A vital part of the oil and gasoline industry, crude oil storage tanks are designed to safely store petroleum products. These tanks come in a variety of types and sizes, and in most instances must be tailored to specific storage needs. In this article, we'll break down the components of crude oil storage tanks, their construction, materials, and functionality.
What Are the Components of an Oil Storage Tank?
Understanding the components of oil storage tanks is essential for ensuring their integrity and safety in the field. Common features include:
Tank Shell: This outer cylindrical structure provides the main containment for crude oil.
Roof Structure: Roofs for oil tanks include fixed roofs (like cone-shaped or dome roofs) or floating roofs (that move up and down with the liquid level), which minimize vapor loss and reduce fire hazards.
Bottom Plate: The tank floor-typically made from welded steel plates-ensures a secure seal to eliminate or avoid leakage.
Manways and Nozzles: These are access points for inspection, cleaning, and oil transfer.
Drainage Systems: These systems are used to remove water and sediment from the tank.
Each of these components plays a critical role in ensuring the safety and efficiency of oil storage operations.
Which Types of Tanks Are Used for Crude Oil Storage?
Depending on their application, crude oil storage tanks come in a variety of types:
Fixed-Roof Tanks: Featuring a permanently attached roof, fixed-roof tanks are suitable for low-volatility crude oil and are designed to minimize vapor emissions.
Floating-Roof Tanks: Ideal for storing volatile crude oil, these tanks feature a roof that rises and falls with the oil level to prevent vapor accumulation. The design reduces environmental emissions and product evaporation.
Horizontal Tanks: Also known as bullet tanks, these cylindrical tanks are commonly used for smaller quantities of crude oil. They are typically aboveground storage tanks (ASTs), making them easier to inspect and maintain.
What Are Oil Storage Tanks Made Of?
The materials used in crude oil storage tanks must be able to withstand corrosion, high temperatures, and environmental stress.
Carbon Steel: Commonly chosen for its durability and cost-effectiveness.
Stainless Steel: Often used for storing highly corrosive or sensitive crude oil.
Fiberglass-Reinforced Plastic (FRP): Lightweight and corrosion-resistant, suitable for specialized applications.
In all instances, construction should be based on the crude oil storage tank design specifications supplied by the project's engineer.
How Big Is a Crude Oil Storage Tank?
Varying greatly in size, crude oil storage tanks have capacities ranging from a few thousand to millions of barrels. For instance:
Small Tanks: Hold up to 10,000 barrels, and are typically used for temporary storage facilities with limited storage, or those handling specialized operations like blending or testing.
Large Tanks: Can store millions of barrels, and are often found in refineries, strategic petroleum reserves, or in export terminals where large inventories are needed to meet global demand.
The design and capacity depend on factors like site constraints, operational requirements, and compliance with oil storage tank construction detail standards.
What Are Crude Oil Storage Tanks Made Of?
The construction of crude oil storage tanks involves careful material selection due to the destructive properties of the materials the tank holds. Environmental compliance and long-term durability must also be considered.
Structural Steel: For the tank body and framework, structural steel is ideal.
Specialized Alloys: Alloys such as carbon steel and stainless steel could be used in tanks exposed to harsh environmental conditions.
Protective Coatings: Both internal and external, coatings should be applied to prevent corrosion and extend tank life.
What Materials Are Used in Oil Storage Tanks?
To optimize performance, oil storage tanks utilize various materials depending on their application:
Epoxy Coatings: Protect the tank from internal and external corrosion, plus prevent leaks and contamination. They can also increase the tank lifespan and reduce maintenance costs.
Thermal Insulation: Use with tanks in extreme temperature conditions. It must be fire-resistant-some insulation is coated with a fireproofing chemical. Ultimately, it helps increase the tank's lifespan.
Concrete Bases: Provide stability and prevent ground seepage.
How Are Oil Storage Tanks Built?
The field construction of oil storage tanks involves several stages:
Design Phase: Detailed engineering, which includes compliance with industry standards such as API 650 (the American Petroleum Institute), EPA, ASTM, and OSHA.
Material Selection: Completed by the engineer, and based on the tank size and oil type.
Construction: On-site assembly, welding, and quality testing. Due to the size of these tanks, they must be field-erected.
Proper construction ensures that tanks meet crude oil storage tank specifications and perform reliably over their lifespan.
Crude oil storage tanks are essential for the safe and efficient storage of petroleum products. By understanding their components, materials, and construction, you can make informed decisions about the best storage solution for your needs.
For guidance on field-erected tanks and the types of oil storage tanks to optimize your facility's performance, contact GNEE today. We'll put our 17 years of experience to work finding the perfect tank for your crude oil storage needs.
Email: sales@gneeheatex.com
FAQ
Q: How do crude oil storage tanks work?
A: Upon being introduced into a storage tank at above atmospheric pressure, crude oil and condensate experience pressure drops which cause gases dissolved in the liquid to vaporize or 'flash' out of the liquid phase and collect in the vapor space between the liquid and the fixed roof of the storage tank.
Q: What is the capacity of a crude oil storage tank?
A: Crude Oil Storage Tank Capacity: Crude oil storage tanks can hold a range from 50,000 to millions of barrels of oil, with sizes often detailed in a crude oil storage tank size chart, like the one shown here.
Q: Do I need planning permission for an oil tank?
A: As of 2022, you won't need planning permission as long as: Your tank does not exceed a 3500-litre capacity. Your tank isn't being stored in front of the main elevation fronting a public road. The height of your tank is not greater than 3 metres.
Q: What is the life expectancy of an oil storage tank?
A: around 20-25 years
While they can last several decades if very well-maintained, most modern oil tanks have a functional lifespan of around 20-25 years, or thereabouts. Older tanks are increasingly prone to corrosion, fatigue and problems if not treated with the proper maintenance and upkeep that they need to continue working.
Q: Why do oil tanks have floating roofs?
A: Floating roofs are made of a structure which floats on the surface of the liquid in order to prevent the formation of a gas overhead, and thus reduces: Fire risks. Atmospheric pollution. Evaporation losses.