SP001 7th Edition – Summary of Changes to the Standard for AST Inspections

April 24, 2024


A Summary of the Latest Updates for AST Inspections Using STI SP001 7th Edition

The Steel Tank Institute (STI) released the 7th Edition of the SP001 Standard for the Inspection of Aboveground Storage Tanks (ASTs) in late February 2024. This release comes six years after updating the previous Edition in January 2018.

The first update is the change to STI’s website, which is now www.stispfa.org. This new website includes much of the same information as the previous website, but the site map of that information is very different, with some data behind a membership wall, including the list of certified inspectors.

Revisions and Definitions

As for the SP001 7th Ed. text, it now includes a few revised and new definitions. The definition of Double-walled AST and Spill Control now specifies that “A tank insulation system or insulating jacket placed on a tank does not constitute a double wall tank.” This clarification distinguishes between insulation and the actual structure of the tank.

The Initial Service Date is specific to the tank “regardless of the AST’s current location or ownership. If the initial service date is unknown (e.g., rented or repurposed AST),” refer to the Inspection Schedule section of SP001.

In addition, the Standard now includes a definition for a Permit-Required Confined Space, providing clear guidelines on the safety requirements for confined spaces in line with the applicable OSHA requirements.

The Ultrasonic Testing Scan (UTS) is further clarified to mean “An ultrasonic scan which scans 100% of a designated surface area.” This scan detects thinning from material loss, not just corrosion.

Relevance to AST Inspections

Several items during formal tank inspections are now specifically mentioned. Manways are now on the list of tank components for inspection. The Basic Tank Anatomy Figure (Figure A.1.2) is revised to include the Manway, Fill Pipe, Tank Gauge, and Tank Support. This enhancement provides a more comprehensive overview of common tank components.

In addition to these updates, tank inspections now specifically include verifying the accuracy of the owner’s STI SP001 AST Record data, inspecting for vegetation growing alongside or against the AST or the foundation, and Ultrasonic Thickness Testing (UTT) readings of the corroded areas if corrosion is evident on the outside surface of the secondary tank shell.

The 7th Edition also broadens the range of potential inspectors, designating the responsibility of conducting Periodic AST inspections and the Leak test to “a qualified party designated by the owner” or “a qualified party designated by the owner or owner’s designee.” A detailed description of the grid pattern for Formal Internal Inspections (FII) is in the 7th  Edition.

If Microbiologically Influenced Corrosion (MIC) is suspected, the standard now suggests testing a sample of liquid from the tank bottom for bacteria that could cause MIC going forward.

A written report is required for each Formal External Inspection (FEI) & Formal Internal Inspection (FII) performed.

Should the integrity of spill control be compromised during an inspection, SP001 7th Ed. includes a reevaluation of the tank category and inspection timetable. This new standard introduces more flexibility and responsiveness to potential issues that may arise during inspections.

In conclusion, the 7th Edition of STI’s SP001 Standard for the Inspection of Aboveground Storage Tanks presents significant updates and clarifications that aim to enhance the inspection process, ensuring the safety and longevity of ASTs.


Benjamin ReynoldsAbout the Author: Benjamin Reynolds is a Senior Project Professional in our Little Rock, Arkansas, office. His experience includes Spill Prevention, Control, and Countermeasures (SPCC), Tank Assessments, Storm Water Pollution Prevention Plans (SWPPPs), and Phase I and II Environmental Site Assessments. He is a Professional Engineer licensed in Arkansas, Oklahoma, Tennessee, and Florida. Reach out to Ben at or on LinkedIn.


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Posted by Diane Samuels at 6:00 am