A737 Gr B plates API standard 650 duplex stainless steel tanks

Atmospheric API standard 650 duplex stainless steel tanks refer to storage tanks whose gas or vapor pressure is greater than -0.02MPa but less than 0.1MPa. Metal atmospheric storage tanks made of steel welded on the ground are often used to store petroleum, chemical and other similar liquids. Atmospheric API standard 650 duplex stainless steel tanks usually have a connecting pipe directly connected to the atmosphere, so that the operating pressure in the storage tank does not exceed the design pressure at all times.

When roof plates, knuckle plates, compression rings, and manways and nozzles including reinforcement are primarily subjected to atmospheric temperature, the rules in API 620 oil tank standard Q.2.3 shall govern.
Large Welded Storage Tanks Secondary Components
In general, secondary components include those components that will not be stressed to a significant level by the refrigerated liquid, those whose failure will not result in leakage of the liquid being stored, those exposed to product vapors, and those that have a design metal temperature of –60°F or higher.

API 650 is constructed from carbon steel, austenitic duplex stainless steel, and API standard 650 duplex stainless steel tanks aluminium A Welding Certification is stipulated by American Society of Mechanical Engineers (ASME), Section 10. There is a required inspection, no third party. The inspection cost is the cost of the NDE.