The API 650 Standard What Every Tank Owner and Operator Should Know

Benefits of storage tank coating

The American Petroleum Institute (API)’s 650 standard, now in its 12th edition, is the most common standard used for regulating above ground storage tanks — particularly welded steel tanks. The API standard 650 is normally used for steel storage tanks that store oil, gasoline, chemicals and produced water.

There are a huge number of facets to the 650 standard. The standard contains rules for how the tanks ought to be designed, constructed, welded, inspected and installed.

Are you as well-versed as you should be about the API’s standards for your welded steel storage tanks? Here’s a brief introduction to the many components of this standard with the top three most crucial components of the API 650 standard:


Steel is the de facto material for the above ground storage tank. However, rimmed and capped steels are both prohibited under the API 650 standard, as is the use of cast iron for any part of the storage tank.


In API 650 Section 9, it’s stated that all welding performed on above ground storage tanks follow the regulations set out in the tank manufacturer’s Weld Procedure Specifications (WPS) and its supporting Procedure Qualification Record (PQR). Additionally, all welding activity that uses welding machinery in lieu of manual welding must be performed under constant supervision to prevent accidents from occurring.

Tank construction and erecting

The API 650 standard makes thorough, specific provisions for the actual construction of steel storage tanks. For example, all tanks are required to be equipped with some form of protection against corrosion when they are constructed, and all steel storage tanks with capacities exceeding 1,100 gallons should have corrosion protection along the floor of the tank as well. All tanks must be constructed to prevent hydrogen-induced cracking from taking place.

Have any other tips or advice on how to keep above ground and field erected tanks up to standards with the API’s regulations? Share with us in the comments below.

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