Thoughts And Perspectives From The Team

The Different Types of Oil Storage Tanks

AUTHOR T Bailey, Inc.

PUBLISHED Dec 15, 2023

The late 1800s saw the introduction of the first steel oil storage tanks. Over successive years, various types were developed for different applications. The profusion of standard tanks ranges from compact 160-gallon double-wall heating oil tanks to 26,400,000-gallon behemoths holding crude oil. Read on for more fascinating facts.


What Is an Oil Storage Tank?

An oil storage tank is any bulk storage tank containing an oil product for processing, or before to use. Aboveground steel welded tanks must conform to the American Petroleum Institute’s API 650 standard.

Oil storage tanks are essential for:

  • Refining crude oil into products such as gasoline, diesel fuel, LPG, kerosene, naphtha, and fuel oil. Large oil storage tanks hold crude oil and derivatives throughout all stages of manufacture.
  • Processing petrochemical feedstock into a plethora of products, including plastics, paints, adhesives, waxes, pharmaceuticals, and fertilizers.
  • Storing oil to heat spaces and water in industrial, commercial and residential boilers and furnaces.


Different Types of Oil Storage Tanks


Fixed Roof Tank

This vertical, cylindrical tank stores oil with an internal vapor pressure close to atmospheric pressure. A pressure-vacuum valve purges the ullage with natural gas. This gas blanketing eliminates air and minimizes evaporation. The roof is commonly a shallow cone or dome.

Floating Roof Tank

A floating roof covering the surface of the product rises and falls according to the level of the contained oil product. This deck protects the contents and minimizes evaporative losses. There are two configurations:

  • External Floating Roof Tank (EFR): The floating roof doubles as the top cover of the tank. There is no ullage. A curtain-like seal between the floating roof and the sidewall prevents evaporative loss from the rim space.
  • Internal Floating Roof Tank (IFR): The tank has an enclosing fixed roof above the floating roof to protect the contents from the elements. Circulation vents enable natural ventilation of the ullage between the two roofs. Alternatively, a conservation vent allows recovery of the vapor for processing.



Benefits and Drawbacks of Oil Storage Tanks



  • Oil barrels are inconvenient to store, and too small for activities and processes that use large amounts of fuel.
  • An onsite tank saves both time and money by reducing the frequency of orders and delivery costs.
  • Buying in bulk is cheaper per gallon.
  • Fitted telemetry monitoring and fuel management systems help to control usage.
  • API 650 tanks assist compliance with health and safety, and environmental regulations.
  • A properly maintained tank will last for many years, and be a valuable physical asset to its owner.



  • Unchecked flaws, cracks, or corrosion increase the risk of failure, which can harm people and the environment.
  • External temperature fluctuations may cause condensation of water inside the tank, leading to the formation of rust and microbial contamination.
  • Contaminants sink to the bottom, forming a troublesome sludge at the base of the tank that can block valves and piping.
  • A lightning strike could cause a catastrophic fire or explosion.


Oil Storage Tank Design

The API 650 standard prescribes design requirements to minimize potential structural failure that may cause environmental damage. This is governed by the US Environmental Protection Agency’s (EPA) Spill Prevention, Control, and Countermeasure (SPCC) regulation (40 CFR Part 112) for aboveground storage tanks.

However, the standard doesn’t specify tank dimensions or design features. Users can select oil storage tank sizes and accessories to suit specific applications. For example, the oil and gas industry requires enormous storage capacity for refining. The largest oil storage tank in the world holds an incredible 250,000 cubic meters of crude oil—or 66,043,050 gallons!

Choosing an oil storage tank design must account for variables, such as:

  • Physical and chemical properties of the stored product.
  • Method of delivery to and distribution from the tank.
  • Minimum and maximum operating temperature and pressure.
  • Health and safety, environmental, and legal requirements.
  • Geophysical properties and location of the site.


T BAILEY, INC.: The Leading Manufacturer of Oil Storage Tanks in the Pacific Northwest

If you’re looking for a superior engineering and manufacturing company, choose T BAILEY, INC. Our company is a certified AISC fabricator with extensive knowledge and experience in the design and fabrication of oil storage tanks.

We stand apart from other oil storage tank manufacturers by offering full support throughout the entire process. From vast tank farms at oil refineries to public works and military installations, we have the in-house and in-the-field capacity to fulfill any requirements.

Talk to our experts for flexible, economical solutions that come in on time and within your budget. Contact us today to discuss your project.