Fixed Roof Tank

• Fully sealed with a cone or dome roof.
• Best for non-volatile liquids (like water or diesel)
• Not ideal for vapors—can cause pressure buildup.
• Maintenance focus: vapor control, roof corrosion, vents.
• Comply with API 650

Floating Roof Tank

• Has a roof that floats directly on the liquid surface.
• Great for volatile liquids (like crude oil, gasoline).
• Reduces vapor losses = safer & environmentally friendly.
• Common issues: seal wear, rainwater collection on roof.
• Comply with API 650

Dome Roof (External + Internal Floating Roof)

• Combines fixed dome with an internal floating roof.
• Double vapor control = improved safety for flammable products.
• Common for aviation fuel, benzene, naphtha.
• Comply with API 650

Bullet Tanks (Horizontal Pressure Vessels)

• Used for pressurized gases (like LPG, butane, propane).
• Elliptical/rounded ends for pressure containment.
• Built to ASME rather than API 650

Spherical Tanks (Horton Spheres)

• Stores high-pressure gases in spherical form.
• Shape distributes pressure evenly = safe for high stress.
• Used in refineries for LPG, ammonia, ethylene.
• Comply with ASME section VIII e.g (API 2510)

Cryogenic Tanks

• Store liquefied gases at very low temperatures (e.g., LNG, nitrogen).
• Multi-layer insulation to maintain ultra-low temps.
• Must comply with special codes API 625

Underground Storage Tanks (USTs)

• Used in gas stations or remote installations
• Minimizes fire risk and saves space
• Requires leak detection and soil protection systems
• Comply with special codes UL58 / UL 1746 (e.g., API 1615)

API 650 Storage Tanks

API 650 storage tanks are large, welded steel tanks designed specifically for storing liquids at atmospheric pressure (or low internal pressure), following the standards set by the American Petroleum Institute for design, fabrication, welding, inspection, and erection of welded steel storage tanks.

Key Highlights

• For liquids at ambient pressure and temperature (e.g., crude oil, chemicals, water).
• Includes requirements for materials, corrosion protection, seismic & wind loads.
• Used widely in oil & gas, petrochemical, and power industries.
• Typically applies to aboveground, cylindrical, vertical tanks.

Design Considerations of API 650 Tanks Include

• Wind/seismic load
• Product type and temperature
• Corrosion allowances
• Foundation and shell design
• Tank height-to-diameter ratio