Large storage tanks handle huge volumes of liquids, gases, and other materials in industries such as oil, gas, chemicals, and water treatment. These tanks face pressure, temperature, weight, and environmental demands every day. A strong design standard helps engineers set clear requirements for tank construction and operation. For large, low-pressure tanks, API 620 provides practical guidance that supports safe, reliable storage.
What API 620 covers
API 620 focuses on large, welded storage tanks that operate at low internal pressures. The standard gives engineers detailed requirements for tank design, materials, fabrication, inspection, testing, and construction. These tanks usually hold liquids or gases under pressure levels above those covered by atmospheric storage standards. API 620 helps engineers select suitable materials and design tank components for the expected operating conditions.
Stronger tank design
Large tanks place significant loads on their walls, roofs, floors, and supporting structures. API 620 gives engineers technical rules for handling these loads during design. Engineers review internal pressure, tank size, temperature, material strength, and other operating factors before selecting dimensions and construction details. This approach helps reduce structural risks and supports dependable tank performance.
Material selection matters
Tank materials must suit the stored product and operating environment. Temperature changes also affect material behavior, especially in large storage systems. API 620 provides requirements that guide material selection and testing. Engineers use these requirements to check strength, toughness, weld quality, and other important properties. Suitable materials help tanks resist cracking, distortion, and other structural problems.
Fabrication and welding standards
Welding plays a major part in large tank construction. Poor welds can weaken critical sections and lead to leaks or structural damage. API 620 sets requirements for welding procedures, qualifications, examinations, and workmanship. Fabricators follow these rules to produce consistent welds and check important joints before the tank enters service.
Inspection and testing
A large storage tank requires thorough inspection before operation. API 620 includes testing and inspection requirements that help teams verify structural quality. Inspectors examine welds, materials, tank components, and completed sections. Testing also helps identify defects that visual checks may miss. These steps give operators stronger confidence in tank integrity.
For facilities handling valuable or hazardous products, strong tank construction supports safer daily operations and reduces the chance of costly structural failures. Following API 620 also gives project teams a consistent reference during design, fabrication, inspection, and commissioning. The result is a storage system built for demanding industrial service and long-term performance.