Many businesses use storage tanks for vapors, non-organic liquids, and organic liquids.
These tanks can range in size from 2 to 60 meters in diameter or more. In order to contain spillage in the event of a tank rupture, they are typically constructed inside containment basins. The majority of storage tanks are made in accordance with API 650 and API 620 specifications of the American Petroleum Institute.
Petroleum production and refining, chemical and petrochemical manufacturing, bulk storage and transfer operations, and other businesses that use or create liquids and vapors are among the industries where storage tanks are used.
API650 Standard: 0 to 2.5 psi Storage Tanks
The API 650 tank standard governs the design and construction of smaller cylindrical storage tanks in a range of sizes and capacities that have a higher temperature range of -40 to 500 degrees F but can hold oil and petroleum products, chemicals, treated water, biofuel, and other contents up to 2.5 PSI.
For lower-pressure indications, API 650 tanks placed by oil storage tank services may be made of carbon steel, austenitic duplex stainless steel, or aluminum with a minimum thickness of 3/16″ and a maximum design process temperature of 200 degrees.
They must have a bottom that is uniformly supported, whether the top is open or closed.
API620 Standard: 0 to 15 psi Storage Tanks
The API 620 tank standard governs the design and construction of large chemical and oil storage tanks that are at least 300 feet in diameter and can hold materials up to 15 PSI, including LNG, cryogenic liquids, and other low-temperature, higher-pressure liquids, gases, and vapors that range from -325 to 250 degrees Fahrenheit.
The permitted tanks installed by oil storage tank services must be cylindrical, built on a flat basis or a raised base, and made of steel that is at least 3/16″ thick since API 620 design must sustain a higher internal pressure.
Only austenitic stainless steel, low-temperature nickel alloys, and carbon steel may be used in construction; the manufacturer must be certified in ASME welding; and tank inspections must be performed by an authorized non-third-party inspector.
Similarities between API 650 and API 620 Tanks
- Both tanks are used for storage purposes.
- Both API 620 & API 650 tanks can be constructed from carbon steel, austenitic stainless steel, and nickel alloys (low temperature only).
- A welding certification is stipulated by the American Society of Mechanical Engineers (ASME), Section 10 for both the tanks.
- A non-destructive inspection is required for both tanks, but a third-party inspection is not required.
Differences between API 650 and API 620 Tanks: API 650 vs API 620
| parameters | API 650 | API 620 |
|---|---|---|
| Description | Welded Steel Tanks for Oil Storage | Design and Construction of Large, Low-Pressure Storage Tanks |
| Configuration | Ground-Supported Bottom, Open or Closed Roof | Any configuration that has a single centered, vertical axis of revolution |
| Shop/Field Erected | Shop (Appendix J) or Field Erected | Field Erected |
| Tank Sizes | Any | tank size larger than 300 ft. |
| Temperature | -40 Deg. F to 500 Deg. F | -325 Deg. F to 250 Deg. F |
| Maximum Pressure | 2.5 psig or 17.2 Kpa | 15 psig |
| Materials | Carbon Steel, Austenitic Stainless Steel, Duplex Stainless Steel, Aluminum | Carbon Steel, Austenitic Stainless Steel, Nickel Alloys (Low Temp only) |
| Industries | Oil, gas, chemicals, water, and bio-fuel storage. Maximum of the most common welded steel tanks used in the industry are designed following API 650. These tanks are typically found in refinery tank farms, terminals, pipelines, and other process facilities. | Tanks like LNG tanks or cryogenic tanks that require high internal pressure are designed as per API 620. |
With that in mind, we hope that this article has helped to clarify some of the important distinctions between API Standards 650 and 620 for storage tanks. Which API model best meets your company’s demands can be determined using the parameters of similarity and difference between the two models that were described before. Will you require a special query for the planning, construction, and welding of the storage tanks? Get in touch with TheAnees as fast as possible!
Thank you, Have a nice day.
