Vertical Storage Tank

Vertical storage tanks are core equipment for storing liquid media at atmospheric pressure on land. Primarily composed of a vertical cylindrical welded steel structure, they are widely used in petroleum, chemical, and energy storage industries. They are mainly divided into two types: fixed roof (dome roof) and floating roof (external/internal floating roof). Design, manufacturing, and acceptance comply with national standards such as GB 50341-2014, GB 50128-2014, and GB 50074-2014.

Core Definition and Classification

1. Basic Definition:

A vertical cylindrical welded steel storage tank, composed of a tank bottom, tank walls, tank top, and accessories, with a design pressure < 0.1 MPa(G) and a design temperature ≤ 90℃, used for storing non-extremely/highly hazardous liquids such as crude oil, refined oil, and chemical raw materials.

2. Main Types and Selection

Basic Structural Components

• 1. Foundation: Plain soil layer → lime-soil layer → sand cushion layer → asphalt sand cushion layer, bearing capacity ≥10 t/m², groundwater level ≥30 cm from foundation, reinforced concrete ring beam in soft soil areas.
• 2. Tank Bottom: Flat bottom structure, steel plate thickness 6–8 mm, directly transfers load to foundation, requires enhanced corrosion protection.
• 3. Tank Wall: Multiple welded steel plates, thickness increasing from top to bottom (pressure increases with liquid level), connection methods include sleeve type, butt type, and hybrid type.
• 4. Tank Roof: Dome roof (radius of curvature 0.8–1.2 times the tank diameter); floating roof (single-disc/double-disc, double-disc type is more rigid and suitable for large tanks).

Main Accessories

A complete vertical storage tank, in addition to the tank body itself, must be equipped with various accessories to ensure its safe and efficient operation.

• Breather valve: Installed on the tank top, it automatically regulates the internal pressure to maintain pressure balance and reduce oil evaporation during oil handling or temperature changes.
• Manhole: Located on the tank wall and top, it allows maintenance personnel to enter and exit, ventilate, and clean the interior.
• Gauge port: Used for manual measurement of oil level, temperature, and sampling.
• Fire sprinkler and foam generator: Used for tank cooling and fire suppression.
• Heater: For high-viscosity, easily solidified oils (such as crude oil and fuel oil), heating coils must be installed inside the tank, using steam or hot water to maintain the oil's fluidity.
• Ladder and platform: Provides access to the tank top for operation and maintenance.
• Lightning and static electricity protection grounding: The oil tank must be reliably grounded to conduct static electricity and prevent lightning strikes.
• Level gauge: An instrument used to monitor the oil level in the tank in real time; various types are available, including mechanical, servo, and radar types.

Basic Parameters (National Standards + Typical Specifications)

1. Core Design Parameters (Mandatory National Standards)

2. Typical Volume and Dimensions (Reference Values)

3. Other Key Parameters

• Medium: Crude oil, gasoline, diesel, kerosene, lubricating oil, chemical solvents, etc.; Class B and Class AB tanks must use floating roof tanks (GB 50074-2014).
• Corrosion Protection: The outer wall is coated with a primer + topcoat for corrosion protection; the inner wall is protected with conductive anti-corrosion coating or sacrificial anode protection depending on the medium.
• Lightning and Static Electricity Protection: A lightning rod is installed on the tank top, and the floating roof and tank wall are bridged with copper braided straps (≥2 points), with a grounding resistance ≤10 Ω.
• Fire Protection: Floating roof tanks are equipped with a floating roof cofferdam foam fire extinguishing system; dome-roof tanks are equipped with a foam generator on the tank top and a cooling spray system on the tank wall.

Selection and Application Points

• 1. Medium Priority: Volatile and flammable media (such as gasoline) must be handled by internal or external floating roof tanks; non-volatile media (such as diesel) can be handled by dome-roof tanks.
• 2. Volume Matching: < 50,000 m³ commonly uses domed/internal floating roofs; ≥50,000 m³ must use external floating roofs, and external floating roof tanks ≥50,000 m³ require double-deck floating roofs with two ladders and platforms.
• 3. Compliance: Strictly adhere to standards such as GB 50341 (design), GB 50128 (construction), GB 50074 (oil depots), and GB 50160 (fire prevention) to ensure safety and acceptance.

Summary:

The core of vertical storage tank selection and parameter design is the matching of media characteristics, volume, and safety regulations. Small tanks (≤1000 m³) mainly use domed roofs, medium-sized tanks (1000–50000 m³) mostly use internal floating roofs, and large tanks (≥50000 m³) are all external floating roofs, and must meet the mandatory requirements of national standards for dimensions, materials, welding, and acceptance.