The Design of Petroleum Storage Tanks

Oil Storage Tank | Petroleum storage tanks are crucial components of the oil and gas industry. They store crude oil, refined petroleum products, and other chemicals, ensuring that the industry has a stable supply chain for processing, refining, and distributing petroleum products. The design of these tanks is essential to ensure that they can safely and efficiently store these hazardous materials.

Storage tanks are containers used to store crude oil, refined petroleum products, and other chemicals. These tanks are essential components of the oil and gas industry, providing a stable supply chain for processing, refining, and distributing petroleum products. The design of these tanks is crucial to ensure that they can safely and efficiently store these hazardous materials. This article provides a comprehensive guide to the design of petroleum storage tanks.

Types of Petroleum Storage Tanks

There are four main types of petroleum storage tanks: fixed roof tanks, floating roof tanks, spherical tanks, and bullet tanks. Each type has its advantages and disadvantages, and the choice of tank depends on several factors, including the type and quantity of the product being stored, the location of the tank, and local regulations.

Fixed Roof Tanks

Fixed roof tanks are the most common type of petroleum storage tank. These tanks are suitable for storing products with low vapor pressures and are commonly used to store crude oil, diesel fuel, and gasoline. They are relatively inexpensive to build and maintain and are suitable for small and large-scale storage.

Floating Roof Tanks

Floating roof tanks have a roof that floats on top of the product being stored. The roof is designed to rise and fall with the level of the product to minimize vapor loss. These tanks are suitable for storing products with high vapor pressures, such as jet fuel and ethanol. Floating roof tanks are more expensive to build and maintain than fixed roof tanks, but they offer superior environmental protection and product quality.

Spherical Tanks

Spherical tanks have a spherical shape that allows them to store large quantities of product in a small space. These tanks are commonly used to store liquefied petroleum gas (LPG), butane, and propane. They are more expensive to build and maintain than other types of tanks but offer several advantages, including increased safety and reduced environmental impact.

Bullet Tanks

Bullet tanks, also known as sphere tanks, are a type of storage tank used for the storage of liquefied gases such as propane, butane, and ammonia. These tanks are designed in a spherical shape to ensure maximum storage capacity with minimum footprint. Bullet tanks are commonly used in industrial and commercial applications where large volumes of liquefied gases are required.

Design Considerations for Petroleum Storage Tanks

The design of petroleum storage tanks must consider several factors to ensure that they can safely and efficiently store hazardous materials. These factors include the materials of construction, tank dimensions, tank capacity, tank orientation, tank foundations, and tank coatings.

Materials of Construction

The materials used in constructing petroleum storage tanks must be compatible with the products being stored. Common materials include carbon steel, stainless steel, and aluminum. The thickness of the tank shell and roof must also be sufficient to withstand the pressure and weight of the stored product.

Tank Dimensions

The dimensions of the tank are determined by the desired capacity and space limitations. Tanks can range in size from small portable tanks to large tanks with a capacity of over 100,000 barrels.

Tank Capacity

The capacity of the tank is determined by the amount of product that needs to be stored. It is essential to ensure that the tank can hold the maximum amount of product while allowing for thermal expansion and contraction.

Tank Orientation

The orientation of the tank is also critical to ensure that it can store the product safely. Tanks can be horizontal or vertical, and the choice of orientation depends on several factors, including space limitations and product characteristics.

Tank Foundations

The tank must be adequately supported to prevent deformation and collapse. The foundation must be strong enough to support the weight of the tank and the product being stored.

Tank Coatings

The tank’s interior and exterior must be coated to prevent corrosion and damage from the stored product. Common coatings include epoxy, polyurethane, and zinc-rich coatings.

Tank Components and Accessories

Petroleum storage tanks must be equipped with several components and accessories to ensure safe and efficient operation. These include manways, nozzles, breather valves, emergency vents, flame arresters, and pressure relief valves.

Manways

Manways are used to provide access to the interior of the tank for cleaning and inspection. They are typically located on the top of the tank and can be either round or rectangular.

Nozzles

Nozzles are used to connect pipes and hoses to the tank for filling and emptying. They must be properly designed and installed to prevent leaks and spills.

Breather Valves

Breather valves are used to allow air to enter and exit the tank during filling and emptying. They are essential for maintaining the structural integrity of the tank and preventing damage from pressure changes.

Emergency Vents

Emergency vents are designed to prevent overpressure or vacuum conditions in the tank. They are crucial for preventing tank rupture or collapse and ensuring safe operation.

Flame Arresters

Flame arresters are installed on the tank to prevent the ignition of flammable vapors. They are essential for preventing fires and explosions in the tank.

Pressure Relief Valves

Pressure relief valves are used to discharge excess pressure in the tank. They are essential for maintaining the structural integrity of the tank and preventing damage due to pressure changes.

Tank Maintenance and Inspection

Petroleum storage tanks must be regularly inspected and maintained to ensure safe and efficient operation. This includes following inspection standards and codes, scheduling inspections at regular intervals, using proper inspection techniques, and performing maintenance and repairs as needed.

Inspection Standards and Codes

There are several industry standards and codes that regulate the design, construction, and maintenance of petroleum storage tanks. These include API 650, API 653, and ASME.

Inspection Frequency

The frequency of tank inspections depends on several factors such as the age of the tank, the products being stored, and local regulations. Tanks should be inspected at least once a year, and more frequently for older tanks or tanks storing hazardous materials.

Inspection Techniques

Inspection techniques include visual inspection, ultrasonic testing, radiographic testing, and magnetic particle inspection. Proper inspection techniques should be used to ensure that any damage or corrosion is detected and addressed promptly.

Maintenance and Repairs

Maintenance and repairs must be performed as needed to ensure that the tank remains in good condition. This includes cleaning and coating the interior and exterior of the tank, replacing damaged components, and repairing any leaks or damage.

Designing and maintaining petroleum storage tanks is a critical task that requires careful consideration of several factors, including materials of construction, tank dimensions, tank capacity, tank orientation, tank foundations, and tank coatings. Proper tank design and maintenance are essential for ensuring the safe and efficient storage of hazardous materials.