API 650: Welded Steel Tanks for Oil Storage

This standard sets minimum requirements for material, design, fabrication, erection and inspection for vertical, cylindrical, aboveground, closed- and open-top, welded storage tanks in different sizes and capacities.

API 650 is widely used for tanks that are designed to internal pressures of 2.5 PSI or less and store products such as crude oil, gasoline, chemicals and produced water.
This standard only applies to tanks with uniformly supported bottoms and to tanks in non-refrigerated service that have a maximum design temperature of 93℃ (200℉) or less.

Carbon, stainless steel and aluminum tanks located in refineries, terminals and pipelines are typically designed according to API 650.