used to block wind, rather than vapor.

Fixed-Roof Tanks

The roof of a fixed-roof tank does not move. They have a solid top that is attached directly to the shell. Depending on age and design, these tanks may or may not be vapor and liquid tight. These tanks meet the minimum requirements for storing most liquids and are the cheapest to construct.

Storage Tank Heaters

Just as it’s essential to choose the right storage vessel for your product and application, your tank heater must meet the specifics of your tank. Wattco custom manufactures electric industrial heaters to meet the specific requirements of your equipment and application. Our team of experts will help you select the right model and specification for you and your budget.

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