API 653 Tank Inspection Template - Atlantis NDT

A structured inspection form template for above-ground storage tank (AST) inspections per API 653. Covers tank identification, external visual inspection, internal inspection with thickness readings, fitness-for-service calculations, and recommendations.

Record UT thickness readings at each clock position around the tank perimeter, within the critical zone (3 inches from the shell-to-bottom weld).

Record annular plate thickness at the same clock positions. Minimum thickness requirements per API 653 Table 4.4.

Record thickness readings for each shell course. Minimum number of readings per course depends on tank diameter and course height per API 653.

For each shell course, calculate t_min using the one-foot method or variable-design-point method:

Where: H = design liquid level (ft), D = tank diameter (ft), G = specific gravity, S = allowable stress (psi), E = joint efficiency

Short-Term Rate = (t_previous - t_current) / (years between inspections)

Long-Term Rate = (t_original - t_current) / (total years in service)

Need this template in an editable Excel or Word format? Contact us for a fully customizable version with automated corrosion rate calculations and built-in formulas.

What this page covers

1. Tank Identification
2. External Visual Inspection
3. Internal Inspection
4. Fitness-for-Service Calculations
5. Recommendations & Action Items
Get the Editable Version
3a. Floor Plate Condition
3b. Critical Zone Thickness Readings (within 3" of shell)
3c. Annular Plate Thickness Readings
3d. Shell Course UT Thickness Readings
4a. Minimum Required Shell Thickness (API 653, Section 4)
4b. Corrosion Rate Calculations
4c. Remaining Life & Next Inspection Date
Common Recommendation Categories

Key points covered

Maximum Inspection Interval (API 653: 20 yrs external, 10 yrs internal, or RBI)

What the API 653 template must capture

Tank inspection records live longer than careers — the corrosion rate that sets the next internal interval may compare readings taken decades apart, which makes consistency of record structure the template's whole job. The critical zones each need their own discipline: floor data as a mapped grid (MFL screening with UT prosecution of indications, not spot readings), shell courses with nominal thickness and joint efficiency recorded so the minimum-thickness calculation is reproducible, settlement as surveyed elevations against the previous survey, not impressions. The determination section must show remaining life and interval per API 653's formulas, signed by the certified inspector of record.

The template should also capture what was NOT examined and why — an internal inspection that could not access under the heating coils is a scoping fact the next campaign needs, and its absence turns into a false assurance.

Where this document sits in the wider system

Templates fail as loose files and work as parts of a system: this document should cross-reference the records that feed it and the decisions it feeds, carry a revision history like any controlled document, and live where the whole team retrieves the CURRENT version — not the copy someone improved privately last year. Companies running their inspection operations on a single system of record generate most of these documents from live data rather than filling them by hand; that is the practical difference between managed records and managed paperwork. Browse all templates and resources, or ask how the generated version works.