API 653 study guide
API 653 · Work through your exam, one topic at a time.
API 653 is the American Petroleum Institute's certification for aboveground storage tank inspectors. API initiated the program with the participation of storage tank owners and users, establishing a uniform national program that assists state and local governments in aboveground storage tank regulations. The API 653 study guide has 5 sections and about 1,883 words.
01Tank Design and Construction
API 653 governs existing tanks; the original design basis comes from API 650 (or the older API 12 series). You still need the shell formula, because every minimum-thickness and remaining-life calculation starts there.
413 words, about 2 min02Inspection, Examination, and Testing
API 653 separates examination (the NDE or measurement itself - visual, UT thickness, MT, PT, RT, vacuum box) from inspection (examination plus evaluation against criteria, performed or directed by an inspector; the authorized inspector holds the API 653 certification). Questions love to blur that line.
365 words, about 2 min03Repair, Alteration, and Reconstruction
A repair restores the tank to its original condition - same thickness or thicker, same configuration, same service. An alteration changes configuration or service: raising or shortening the shell, changing diameter, replacing the bottom or roof type, adding a nozzle beyond the allowed limits, or switching to a product with a higher specific gravity.
357 words, about 2 min04Operation, Maintenance, and Safety
Operations questions are really design-envelope questions. The maximum design liquid level is a structural limit; the maximum operating level sits below it with margin for alarm response, and the fill height corresponding to a given volume changes with product specific gravity because shell thickness demand is proportional to G.
353 words, about 2 min05Decommissioning, Relocation, and Records
Decommissioning starts with making the tank safe: empty, drain, isolate with blinds and lockout, clean sludge per API 2015/2016, gas-free and vent, and control entry. A tank that is idle but retained is not a closed case - corrosion continues, cathodic protection must be maintained, and vents and seals still need attention.
395 words, about 2 min