What is API 620?

API 620 is a standard published by the American Petroleum Institute (API) that covers the design and construction of large, welded, low-pressure storage tanks. It provides requirements for material selection, design, fabrication, erection, testing, and inspection. These tanks are commonly used to store a variety of products, including petroleum, chemicals, and other liquids, at relatively low pressures (typically up to 15 psi).